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JDK 17 java.base.jmod - Base Module
JDK 17 java.base.jmod is the JMOD file for JDK 17 Base module.
JDK 17 Base module compiled class files are stored in \fyicenter\jdk-17.0.5\jmods\java.base.jmod.
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JDK 17 Base module source code files are stored in \fyicenter\jdk-17.0.5\lib\src.zip\java.base.
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⏎ java/lang/invoke/VarHandle.java
/* * Copyright (c) 2014, 2020, Oracle and/or its affiliates. All rights reserved. * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. * * * * * * * * * * * * * * * * * * * * */ package java.lang.invoke; import java.lang.constant.ClassDesc; import java.lang.constant.Constable; import java.lang.constant.ConstantDesc; import java.lang.constant.ConstantDescs; import java.lang.constant.DirectMethodHandleDesc; import java.lang.constant.DynamicConstantDesc; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.Objects; import java.util.Optional; import java.util.function.BiFunction; import java.util.function.Function; import jdk.internal.util.Preconditions; import jdk.internal.vm.annotation.DontInline; import jdk.internal.vm.annotation.ForceInline; import jdk.internal.vm.annotation.IntrinsicCandidate; import jdk.internal.vm.annotation.Stable; import static java.lang.invoke.MethodHandleStatics.UNSAFE; /** * A VarHandle is a dynamically strongly typed reference to a variable, or to a * parametrically-defined family of variables, including static fields, * non-static fields, array elements, or components of an off-heap data * structure. Access to such variables is supported under various * <em>access modes</em>, including plain read/write access, volatile * read/write access, and compare-and-set. * * <p>VarHandles are immutable and have no visible state. VarHandles cannot be * subclassed by the user. * * <p>A VarHandle has: * <ul> * <li>a {@link #varType variable type} T, the type of every variable referenced * by this VarHandle; and * <li>a list of {@link #coordinateTypes coordinate types} * {@code CT1, CT2, ..., CTn}, the types of <em>coordinate expressions</em> that * jointly locate a variable referenced by this VarHandle. * </ul> * Variable and coordinate types may be primitive or reference, and are * represented by {@code Class} objects. The list of coordinate types may be * empty. * * <p>Factory methods that produce or {@link java.lang.invoke.MethodHandles.Lookup * lookup} VarHandle instances document the supported variable type and the list * of coordinate types. * * <p>Each access mode is associated with one <em>access mode method</em>, a * <a href="MethodHandle.html#sigpoly">signature polymorphic</a> method named * for the access mode. When an access mode method is invoked on a VarHandle * instance, the initial arguments to the invocation are coordinate expressions * that indicate in precisely which object the variable is to be accessed. * Trailing arguments to the invocation represent values of importance to the * access mode. For example, the various compare-and-set or compare-and-exchange * access modes require two trailing arguments for the variable's expected value * and new value. * * <p>The arity and types of arguments to the invocation of an access mode * method are not checked statically. Instead, each access mode method * specifies an {@link #accessModeType(AccessMode) access mode type}, * represented as an instance of {@link MethodType}, that serves as a kind of * method signature against which the arguments are checked dynamically. An * access mode type gives formal parameter types in terms of the coordinate * types of a VarHandle instance and the types for values of importance to the * access mode. An access mode type also gives a return type, often in terms of * the variable type of a VarHandle instance. When an access mode method is * invoked on a VarHandle instance, the symbolic type descriptor at the * call site, the run time types of arguments to the invocation, and the run * time type of the return value, must <a href="#invoke">match</a> the types * given in the access mode type. A runtime exception will be thrown if the * match fails. * * For example, the access mode method {@link #compareAndSet} specifies that if * its receiver is a VarHandle instance with coordinate types * {@code CT1, ..., CTn} and variable type {@code T}, then its access mode type * is {@code (CT1 c1, ..., CTn cn, T expectedValue, T newValue)boolean}. * Suppose that a VarHandle instance can access array elements, and that its * coordinate types are {@code String[]} and {@code int} while its variable type * is {@code String}. The access mode type for {@code compareAndSet} on this * VarHandle instance would be * {@code (String[] c1, int c2, String expectedValue, String newValue)boolean}. * Such a VarHandle instance may be produced by the * {@link MethodHandles#arrayElementVarHandle(Class) array factory method} and * access array elements as follows: * <pre> {@code * String[] sa = ... * VarHandle avh = MethodHandles.arrayElementVarHandle(String[].class); * boolean r = avh.compareAndSet(sa, 10, "expected", "new"); * }</pre> * * <p>Access modes control atomicity and consistency properties. * <em>Plain</em> read ({@code get}) and write ({@code set}) * accesses are guaranteed to be bitwise atomic only for references * and for primitive values of at most 32 bits, and impose no observable * ordering constraints with respect to threads other than the * executing thread. <em>Opaque</em> operations are bitwise atomic and * coherently ordered with respect to accesses to the same variable. * In addition to obeying Opaque properties, <em>Acquire</em> mode * reads and their subsequent accesses are ordered after matching * <em>Release</em> mode writes and their previous accesses. In * addition to obeying Acquire and Release properties, all * <em>Volatile</em> operations are totally ordered with respect to * each other. * * <p>Access modes are grouped into the following categories: * <ul> * <li>read access modes that get the value of a variable under specified * memory ordering effects. * The set of corresponding access mode methods belonging to this group * consists of the methods * {@link #get get}, * {@link #getVolatile getVolatile}, * {@link #getAcquire getAcquire}, * {@link #getOpaque getOpaque}. * <li>write access modes that set the value of a variable under specified * memory ordering effects. * The set of corresponding access mode methods belonging to this group * consists of the methods * {@link #set set}, * {@link #setVolatile setVolatile}, * {@link #setRelease setRelease}, * {@link #setOpaque setOpaque}. * <li>atomic update access modes that, for example, atomically compare and set * the value of a variable under specified memory ordering effects. * The set of corresponding access mode methods belonging to this group * consists of the methods * {@link #compareAndSet compareAndSet}, * {@link #weakCompareAndSetPlain weakCompareAndSetPlain}, * {@link #weakCompareAndSet weakCompareAndSet}, * {@link #weakCompareAndSetAcquire weakCompareAndSetAcquire}, * {@link #weakCompareAndSetRelease weakCompareAndSetRelease}, * {@link #compareAndExchangeAcquire compareAndExchangeAcquire}, * {@link #compareAndExchange compareAndExchange}, * {@link #compareAndExchangeRelease compareAndExchangeRelease}, * {@link #getAndSet getAndSet}, * {@link #getAndSetAcquire getAndSetAcquire}, * {@link #getAndSetRelease getAndSetRelease}. * <li>numeric atomic update access modes that, for example, atomically get and * set with addition the value of a variable under specified memory ordering * effects. * The set of corresponding access mode methods belonging to this group * consists of the methods * {@link #getAndAdd getAndAdd}, * {@link #getAndAddAcquire getAndAddAcquire}, * {@link #getAndAddRelease getAndAddRelease}, * <li>bitwise atomic update access modes that, for example, atomically get and * bitwise OR the value of a variable under specified memory ordering * effects. * The set of corresponding access mode methods belonging to this group * consists of the methods * {@link #getAndBitwiseOr getAndBitwiseOr}, * {@link #getAndBitwiseOrAcquire getAndBitwiseOrAcquire}, * {@link #getAndBitwiseOrRelease getAndBitwiseOrRelease}, * {@link #getAndBitwiseAnd getAndBitwiseAnd}, * {@link #getAndBitwiseAndAcquire getAndBitwiseAndAcquire}, * {@link #getAndBitwiseAndRelease getAndBitwiseAndRelease}, * {@link #getAndBitwiseXor getAndBitwiseXor}, * {@link #getAndBitwiseXorAcquire getAndBitwiseXorAcquire}, * {@link #getAndBitwiseXorRelease getAndBitwiseXorRelease}. * </ul> * * <p>Factory methods that produce or {@link java.lang.invoke.MethodHandles.Lookup * lookup} VarHandle instances document the set of access modes that are * supported, which may also include documenting restrictions based on the * variable type and whether a variable is read-only. If an access mode is not * supported then the corresponding access mode method will on invocation throw * an {@code UnsupportedOperationException}. Factory methods should document * any additional undeclared exceptions that may be thrown by access mode * methods. * The {@link #get get} access mode is supported for all * VarHandle instances and the corresponding method never throws * {@code UnsupportedOperationException}. * If a VarHandle references a read-only