org.mapdb

Class LongConcurrentHashMap.Segment<V>

java.lang.Object

java.util.concurrent.locks.ReentrantLock

org.mapdb.LongConcurrentHashMap.Segment<V>

All Implemented Interfaces:

java.io.Serializable, java.util.concurrent.locks.Lock

Enclosing class:

LongConcurrentHashMap<V>

static final class LongConcurrentHashMap.Segment<V>
extends java.util.concurrent.locks.ReentrantLock
implements java.io.Serializable

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 and Description
(package private) int	count The number of elements in this segment's region.
(package private) 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 long	serialVersionUID
(package private) LongConcurrentHashMap.HashEntry<V>[]	table The per-segment table.
(package private) int	threshold The table is rehashed when its size exceeds this threshold.

Constructor Summary

Constructors

Constructor and Description
Segment(int initialCapacity, float lf)

Method Summary

Modifier and Type	Method and Description
(package private) void	clear()
(package private) boolean	containsKey(long key, int hash)
(package private) boolean	containsValue(java.lang.Object value)
(package private) V	get(long key, int hash)
(package private) LongConcurrentHashMap.HashEntry<V>	getFirst(int hash) Returns properly casted first entry of bin for given hash.
(package private) static <V> LongConcurrentHashMap.Segment<V>[]	newArray(int i)
(package private) V	put(long key, int hash, V value, boolean onlyIfAbsent)
(package private) V	readValueUnderLock(LongConcurrentHashMap.HashEntry<V> e) Reads value field of an entry under lock.
(package private) void	rehash()
(package private) V	remove(long key, int hash, java.lang.Object value) Remove; match on key only if value null, else match both.
(package private) V	replace(long key, int hash, V newValue)
(package private) boolean	replace(long key, int hash, V oldValue, V newValue)
(package private) void	setTable(LongConcurrentHashMap.HashEntry<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 Detail

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 LongConcurrentHashMap.HashEntry<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.

Constructor Detail

Segment

Segment(int initialCapacity,
        float lf)

Method Detail

newArray

static <V> LongConcurrentHashMap.Segment<V>[] newArray(int i)

setTable

void setTable(LongConcurrentHashMap.HashEntry<V>[] newTable)

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

getFirst

LongConcurrentHashMap.HashEntry<V> getFirst(int hash)

Returns properly casted first entry of bin for given hash.

readValueUnderLock

V readValueUnderLock(LongConcurrentHashMap.HashEntry<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(long key,
      int hash)

containsKey

boolean containsKey(long key,
                    int hash)

containsValue

boolean containsValue(java.lang.Object value)

replace

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

replace

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

put

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

rehash

void rehash()

remove

V remove(long key,
         int hash,
         java.lang.Object value)

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

clear

void clear()