Module jdk.dynalink

Package jdk.dynalink.linker.support

Class CompositeTypeBasedGuardingDynamicLinker

java.lang.Object

jdk.dynalink.linker.support.CompositeTypeBasedGuardingDynamicLinker

All Implemented Interfaces:

GuardingDynamicLinker, TypeBasedGuardingDynamicLinker

public class CompositeTypeBasedGuardingDynamicLinker
extends Object
implements TypeBasedGuardingDynamicLinker

A composite type-based guarding dynamic linker. When a receiver of a not yet seen class is encountered, all linkers are queried sequentially on their TypeBasedGuardingDynamicLinker.canLinkType(Class) method. The linkers returning true are then bound to the class, and next time a receiver of same type is encountered, the linking is delegated to those linkers only, speeding up dispatch.

Constructor Summary

Constructors

Constructor and Description
CompositeTypeBasedGuardingDynamicLinker(Iterable<? extends TypeBasedGuardingDynamicLinker> linkers) Creates a new composite type-based linker.

Method Summary

Modifier and Type	Method and Description
boolean	canLinkType(Class<?> type) Returns true if at least one of the composite linkers returns true from TypeBasedGuardingDynamicLinker.canLinkType(Class) for the type.
GuardedInvocation	getGuardedInvocation(LinkRequest linkRequest, LinkerServices linkerServices) Creates a guarded invocation appropriate for a particular invocation with the specified arguments at a call site.
static List<GuardingDynamicLinker>	optimize(Iterable<? extends GuardingDynamicLinker> linkers) Optimizes a list of type-based linkers.

Methods inherited from class java.lang.Object

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

Constructor Detail

CompositeTypeBasedGuardingDynamicLinker

public CompositeTypeBasedGuardingDynamicLinker(Iterable<? extends TypeBasedGuardingDynamicLinker> linkers)

Creates a new composite type-based linker.

Parameters:

linkers - the component linkers

Throws:

NullPointerException - if linkers or any of its elements are null.

Method Detail

canLinkType

public boolean canLinkType(Class<?> type)

Returns true if at least one of the composite linkers returns true from TypeBasedGuardingDynamicLinker.canLinkType(Class) for the type.

Specified by:

canLinkType in interface TypeBasedGuardingDynamicLinker

Parameters:

type - the type to link

Returns:

true true if at least one of the composite linkers returns true from TypeBasedGuardingDynamicLinker.canLinkType(Class), false otherwise.

getGuardedInvocation

public GuardedInvocation getGuardedInvocation(LinkRequest linkRequest,
                                              LinkerServices linkerServices)
                                       throws Exception

Description copied from interface: GuardingDynamicLinker

Creates a guarded invocation appropriate for a particular invocation with the specified arguments at a call site.

Specified by:

getGuardedInvocation in interface GuardingDynamicLinker

Parameters:

linkRequest - the object describing the request for linking a particular invocation

linkerServices - linker services

Returns:

a guarded invocation with a method handle suitable for the arguments, as well as a guard condition that if fails should trigger relinking. Must return null if it can't resolve the invocation. If the returned invocation is unconditional (which is actually quite rare), the guard in the return value can be null. The invocation can also have any number of switch points for asynchronous invalidation of the linkage, as well as a Throwable subclass that describes an expected exception condition that also triggers relinking (often it is faster to rely on an infrequent but expected ClassCastException than on an always evaluated instanceof guard). While the linker must produce an invocation with parameter types matching those in the call site descriptor of the link request, it should not try to match the return type expected at the call site except when it can do it with only the conversions that lose neither precision nor magnitude, see LinkerServices.asTypeLosslessReturn(MethodHandle, MethodType) for further explanation.

Throws:

Exception - if the operation fails for whatever reason

optimize

public static List<GuardingDynamicLinker> optimize(Iterable<? extends GuardingDynamicLinker> linkers)

Optimizes a list of type-based linkers. If a group of adjacent linkers in the list all implement TypeBasedGuardingDynamicLinker, they will be replaced with a single instance of CompositeTypeBasedGuardingDynamicLinker that contains them.

Parameters:

linkers - the list of linkers to optimize

Returns:

the optimized list

Throws:

NullPointerException - if linkers or any of its elements are null.