variable (for example a {@code final} * field) then write, atomic update, numeric atomic update, and bitwise atomic * update access modes are not supported and corresponding methods throw * {@code UnsupportedOperationException}. * Read/write access modes (if supported), with the exception of * {@code get} and {@code set}, provide atomic access for * reference types and all primitive types. * Unless stated otherwise in the documentation of a factory method, the access * modes {@code get} and {@code set} (if supported) provide atomic access for * reference types and all primitives types, with the exception of {@code long} * and {@code double} on 32-bit platforms. * * <p>Access modes will override any memory ordering effects specified at * the declaration site of a variable. For example, a VarHandle accessing * a field using the {@code get} access mode will access the field as * specified <em>by its access mode</em> even if that field is declared * {@code volatile}. When mixed access is performed extreme care should be * taken since the Java Memory Model may permit surprising results. * * <p>In addition to supporting access to variables under various access modes, * a set of static methods, referred to as memory fence methods, is also * provided for fine-grained control of memory ordering. * * The Java Language Specification permits other threads to observe operations * as if they were executed in orders different than are apparent in program * source code, subject to constraints arising, for example, from the use of * locks, {@code volatile} fields or VarHandles. The static methods, * {@link #fullFence fullFence}, {@link #acquireFence acquireFence}, * {@link #releaseFence releaseFence}, {@link #loadLoadFence loadLoadFence} and * {@link #storeStoreFence storeStoreFence}, can also be used to impose * constraints. Their specifications, as is the case for certain access modes, * are phrased in terms of the lack of "reorderings" -- observable ordering * effects that might otherwise occur if the fence was not present. More * precise phrasing of the specification of access mode methods and memory fence * methods may accompany future updates of the Java Language Specification. * * <h2>Compiling invocation of access mode methods</h2> * A Java method call expression naming an access mode method can invoke a * VarHandle from Java source code. From the viewpoint of source code, these * methods can take any arguments and their polymorphic result (if expressed) * can be cast to any return type. Formally this is accomplished by giving the * access mode methods variable arity {@code Object} arguments and * {@code Object} return types (if the return type is polymorphic), but they * have an additional quality called <em>signature polymorphism</em> which * connects this freedom of invocation directly to the JVM execution stack. * <p> * As is usual with virtual methods, source-level calls to access mode methods * compile to an {@code invokevirtual} instruction. More unusually, the * compiler must record the actual argument types, and may not perform method * invocation conversions on the arguments. Instead, it must generate * instructions to push them on the stack according to their own unconverted * types. The VarHandle object itself will be pushed on the stack before the * arguments. The compiler then generates an {@code invokevirtual} instruction * that invokes the access mode method with a symbolic type descriptor which * describes the argument and return types. * <p> * To issue a complete symbolic type descriptor, the compiler must also * determine the return type (if polymorphic). This is based on a cast on the * method invocation expression, if there is one, or else {@code Object} if the * invocation is an expression, or else {@code void} if the invocation is a * statement. The cast may be to a primitive type (but not {@code void}). * <p> * As a corner case, an uncasted {@code null} argument is given a symbolic type * descriptor of {@code java.lang.Void}. The ambiguity with the type * {@code Void} is harmless, since there are no references of type {@code Void} * except the null reference. * * * <h2><a id="invoke">Performing invocation of access mode methods</a></h2> * The first time an {@code invokevirtual} instruction is executed it is linked * by symbolically resolving the names in the instruction and verifying that * the method call is statically legal. This also holds for calls to access mode * methods. In this case, the symbolic type descriptor emitted by the compiler * is checked for correct syntax, and names it contains are resolved. Thus, an * {@code invokevirtual} instruction which invokes an access mode method will * always link, as long as the symbolic type descriptor is syntactically * well-formed and the types exist. * <p> * When the {@code invokevirtual} is executed after linking, the receiving * VarHandle's access mode type is first checked by the JVM to ensure that it * matches the symbolic type descriptor. If the type * match fails, it means that the access mode method which the caller is * invoking is not present on the individual VarHandle being invoked. * * <p id="invoke-behavior"> * Invocation of an access mode method behaves, by default, as if an invocation of * {@link MethodHandle#invoke}, where the receiving method handle accepts the * VarHandle instance as the leading argument. More specifically, the * following, where {@code {access-mode}} corresponds to the access mode method * name: * <pre> {@code * VarHandle vh = .. * R r = (R) vh.{access-mode}(p1, p2, ..., pN); * }</pre> * behaves as if: * <pre> {@code * VarHandle vh = .. * VarHandle.AccessMode am = VarHandle.AccessMode.valueFromMethodName("{access-mode}"); * MethodHandle mh = MethodHandles.varHandleExactInvoker( * am, * vh.accessModeType(am)); * * R r = (R) mh.invoke(vh, p1, p2, ..., pN) * }</pre> * (modulo access mode methods do not declare throwing of {@code Throwable}). * This is equivalent to: * <pre> {@code * MethodHandle mh = MethodHandles.lookup().findVirtual( * VarHandle.class, * "{access-mode}", * MethodType.methodType(R, p1, p2, ..., pN)); * * R r = (R) mh.invokeExact(vh, p1, p2, ..., pN) * }</pre> * where the desired method type is the symbolic type descriptor and a * {@link MethodHandle#invokeExact} is performed, since before invocation of the * target, the handle will apply reference casts as necessary and box, unbox, or * widen primitive values, as if by {@link MethodHandle#asType asType} (see also * {@link MethodHandles#varHandleInvoker}). * * More concisely, such behavior is equivalent to: * <pre> {@code * VarHandle vh = .. * VarHandle.AccessMode am = VarHandle.AccessMode.valueFromMethodName("{access-mode}"); * MethodHandle mh = vh.toMethodHandle(am); * * R r = (R) mh.invoke(p1, p2, ..., pN) * }</pre> * Where, in this case, the method handle is bound to the VarHandle instance. * * <p id="invoke-exact-behavior"> * A VarHandle's invocation behavior can be adjusted (see {@link #withInvokeExactBehavior}) such that invocation of * an access mode method behaves as if invocation of {@link MethodHandle#invokeExact}, * where the receiving method handle accepts the VarHandle instance as the leading argument. * More specifically, the following, where {@code {access-mode}} corresponds to the access mode method * name: * <pre> {@code * VarHandle vh = .. * R r = (R) vh.{access-mode}(p1, p2, ..., pN); * }</pre> * behaves as if: * <pre> {@code * VarHandle vh = .. * VarHandle.AccessMode am = VarHandle.AccessMode.valueFromMethodName("{access-mode}"); * MethodHandle mh = MethodHandles.varHandleExactInvoker( * am, * vh.accessModeType(am)); * * R r = (R) mh.invokeExact(vh, p1, p2, ..., pN) * }</pre> * (modulo access mode methods do not declare throwing of {@code Throwable}). * * More concisely, such behavior is equivalent to: * <pre> {@code * VarHandle vh = .. * VarHandle.AccessMode am = VarHandle.AccessMode.valueFromMethodName("{access-mode}"); * MethodHandle mh = vh.toMethodHandle(am); * * R r = (R) mh.invokeExact(p1, p2, ..., pN) * }</pre> * Where, in this case, the method handle is bound to the VarHandle instance. * * <h2>Invocation checking</h2> * In typical programs, VarHandle access mode type matching will usually * succeed. But if a match fails, the JVM will throw a * {@link WrongMethodTypeException}. * <p> * Thus, an access mode type mismatch which might show up as a linkage error * in a statically typed program can show up as a dynamic * {@code WrongMethodTypeException} in a program which uses VarHandles. * <p> * Because access mode types contain "live" {@code Class} objects, method type * matching takes into account both type names and class loaders. * Thus, even if a VarHandle {@code VH} is created in one class loader * {@code L1} and used in another {@code L2}, VarHandle access mode method * calls are type-safe, because the caller's symbolic type descriptor, as * resolved in {@code L2}, is matched against the original callee method's * symbolic type descriptor, as resolved in {@code L1}. The resolution in * {@code L1} happens when {@code VH} is created and its access mode types are * assigned, while the resolution in {@code L2} happens when the * {@code invokevirtual} instruction is linked. * <p> * Apart from type descriptor checks, a VarHandles's capability to * access it's variables is unrestricted. * If a VarHandle is formed on a non-public