| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package org.apache.hadoop.hbase.procedure2; |
| |
| import java.util.Iterator; |
| import java.util.concurrent.TimeUnit; |
| import java.util.concurrent.locks.Condition; |
| import java.util.concurrent.locks.ReentrantLock; |
| |
| import org.apache.yetus.audience.InterfaceAudience; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| @InterfaceAudience.Private |
| public abstract class AbstractProcedureScheduler implements ProcedureScheduler { |
| private static final Logger LOG = LoggerFactory.getLogger(AbstractProcedureScheduler.class); |
| private final ReentrantLock schedulerLock = new ReentrantLock(); |
| private final Condition schedWaitCond = schedulerLock.newCondition(); |
| private boolean running = false; |
| |
| // TODO: metrics |
| private long pollCalls = 0; |
| private long nullPollCalls = 0; |
| |
| @Override |
| public void start() { |
| schedLock(); |
| try { |
| running = true; |
| } finally { |
| schedUnlock(); |
| } |
| } |
| |
| @Override |
| public void stop() { |
| schedLock(); |
| try { |
| running = false; |
| schedWaitCond.signalAll(); |
| } finally { |
| schedUnlock(); |
| } |
| } |
| |
| @Override |
| public void signalAll() { |
| schedLock(); |
| try { |
| schedWaitCond.signalAll(); |
| } finally { |
| schedUnlock(); |
| } |
| } |
| |
| // ========================================================================== |
| // Add related |
| // ========================================================================== |
| /** |
| * Add the procedure to the queue. |
| * NOTE: this method is called with the sched lock held. |
| * @param procedure the Procedure to add |
| * @param addFront true if the item should be added to the front of the queue |
| */ |
| protected abstract void enqueue(Procedure procedure, boolean addFront); |
| |
| @Override |
| public void addFront(final Procedure procedure) { |
| push(procedure, true, true); |
| } |
| |
| @Override |
| public void addFront(final Procedure procedure, boolean notify) { |
| push(procedure, true, notify); |
| } |
| |
| @Override |
| public void addFront(Iterator<Procedure> procedureIterator) { |
| schedLock(); |
| try { |
| int count = 0; |
| while (procedureIterator.hasNext()) { |
| Procedure procedure = procedureIterator.next(); |
| if (LOG.isTraceEnabled()) { |
| LOG.trace("Wake " + procedure); |
| } |
| push(procedure, /* addFront= */ true, /* notify= */false); |
| count++; |
| } |
| wakePollIfNeeded(count); |
| } finally { |
| schedUnlock(); |
| } |
| } |
| |
| @Override |
| public void addBack(final Procedure procedure) { |
| push(procedure, false, true); |
| } |
| |
| @Override |
| public void addBack(final Procedure procedure, boolean notify) { |
| push(procedure, false, notify); |
| } |
| |
| protected void push(final Procedure procedure, final boolean addFront, final boolean notify) { |
| schedLock(); |
| try { |
| enqueue(procedure, addFront); |
| if (notify) { |
| schedWaitCond.signal(); |
| } |
| } finally { |
| schedUnlock(); |
| } |
| } |
| |
| // ========================================================================== |
| // Poll related |
| // ========================================================================== |
| /** |
| * Fetch one Procedure from the queue |
| * NOTE: this method is called with the sched lock held. |
| * @return the Procedure to execute, or null if nothing is available. |
| */ |
| protected abstract Procedure dequeue(); |
| |
| @Override |
| public Procedure poll() { |
| return poll(-1); |
| } |
| |
| @Override |
| public Procedure poll(long timeout, TimeUnit unit) { |
| return poll(unit.toNanos(timeout)); |
| } |
| |
| @edu.umd.cs.findbugs.annotations.SuppressWarnings("WA_AWAIT_NOT_IN_LOOP") |
| public Procedure poll(final long nanos) { |
| schedLock(); |
| try { |
| if (!running) { |
| LOG.debug("the scheduler is not running"); |
