Class AbstractWeakConcurrentMap<K,V,L>
java.lang.Object
java.lang.ref.ReferenceQueue<K>
io.opentelemetry.context.internal.shaded.AbstractWeakConcurrentMap<K,V,L>
- 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.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionprivate class
private class
static final class
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Field Summary
FieldsModifier and TypeFieldDescription(package private) final ConcurrentMap
<AbstractWeakConcurrentMap.WeakKey<K>, V> -
Constructor Summary
ConstructorsModifierConstructorDescriptionprotected
protected
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Method Summary
Modifier and TypeMethodDescriptionint
Returns the approximate size of this map where the returned number is at least as big as the actual number of entries.void
clear()
Clears the entire map.boolean
containsKey
(K key) protected V
defaultValue
(K key) Creates a default value.void
Cleans all unused references.getIfPresent
(K key) protected abstract L
getLookupKey
(K key) Override with care as it can cause lookup failures if done incorrectly.iterator()
putIfAbsent
(K key, V value) putIfProbablyAbsent
(K key, V value) protected abstract void
resetLookupKey
(L lookupKey) Resets any reusable state in the lookup key.void
run()
toString()
Methods inherited from class java.lang.ref.ReferenceQueue
poll, remove, remove
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods inherited from interface java.lang.Iterable
forEach, spliterator
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Field Details
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target
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Constructor Details
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AbstractWeakConcurrentMap
protected AbstractWeakConcurrentMap() -
AbstractWeakConcurrentMap
- Parameters:
target
- ConcurrentMap implementation that this class wraps.
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Method Details
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getLookupKey
Override with care as it can cause lookup failures if done incorrectly. The result must have the sameObject.hashCode()
as the input and beequal to
a weak reference of the key. When overriding this, also overrideresetLookupKey(L)
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resetLookupKey
Resets any reusable state in the lookup key. -
get
- Parameters:
key
- The key of the entry.- Returns:
- The value of the entry or the default value if it did not exist.
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getIfPresent
- Parameters:
key
- The key of the entry.- Returns:
- The value of the entry or null if it did not exist.
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containsKey
- Parameters:
key
- The key of the entry.- Returns:
true
if the key already defines a value.
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put
- Parameters:
key
- The key of the entry.value
- The value of the entry.- Returns:
- The previous entry or
null
if it does not exist.
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putIfAbsent
- Parameters:
key
- The key of the entry.value
- The value of the entry.- Returns:
- The previous entry or
null
if it does not exist.
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putIfProbablyAbsent
- Parameters:
key
- The key of the entry.value
- The value of the entry.- Returns:
- The previous entry or
null
if it does not exist.
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remove
- Parameters:
key
- The key of the entry.- Returns:
- The removed entry or
null
if it does not exist.
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clear
public void clear()Clears the entire map. -
defaultValue
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.
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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.
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run
public void run() -
iterator
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toString
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