variable by a class that has access * to that variable, the resulting VarHandle can be used in any place by any * caller who receives a reference to it. * <p> * Unlike with the Core Reflection API, where access is checked every time a * reflective method is invoked, VarHandle access checking is performed * <a href="MethodHandles.Lookup.html#access">when the VarHandle is * created</a>. * Thus, VarHandles to non-public variables, or to variables in non-public * classes, should generally be kept secret. They should not be passed to * untrusted code unless their use from the untrusted code would be harmless. * * * <h2>VarHandle creation</h2> * Java code can create a VarHandle that directly accesses any field that is * accessible to that code. This is done via a reflective, capability-based * API called {@link java.lang.invoke.MethodHandles.Lookup * MethodHandles.Lookup}. * For example, a VarHandle for a non-static field can be obtained * from {@link java.lang.invoke.MethodHandles.Lookup#findVarHandle * Lookup.findVarHandle}. * There is also a conversion method from Core Reflection API objects, * {@link java.lang.invoke.MethodHandles.Lookup#unreflectVarHandle * Lookup.unreflectVarHandle}. * <p> * Access to protected field members is restricted to receivers only of the * accessing class, or one of its subclasses, and the accessing class must in * turn be a subclass (or package sibling) of the protected member's defining * class. If a VarHandle refers to a protected non-static field of a declaring * class outside the current package, the receiver argument will be narrowed to * the type of the accessing class. * * <h2>Interoperation between VarHandles and the Core Reflection API</h2> * Using factory methods in the {@link java.lang.invoke.MethodHandles.Lookup * Lookup} API, any field represented by a Core Reflection API object * can be converted to a behaviorally equivalent VarHandle. * For example, a reflective {@link java.lang.reflect.Field Field} can * be converted to a VarHandle using * {@link java.lang.invoke.MethodHandles.Lookup#unreflectVarHandle * Lookup.unreflectVarHandle}. * The resulting VarHandles generally provide more direct and efficient * access to the underlying fields. * <p> * As a special case, when the Core Reflection API is used to view the * signature polymorphic access mode methods in this class, they appear as * ordinary non-polymorphic methods. Their reflective appearance, as viewed by * {@link java.lang.Class#getDeclaredMethod Class.getDeclaredMethod}, * is unaffected by their special status in this API. * For example, {@link java.lang.reflect.Method#getModifiers * Method.getModifiers} * will report exactly those modifier bits required for any similarly * declared method, including in this case {@code native} and {@code varargs} * bits. * <p> * As with any reflected method, these methods (when reflected) may be invoked * directly via {@link java.lang.reflect.Method#invoke java.lang.reflect.Method.invoke}, * via JNI, or indirectly via * {@link java.lang.invoke.MethodHandles.Lookup#unreflect Lookup.unreflect}. * However, such reflective calls do not result in access mode method * invocations. Such a call, if passed the required argument (a single one, of * type {@code Object[]}), will ignore the argument and will throw an * {@code UnsupportedOperationException}. * <p> * Since {@code invokevirtual} instructions can natively invoke VarHandle * access mode methods under any symbolic type descriptor, this reflective view * conflicts with the normal presentation of these methods via bytecodes. * Thus, these native methods, when reflectively viewed by * {@code Class.getDeclaredMethod}, may be regarded as placeholders only. * <p> * In order to obtain an invoker method for a particular access mode type, * use {@link java.lang.invoke.MethodHandles#varHandleExactInvoker} or * {@link java.lang.invoke.MethodHandles#varHandleInvoker}. The * {@link java.lang.invoke.MethodHandles.Lookup#findVirtual Lookup.findVirtual} * API is also able to return a method handle to call an access mode method for * any specified access mode type and is equivalent in behavior to * {@link java.lang.invoke.MethodHandles#varHandleInvoker}. * * <h2>Interoperation between VarHandles and Java generics</h2> * A VarHandle can be obtained for a variable, such as a field, which is * declared with Java generic types. As with the Core Reflection API, the * VarHandle's variable type will be constructed from the erasure of the * source-level type. When a VarHandle access mode method is invoked, the * types * of its arguments or the return value cast type may be generic types or type * instances. If this occurs, the compiler will replace those types by their * erasures when it constructs the symbolic type descriptor for the * {@code invokevirtual} instruction. * * @see MethodHandle * @see MethodHandles * @see MethodType * @since 9 */ public abstract class VarHandle implements Constable { final VarForm vform; final boolean exact; VarHandle(VarForm vform) { this(vform, false); } VarHandle(VarForm vform, boolean exact) { this.vform = vform; this.exact = exact; } RuntimeException unsupported() { return new UnsupportedOperationException(); } boolean isDirect() { return true; } VarHandle asDirect() { return this; } VarHandle target() { return null; } /** * Returns {@code true} if this VarHandle has <a href="#invoke-exact-behavior"><em>invoke-exact behavior</em></a>. * * @see #withInvokeExactBehavior() * @see #withInvokeBehavior() * @return {@code true} if this VarHandle has <a href="#invoke-exact-behavior"><em>invoke-exact behavior</em></a>. * @since 16 */ public boolean hasInvokeExactBehavior() { return exact; } // Plain accessors /** * Returns the value of a variable, with memory semantics of reading as * if the variable was declared non-{@code volatile}. Commonly referred to * as plain read access. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn)T}. * * <p>The symbolic type descriptor at the call site of {@code get} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET)} on this VarHandle. * * <p>This access mode is supported by all VarHandle instances and never * throws {@code UnsupportedOperationException}. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn)} * , statically represented using varargs. * @return the signature-polymorphic result that is the value of the * variable * , statically represented using {@code Object}. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object get(Object... args); /** * Sets the value of a variable to the {@code newValue}, with memory * semantics of setting as if the variable was declared non-{@code volatile} * and non-{@code final}. Commonly referred to as plain write access. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T newValue)void} * * <p>The symbolic type descriptor at the call site of {@code set} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.SET)} on this VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T newValue)} * , statically represented using varargs. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate void set(Object... args); // Volatile accessors /** * Returns the value of a variable, with memory semantics of reading as if * the variable was declared {@code volatile}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn)T}. * * <p>The symbolic type descriptor at the call site of {@code getVolatile} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_VOLATILE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn)} * , statically represented using varargs. * @return the signature-polymorphic result that is the value of the * variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getVolatile(Object... args); /** * Sets the value of a variable to the {@code newValue}, with memory * semantics of setting as if the variable was declared {@code volatile}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T newValue)void}. * * <p>The symbolic type descriptor at the call site of {@code setVolatile} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.SET_VOLATILE)} on this * VarHandle. * * @apiNote * Ignoring the many semantic differences from C and C++, this method has * memory ordering effects compatible with {@code memory_order_seq_cst}. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T newValue)} * , statically represented using varargs. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate void setVolatile(Object... args); /** * Returns the value of a variable, accessed in program order, but with no * assurance of memory ordering effects with respect to other threads. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn)T}. * * <p>The symbolic type descriptor at the call site of {@code getOpaque} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_OPAQUE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn)} * , statically represented using varargs. * @return the signature-polymorphic result that is the value of the * variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getOpaque(Object... args); /** * Sets the value of a variable to the {@code newValue}, in program order, * but with no assurance of memory ordering effects with respect to other * threads. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T newValue)void}. * * <p>The symbolic type descriptor at the call site of {@code setOpaque} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.SET_OPAQUE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T newValue)} * , statically represented using varargs. