org.dynalang.dynalink

Class ChainedCallSite

java.lang.Object

java.lang.invoke.CallSite

java.lang.invoke.MutableCallSite

org.dynalang.dynalink.support.AbstractRelinkableCallSite

org.dynalang.dynalink.ChainedCallSite

All Implemented Interfaces:

RelinkableCallSite

public class ChainedCallSite
extends AbstractRelinkableCallSite

A relinkable call site that maintains a chain of linked method handles. In the default implementation, up to 8 method handles can be chained, cascading from one to the other through MethodHandles.guardWithTest(MethodHandle, MethodHandle, MethodHandle). When this call site has to link a new method handle and the length of the chain is already at the maximum, it will throw away the oldest method handle. Switchpoint-invalidated handles in the chain are removed eagerly (on each linking request, and whenever a switchpoint-invalidated method handle is traversed during invocation). There is currently no profiling attached to the handles in the chain, so they are never reordered based on usage; the most recently linked method handle is always at the start of the chain.

Constructor Summary

Constructors

Constructor and Description
ChainedCallSite(CallSiteDescriptor descriptor) Creates a new chained call site.

Method Summary

Methods

Modifier and Type	Method and Description
protected int	getMaxChainLength() The maximum number of method handles in the chain.
void	setGuardedInvocation(GuardedInvocation invocation, MethodHandle relink) This method will be called once by the dynamic linker every time the call site is relinked.

Methods inherited from class org.dynalang.dynalink.support.AbstractRelinkableCallSite

getDescriptor, setRelinkAndInvoke

Methods inherited from class java.lang.invoke.MutableCallSite

dynamicInvoker, getTarget, setTarget, syncAll

Methods inherited from class java.lang.invoke.CallSite

type

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ChainedCallSite

public ChainedCallSite(CallSiteDescriptor descriptor)

Creates a new chained call site.

Parameters:

descriptor - the descriptor for the call site.

Method Detail

getMaxChainLength

protected int getMaxChainLength()

The maximum number of method handles in the chain. Defaults to 8. You can override it in a subclass if you need to change the value. If your override returns a value less than 1, the code will break.

Returns:

the maximum number of method handles in the chain.

setGuardedInvocation

public void setGuardedInvocation(GuardedInvocation invocation,
                        MethodHandle relink)

Description copied from interface: RelinkableCallSite

This method will be called once by the dynamic linker every time the call site is relinked.

Parameters:

invocation - the guarded invocation that the call site should set as its current target. Note that the call sites are allowed to keep other non-invalidated invocations around for implementation of polymorphic inline caches.

relink - the fallback method. This is a method matching the method type of the call site that is supplied by the DynamicLinker to be used by this call site as a 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 discover the adequate target for the invocation, subsequently invoke RelinkableCallSite.setGuardedInvocation(GuardedInvocation, MethodHandle), and finally invoke the target.