AbstractQueuedSynchronizer.ConditionObject (Java SE 12 & JDK 12 )
Keywords: java.util.concurrent.locks.AbstractQueuedSynchronizer.ConditionObject class

Module java.base
Package java.util.concurrent.locks

## Class AbstractQueuedSynchronizer.ConditionObject

- java.lang.Object
- - java.util.concurrent.locks.AbstractQueuedSynchronizer.ConditionObject

- All Implemented Interfaces:
    `Serializable`, `Condition`
  Enclosing class:
    AbstractQueuedSynchronizer

      public class AbstractQueuedSynchronizer.ConditionObject
      extends Object
      implements Condition, Serializable

  Condition implementation for a `AbstractQueuedSynchronizer` serving as the basis of a `Lock` implementation.

  Method documentation for this class describes mechanics, not behavioral specifications from the point of view of Lock and Condition users. Exported versions of this class will in general need to be accompanied by documentation describing condition semantics that rely on those of the associated `AbstractQueuedSynchronizer`.

  This class is Serializable, but all fields are transient, so deserialized conditions have no waiters.

  See Also:
    Serialized Form

- - ### Constructor Summary

    Constructors
    Constructor | Description
    --- | ---
    `ConditionObject()` | Creates a new `ConditionObject` instance.

  - ### Method Summary

    Modifier and Type | Method | Description
    --- | --- | ---
    `void` | `await()` | Implements interruptible condition wait.
    `boolean` | `await​(long time, TimeUnit unit)` | Implements timed condition wait.
    `long` | `awaitNanos​(long nanosTimeout)` | Implements timed condition wait.
    `void` | `awaitUninterruptibly()` | Implements uninterruptible condition wait.
    `boolean` | `awaitUntil​(Date deadline)` | Implements absolute timed condition wait.
    `protected Collection<Thread>` | `getWaitingThreads()` | Returns a collection containing those threads that may be waiting on this Condition.
    `protected int` | `getWaitQueueLength()` | Returns an estimate of the number of threads waiting on this condition.
    `protected boolean` | `hasWaiters()` | Queries whether any threads are waiting on this condition.
    `void` | `signal()` | Moves the longest-waiting thread, if one exists, from the wait queue for this condition to the wait queue for the owning lock.
    `void` | `signalAll()` | Moves all threads from the wait queue for this condition to the wait queue for the owning lock.

    - ### Methods declared in class java.lang.Object

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

- - ### Constructor Detail

    - #### ConditionObject

          public ConditionObject()

      Creates a new `ConditionObject` instance.

  - ### Method Detail

    - #### signal

          public final void signal()

      Moves the longest-waiting thread, if one exists, from the wait queue for this condition to the wait queue for the owning lock.
      Specified by:
        `signal` in interface `Condition`
      Throws:
        `IllegalMonitorStateException` - if `AbstractQueuedSynchronizer.isHeldExclusively()` returns `false`

    - #### signalAll

          public final void signalAll()

      Moves all threads from the wait queue for this condition to the wait queue for the owning lock.
      Specified by:
        `signalAll` in interface `Condition`
      Throws:
        `IllegalMonitorStateException` - if `AbstractQueuedSynchronizer.isHeldExclusively()` returns `false`

    - #### awaitUninterruptibly

          public final void awaitUninterruptibly()

      Implements uninterruptible condition wait.
      1. Save lock state returned by `AbstractQueuedSynchronizer.getState()`.
      2. Invoke `AbstractQueuedSynchronizer.release(int)` with saved state as argument, throwing IllegalMonitorStateException if it fails.
      3. Block until signalled.
      4. Reacquire by invoking specialized version of `AbstractQueuedSynchronizer.acquire(int)` with saved state as argument.
      Specified by:
        `awaitUninterruptibly` in interface `Condition`

    - #### await

          public final void await()
                           throws InterruptedException

      Implements interruptible condition wait.
      1. If current thread is interrupted, throw InterruptedException.
      2. Save lock state returned by `AbstractQueuedSynchronizer.getState()`.
      3. Invoke `AbstractQueuedSynchronizer.release(int)` with saved state as argument, throwing IllegalMonitorStateException if it fails.
      4. Block until signalled or interrupted.
      5. Reacquire by invoking specialized version of `AbstractQueuedSynchronizer.acquire(int)` with saved state as argument.
      6. If interrupted while blocked in step 4, throw InterruptedException.
      Specified by:
        `await` in interface `Condition`
      Throws:
        `InterruptedException` - if the current thread is interrupted (and interruption of thread suspension is supported)

