Package org.apache.ignite.internal.processors.datastructures

Class GridCacheLockImpl

    • Method Detail

      • onUpdate

        public void onUpdate​(GridCacheLockState val)
        Callback to notify reentrant lock on changes.
        Specified by:
        onUpdate in interface GridCacheLockEx
        Parameters:
        val - New reentrant lock state.

      • onNodeRemoved

        public void onNodeRemoved​(UUID nodeId)
        Callback to notify semaphore on topology changes.
        Specified by:
        onNodeRemoved in interface GridCacheLockEx
        Parameters:
        nodeId - Id of the node that left the grid.

      • onReconnected

        public void onReconnected​(UUID nodeId)
        Callback to notify local reentrant lock instance on node reconnected.
        Specified by:
        onReconnected in interface GridCacheLockEx
        Parameters:
        nodeId - Node ID.

      • onStop

        public void onStop()
        Callback to notify local reentrant lock instance on node stop.
        Specified by:
        onStop in interface GridCacheLockEx

      • lock

        public void lock()
        Acquires the distributed reentrant lock.

        Acquires the lock if it is not held by another thread and returns immediately, setting the lock hold count to one.

        If the current thread already holds this lock then the hold count is incremented by one and the method returns immediately.

        If the lock is held by another thread then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:

        • The lock is acquired by the current thread; or
        • Lock is broken (any node failed while owning this lock), and lock is created in non-failoverSafe mode.
        • Local node is stopped.
        Specified by:
        lock in interface IgniteLock
        Specified by:
        lock in interface Lock

      • lockInterruptibly

        public void lockInterruptibly()
                       throws IgniteInterruptedException
        Acquires the lock unless the current thread is interrupted.

        Acquires the lock if it is not held by another thread and returns immediately, setting the lock hold count to one.

        If the current thread already holds this lock then the hold count is incremented by one and the method returns immediately.

        If the lock is held by another thread then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of four things happens:

        • The lock is acquired by the current thread; or
        • Some other thread interrupts the current thread.
        • Lock is broken (any node failed while owning this lock), and lock is created in non-failoverSafe mode.
        • Local node is stopped.

        If the lock is acquired by the current thread then the lock hold count is set to one.

        If the current thread:

        • has its interrupted status set on entry to this method; or
        • is interrupted while acquiring the lock; or then IgniteInterruptedException is thrown and the current thread's interrupted status is cleared.

        IgniteException is thrown in case:

        • the lock is broken before or during the attempt to acquire this lock; or
        • local node is stopped,

        In this implementation, as this method is an explicit interruption point, preference is given to responding to the interrupt over normal or reentrant acquisition of the lock.

        Specified by:
        lockInterruptibly in interface IgniteLock
        Specified by:
        lockInterruptibly in interface Lock
        Throws:
        IgniteInterruptedException - if the current thread is interrupted

      • tryLock

        public boolean tryLock()
        Acquires the lock only if it is free at the time of invocation.

        Acquires the lock if it is available and returns immediately with the value true. If the lock is not available then this method will return immediately with the value false.

        A typical usage idiom for this method would be: 

         
 Lock lock = ...;
 if (lock.tryLock()) {
   try {
     // manipulate protected state
   } finally {
     lock.unlock();
   }
 } else {
   // perform alternative actions
 }
        This usage ensures that the lock is unlocked if it was acquired, and doesn't try to unlock if the lock was not acquired. If node is stopped, or any node failed while owning the lock in non-failoverSafe mode, then IgniteException is thrown.
        Specified by:
        tryLock in interface IgniteLock
        Specified by:
        tryLock in interface Lock
        Returns:
        true if the lock was acquired and false otherwise

      • tryLock

        public boolean tryLock​(long timeout,
                       TimeUnit unit)
                throws IgniteInterruptedException
        Acquires the lock if it is not held by another thread within the given waiting time and the current thread has not been interrupted.

        Acquires the lock if it is not held by another thread and returns immediately with the value true, setting the lock hold count to one.

        If the current thread already holds this lock then the hold count is incremented by one and the method returns true.

        If the lock is held by another thread then the current thread becomes disabled for thread scheduling purposes and lies dormant until one of five things happens:

        • The lock is acquired by the current thread; or
        • Some other thread interrupts the current thread; or
        • Lock is broken (any node failed while owning this lock), and lock is created in non-failoverSafe mode.
        • Local node is stopped.
        • The specified waiting time elapses

        If the lock is acquired then the value true is returned and the lock hold count is set to one.

        If the current thread:

        • has its interrupted status set on entry to this method; or
        • is interrupted while acquiring the lock; or
        then IgniteInterruptedException is thrown and the current thread's interrupted status is cleared.

        IgniteException is thrown in case:

        • the lock is broken before or during the attempt to acquire this lock; or
        • local node is stopped,

        If the specified waiting time elapses then the value false is returned. If the time is less than or equal to zero, the method will not wait at all.

        In this implementation, as this method is an explicit interruption point, preference is given to responding to the interrupt over normal or reentrant acquisition of the lock, and over reporting the elapse of the waiting time.

