Package org.elasticsearch.common.util.concurrent

Class KeyedLock<T>

  • public final class KeyedLock<T>
extends java.lang.Object
    This class manages locks. Locks can be accessed with an identifier and are created the first time they are acquired and removed if no thread hold the lock. The latter is important to assure that the list of locks does not grow infinitely. Note: this lock is reentrant

    • Constructor Summary

      Constructors 
      Constructor Description
      KeyedLock()
      Creates a non-fair lock
      KeyedLock​(boolean fair)
      Creates a new lock

    • Method Summary

      Modifier and Type Method Description
      Releasable acquire​(T key)
      Acquires a lock for the given key.
      boolean hasLockedKeys()
      Returns true if this lock has at least one locked key.
      boolean isHeldByCurrentThread​(T key)
      Returns true iff the caller thread holds the lock for the given key
      Releasable tryAcquire​(T key)
      Tries to acquire the lock for the given key and returns it.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • KeyedLock

        public KeyedLock​(boolean fair)
        Creates a new lock
        Parameters:
        fair - Use fair locking, ie threads get the lock in the order they requested it

      • KeyedLock

        public KeyedLock()
        Creates a non-fair lock

    • Method Detail

      • acquire

        public Releasable acquire​(T key)
        Acquires a lock for the given key. The key is compared by it's equals method not by object identity. The lock can be acquired by the same thread multiple times. The lock is released by closing the returned Releasable.

      • tryAcquire

        public Releasable tryAcquire​(T key)
        Tries to acquire the lock for the given key and returns it. If the lock can't be acquired null is returned.

      • isHeldByCurrentThread

        public boolean isHeldByCurrentThread​(T key)
        Returns true iff the caller thread holds the lock for the given key

      • hasLockedKeys

        public boolean hasLockedKeys()
        Returns true if this lock has at least one locked key.