Package java.util.concurrent.locks
The Lock
interface supports
locking disciplines that differ in semantics (reentrant, fair, etc),
and that can be used in non-block-structured contexts including
hand-over-hand and lock reordering algorithms. The main implementation
is ReentrantLock
.
The ReadWriteLock
interface
similarly defines locks that may be shared among readers but are
exclusive to writers. Only a single implementation, ReentrantReadWriteLock
, is provided, since
it covers most standard usage contexts. But programmers may create
their own implementations to cover nonstandard requirements.
The Condition
interface
describes condition variables that may be associated with Locks.
These are similar in usage to the implicit monitors accessed using
Object.wait
, but offer extended capabilities.
In particular, multiple Condition
objects may be associated
with a single Lock
. To avoid compatibility issues, the
names of Condition
methods are different from the
corresponding Object
versions.
The AbstractQueuedSynchronizer
class serves as a useful superclass for defining locks and other
synchronizers that rely on queuing blocked threads. The AbstractQueuedLongSynchronizer
class
provides the same functionality but extends support to 64 bits of
synchronization state. Both extend class AbstractOwnableSynchronizer
, a simple
class that helps record the thread currently holding exclusive
synchronization. The LockSupport
class provides lower-level blocking and unblocking support that is
useful for those developers implementing their own customized lock
classes.
- Since:
- 1.5
-
ClassDescriptionA synchronizer that may be exclusively owned by a thread.A version of
AbstractQueuedSynchronizer
in which synchronization state is maintained as along
.Provides a framework for implementing blocking locks and related synchronizers (semaphores, events, etc) that rely on first-in-first-out (FIFO) wait queues.Lock
implementations provide more extensive locking operations than can be obtained usingsynchronized
methods and statements.Basic thread blocking primitives for creating locks and other synchronization classes.AReadWriteLock
maintains a pair of associatedlocks
, one for read-only operations and one for writing.A reentrant mutual exclusionLock
with the same basic behavior and semantics as the implicit monitor lock accessed usingsynchronized
methods and statements, but with extended capabilities.An implementation ofReadWriteLock
supporting similar semantics toReentrantLock
.The lock returned by methodReentrantReadWriteLock.readLock()
.The lock returned by methodReentrantReadWriteLock.writeLock()
.A capability-based lock with three modes for controlling read/write access.