WeakIdentityHashMap.WeakBucket

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gnu.java.util
Class WeakIdentityHashMap.WeakBucket

java.lang.Object
  java.lang.ref.Reference
      java.lang.ref.WeakReference
          gnu.java.util.WeakIdentityHashMap.WeakBucket

Enclosing class:: WeakIdentityHashMap

private static class WeakIdentityHashMap.WeakBucket
extends java.lang.ref.WeakReference

A bucket is a weak reference to the key, that contains a strong reference to the value, a pointer to the next bucket and its slot number.
It would be cleaner to have a WeakReference as field, instead of extending it, but if a weak reference gets cleared, we only get the weak reference (by queue.poll) and wouldn't know where to look for this reference in the hashtable, to remove that entry.

Nested Class Summary

(package private) class WeakIdentityHashMap.WeakBucket.WeakEntry
          This class gives the Entry representation of the current bucket.

Field Summary

(package private) WeakIdentityHashMap.WeakBucket next
          The next bucket describing another entry that uses the same slot.

(package private) int slot
          The slot of this entry.

(package private) java.lang.Object value
          The value of this entry.

Fields inherited from class java.lang.ref.Reference

Constructor Summary

WeakIdentityHashMap.WeakBucket(java.lang.Object key, java.lang.ref.ReferenceQueue queue, java.lang.Object value, int slot)
          Creates a new bucket for the given key/value pair and the specified slot.

Method Summary

(package private) WeakIdentityHashMap.WeakBucket.WeakEntry getEntry()
          This returns the entry stored in this bucket, or null, if the bucket got cleared in the mean time.

Methods inherited from class java.lang.ref.Reference

clear, enqueue, get, isEnqueued

Methods inherited from class java.lang.Object

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

Field Detail

value

java.lang.Object value

The value of this entry. The key is stored in the weak reference that we extend.

WeakIdentityHashMap.WeakBucket next

The next bucket describing another entry that uses the same slot.

slot

int slot

The slot of this entry. This should be Math.abs(key.hashCode() % buckets.length). But since the key may be silently removed we have to remember the slot number. If this bucket was removed the slot is -1. This marker will prevent the bucket from being removed twice.

Constructor Detail