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 Details

    • 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 Details

    • 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.