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The UnboundID LDAP SDK for Java is a fast, comprehensive, and easy-to-use
Java API for communicating with LDAP directory servers and performing
related tasks like reading and writing LDIF, encoding and decoding data
using base64 and ASN.1 BER, and performing secure communication. This
package contains the Standard Edition of the LDAP SDK, which is a
complete, general-purpose library for communicating with LDAPv3 directory
servers.
/*
* Copyright 2008-2022 Ping Identity Corporation
* All Rights Reserved.
*/
/*
* Copyright 2008-2022 Ping Identity Corporation
*
* Licensed 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.
*/
/*
* Copyright (C) 2008-2022 Ping Identity Corporation
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License (GPLv2 only)
* or the terms of the GNU Lesser General Public License (LGPLv2.1 only)
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see .
*/
package com.unboundid.util.parallel;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.atomic.AtomicReference;
import com.unboundid.util.Debug;
import com.unboundid.util.InternalUseOnly;
import com.unboundid.util.NotNull;
import com.unboundid.util.StaticUtils;
import com.unboundid.util.ThreadSafety;
import com.unboundid.util.ThreadSafetyLevel;
/**
* This class provides an asynchronous mechanism to do parallel processing of
* items that undergo identical processing. It can be used as part of a
* pipeline where input items are submitted without waiting for them to
* complete. To prevent a backlog of input or output items, a maximum
* capacity should be set on the {@code pendingQueue} and {@code outputQueue}
* if one is used.
*
* The {@link ParallelProcessor} passed into the constructor is wholly owned
* by this instance. It should not be used elsewhere after constructing this
* instance. It will be shut down when this instance's {@code shutdown()}
* method is called.
*
* When this AsynchronousParallelProcessor is no longer needed, {@code shutdown}
* must be called to terminate all worker threads.
*
* This class is intended to only be used internally by the SDK.
*
* @param The type of the input items of {@code processAll}.
* @param The type of the output items of {@code processAll}.
*/
@InternalUseOnly()
@ThreadSafety(level=ThreadSafetyLevel.COMPLETELY_THREADSAFE)
public final class AsynchronousParallelProcessor
{
// Queue of input items.
@NotNull private final BlockingQueue pendingQueue;
// The ParallelProcessor that is used to process the input items.
@NotNull private final ParallelProcessor parallelProcessor;
// Processor for the results.
@NotNull private final ResultProcessor resultProcessor;
// Thread that pulls items from pendingQueue, passes them to
// parallelProcessor, and processes the results.
@NotNull private final InvokerThread invokerThread;
// Set to true when this is shutdown.
@NotNull private final AtomicBoolean shutdown = new AtomicBoolean(false);
// Set by worker threads to signal that there was a problem during processing.
// Once this is set, all calls to submit() will fail with this exception.
@NotNull private final AtomicReference invocationException =
new AtomicReference<>();
/**
* Constructs a new AsynchronousParallelProcessor with the specified
* parameters.
*
* @param pendingQueue The queue where pending input items will be stored.
* If processing of input items cannot keep up with the
* rate that they are submitted, then this queue can grow
* without bound unless it was created with a maximum
* capacity. This queue must be used exclusively by this
* instance.
* @param parallelProcessor The ParallelProcessor that is used to process
* the submitted input items. It must be used
* exclusively by this instance. When this instance
* is shutdown, the ParallelProcessor will be
* shutdown too.
* @param resultProcessor The ResultProcessor that is invoked sequentially
* for each result.
*/
public AsynchronousParallelProcessor(
@NotNull final BlockingQueue pendingQueue,
@NotNull final ParallelProcessor parallelProcessor,
@NotNull final ResultProcessor resultProcessor)
{
this.pendingQueue = pendingQueue;
this.parallelProcessor = parallelProcessor;
this.resultProcessor = resultProcessor;
invokerThread = new InvokerThread();
invokerThread.start();
}
/**
* Constructs a new AsynchronousParallelProcessor with the specified
* parameters.
*
* @param pendingQueue The queue where pending input items will be stored.
* If processing of input items cannot keep up with the
* rate that they are submitted, then this queue can grow
* without bound unless it was created with a maximum
* capacity. This queue must be used exclusively by this
* instance.
