Package io.opentelemetry.context.internal.shaded

Class AbstractWeakConcurrentMap<K,V,L>

java.lang.Object
java.lang.ref.ReferenceQueue<K>
io.opentelemetry.context.internal.shaded.AbstractWeakConcurrentMap<K,V,L>
All Implemented Interfaces:
Iterable<Map.Entry<K,V>>, Runnable
Direct Known Subclasses:
WeakConcurrentMap
abstract class AbstractWeakConcurrentMap<K,V,L> extends ReferenceQueue<K> implements Runnable, Iterable<Map.Entry<K,V>>
A thread-safe map with weak keys. Entries are based on a key's system hash code and keys are considered equal only by reference equality. This class offers an abstract-base implementation that allows to override methods. This class does not implement the Map interface because this implementation is incompatible with the map contract. While iterating over a map's entries, any key that has not passed iteration is referenced non-weakly.

This class has been copied as is from https://github.com/raphw/weak-lock-free/blob/ad0e5e0c04d4a31f9485bf12b89afbc9d75473b3/src/main/java/com/blogspot/mydailyjava/weaklockfree/WeakConcurrentMap.java

This class is internal and is hence not for public use. Its APIs are unstable and can change at any time.

  • Field Details

  • Constructor Details

    • AbstractWeakConcurrentMap

      protected AbstractWeakConcurrentMap()

    • AbstractWeakConcurrentMap

      protected AbstractWeakConcurrentMap(ConcurrentMap<AbstractWeakConcurrentMap.WeakKey<K>,V> target)
      Parameters:
      target - ConcurrentMap implementation that this class wraps.

  • Method Details

    • getLookupKey

      protected abstract L getLookupKey(K key)
      Override with care as it can cause lookup failures if done incorrectly. The result must have the same Object.hashCode() as the input and be equal to a weak reference of the key. When overriding this, also override resetLookupKey(L).

    • resetLookupKey

      protected abstract void resetLookupKey(L lookupKey)
      Resets any reusable state in the lookup key.

    • get

      public V get(K key)
      Parameters:
      key - The key of the entry.
      Returns:
      The value of the entry or the default value if it did not exist.

    • getIfPresent

      public V getIfPresent(K key)
      Parameters:
      key - The key of the entry.
      Returns:
      The value of the entry or null if it did not exist.

    • containsKey

      public boolean containsKey(K key)
      Parameters:
      key - The key of the entry.
      Returns:
      true if the key already defines a value.

    • put

      public V put(K key, V value)
      Parameters:
      key - The key of the entry.
      value - The value of the entry.
      Returns:
      The previous entry or null if it does not exist.

    • putIfAbsent

      public V putIfAbsent(K key, V value)
      Parameters:
      key - The key of the entry.
      value - The value of the entry.
      Returns:
      The previous entry or null if it does not exist.

    • putIfProbablyAbsent

      public V putIfProbablyAbsent(K key, V value)
      Parameters:
      key - The key of the entry.
      value - The value of the entry.
      Returns:
      The previous entry or null if it does not exist.

    • remove

      public V remove(K key)
      Parameters:
      key - The key of the entry.
      Returns:
      The removed entry or null if it does not exist.

    • clear

      public void clear()
      Clears the entire map.

    • defaultValue

      protected V defaultValue(K key)
      Creates a default value. There is no guarantee that the requested value will be set as a once it is created in case that another thread requests a value for a key concurrently.
      Parameters:
      key - The key for which to create a default value.
      Returns:
      The default value for a key without value or null for not defining a default value.

    • expungeStaleEntries

      public void expungeStaleEntries()
      Cleans all unused references.

    • approximateSize

      public int approximateSize()
      Returns the approximate size of this map where the returned number is at least as big as the actual number of entries.
      Returns:
      The minimum size of this map.

    • run

      public void run()
      Specified by:
      run in interface Runnable

    • iterator

      public Iterator<Map.Entry<K,V>> iterator()
      Specified by:
      iterator in interface Iterable<K>

    • toString

      public String toString()
      Overrides:
      toString in class Object