| return null; |
| } |
| |
| if (!queueHasRunnables()) { |
| // WA_AWAIT_NOT_IN_LOOP: we are not in a loop because we want the caller |
| // to take decisions after a wake/interruption. |
| if (nanos < 0) { |
| schedWaitCond.await(); |
| } else { |
| schedWaitCond.awaitNanos(nanos); |
| } |
| if (!queueHasRunnables()) { |
| nullPollCalls++; |
| return null; |
| } |
| } |
| final Procedure pollResult = dequeue(); |
| |
| pollCalls++; |
| nullPollCalls += (pollResult == null) ? 1 : 0; |
| return pollResult; |
| } catch (InterruptedException e) { |
| Thread.currentThread().interrupt(); |
| nullPollCalls++; |
| return null; |
| } finally { |
| schedUnlock(); |
| } |
| } |
| |
| // ========================================================================== |
| // Utils |
| // ========================================================================== |
| /** |
| * Returns the number of elements in this queue. |
| * NOTE: this method is called with the sched lock held. |
| * @return the number of elements in this queue. |
| */ |
| protected abstract int queueSize(); |
| |
| /** |
| * Returns true if there are procedures available to process. |
| * NOTE: this method is called with the sched lock held. |
| * @return true if there are procedures available to process, otherwise false. |
| */ |
| protected abstract boolean queueHasRunnables(); |
| |
| @Override |
| public int size() { |
| schedLock(); |
| try { |
| return queueSize(); |
| } finally { |
| schedUnlock(); |
| } |
| } |
| |
| @Override |
| public boolean hasRunnables() { |
| schedLock(); |
| try { |
| return queueHasRunnables(); |
| } finally { |
| schedUnlock(); |
| } |
| } |
| |
| // ============================================================================ |
| // TODO: Metrics |
| // ============================================================================ |
| public long getPollCalls() { |
| return pollCalls; |
| } |
| |
| public long getNullPollCalls() { |
| return nullPollCalls; |
| } |
| |
| // ========================================================================== |
| // Procedure Events |
| // ========================================================================== |
| |
| /** |
| * Wake up all of the given events. |
| * Note that we first take scheduler lock and then wakeInternal() synchronizes on the event. |
| * Access should remain package-private. Use ProcedureEvent class to wake/suspend events. |
| * @param events the list of events to wake |
| */ |
| public void wakeEvents(ProcedureEvent[] events) { |
| schedLock(); |
| try { |
| for (ProcedureEvent event : events) { |
| if (event == null) { |
| continue; |
| } |
| event.wakeInternal(this); |
| } |
| } finally { |
| schedUnlock(); |
| } |
| } |
| |
| /** |
| * Wakes up given waiting procedures by pushing them back into scheduler queues. |
| * @return size of given {@code waitQueue}. |
| */ |
| protected int wakeWaitingProcedures(LockAndQueue lockAndQueue) { |
| return lockAndQueue.wakeWaitingProcedures(this); |
| } |
| |
| protected void waitProcedure(LockAndQueue lockAndQueue, final Procedure proc) { |
| lockAndQueue.addLast(proc); |
| } |
| |
| protected void wakeProcedure(final Procedure procedure) { |
| LOG.trace("Wake {}", procedure); |
| push(procedure, /* addFront= */ true, /* notify= */false); |
| } |
| |
| // ========================================================================== |
| // Internal helpers |
| // ========================================================================== |
| protected void schedLock() { |
| schedulerLock.lock(); |
| } |
| |
| protected void schedUnlock() { |
| schedulerLock.unlock(); |
| } |
| |
| protected void wakePollIfNeeded(final int waitingCount) { |
| if (waitingCount <= 0) { |
| return; |
| } |
| if (waitingCount == 1) { |
| schedWaitCond.signal(); |
| } else { |
| schedWaitCond.signalAll(); |
| } |
| } |
| } |