RelinkableCallSite
public class ChainedCallSite extends AbstractRelinkableCallSite
GuardedInvocation
s it was linked with, and on each relink request builds a cascading chain of method handles of one invocation falling back to the next one. The number of remembered invocations can be customized by overriding getMaxChainLength()
in a subclass. When this call site is relinked with a new invocation and the length of the chain is already at the maximum, it will throw away the oldest invocation. Invocations with invalidated switch points and ones for which their invalidating exception triggered are removed eagerly from the chain. The invocations are never reordered; the most recently linked method handle is always at the start of the chain and the least recently linked at its end. The call site can be safely relinked on more than one thread concurrently. Race conditions in linking are resolved by throwing away the GuardedInvocation
produced on the losing thread without incorporating it into the chain, so it can lead to repeated linking for the same arguments.Constructor | Description |
---|---|
ChainedCallSite |
Creates a new chained call site. |
Modifier and Type | Method | Description |
---|---|---|
protected int |
getMaxChainLength() |
The maximum number of method handles in the chain. |
void |
relink |
This method will be called by the dynamic linker every time the call site is relinked (but see RelinkableCallSite.resetAndRelink(GuardedInvocation, MethodHandle) for an exception). |
void |
resetAndRelink |
This method will be called by the dynamic linker every time the call site is relinked and the linker wishes the call site to throw away any prior linkage state (that is how it differs from RelinkableCallSite.relink(GuardedInvocation, MethodHandle) ). |
getDescriptor, initialize
dynamicInvoker, getTarget, setTarget, syncAll
public ChainedCallSite(CallSiteDescriptor descriptor)
descriptor
- the descriptor for the call site.protected int getMaxChainLength()
RuntimeException
will be thrown.public void relink(GuardedInvocation guardedInvocation, MethodHandle relinkAndInvoke)
RelinkableCallSite
RelinkableCallSite.resetAndRelink(GuardedInvocation, MethodHandle)
for an exception). It will be passed a GuardedInvocation
that the call site should incorporate into its target method handle. When this method is called, the call site is allowed to keep other non-invalidated invocations around for implementation of polymorphic inline caches and compose them with this invocation to form its final target.guardedInvocation
- the guarded invocation that the call site should incorporate into its target method handle.relinkAndInvoke
- a relink-and-invoke method handle. This is a method handle matching the method type of the call site that is supplied by the DynamicLinker
as a callback. It should be used by this call site as the ultimate fallback when it can't invoke its target with the passed arguments. The fallback method is such that when it's invoked, it'll try to obtain an adequate target GuardedInvocation
for the invocation, and subsequently invoke RelinkableCallSite.relink(GuardedInvocation, MethodHandle)
or RelinkableCallSite.resetAndRelink(GuardedInvocation, MethodHandle)
, and finally invoke the target.public void resetAndRelink(GuardedInvocation guardedInvocation, MethodHandle relinkAndInvoke)
RelinkableCallSite
RelinkableCallSite.relink(GuardedInvocation, MethodHandle)
). It will be passed a GuardedInvocation
that the call site should use to build its new target method handle. When this method is called, the call site is discouraged from keeping any previous state, and is supposed to only link the current invocation.guardedInvocation
- the guarded invocation that the call site should use to build its target method handle.relinkAndInvoke
- a relink-and-invoke method handle. This is a method handle matching the method type of the call site that is supplied by the DynamicLinker
as a callback. It should be used by this call site as the ultimate fallback when it can't invoke its target with the passed arguments. The fallback method is such that when it's invoked, it'll try to obtain an adequate target GuardedInvocation
for the invocation, and subsequently invoke RelinkableCallSite.relink(GuardedInvocation, MethodHandle)
or RelinkableCallSite.resetAndRelink(GuardedInvocation, MethodHandle)
, and finally invoke the target.
© 1993, 2023, Oracle and/or its affiliates. All rights reserved.
Documentation extracted from Debian's OpenJDK Development Kit package.
Licensed under the GNU General Public License, version 2, with the Classpath Exception.
Various third party code in OpenJDK is licensed under different licenses (see Debian package).
Java and OpenJDK are trademarks or registered trademarks of Oracle and/or its affiliates.
https://docs.oracle.com/en/java/javase/21/docs/api/jdk.dynalink/jdk/dynalink/support/ChainedCallSite.html