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate void setOpaque(Object... args); // Lazy accessors /** * Returns the value of a variable, and ensures that subsequent loads and * stores are not reordered before this access. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn)T}. * * <p>The symbolic type descriptor at the call site of {@code getAcquire} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_ACQUIRE)} on this * VarHandle. * * @apiNote * Ignoring the many semantic differences from C and C++, this method has * memory ordering effects compatible with {@code memory_order_acquire} * ordering. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn)} * , statically represented using varargs. * @return the signature-polymorphic result that is the value of the * variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAcquire(Object... args); /** * Sets the value of a variable to the {@code newValue}, and ensures that * prior loads and stores are not reordered after this access. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T newValue)void}. * * <p>The symbolic type descriptor at the call site of {@code setRelease} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.SET_RELEASE)} on this * VarHandle. * * @apiNote * Ignoring the many semantic differences from C and C++, this method has * memory ordering effects compatible with {@code memory_order_release} * ordering. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T newValue)} * , statically represented using varargs. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate void setRelease(Object... args); // Compare and set accessors /** * Atomically sets the value of a variable to the {@code newValue} with the * memory semantics of {@link #setVolatile} if the variable's current value, * referred to as the <em>witness value</em>, {@code ==} the * {@code expectedValue}, as accessed with the memory semantics of * {@link #getVolatile}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)boolean}. * * <p>The symbolic type descriptor at the call site of {@code * compareAndSet} must match the access mode type that is the result of * calling {@code accessModeType(VarHandle.AccessMode.COMPARE_AND_SET)} on * this VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)} * , statically represented using varargs. * @return {@code true} if successful, otherwise {@code false} if the * witness value was not the same as the {@code expectedValue}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate boolean compareAndSet(Object... args); /** * Atomically sets the value of a variable to the {@code newValue} with the * memory semantics of {@link #setVolatile} if the variable's current value, * referred to as the <em>witness value</em>, {@code ==} the * {@code expectedValue}, as accessed with the memory semantics of * {@link #getVolatile}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)T}. * * <p>The symbolic type descriptor at the call site of {@code * compareAndExchange} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.COMPARE_AND_EXCHANGE)} * on this VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)} * , statically represented using varargs. * @return the signature-polymorphic result that is the witness value, which * will be the same as the {@code expectedValue} if successful * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type is not * compatible with the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type is compatible with the * caller's symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object compareAndExchange(Object... args); /** * Atomically sets the value of a variable to the {@code newValue} with the * memory semantics of {@link #set} if the variable's current value, * referred to as the <em>witness value</em>, {@code ==} the * {@code expectedValue}, as accessed with the memory semantics of * {@link #getAcquire}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)T}. * * <p>The symbolic type descriptor at the call site of {@code * compareAndExchangeAcquire} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.COMPARE_AND_EXCHANGE_ACQUIRE)} on * this VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)} * , statically represented using varargs. * @return the signature-polymorphic result that is the witness value, which * will be the same as the {@code expectedValue} if successful * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #set(Object...) * @see #getAcquire(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object compareAndExchangeAcquire(Object... args); /** * Atomically sets the value of a variable to the {@code newValue} with the * memory semantics of {@link #setRelease} if the variable's current value, * referred to as the <em>witness value</em>, {@code ==} the * {@code expectedValue}, as accessed with the memory semantics of * {@link #get}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)T}. * * <p>The symbolic type descriptor at the call site of {@code * compareAndExchangeRelease} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.COMPARE_AND_EXCHANGE_RELEASE)} * on this VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)} * , statically represented using varargs. * @return the signature-polymorphic result that is the witness value, which * will be the same as the {@code expectedValue} if successful * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setRelease(Object...) * @see #get(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object compareAndExchangeRelease(Object... args); // Weak (spurious failures allowed) /** * Possibly atomically sets the value of a variable to the {@code newValue} * with the semantics of {@link #set} if the variable's current value, * referred to as the <em>witness value</em>, {@code ==} the * {@code expectedValue}, as accessed with the memory semantics of * {@link #get}. * * <p>This operation may fail spuriously (typically, due to memory * contention) even if the witness value does match the expected value. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)boolean}. * * <p>The symbolic type descriptor at the call site of {@code * weakCompareAndSetPlain} must match the access mode type that is the result of * calling {@code accessModeType(VarHandle.AccessMode.WEAK_COMPARE_AND_SET_PLAIN)} * on this VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)} * , statically represented using varargs. * @return {@code true} if successful, otherwise {@code false} if the * witness value was not the same as the {@code expectedValue} or if this * operation spuriously failed. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #set(Object...) * @see #get(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate boolean weakCompareAndSetPlain(Object... args); /** * Possibly atomically sets the value of a variable to the {@code newValue} * with the memory semantics of {@link #setVolatile} if the variable's * current value, referred to as the <em>witness value</em>, {@code ==} the * {@code expectedValue}, as accessed with the memory semantics of * {@link #getVolatile}. * * <p>This operation may fail spuriously (typically, due to memory * contention) even if the witness value does match the expected value. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)boolean}. * * <p>The symbolic type descriptor at the call site of {@code * weakCompareAndSet} must match the access mode type that is the * result of calling {@code accessModeType(VarHandle.AccessMode.WEAK_COMPARE_AND_SET)} * on this VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)} * , statically represented using varargs. * @return {@code true} if successful, otherwise {@code false} if the * witness value was not the same as the {@code expectedValue} or if this * operation spuriously failed. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate boolean weakCompareAndSet(Object... args); /** * Possibly atomically sets the value of a variable to the {@code newValue} * with the semantics of {@link #set} if the variable's current value, * referred to as the <em>witness value</em>, {@code ==} the * {@code expectedValue}, as accessed with the memory semantics of * {@link #getAcquire}. * * <p>This operation may fail spuriously (typically, due to memory * contention) even if the witness value does match the expected value. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)boolean}. * * <p>The symbolic type descriptor at the call site of {@code * weakCompareAndSetAcquire} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.WEAK_COMPARE_AND_SET_ACQUIRE)} * on this VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)} * , statically represented using varargs. * @return {@code true} if successful, otherwise {@code false} if the * witness value was not the same as the {@code expectedValue} or if this * operation spuriously failed. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #set(Object...) * @see #getAcquire(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate boolean weakCompareAndSetAcquire(Object... args); /** * Possibly atomically sets the value of a variable to the {@code newValue} * with the semantics of {@link #setRelease} if the variable's current * value, referred to as the <em>witness value</em>, {@code ==} the * {@code expectedValue}, as accessed with the memory semantics of * {@link #get}. * * <p>This operation may fail spuriously (typically, due to memory * contention) even if the witness value does match the expected value. