Class Finalizer

  • All Implemented Interfaces:
    java.lang.Runnable

    public class Finalizer
    extends java.lang.Object
    implements java.lang.Runnable
    Thread that finalizes referents. All references should implement com.google.common.base.FinalizableReference.

    While this class is public, we consider it to be *internal* and not part of our published API. It is public so we can access it reflectively across class loaders in secure environments.

    This class can't depend on other Google Collections code. If we were to load this class in the same class loader as the rest of Google Collections, this thread would keep an indirect strong reference to the class loader and prevent it from being garbage collected. This poses a problem for environments where you want to throw away the class loader. For example, dynamically reloading a web application or unloading an OSGi bundle.

    com.google.common.base.FinalizableReferenceQueue loads this class in its own class loader. That way, this class doesn't prevent the main class loader from getting garbage collected, and this class can detect when the main class loader has been garbage collected and stop itself.

    • Constructor Summary

      Constructors 
      Modifier Constructor Description
      private Finalizer​(java.lang.Class<?> finalizableReferenceClass, java.lang.Object frq)
      Constructs a new finalizer thread.
    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      private boolean cleanUp​(java.lang.ref.Reference<?> reference)
      Cleans up a single reference.
      private java.lang.reflect.Method getFinalizeReferentMethod()
      Looks up FinalizableReference.finalizeReferent() method.
      static java.lang.reflect.Constructor<java.lang.Thread> getInheritableThreadLocalsConstructor()  
      static java.lang.reflect.Field getInheritableThreadLocalsField()  
      void run()
      Loops continuously, pulling references off the queue and cleaning them up.
      void start()  
      static java.lang.ref.ReferenceQueue<java.lang.Object> startFinalizer​(java.lang.Class<?> finalizableReferenceClass, java.lang.Object frq)
      Starts the Finalizer thread.
      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
    • Field Detail

      • logger

        private static final java.util.logging.Logger logger
      • FINALIZABLE_REFERENCE

        private static final java.lang.String FINALIZABLE_REFERENCE
        Name of FinalizableReference.class.
        See Also:
        Constant Field Values
      • thread

        private java.lang.Thread thread
      • finalizableReferenceClassReference

        private final java.lang.ref.WeakReference<java.lang.Class<?>> finalizableReferenceClassReference
      • frqReference

        private final java.lang.ref.PhantomReference<java.lang.Object> frqReference
      • queue

        private final java.lang.ref.ReferenceQueue<java.lang.Object> queue
      • inheritableThreadLocals

        private static final java.lang.reflect.Field inheritableThreadLocals
      • inheritableThreadlocalsConstructor

        private static final java.lang.reflect.Constructor<java.lang.Thread> inheritableThreadlocalsConstructor
    • Constructor Detail

      • Finalizer

        private Finalizer​(java.lang.Class<?> finalizableReferenceClass,
                          java.lang.Object frq)
        Constructs a new finalizer thread.
    • Method Detail

      • startFinalizer

        public static java.lang.ref.ReferenceQueue<java.lang.Object> startFinalizer​(java.lang.Class<?> finalizableReferenceClass,
                                                                                    java.lang.Object frq)
        Starts the Finalizer thread. FinalizableReferenceQueue calls this method reflectively.
        Parameters:
        finalizableReferenceClass - FinalizableReference.class
        frq - reference to instance of FinalizableReferenceQueue that started this thread
        Returns:
        ReferenceQueue which Finalizer will poll
      • start

        public void start()
      • run

        public void run()
        Loops continuously, pulling references off the queue and cleaning them up.
        Specified by:
        run in interface java.lang.Runnable
      • cleanUp

        private boolean cleanUp​(java.lang.ref.Reference<?> reference)
        Cleans up a single reference. Catches and logs all throwables.
      • getFinalizeReferentMethod

        private java.lang.reflect.Method getFinalizeReferentMethod()
        Looks up FinalizableReference.finalizeReferent() method.
      • getInheritableThreadLocalsField

        public static java.lang.reflect.Field getInheritableThreadLocalsField()
      • getInheritableThreadLocalsConstructor

        public static java.lang.reflect.Constructor<java.lang.Thread> getInheritableThreadLocalsConstructor()