        Specified by:
        tryLock in interface IgniteLock
        Specified by:
        tryLock in interface Lock
        Parameters:
        timeout - the time to wait for the lock
        unit - the time unit of the timeout argument
        Returns:
        true if the lock was free and was acquired by the current thread, or the lock was already held by the current thread; and false if the waiting time elapsed before the lock could be acquired
        Throws:
        IgniteInterruptedException - if the current thread is interrupted

      • unlock

        public void unlock()
        Releases the lock. If lock is not owned by current thread, then an IllegalMonitorStateException is thrown. If lock is already broken prior to invocation of this method, and lock is created in non-failover safe mode, then IgniteException is thrown.
        Specified by:
        unlock in interface IgniteLock
        Specified by:
        unlock in interface Lock

      • getOrCreateCondition

        public IgniteCondition getOrCreateCondition​(String name)
        Returns a Condition instance for use with this IgniteLock instance.
        • If this lock is not held when any of the Condition waiting or signalling methods are called, then an IllegalMonitorStateException is thrown.
        • When the condition waiting methods are called the lock is released and, before they return, the lock is reacquired and the lock hold count restored to what it was when the method was called.
        • If a thread is interrupted while waiting then the wait will terminate, an IgniteInterruptedException will be thrown, and the thread's interrupted status will be cleared.
        • Waiting threads are signalled in FIFO order.
        Specified by:
        getOrCreateCondition in interface IgniteLock
        Parameters:
        name - Name of the distributed condition object
        Returns:
        the Condition object

      • getHoldCount

        public int getHoldCount()
        Queries the number of holds on this lock by the current thread.
        Specified by:
        getHoldCount in interface IgniteLock
        Returns:
        the number of holds on this lock by the current thread, or zero if this lock is not held by the current thread

      • isHeldByCurrentThread

        public boolean isHeldByCurrentThread()
        Queries if this lock is held by the current thread.
        Specified by:
        isHeldByCurrentThread in interface IgniteLock
        Returns:
        true if current thread holds this lock and false otherwise

      • isLocked

        public boolean isLocked()
        Queries if this lock is held by any thread on any node. This method is designed for use in monitoring of the system state, not for synchronization control.
        Specified by:
        isLocked in interface IgniteLock
        Returns:
        true if any thread on this or any other node holds this lock and false otherwise

      • hasQueuedThreads

        public boolean hasQueuedThreads()
        Queries whether any threads on this node are waiting to acquire this lock. Note that because cancellations may occur at any time, a true return does not guarantee that any other thread will ever acquire this lock. This method is designed primarily for use in monitoring of the system state.
        Specified by:
        hasQueuedThreads in interface IgniteLock
        Returns:
        true if there may be other threads on this node waiting to acquire the lock

      • hasQueuedThread

        public boolean hasQueuedThread​(Thread thread)
        Queries whether the given thread is waiting to acquire this lock. Note that because cancellations may occur at any time, a true return does not guarantee that this thread will ever acquire this lock. This method is designed primarily for use in monitoring of the system state.
        Specified by:
        hasQueuedThread in interface IgniteLock
        Parameters:
        thread - the thread
        Returns:
        true if the given thread is queued waiting for this lock

      • hasWaiters

        public boolean hasWaiters​(IgniteCondition condition)
        Queries whether any threads on this node are waiting on the given condition associated with this lock. Note that because timeouts and interrupts may occur at any time, a true return does not guarantee that a future signal will awaken any threads. This method is designed primarily for use in monitoring of the system state.
        Specified by:
        hasWaiters in interface IgniteLock
        Parameters:
        condition - the condition
        Returns:
        true if there are any waiting threads on this node

      • getWaitQueueLength

        public int getWaitQueueLength​(IgniteCondition condition)
        Returns an estimate of the number of threads on this node that are waiting on the given condition associated with this lock. Note that because timeouts and interrupts may occur at any time, the estimate serves only as an upper bound on the actual number of waiters. This method is designed for use in monitoring of the system state, not for synchronization control.
        Specified by:
        getWaitQueueLength in interface IgniteLock
        Parameters:
        condition - the condition
        Returns:
        the estimated number of waiting threads on this node

      • isFailoverSafe

        public boolean isFailoverSafe()
        Description copied from interface: IgniteLock
        Returns true if this lock is safe to use after node failure. If not, IgniteInterruptedException is thrown on every other node after node failure.
        Specified by:
        isFailoverSafe in interface IgniteLock
        Returns:
        true if this reentrant lock has failoverSafe set true

      • isFair

        public boolean isFair()
        Description copied from interface: IgniteLock
        Returns true if this lock is fair. Fairness flag can only be set on lock creation.
        Specified by:
        isFair in interface IgniteLock
        Returns:
        true if this reentrant lock has fairness flag set true.

      • isBroken

        public boolean isBroken()
        Returns true if any node that owned the locked failed before releasing the lock.
        Specified by:
        isBroken in interface IgniteLock
        Returns:
        true if any node failed while owning the lock since the lock on this node was initialized.