Package io.debezium.util

Class BoundedConcurrentHashMap.Segment<K,V>

java.lang.Object

java.util.concurrent.locks.ReentrantLock

io.debezium.util.BoundedConcurrentHashMap.Segment<K,V>

All Implemented Interfaces:

Serializable, Lock

Enclosing class:

BoundedConcurrentHashMap<K,V>

static final class BoundedConcurrentHashMap.Segment<K,V>
extends ReentrantLock

Segments are specialized versions of hash tables. This subclasses from ReentrantLock opportunistically, just to simplify some locking and avoid separate construction.

Field Summary

Fields

Modifier and Type	Field	Description
(package private) int	count	The number of elements in this segment's region.
(package private) final int	evictCap
(package private) final BoundedConcurrentHashMap.EvictionPolicy<K,V>	eviction
(package private) final BoundedConcurrentHashMap.EvictionListener<K,V>	evictionListener
(package private) final float	loadFactor	The load factor for the hash table.
(package private) int	modCount	Number of updates that alter the size of the table.
private static final long	serialVersionUID
(package private) BoundedConcurrentHashMap.HashEntry<K,V>[]	table	The per-segment table.
(package private) int	threshold	The table is rehashed when its size exceeds this threshold.

Constructor Summary

Constructors

Constructor	Description
Segment(int cap, int evictCap, float lf, BoundedConcurrentHashMap.Eviction es, BoundedConcurrentHashMap.EvictionListener<K,V> listener)

Method Summary

Modifier and Type	Method	Description
private Set<BoundedConcurrentHashMap.HashEntry<K,V>>	attemptEviction(boolean lockedAlready)
(package private) void	clear()
(package private) boolean	containsKey(Object key, int hash)
(package private) boolean	containsValue(Object value)
(package private) V	get(Object key, int hash)
(package private) BoundedConcurrentHashMap.EvictionListener<K,V>	getEvictionListener()
(package private) BoundedConcurrentHashMap.HashEntry<K,V>	getFirst(int hash)	Returns properly casted first entry of bin for given hash.
(package private) static <K, V> BoundedConcurrentHashMap.Segment<K,V>[]	newArray(int i)
private void	notifyEvictionListener(Set<BoundedConcurrentHashMap.HashEntry<K,V>> evicted)
(package private) V	put(K key, int hash, V value, boolean onlyIfAbsent)
(package private) V	readValueUnderLock(BoundedConcurrentHashMap.HashEntry<K,V> e)	Reads value field of an entry under lock.
(package private) void	rehash()
(package private) V	remove(Object key, int hash, Object value)	Remove; match on key only if value null, else match both.
(package private) V	replace(K key, int hash, V newValue)
(package private) boolean	replace(K key, int hash, V oldValue, V newValue)
(package private) void	setTable(BoundedConcurrentHashMap.HashEntry<K,V>[] newTable)	Sets table to new HashEntry array.

Methods inherited from class java.util.concurrent.locks.ReentrantLock

getHoldCount, getOwner, getQueuedThreads, getQueueLength, getWaitingThreads, getWaitQueueLength, hasQueuedThread, hasQueuedThreads, hasWaiters, isFair, isHeldByCurrentThread, isLocked, lock, lockInterruptibly, newCondition, toString, tryLock, tryLock, unlock

Methods inherited from class java.lang.Object

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

Field Details

serialVersionUID

private static final long serialVersionUID

See Also:

• Constant Field Values

count

transient volatile int count

The number of elements in this segment's region.

modCount

transient int modCount

Number of updates that alter the size of the table. This is used during bulk-read methods to make sure they see a consistent snapshot: If modCounts change during a traversal of segments computing size or checking containsValue, then we might have an inconsistent view of state so (usually) must retry.

threshold

transient int threshold

The table is rehashed when its size exceeds this threshold. (The value of this field is always (int)(capacity * loadFactor).)

table

transient volatile BoundedConcurrentHashMap.HashEntry<K,V>[] table

The per-segment table.

loadFactor

final float loadFactor

The load factor for the hash table. Even though this value is same for all segments, it is replicated to avoid needing links to outer object.

evictCap

final int evictCap

eviction

final transient BoundedConcurrentHashMap.EvictionPolicy<K,V> eviction

evictionListener

final transient BoundedConcurrentHashMap.EvictionListener<K,V> evictionListener

Constructor Details

Segment

Segment(int cap,
 int evictCap,
 float lf,
 BoundedConcurrentHashMap.Eviction es,
 BoundedConcurrentHashMap.EvictionListener<K,V> listener)

Method Details

newArray

static <K,
V>
BoundedConcurrentHashMap.Segment<K,V>[] newArray(int i)

getEvictionListener

BoundedConcurrentHashMap.EvictionListener<K,V> getEvictionListener()

setTable

void setTable(BoundedConcurrentHashMap.HashEntry<K,V>[] newTable)

Sets table to new HashEntry array. Call only while holding lock or in constructor.

getFirst

BoundedConcurrentHashMap.HashEntry<K,V> getFirst(int hash)

Returns properly casted first entry of bin for given hash.

readValueUnderLock

V readValueUnderLock(BoundedConcurrentHashMap.HashEntry<K,V> e)

Reads value field of an entry under lock. Called if value field ever appears to be null. This is possible only if a compiler happens to reorder a HashEntry initialization with its table assignment, which is legal under memory model but is not known to ever occur.

get

V get(Object key,
 int hash)

containsKey

boolean containsKey(Object key,
 int hash)

containsValue

boolean containsValue(Object value)

replace

boolean replace(K key,
 int hash,
 V oldValue,
 V newValue)

replace

V replace(K key,
 int hash,
 V newValue)

put

V put(K key,
 int hash,
 V value,
 boolean onlyIfAbsent)

rehash

void rehash()

remove

V remove(Object key,
 int hash,
 Object value)

Remove; match on key only if value null, else match both.

clear

void clear()

attemptEviction

private Set<BoundedConcurrentHashMap.HashEntry<K,V>> attemptEviction(boolean lockedAlready)

notifyEvictionListener

private void notifyEvictionListener(Set<BoundedConcurrentHashMap.HashEntry<K,V>> evicted)