OpenJDK 27 · java.lang.invoke.VolatileCallSite · APIdia, the JavaDoc alternative

A VolatileCallSite is a CallSite whose target acts like a volatile variable. An invokedynamic instruction linked to a VolatileCallSite sees updates to its call site target immediately, even if the update occurs in another thread. There may be a performance penalty for such tight coupling between threads.

Unlike MutableCallSite, there is no syncAll operation on volatile call sites, since every write to a volatile variable is implicitly synchronized with reader threads.

In other respects, a VolatileCallSite is interchangeable with MutableCallSite.

Constructor Summary

Access	Constructor and Description
public	VolatileCallSite(MethodType the method type that this call site will have type) Creates a call site with a volatile binding to its target.
public	VolatileCallSite(MethodHandle the method handle that will be the initial target of the call site target) Creates a call site with a volatile binding to its target.

Method Summary

Modifier and Type	Method and Description
public final MethodHandle	dynamicInvoker() Implements abstract java.lang.invoke.CallSite.dynamicInvoker. Produces a method handle equivalent to an invokedynamic instruction which has been linked to this call site.
public final MethodHandle	Returns: the linkage state of this call site, a method handle which can change over time getTarget() Implements abstract java.lang.invoke.CallSite.getTarget. Returns the target method of the call site, which behaves like a `volatile` field of the `VolatileCallSite`.
public void	setTarget(MethodHandle the new target newTarget) Implements abstract java.lang.invoke.CallSite.setTarget. Updates the target method of this call site, as a volatile variable.

Inherited from java.lang.invoke.CallSite:: getTargetVolatile makeDynamicInvoker makeSite setTargetNormal setTargetVolatile type

Constructor Detail

VolatileCallSite back to summary

VolatileCallSite	back to summary
public VolatileCallSite(MethodType type) Creates a call site with a volatile binding to its target. The initial target is set to a method handle of the given type which will throw an `IllegalStateException` if called. Parameters type:MethodType the method type that this call site will have Exceptions NullPointerException: if the proposed type is null

public VolatileCallSite(MethodType type)

Creates a call site with a volatile binding to its target. The initial target is set to a method handle of the given type which will throw an IllegalStateException if called.

Parameters

type:MethodType: the method type that this call site will have

Exceptions

NullPointerException:: if the proposed type is null

VolatileCallSite	back to summary
public VolatileCallSite(MethodHandle target) Creates a call site with a volatile binding to its target. The target is set to the given value. Parameters target:MethodHandle the method handle that will be the initial target of the call site Exceptions NullPointerException: if the proposed target is null

VolatileCallSite

back to summary

public VolatileCallSite(MethodHandle target)

Creates a call site with a volatile binding to its target. The target is set to the given value.

Parameters

target:MethodHandle: the method handle that will be the initial target of the call site

Exceptions

NullPointerException:: if the proposed target is null

Method Detail

dynamicInvoker back to summary

dynamicInvoker	back to summary
public final MethodHandle dynamicInvoker() Implements abstract java.lang.invoke.CallSite.dynamicInvoker. Doc from java.lang.invoke.CallSite.dynamicInvoker. Produces a method handle equivalent to an invokedynamic instruction which has been linked to this call site. This method is equivalent to the following code: `MethodHandle getTarget, invoker, result; getTarget = MethodHandles.publicLookup().bind(this, "getTarget", MethodType.methodType(MethodHandle.class)); invoker = MethodHandles.exactInvoker(this.type()); result = MethodHandles.foldArguments(invoker, getTarget)` Annotations @Override

public final MethodHandle dynamicInvoker()

Implements abstract java.lang.invoke.CallSite.dynamicInvoker.

Doc from java.lang.invoke.CallSite.dynamicInvoker.

Produces a method handle equivalent to an invokedynamic instruction which has been linked to this call site.

This method is equivalent to the following code:

MethodHandle getTarget, invoker, result;
getTarget = MethodHandles.publicLookup().bind(this, "getTarget", MethodType.methodType(MethodHandle.class));
invoker = MethodHandles.exactInvoker(this.type());
result = MethodHandles.foldArguments(invoker, getTarget)

Annotations

@Override

getTarget back to summary

getTarget	back to summary
public final MethodHandle getTarget() Implements abstract java.lang.invoke.CallSite.getTarget. Returns the target method of the call site, which behaves like a `volatile` field of the `VolatileCallSite`. The interactions of `getTarget` with memory are the same as of a read from a `volatile` field. In particular, the current thread is required to issue a fresh read of the target from memory, and must not fail to see a recent update to the target by another thread. Returns:MethodHandle the linkage state of this call site, a method handle which can change over time Annotations @Override See Also `setTarget`

public final MethodHandle getTarget()

Implements abstract java.lang.invoke.CallSite.getTarget.

Returns the target method of the call site, which behaves like a volatile field of the VolatileCallSite.

The interactions of getTarget with memory are the same as of a read from a volatile field.

In particular, the current thread is required to issue a fresh read of the target from memory, and must not fail to see a recent update to the target by another thread.

Returns:MethodHandle

the linkage state of this call site, a method handle which can change over time

Annotations

@Override

See Also

setTarget

setTarget back to summary

setTarget	back to summary
public void setTarget(MethodHandle newTarget) Implements abstract java.lang.invoke.CallSite.setTarget. Updates the target method of this call site, as a volatile variable. The type of the new target must agree with the type of the old target. The interactions with memory are the same as of a write to a volatile field. In particular, any threads is guaranteed to see the updated target the next time it calls `getTarget`. Parameters newTarget:MethodHandle the new target Annotations @Override Exceptions NullPointerException: if the proposed new target is null WrongMethodTypeException: if the proposed new target has a method type that differs from the previous target See Also `getTarget`

public void setTarget(MethodHandle newTarget)

Implements abstract java.lang.invoke.CallSite.setTarget.

Updates the target method of this call site, as a volatile variable. The type of the new target must agree with the type of the old target.

The interactions with memory are the same as of a write to a volatile field. In particular, any threads is guaranteed to see the updated target the next time it calls getTarget.

Parameters

newTarget:MethodHandle: the new target

Annotations

@Override

Exceptions

NullPointerException:: if the proposed new target is null
WrongMethodTypeException:: if the proposed new target has a method type that differs from the previous target

See Also

getTarget

public non-sealed Class VolatileCallSite

Field Summary

Constructor Summary

Method Summary

Constructor Detail

Method Detail