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)boolean}. * * <p>The symbolic type descriptor at the call site of {@code * weakCompareAndSetRelease} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.WEAK_COMPARE_AND_SET_RELEASE)} * on this VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T expectedValue, T newValue)} * , statically represented using varargs. * @return {@code true} if successful, otherwise {@code false} if the * witness value was not the same as the {@code expectedValue} or if this * operation spuriously failed. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setRelease(Object...) * @see #get(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate boolean weakCompareAndSetRelease(Object... args); /** * Atomically sets the value of a variable to the {@code newValue} with the * memory semantics of {@link #setVolatile} and returns the variable's * previous value, as accessed with the memory semantics of * {@link #getVolatile}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T newValue)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndSet} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_SET)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T newValue)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndSet(Object... args); /** * Atomically sets the value of a variable to the {@code newValue} with the * memory semantics of {@link #set} and returns the variable's * previous value, as accessed with the memory semantics of * {@link #getAcquire}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T newValue)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndSetAcquire} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_SET_ACQUIRE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T newValue)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndSetAcquire(Object... args); /** * Atomically sets the value of a variable to the {@code newValue} with the * memory semantics of {@link #setRelease} and returns the variable's * previous value, as accessed with the memory semantics of * {@link #get}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T newValue)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndSetRelease} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_SET_RELEASE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T newValue)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndSetRelease(Object... args); // Primitive adders // Throw UnsupportedOperationException for refs /** * Atomically adds the {@code value} to the current value of a variable with * the memory semantics of {@link #setVolatile}, and returns the variable's * previous value, as accessed with the memory semantics of * {@link #getVolatile}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T value)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndAdd} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_ADD)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T value)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndAdd(Object... args); /** * Atomically adds the {@code value} to the current value of a variable with * the memory semantics of {@link #set}, and returns the variable's * previous value, as accessed with the memory semantics of * {@link #getAcquire}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T value)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndAddAcquire} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_ADD_ACQUIRE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T value)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndAddAcquire(Object... args); /** * Atomically adds the {@code value} to the current value of a variable with * the memory semantics of {@link #setRelease}, and returns the variable's * previous value, as accessed with the memory semantics of * {@link #get}. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T value)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndAddRelease} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_ADD_RELEASE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T value)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndAddRelease(Object... args); // Bitwise operations // Throw UnsupportedOperationException for refs /** * Atomically sets the value of a variable to the result of * bitwise OR between the variable's current value and the {@code mask} * with the memory semantics of {@link #setVolatile} and returns the * variable's previous value, as accessed with the memory semantics of * {@link #getVolatile}. * * <p>If the variable type is the non-integral {@code boolean} type then a * logical OR is performed instead of a bitwise OR. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T mask)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndBitwiseOr} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_BITWISE_OR)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T mask)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndBitwiseOr(Object... args); /** * Atomically sets the value of a variable to the result of * bitwise OR between the variable's current value and the {@code mask} * with the memory semantics of {@link #set} and returns the * variable's previous value, as accessed with the memory semantics of * {@link #getAcquire}. * * <p>If the variable type is the non-integral {@code boolean} type then a * logical OR is performed instead of a bitwise OR. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T mask)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndBitwiseOrAcquire} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_BITWISE_OR_ACQUIRE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T mask)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #set(Object...) * @see #getAcquire(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndBitwiseOrAcquire(Object... args); /** * Atomically sets the value of a variable to the result of * bitwise OR between the variable's current value and the {@code mask} * with the memory semantics of {@link #setRelease} and returns the * variable's previous value, as accessed with the memory semantics of * {@link #get}. * * <p>If the variable type is the non-integral {@code boolean} type then a * logical OR is performed instead of a bitwise OR. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T mask)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndBitwiseOrRelease} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_BITWISE_OR_RELEASE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T mask)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setRelease(Object...) * @see #get(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndBitwiseOrRelease(Object... args); /** * Atomically sets the value of a variable to the result of * bitwise AND between the variable's current value and the {@code mask} * with the memory semantics of {@link #setVolatile} and returns the * variable's previous value, as accessed with the memory semantics of * {@link #getVolatile}. * * <p>If the variable type is the non-integral {@code boolean} type then a * logical AND is performed instead of a bitwise AND. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T mask)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndBitwiseAnd} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_BITWISE_AND)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T mask)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndBitwiseAnd(Object... args); /** * Atomically sets the value of a variable to the result of * bitwise AND between the variable's current value and the {@code mask} * with the memory semantics of {@link #set} and returns the * variable's previous value, as accessed with the memory semantics of * {@link #getAcquire}. * * <p>If the variable type is the non-integral {@code boolean} type then a * logical AND is performed instead of a bitwise AND. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T mask)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndBitwiseAndAcquire} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_BITWISE_AND_ACQUIRE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T mask)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #set(Object...) * @see #getAcquire(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndBitwiseAndAcquire(Object... args); /** * Atomically sets the value of a variable to the result of * bitwise AND between the variable's current value and the {@code mask} * with the memory semantics of {@link #setRelease} and returns the * variable's previous value, as accessed with the memory semantics of * {@link #get}. * * <p>If the variable type is the non-integral {@code boolean} type then a * logical AND is performed instead of a bitwise AND. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T mask)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndBitwiseAndRelease} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_BITWISE_AND_RELEASE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T mask)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setRelease(Object...) * @see #get(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndBitwiseAndRelease(Object... args); /** * Atomically sets the value of a variable to the result of * bitwise XOR between the variable's current value and the {@code mask} * with the memory semantics of {@link #setVolatile} and returns the * variable's previous value, as accessed with the memory semantics of * {@link #getVolatile}. * * <p>If the variable type is the non-integral {@code boolean} type then a * logical XOR is performed instead of a bitwise XOR. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T mask)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndBitwiseXor} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_BITWISE_XOR)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T mask)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setVolatile(Object...) * @see #getVolatile(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndBitwiseXor(Object... args); /** * Atomically sets the value of a variable to the result of * bitwise XOR between the variable's current value and the {@code mask} * with the memory semantics of {@link #set} and returns the * variable's previous value, as accessed with the memory semantics of * {@link #getAcquire}. * * <p>If the variable type is the non-integral {@code boolean} type then a * logical XOR is performed instead of a bitwise XOR. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T mask)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndBitwiseXorAcquire} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_BITWISE_XOR_ACQUIRE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T mask)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #set(Object...) * @see #getAcquire(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndBitwiseXorAcquire(Object... args); /** * Atomically sets the value of a variable to the result of * bitwise XOR between the variable's current value and the {@code mask} * with the memory semantics of {@link #setRelease} and returns the * variable's previous value, as accessed with the memory semantics of * {@link #get}. * * <p>If the variable type is the non-integral {@code boolean} type then a * logical XOR is performed instead of a bitwise XOR. * * <p>The method signature is of the form {@code (CT1 ct1, ..., CTn ctn, T mask)T}. * * <p>The symbolic type descriptor at the call site of {@code getAndBitwiseXorRelease} * must match the access mode type that is the result of calling * {@code accessModeType(VarHandle.AccessMode.GET_AND_BITWISE_XOR_RELEASE)} on this * VarHandle. * * @param args the signature-polymorphic parameter list of the form * {@code (CT1 ct1, ..., CTn ctn, T mask)} * , statically represented using varargs. * @return the signature-polymorphic result that is the previous value of * the variable * , statically represented using {@code Object}. * @throws UnsupportedOperationException if the access mode is unsupported * for this VarHandle. * @throws WrongMethodTypeException if the access mode type does not * match the caller's symbolic type descriptor. * @throws ClassCastException if the access mode type matches the caller's * symbolic type descriptor, but a reference cast fails. * @see #setRelease(Object...) * @see #get(Object...) */ public final native @MethodHandle.PolymorphicSignature @IntrinsicCandidate Object getAndBitwiseXorRelease(Object... args); /** * Returns a VarHandle, with access to the same variable(s) as this VarHandle, but whose * invocation behavior of access mode methods is adjusted to * <a href="#invoke-exact-behavior"><em>invoke-exact behavior</em></a>. * <p> * If this VarHandle already has invoke-exact behavior this VarHandle is returned. * <p> * Invoking {@link #hasInvokeExactBehavior()} on the returned var handle * is guaranteed to return {@code true}. * * @apiNote * Invoke-exact behavior guarantees that upon invocation of an access mode method * the types and arity of the arguments must match the {@link #accessModeType(AccessMode) access mode type}, * otherwise a {@link WrongMethodTypeException} is thrown. * * @see #withInvokeBehavior() * @see #hasInvokeExactBehavior() * @return a VarHandle with invoke-exact behavior * @since 16 */ public abstract VarHandle withInvokeExactBehavior(); /** * Returns a VarHandle, with access to the same variable(s) as this VarHandle, but whose * invocation behavior of access mode methods is adjusted to * <a href="#invoke-behavior"><em>invoke behavior</em></a>. * <p> * If this VarHandle already has invoke behavior this VarHandle is returned. * <p> * Invoking {@link #hasInvokeExactBehavior()} on the returned var handle * is guaranteed to return {@code false}. * * @see #withInvokeExactBehavior() * @see #hasInvokeExactBehavior() * @return a VarHandle with invoke behavior * @since 16 */ public abstract VarHandle withInvokeBehavior(); enum AccessType { GET(Object.class), SET(void.class), COMPARE_AND_SET(boolean.class), COMPARE_AND_EXCHANGE(Object.class), GET_AND_UPDATE(Object.class); static final int COUNT = GET_AND_UPDATE.ordinal() + 1; static { assert (COUNT == values().length); } final Class<?> returnType; final boolean isMonomorphicInReturnType; AccessType(Class<?> returnType) { this.returnType = returnType; isMonomorphicInReturnType = returnType != Object.class; } MethodType accessModeType(Class<?> receiver, Class<?> value, Class<?>... intermediate) { Class<?>[] ps; int i; switch (this) { case GET: ps = allocateParameters(0, receiver, intermediate); fillParameters(ps, receiver, intermediate); return MethodType.methodType(value, ps); case SET: ps = allocateParameters(1, receiver, intermediate); i = fillParameters(ps, receiver, intermediate); ps[i] = value; return MethodType.methodType(void.class, ps); case COMPARE_AND_SET: ps = allocateParameters(2, receiver, intermediate); i = fillParameters(ps, receiver, intermediate); ps[i++] = value; ps[i] = value; return MethodType.methodType(boolean.class, ps); case COMPARE_AND_EXCHANGE: ps = allocateParameters(2, receiver, intermediate); i = fillParameters(ps, receiver, intermediate); ps[i++] = value; ps[i] = value; return MethodType.methodType(value, ps); case GET_AND_UPDATE: ps = allocateParameters(1, receiver, intermediate); i = fillParameters(ps, receiver, intermediate); ps[i] = value; return MethodType.methodType(value, ps); default: throw new InternalError("Unknown AccessType"); } } private static Class<?>[] allocateParameters(int values, Class<?> receiver, Class<?>... intermediate) { int size = ((receiver != null) ? 1 : 0) + intermediate.length + values; return new Class<?>[size]; } private static int fillParameters(Class<?>[] ps, Class<?> receiver, Class<?>... intermediate) { int i = 0; if (receiver != null) ps[i++] = receiver; for (int j = 0; j < intermediate.length; j++) ps[i++] = intermediate[j]; return i; } } /** * The set of access modes that specify how a variable, referenced by a * VarHandle, is accessed. */ public enum AccessMode { /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#get VarHandle.get} */ GET("get", AccessType.GET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#set VarHandle.set} */ SET("set", AccessType.SET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getVolatile VarHandle.getVolatile} */ GET_VOLATILE("getVolatile", AccessType.GET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#setVolatile VarHandle.setVolatile} */ SET_VOLATILE("setVolatile", AccessType.SET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAcquire VarHandle.getAcquire} */ GET_ACQUIRE("getAcquire", AccessType.GET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#setRelease VarHandle.setRelease} */ SET_RELEASE("setRelease", AccessType.SET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getOpaque VarHandle.getOpaque} */ GET_OPAQUE("getOpaque", AccessType.GET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#setOpaque VarHandle.setOpaque} */ SET_OPAQUE("setOpaque", AccessType.SET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#compareAndSet VarHandle.compareAndSet} */ COMPARE_AND_SET("compareAndSet", AccessType.COMPARE_AND_SET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#compareAndExchange VarHandle.compareAndExchange} */ COMPARE_AND_EXCHANGE("compareAndExchange", AccessType.COMPARE_AND_EXCHANGE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#compareAndExchangeAcquire VarHandle.compareAndExchangeAcquire} */ COMPARE_AND_EXCHANGE_ACQUIRE("compareAndExchangeAcquire", AccessType.COMPARE_AND_EXCHANGE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#compareAndExchangeRelease VarHandle.compareAndExchangeRelease} */ COMPARE_AND_EXCHANGE_RELEASE("compareAndExchangeRelease", AccessType.COMPARE_AND_EXCHANGE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#weakCompareAndSetPlain VarHandle.weakCompareAndSetPlain} */ WEAK_COMPARE_AND_SET_PLAIN("weakCompareAndSetPlain", AccessType.COMPARE_AND_SET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#weakCompareAndSet VarHandle.weakCompareAndSet} */ WEAK_COMPARE_AND_SET("weakCompareAndSet", AccessType.COMPARE_AND_SET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#weakCompareAndSetAcquire VarHandle.weakCompareAndSetAcquire} */ WEAK_COMPARE_AND_SET_ACQUIRE("weakCompareAndSetAcquire", AccessType.COMPARE_AND_SET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#weakCompareAndSetRelease VarHandle.weakCompareAndSetRelease} */ WEAK_COMPARE_AND_SET_RELEASE("weakCompareAndSetRelease", AccessType.COMPARE_AND_SET), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndSet VarHandle.getAndSet} */ GET_AND_SET("getAndSet", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndSetAcquire VarHandle.getAndSetAcquire} */ GET_AND_SET_ACQUIRE("getAndSetAcquire", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndSetRelease VarHandle.getAndSetRelease} */ GET_AND_SET_RELEASE("getAndSetRelease", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndAdd VarHandle.getAndAdd} */ GET_AND_ADD("getAndAdd", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndAddAcquire VarHandle.getAndAddAcquire} */ GET_AND_ADD_ACQUIRE("getAndAddAcquire", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndAddRelease VarHandle.getAndAddRelease} */ GET_AND_ADD_RELEASE("getAndAddRelease", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndBitwiseOr VarHandle.getAndBitwiseOr} */ GET_AND_BITWISE_OR("getAndBitwiseOr", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndBitwiseOrRelease VarHandle.getAndBitwiseOrRelease} */ GET_AND_BITWISE_OR_RELEASE("getAndBitwiseOrRelease", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndBitwiseOrAcquire VarHandle.getAndBitwiseOrAcquire} */ GET_AND_BITWISE_OR_ACQUIRE("getAndBitwiseOrAcquire", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndBitwiseAnd VarHandle.getAndBitwiseAnd} */ GET_AND_BITWISE_AND("getAndBitwiseAnd", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndBitwiseAndRelease VarHandle.getAndBitwiseAndRelease} */ GET_AND_BITWISE_AND_RELEASE("getAndBitwiseAndRelease", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndBitwiseAndAcquire VarHandle.getAndBitwiseAndAcquire} */ GET_AND_BITWISE_AND_ACQUIRE("getAndBitwiseAndAcquire", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndBitwiseXor VarHandle.getAndBitwiseXor} */ GET_AND_BITWISE_XOR("getAndBitwiseXor", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndBitwiseXorRelease VarHandle.getAndBitwiseXorRelease} */ GET_AND_BITWISE_XOR_RELEASE("getAndBitwiseXorRelease", AccessType.GET_AND_UPDATE), /** * The access mode whose access is specified by the corresponding * method * {@link VarHandle#getAndBitwiseXorAcquire VarHandle.getAndBitwiseXorAcquire} */ GET_AND_BITWISE_XOR_ACQUIRE("getAndBitwiseXorAcquire", AccessType.GET_AND_UPDATE), ; static final int COUNT = GET_AND_BITWISE_XOR_ACQUIRE.ordinal() + 1; static { assert (COUNT == values().length); } final String methodName; final AccessType at; AccessMode(final String methodName, AccessType at) { this.methodName = methodName; this.at = at; } /** * Returns the {@code VarHandle} signature-polymorphic method name * associated with this {@code AccessMode} value. * * @return the signature-polymorphic method name * @see #valueFromMethodName */ public String methodName() { return methodName; } /** * Returns the {@code AccessMode} value associated with the specified * {@code VarHandle} signature-polymorphic method name. * * @param methodName the signature-polymorphic method name * @return the {@code AccessMode} value * @throws IllegalArgumentException if there is no {@code AccessMode} * value associated with method name (indicating the method * name does not correspond to a {@code VarHandle} * signature-polymorphic method name). * @see #methodName() */ public static AccessMode valueFromMethodName(String methodName) { return switch (methodName) { case "get" -> GET; case "set" -> SET; case "getVolatile" -> GET_VOLATILE; case "setVolatile" -> SET_VOLATILE; case "getAcquire" -> GET_ACQUIRE; case "setRelease" -> SET_RELEASE; case "getOpaque" -> GET_OPAQUE; case "setOpaque" -> SET_OPAQUE; case "compareAndSet" -> COMPARE_AND_SET; case "compareAndExchange" -> COMPARE_AND_EXCHANGE; case "compareAndExchangeAcquire" -> COMPARE_AND_EXCHANGE_ACQUIRE; case "compareAndExchangeRelease" -> COMPARE_AND_EXCHANGE_RELEASE; case "weakCompareAndSet" -> WEAK_COMPARE_AND_SET; case "weakCompareAndSetPlain" -> WEAK_COMPARE_AND_SET_PLAIN; case "weakCompareAndSetAcquire" -> WEAK_COMPARE_AND_SET_ACQUIRE; case "weakCompareAndSetRelease" -> WEAK_COMPARE_AND_SET_RELEASE; case "getAndSet" -> GET_AND_SET; case "getAndSetAcquire" -> GET_AND_SET_ACQUIRE; case "getAndSetRelease" -> GET_AND_SET_RELEASE; case "getAndAdd" -> GET_AND_ADD; case "getAndAddAcquire" -> GET_AND_ADD_ACQUIRE; case "getAndAddRelease" -> GET_AND_ADD_RELEASE; case "getAndBitwiseOr" -> GET_AND_BITWISE_OR; case "getAndBitwiseOrRelease" -> GET_AND_BITWISE_OR_RELEASE; case "getAndBitwiseOrAcquire" -> GET_AND_BITWISE_OR_ACQUIRE; case "getAndBitwiseAnd" -> GET_AND_BITWISE_AND; case "getAndBitwiseAndRelease" -> GET_AND_BITWISE_AND_RELEASE; case "getAndBitwiseAndAcquire" -> GET_AND_BITWISE_AND_ACQUIRE; case "getAndBitwiseXor" -> GET_AND_BITWISE_XOR; case "getAndBitwiseXorRelease" -> GET_AND_BITWISE_XOR_RELEASE; case "getAndBitwiseXorAcquire" -> GET_AND_BITWISE_XOR_ACQUIRE; default -> throw new IllegalArgumentException("No AccessMode value for method name " + methodName); }; } } static final class AccessDescriptor { final MethodType symbolicMethodTypeExact; final MethodType symbolicMethodTypeErased; final MethodType symbolicMethodTypeInvoker; final Class<?> returnType; final int type; final int mode; public AccessDescriptor(MethodType symbolicMethodType, int type, int mode) { this.symbolicMethodTypeExact = symbolicMethodType; this.symbolicMethodTypeErased = symbolicMethodType.erase(); this.symbolicMethodTypeInvoker = symbolicMethodType.insertParameterTypes(0, VarHandle.class); this.returnType = symbolicMethodType.returnType(); this.type = type; this.mode = mode; } } /** * Returns a compact textual description of this {@linkplain VarHandle}, * including the type of variable described, and a description of its coordinates. * * @return A compact textual description of this {@linkplain VarHandle} */ @Override public final String toString() { return String.format("VarHandle[varType=%s, coord=%s]", varType().getName(), coordinateTypes()); } /** * Returns the variable type of variables referenced by this VarHandle. * * @return the variable type of variables referenced by this VarHandle */ public Class<?> varType() { MethodType typeSet = accessModeType(AccessMode.SET); return typeSet.parameterType(typeSet.parameterCount() - 1); } /** * Returns the coordinate types for this VarHandle. * * @return the coordinate types for this VarHandle. The returned * list is unmodifiable */ public List<Class<?>> coordinateTypes() { MethodType typeGet = accessModeType(AccessMode.GET); return typeGet.parameterList(); } /** * Obtains the access mode type for this VarHandle and a given access mode. * * <p>The access mode type's parameter types will consist of a prefix that * is the coordinate types of this VarHandle followed by further * types as defined by the access mode method. * The access mode type's return type is defined by the return type of the * access mode method. * * @param accessMode the access mode, corresponding to the * signature-polymorphic method of the same name * @return the access mode type for the given access mode */ public final MethodType accessModeType(AccessMode accessMode) { return accessModeType(accessMode.at.ordinal()); } @ForceInline final void checkExactAccessMode(VarHandle.AccessDescriptor ad) { if (exact && accessModeType(ad.type) != ad.symbolicMethodTypeExact) { throwWrongMethodTypeException(ad); } } @DontInline private final void throwWrongMethodTypeException(VarHandle.AccessDescriptor ad) { throw new WrongMethodTypeException("expected " + accessModeType(ad.type) + " but found " + ad.symbolicMethodTypeExact); } @ForceInline final MethodType accessModeType(int accessTypeOrdinal) { TypesAndInvokers tis = getTypesAndInvokers(); MethodType mt = tis.methodType_table[accessTypeOrdinal]; if (mt == null) { mt = tis.methodType_table[accessTypeOrdinal] = accessModeTypeUncached(accessTypeOrdinal); } return mt; } final MethodType accessModeTypeUncached(int accessTypeOrdinal) { return accessModeTypeUncached(AccessType.values()[accessTypeOrdinal]); } abstract MethodType accessModeTypeUncached(AccessType accessMode); /** * Returns {@code true} if the given access mode is supported, otherwise * {@code false}. * * <p>The return of a {@code false} value for a given access mode indicates * that an {@code UnsupportedOperationException} is thrown on invocation * of the corresponding access mode method. * * @param accessMode the access mode, corresponding to the * signature-polymorphic method of the same name * @return {@code true} if the given access mode is supported, otherwise * {@code false}. */ public final boolean isAccessModeSupported(AccessMode accessMode) { return vform.getMemberNameOrNull(accessMode.ordinal()) != null; } /** * Obtains a method handle bound to this VarHandle and the given access * mode. * * @apiNote This method, for a VarHandle {@code vh} and access mode * {@code {access-mode}}, returns a method handle that is equivalent to * method handle {@code bmh} in the following code (though it may be more * efficient): * <pre>{@code * MethodHandle mh = MethodHandles.varHandleExactInvoker( * vh.accessModeType(VarHandle.AccessMode.