* @param parallelProcessor The ParallelProcessor that is used to process
* the submitted input items. It must be used
* exclusively by this instance. When this instance
* is shutdown, the ParallelProcessor will be
* shutdown too.
* @param outputQueue The output queue where results will be submitted
* sequentially in the order that they were submitted.
* If the queue has maximum capacity, then processing
* will cease while waiting for capacity in the queue.
*/
public AsynchronousParallelProcessor(
@NotNull final BlockingQueue pendingQueue,
@NotNull final ParallelProcessor parallelProcessor,
@NotNull final BlockingQueue> outputQueue)
{
this(pendingQueue, parallelProcessor, new OutputEnqueuer<>(outputQueue));
}
/**
* Submits the specified item for processing, waiting if necessary for
* room in the pendingQueue.
*
* @param input The input item to process. It must not be {@code null}.
*
* @throws InterruptedException If this thread is interrupted during
* processing.
*/
public synchronized void submit(@NotNull final I input)
throws InterruptedException
{
if (shutdown.get())
{
throw new IllegalStateException("cannot call submit() after shutdown()");
}
final Throwable resultProcessingError = invocationException.get();
if (resultProcessingError != null)
{
shutdown();
StaticUtils.throwErrorOrRuntimeException(resultProcessingError);
}
pendingQueue.put(input);
}
/**
* Shuts this down. This includes waiting for all worker threads to
* finish. Processing of all input items will complete before this call
* returns. It is not an error to call {@code shutdown()} more than once,
* but it is an error to call {@code submit()} after {@code shutdown()} has
* been called.
*
* @throws InterruptedException If this thread is interrupted during
* processing.
*/
public synchronized void shutdown()
throws InterruptedException
{
if (shutdown.getAndSet(true))
{
// Already shut down.
return;
}
// The invoker thread will not exit until it has completed all
// of the pending items.
invokerThread.join();
parallelProcessor.shutdown();
}
/**
* ResultProcessor implementation that enqueues results.
*
* @param The type of the input items of {@code processAll}.
* @param The type of the output items of {@code processAll}.
*/
private static final class OutputEnqueuer
implements ResultProcessor
{
@NotNull private final BlockingQueue> outputQueue;
/**
* Constructor.
*
* @param outputQueue The queue where results will be enqueued.
*/
private OutputEnqueuer(
@NotNull final BlockingQueue> outputQueue)
{
this.outputQueue = outputQueue;
}
/**
* {@inheritDoc}
*/
@Override()
public void processResult(@NotNull final Result ioResult)
throws Exception
{
outputQueue.put(ioResult);
}
}
/**
* This thread pulls items from pendingQueue, processes them in parallel,
* and passes the results to resultProcessor. And then does it all over again
* until it's shutdown and there is no more to process.
*/
private final class InvokerThread
extends Thread
{
/**
* Constructor.
*/
private InvokerThread()
{
super("Asynchronous Parallel Processor");
setDaemon(true);
}
/**
* Pulls items from pendingQueue, processes them in parallel,
* and passes the results to resultProcessor. And then does it all over
* again until it's shutdown and there is no more to process.
*/
@Override()
public void run()
{
while (!(shutdown.get() && pendingQueue.isEmpty()))
{
try
{
final I item = pendingQueue.poll(100, TimeUnit.MILLISECONDS);
if (item != null)
{
final List items = new ArrayList<>(1 + pendingQueue.size());
items.add(item);
pendingQueue.drainTo(items);
final List> results =
parallelProcessor.processAll(items);
for (final Result result : results)
{
resultProcessor.processResult(result);
}
}
}
catch (final Throwable e)
{
Debug.debugException(e);
// It's in the contract of this class that nothing in this try
// block should throw an exception under normal operating conditions.
// So if we ever catch something here, then we treat that it as
// a terminating condition. This thread will continue to run to
// drain any remaining items from the queue, so that we can shutdown
// reasonably cleanly. However, we will not accept any new input
// item submissions. That is, future calls to submit() will force
// a shutdown and then throw an Exception, which includes e as the
// original cause. We use compareAndSet so that we only keep track
// of the first caught exception.
invocationException.compareAndSet(null, e);
}
}
}
}
}