Package com.google.common.base.internal

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 Guava code. If we were to load this class in the same class loader as the rest of Guava, 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.ref.ReferenceQueue<java.lang.Object> queue, java.lang.ref.PhantomReference<java.lang.Object> frqReference)
      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 static java.lang.reflect.Constructor<java.lang.Thread> getBigThreadConstructor()  
      private java.lang.reflect.Method getFinalizeReferentMethod()
      Looks up FinalizableReference.finalizeReferent() method.
      private static java.lang.reflect.Field getInheritableThreadLocalsField()  
      void run()
      Loops continuously, pulling references off the queue and cleaning them up.
      static void startFinalizer​(java.lang.Class<?> finalizableReferenceClass, java.lang.ref.ReferenceQueue<java.lang.Object> queue, java.lang.ref.PhantomReference<java.lang.Object> frqReference)
      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

      • 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

      • bigThreadConstructor

        private static final java.lang.reflect.Constructor<java.lang.Thread> bigThreadConstructor

      • inheritableThreadLocals

        private static final java.lang.reflect.Field inheritableThreadLocals

    • Constructor Detail

      • Finalizer

        private Finalizer​(java.lang.Class<?> finalizableReferenceClass,
                  java.lang.ref.ReferenceQueue<java.lang.Object> queue,
                  java.lang.ref.PhantomReference<java.lang.Object> frqReference)
        Constructs a new finalizer thread.

    • Method Detail

      • startFinalizer

        public static void startFinalizer​(java.lang.Class<?> finalizableReferenceClass,
                                  java.lang.ref.ReferenceQueue<java.lang.Object> queue,
                                  java.lang.ref.PhantomReference<java.lang.Object> frqReference)
        Starts the Finalizer thread. FinalizableReferenceQueue calls this method reflectively.
        Parameters:
        finalizableReferenceClass - FinalizableReference.class.
        queue - a reference queue that the thread will poll.
        frqReference - a phantom reference to the FinalizableReferenceQueue, which will be queued either when the FinalizableReferenceQueue is no longer referenced anywhere, or when its close() method is called.

      • 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.
        Returns:
        true if the caller should continue, false if the associated FinalizableReferenceQueue is no longer referenced.

      • getFinalizeReferentMethod

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

      • getInheritableThreadLocalsField

        private static java.lang.reflect.Field getInheritableThreadLocalsField()

      • getBigThreadConstructor

        private static java.lang.reflect.Constructor<java.lang.Thread> getBigThreadConstructor()