VolatileCallSite

public class VolatileCallSite
extends CallSite

java.lang.Object
↳	java.lang.invoke.CallSite
	↳	java.lang.invoke.VolatileCallSite

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.

In other respects, a VolatileCallSite is interchangeable with MutableCallSite.

See also:

MutableCallSite

Summary

Public constructors
`VolatileCallSite(MethodHandle target)` Creates a call site with a volatile binding to its target.
`VolatileCallSite(MethodType type)` Creates a call site with a volatile binding to its target.

Public methods
`final MethodHandle`	`dynamicInvoker()` Produces a method handle equivalent to an invokedynamic instruction which has been linked to this call site.
`final MethodHandle`	`getTarget()` Returns the target method of the call site, which behaves like a `volatile` field of the `VolatileCallSite`.
`void`	`setTarget(MethodHandle newTarget)` Updates the target method of this call site, as a volatile variable.

Inherited methods

From class


        
          java.lang.invoke.CallSite

`abstract MethodHandle`	`dynamicInvoker()` Produces a method handle equivalent to an invokedynamic instruction which has been linked to this call site.
`abstract MethodHandle`	`getTarget()` Returns the target method of the call site, according to the behavior defined by this call site's specific class.
`abstract void`	`setTarget(MethodHandle newTarget)` Updates the target method of this call site, according to the behavior defined by this call site's specific class.
`MethodType`	`type()` Returns the type of this call site's target.

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

Public constructors

VolatileCallSite

Added in API level 26

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

Throws
`NullPointerException`	if the proposed target is null

VolatileCallSite

Added in API level 26

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

Throws
`NullPointerException`	if the proposed type is null

Public methods

dynamicInvoker

Added in API level 26

public final MethodHandle 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)

Returns
`MethodHandle`	a method handle which always invokes this call site's current target

getTarget

Added in API level 26

public final MethodHandle 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

See also:

setTarget(MethodHandle)

setTarget

Added in API level 26

public void setTarget (MethodHandle newTarget)

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

Throws
`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()