{access-mode})); * * MethodHandle bmh = mh.bindTo(vh); * }</pre> * * @param accessMode the access mode, corresponding to the * signature-polymorphic method of the same name * @return a method handle bound to this VarHandle and the given access mode */ public MethodHandle toMethodHandle(AccessMode accessMode) { if (isAccessModeSupported(accessMode)) { MethodHandle mh = getMethodHandle(accessMode.ordinal()); return mh.bindTo(this); } else { // Ensure an UnsupportedOperationException is thrown return MethodHandles.varHandleInvoker(accessMode, accessModeType(accessMode)). bindTo(this); } } /** * Return a nominal descriptor for this instance, if one can be * constructed, or an empty {@link Optional} if one cannot be. * * @return An {@link Optional} containing the resulting nominal descriptor, * or an empty {@link Optional} if one cannot be constructed. * @since 12 */ @Override public Optional<VarHandleDesc> describeConstable() { // partial function for field and array only return Optional.empty(); } @Stable TypesAndInvokers typesAndInvokers; static class TypesAndInvokers { final @Stable MethodType[] methodType_table = new MethodType[VarHandle.AccessType.COUNT]; final @Stable MethodHandle[] methodHandle_table = new MethodHandle[AccessMode.COUNT]; } @ForceInline private final TypesAndInvokers getTypesAndInvokers() { TypesAndInvokers tis = typesAndInvokers; if (tis == null) { tis = typesAndInvokers = new TypesAndInvokers(); } return tis; } @ForceInline MethodHandle getMethodHandle(int mode) { TypesAndInvokers tis = getTypesAndInvokers(); MethodHandle mh = tis.methodHandle_table[mode]; if (mh == null) { mh = tis.methodHandle_table[mode] = getMethodHandleUncached(mode); } return mh; } private final MethodHandle getMethodHandleUncached(int mode) { MethodType mt = accessModeType(AccessMode.values()[mode]). insertParameterTypes(0, VarHandle.class); MemberName mn = vform.getMemberName(mode); DirectMethodHandle dmh = DirectMethodHandle.make(mn); // Such a method handle must not be publicly exposed directly // otherwise it can be cracked, it must be transformed or rebound // before exposure MethodHandle mh = dmh.copyWith(mt, dmh.form); assert mh.type().erase() == mn.getMethodType().erase(); return mh; } /*non-public*/ final void updateVarForm(VarForm newVForm) { if (vform == newVForm) return; UNSAFE.putReference(this, VFORM_OFFSET, newVForm); UNSAFE.fullFence(); } static final BiFunction<String, List<Number>, ArrayIndexOutOfBoundsException> AIOOBE_SUPPLIER = Preconditions.outOfBoundsExceptionFormatter( new Function<String, ArrayIndexOutOfBoundsException>() { @Override public ArrayIndexOutOfBoundsException apply(String s) { return new ArrayIndexOutOfBoundsException(s); } }); private static final long VFORM_OFFSET; static { VFORM_OFFSET = UNSAFE.objectFieldOffset(VarHandle.class, "vform"); // The VarHandleGuards must be initialized to ensure correct // compilation of the guard methods UNSAFE.ensureClassInitialized(VarHandleGuards.class); } // Fence methods /** * Ensures that loads and stores before the fence will not be reordered * with * loads and stores after the fence. * * @apiNote Ignoring the many semantic differences from C and C++, this * method has memory ordering effects compatible with * {@code atomic_thread_fence(memory_order_seq_cst)} */ @ForceInline public static void fullFence() { UNSAFE.fullFence(); } /** * Ensures that loads before the fence will not be reordered with loads and * stores after the fence. * * @apiNote Ignoring the many semantic differences from C and C++, this * method has memory ordering effects compatible with * {@code atomic_thread_fence(memory_order_acquire)} */ @ForceInline public static void acquireFence() { UNSAFE.loadFence(); } /** * Ensures that loads and stores before the fence will not be * reordered with stores after the fence. * * @apiNote Ignoring the many semantic differences from C and C++, this * method has memory ordering effects compatible with * {@code atomic_thread_fence(memory_order_release)} */ @ForceInline public static void releaseFence() { UNSAFE.storeFence(); } /** * Ensures that loads before the fence will not be reordered with * loads after the fence. */ @ForceInline public static void loadLoadFence() { UNSAFE.loadLoadFence(); } /** * Ensures that stores before the fence will not be reordered with * stores after the fence. */ @ForceInline public static void storeStoreFence() { UNSAFE.storeStoreFence(); } /** * A <a href="{@docRoot}/java.base/java/lang/constant/package-summary.html#nominal">nominal descriptor</a> for a * {@link VarHandle} constant. * * @since 12 */ public static final class VarHandleDesc extends DynamicConstantDesc<VarHandle> { /** * Kinds of variable handle descs */ private enum Kind { FIELD(ConstantDescs.BSM_VARHANDLE_FIELD), STATIC_FIELD(ConstantDescs.BSM_VARHANDLE_STATIC_FIELD), ARRAY(ConstantDescs.BSM_VARHANDLE_ARRAY); final DirectMethodHandleDesc bootstrapMethod; Kind(DirectMethodHandleDesc bootstrapMethod) { this.bootstrapMethod = bootstrapMethod; } ConstantDesc[] toBSMArgs(ClassDesc declaringClass, ClassDesc varType) { return switch (this) { case FIELD, STATIC_FIELD -> new ConstantDesc[]{declaringClass, varType}; case ARRAY -> new ConstantDesc[]{declaringClass}; default -> throw new InternalError("Cannot reach here"); }; } } private final Kind kind; private final ClassDesc declaringClass; private final ClassDesc varType; /** * Construct a {@linkplain VarHandleDesc} given a kind, name, and declaring * class. * * @param kind the kind of the var handle * @param name the unqualified name of the field, for field var handles; otherwise ignored * @param declaringClass a {@link ClassDesc} describing the declaring class, * for field var handles * @param varType a {@link ClassDesc} describing the type of the variable * @throws NullPointerException if any required argument is null * @jvms 4.2.2 Unqualified Names */ private VarHandleDesc(Kind kind, String name, ClassDesc declaringClass, ClassDesc varType) { super(kind.bootstrapMethod, name, ConstantDescs.CD_VarHandle, kind.toBSMArgs(declaringClass, varType)); this.kind = kind; this.declaringClass = declaringClass; this.varType = varType; } /** * Returns a {@linkplain VarHandleDesc} corresponding to a {@link VarHandle} * for an instance field. * * @param name the unqualified name of the field * @param declaringClass a {@link ClassDesc} describing the declaring class, * for field var handles * @param fieldType a {@link ClassDesc} describing the type of the field * @return the {@linkplain VarHandleDesc} * @throws NullPointerException if any of the arguments are null * @jvms 4.2.2 Unqualified Names */ public static VarHandleDesc ofField(ClassDesc declaringClass, String name, ClassDesc fieldType) { Objects.requireNonNull(declaringClass); Objects.requireNonNull(name); Objects.requireNonNull(fieldType); return new VarHandleDesc(Kind.FIELD, name, declaringClass, fieldType); } /** * Returns a {@linkplain VarHandleDesc} corresponding to a {@link VarHandle} * for a static field. * * @param name the unqualified name of the field * @param declaringClass a {@link ClassDesc} describing the declaring class, * for field var handles * @param fieldType a {@link ClassDesc} describing the type of the field * @return the {@linkplain VarHandleDesc} * @throws NullPointerException if any of the arguments are null * @jvms 4.2.2 Unqualified Names */ public static VarHandleDesc ofStaticField(ClassDesc declaringClass, String name, ClassDesc fieldType) { Objects.requireNonNull(declaringClass); Objects.requireNonNull(name); Objects.requireNonNull(fieldType); return new VarHandleDesc(Kind.STATIC_FIELD, name, declaringClass, fieldType); } /** * Returns a {@linkplain VarHandleDesc} corresponding to a {@link VarHandle} * for an array type. * * @param arrayClass a {@link ClassDesc} describing the type of the array * @return the {@linkplain VarHandleDesc} * @throws NullPointerException if any of the arguments are null */ public static VarHandleDesc ofArray(ClassDesc arrayClass) { Objects.requireNonNull(arrayClass); if (!arrayClass.isArray()) throw new IllegalArgumentException("Array class argument not an array: " + arrayClass); return new VarHandleDesc(Kind.ARRAY, ConstantDescs.DEFAULT_NAME, arrayClass, arrayClass.componentType()); } /** * Returns a {@link ClassDesc} describing the type of the variable described * by this descriptor. * * @return the variable type */ public ClassDesc varType() { return varType; } @Override public VarHandle resolveConstantDesc(MethodHandles.Lookup lookup) throws ReflectiveOperationException { return switch (kind) { case FIELD -> lookup.findVarHandle((Class<?>) declaringClass.resolveConstantDesc(lookup), constantName(), (Class<?>) varType.resolveConstantDesc(lookup)); case STATIC_FIELD -> lookup.findStaticVarHandle((Class<?>) declaringClass.resolveConstantDesc(lookup), constantName(), (Class<?>) varType.resolveConstantDesc(lookup)); case ARRAY -> MethodHandles.arrayElementVarHandle((Class<?>) declaringClass.resolveConstantDesc(lookup)); default -> throw new InternalError("Cannot reach here"); }; } /** * Returns a compact textual description of this constant description. * For a field {@linkplain VarHandle}, includes the owner, name, and type * of the field, and whether it is static; for an array {@linkplain VarHandle}, * the name of the component type. * * @return A compact textual description of this descriptor */ @Override public String toString() { return switch (kind) { case FIELD, STATIC_FIELD -> String.format("VarHandleDesc[%s%s.%s:%s]", (kind == Kind.STATIC_FIELD) ? "static " : "", declaringClass.displayName(), constantName(), varType.displayName()); case ARRAY -> String.format("VarHandleDesc[%s[]]", declaringClass.displayName()); default -> throw new InternalError("Cannot reach here"); }; } } }
⏎ java/lang/invoke/VarHandle.java
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