    - #### awaitNanos

          public final long awaitNanos​(long nanosTimeout)
                                throws InterruptedException

      Implements timed condition wait.
      1. If current thread is interrupted, throw InterruptedException.
      2. Save lock state returned by `AbstractQueuedSynchronizer.getState()`.
      3. Invoke `AbstractQueuedSynchronizer.release(int)` with saved state as argument, throwing IllegalMonitorStateException if it fails.
      4. Block until signalled, interrupted, or timed out.
      5. Reacquire by invoking specialized version of `AbstractQueuedSynchronizer.acquire(int)` with saved state as argument.
      6. If interrupted while blocked in step 4, throw InterruptedException.
      Specified by:
        `awaitNanos` in interface `Condition`
      Parameters:
        `nanosTimeout` - the maximum time to wait, in nanoseconds
      Returns:
        an estimate of the `nanosTimeout` value minus the time spent waiting upon return from this method. A positive value may be used as the argument to a subsequent call to this method to finish waiting out the desired time. A value less than or equal to zero indicates that no time remains.
      Throws:
        `InterruptedException` - if the current thread is interrupted (and interruption of thread suspension is supported)

    - #### awaitUntil

          public final boolean awaitUntil​(Date deadline)
                                   throws InterruptedException

      Implements absolute timed condition wait.
      1. If current thread is interrupted, throw InterruptedException.
      2. Save lock state returned by `AbstractQueuedSynchronizer.getState()`.
      3. Invoke `AbstractQueuedSynchronizer.release(int)` with saved state as argument, throwing IllegalMonitorStateException if it fails.
      4. Block until signalled, interrupted, or timed out.
      5. Reacquire by invoking specialized version of `AbstractQueuedSynchronizer.acquire(int)` with saved state as argument.
      6. If interrupted while blocked in step 4, throw InterruptedException.
      7. If timed out while blocked in step 4, return false, else true.
      Specified by:
        `awaitUntil` in interface `Condition`
      Parameters:
        `deadline` - the absolute time to wait until
      Returns:
        `false` if the deadline has elapsed upon return, else `true`
      Throws:
        `InterruptedException` - if the current thread is interrupted (and interruption of thread suspension is supported)

    - #### await

          public final boolean await​(long time,
                                     TimeUnit unit)
                              throws InterruptedException

      Implements timed condition wait.
      1. If current thread is interrupted, throw InterruptedException.
      2. Save lock state returned by `AbstractQueuedSynchronizer.getState()`.
      3. Invoke `AbstractQueuedSynchronizer.release(int)` with saved state as argument, throwing IllegalMonitorStateException if it fails.
      4. Block until signalled, interrupted, or timed out.
      5. Reacquire by invoking specialized version of `AbstractQueuedSynchronizer.acquire(int)` with saved state as argument.
      6. If interrupted while blocked in step 4, throw InterruptedException.
      7. If timed out while blocked in step 4, return false, else true.
      Specified by:
        `await` in interface `Condition`
      Parameters:
        `time` - the maximum time to wait
        `unit` - the time unit of the `time` argument
      Returns:
        `false` if the waiting time detectably elapsed before return from the method, else `true`
      Throws:
        `InterruptedException` - if the current thread is interrupted (and interruption of thread suspension is supported)

    - #### hasWaiters

          protected final boolean hasWaiters()

      Queries whether any threads are waiting on this condition. Implements `AbstractQueuedSynchronizer.hasWaiters(ConditionObject)`.
      Returns:
        `true` if there are any waiting threads
      Throws:
        `IllegalMonitorStateException` - if `AbstractQueuedSynchronizer.isHeldExclusively()` returns `false`

    - #### getWaitQueueLength

          protected final int getWaitQueueLength()

      Returns an estimate of the number of threads waiting on this condition. Implements `AbstractQueuedSynchronizer.getWaitQueueLength(ConditionObject)`.
      Returns:
        the estimated number of waiting threads
      Throws:
        `IllegalMonitorStateException` - if `AbstractQueuedSynchronizer.isHeldExclusively()` returns `false`

    - #### getWaitingThreads

          protected final Collection<Thread> getWaitingThreads()

      Returns a collection containing those threads that may be waiting on this Condition. Implements `AbstractQueuedSynchronizer.getWaitingThreads(ConditionObject)`.
      Returns:
        the collection of threads
      Throws:
        `IllegalMonitorStateException` - if `AbstractQueuedSynchronizer.isHeldExclusively()` returns `false`