| /* |
| * 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. |
| */ |
| using Lucene.Net.Support; |
| using Lucene.Net.Util; |
| using System; |
| using System.Collections.Generic; |
| using System.Linq; |
| using System.Text; |
| using System.Threading; |
| using System.Threading.Tasks; |
| using Directory = Lucene.Net.Store.Directory; |
| |
| namespace Lucene.Net.Index |
| { |
| /// <summary> |
| /// A <seealso cref="MergeScheduler"/> that runs each merge using |
| /// Tasks on the default TaskScheduler. |
| /// |
| /// <p>If more than <seealso cref="#GetMaxMergeCount"/> merges are |
| /// requested then this class will forcefully throttle the |
| /// incoming threads by pausing until one more more merges |
| /// complete.</p> |
| /// |
| /// LUCENENET specific |
| /// </summary> |
| public class TaskMergeScheduler : MergeScheduler, IConcurrentMergeScheduler |
| { |
| public const string COMPONENT_NAME = "CMS"; |
| |
| private readonly TaskScheduler _taskScheduler = TaskScheduler.Default; |
| private readonly ReaderWriterLockSlim _lock = new ReaderWriterLockSlim(); |
| private readonly ManualResetEventSlim _manualResetEvent = new ManualResetEventSlim(); |
| /// <summary> |
| /// List of currently active <seealso cref="MergeThread"/>s.</summary> |
| private readonly IList<MergeThread> _mergeThreads = new List<MergeThread>(); |
| |
| /// <summary> |
| /// How many <seealso cref="MergeThread"/>s have kicked off (this is use |
| /// to name them). |
| /// </summary> |
| private int _mergeThreadCount; |
| |
| /// <summary> |
| /// <seealso cref="Directory"/> that holds the index. </summary> |
| private Directory _directory; |
| |
| /// <summary> |
| /// <seealso cref="IndexWriter"/> that owns this instance. |
| /// </summary> |
| private IndexWriter _writer; |
| |
| /// <summary> |
| /// Sole constructor, with all settings set to default |
| /// values. |
| /// </summary> |
| public TaskMergeScheduler() : base() |
| { |
| MaxThreadCount = _taskScheduler.MaximumConcurrencyLevel; |
| MaxMergeCount = _taskScheduler.MaximumConcurrencyLevel; |
| } |
| |
| /// <summary> |
| /// Sets the maximum number of merge threads and simultaneous merges allowed. |
| /// </summary> |
| /// <param name="maxMergeCount"> the max # simultaneous merges that are allowed. |
| /// If a merge is necessary yet we already have this many |
| /// threads running, the incoming thread (that is calling |
| /// add/updateDocument) will block until a merge thread |
| /// has completed. Note that we will only run the |
| /// smallest <code>maxThreadCount</code> merges at a time. </param> |
| /// <param name="maxThreadCount"> the max # simultaneous merge threads that should |
| /// be running at once. this must be <= <code>maxMergeCount</code> </param> |
| public void SetMaxMergesAndThreads(int maxMergeCount, int maxThreadCount) |
| { |
| // This is handled by TaskScheduler.Default.MaximumConcurrencyLevel |
| } |
| |
| /// <summary> |
| /// Max number of merge threads allowed to be running at |
| /// once. When there are more merges then this, we |
| /// forcefully pause the larger ones, letting the smaller |
| /// ones run, up until maxMergeCount merges at which point |
| /// we forcefully pause incoming threads (that presumably |
| /// are the ones causing so much merging). |
| /// </summary> |
| /// <seealso cref= #setMaxMergesAndThreads(int, int) </seealso> |
| public int MaxThreadCount { get; private set; } |
| |
| /// <summary> |
| /// Max number of merges we accept before forcefully |
| /// throttling the incoming threads |
| /// </summary> |
| public int MaxMergeCount { get; private set; } |
| |
| /// <summary> |
| /// Return the priority that merge threads run at. This is always the same. |
| /// </summary> |
| public int MergeThreadPriority |
| { |
| get |
| { |
| return (int)ThreadPriority.Normal; |
| } |
| set |
| { |
| } |
| } |
| |
| /// <summary> |
| /// Called whenever the running merges have changed, to pause & unpause |
| /// threads. this method sorts the merge threads by their merge size in |
| /// descending order and then pauses/unpauses threads from first to last -- |
| /// that way, smaller merges are guaranteed to run before larger ones. |
| /// </summary> |
| private void UpdateMergeThreads() |
| { |
| foreach (var merge in _mergeThreads.ToArray()) |
| { |
| // Prune any dead threads |
| if (!merge.IsAlive) |
| { |
| _mergeThreads.Remove(merge); |
| merge.Dispose(); |
| } |
| } |
| } |
| |
| /// <summary> |
| /// Returns true if verbosing is enabled. this method is usually used in |
| /// conjunction with <seealso cref="#message(String)"/>, like that: |
| /// |
| /// <pre class="prettyprint"> |
| /// if (verbose()) { |
| /// message("your message"); |
| /// } |
| /// </pre> |
| /// </summary> |
| protected internal bool Verbose() |
| { |
| return _writer != null && _writer.infoStream.IsEnabled(COMPONENT_NAME); |
| } |
| |
| /// <summary> |
| /// Outputs the given message - this method assumes <seealso cref="#verbose()"/> was |
| /// called and returned true. |
| /// </summary> |
| protected internal virtual void Message(string message) |
| { |
| _writer.infoStream.Message(COMPONENT_NAME, message); |
| } |
| |
| public override void Dispose() |
| { |
| Sync(); |
| _manualResetEvent.Dispose(); |
| } |
| |
| /// <summary> |
| /// Wait for any running merge threads to finish. |
| /// This call is not interruptible as used by <seealso cref="#Dispose()"/>. |
| /// </summary> |
| public virtual void Sync() |
| { |
| foreach (var merge in _mergeThreads.ToArray()) |
| { |
| if (!merge.IsAlive) |
| { |
| continue; |
| } |
| |
| try |
| { |
| merge.Wait(); |
| } |
| catch (OperationCanceledException) |
| { |
| // expected when we cancel. |
| } |
| catch (AggregateException ae) |
| { |
| ae.Handle(x => x is OperationCanceledException); |
| |
| foreach (var exception in ae.InnerExceptions) |
| { |
| HandleMergeException(ae); |
| } |
| } |
| } |
| } |
| |
| /// <summary> |
| /// Returns the number of merge threads that are alive. Note that this number |
| /// is <= <seealso cref="#mergeThreads"/> size. |
| /// </summary> |
| private int MergeThreadCount() |
| { |
| return _mergeThreads.Count(x => x.IsAlive && x.CurrentMerge != null); |
| } |
| |
| public override void Merge(IndexWriter writer, MergeTrigger trigger, bool newMergesFound) |
| { |
| using (_lock.Write()) |
| { |
| _writer = writer; |
| _directory = writer.Directory; |
| |
| if (Verbose()) |
| { |
| Message("now merge"); |
| Message(" index: " + writer.SegString()); |
| } |
| |
| // First, quickly run through the newly proposed merges |
| // and add any orthogonal merges (ie a merge not |
| // involving segments already pending to be merged) to |
| // the queue. If we are way behind on merging, many of |
| // these newly proposed merges will likely already be |
| // registered. |
| |
| // Iterate, pulling from the IndexWriter's queue of |
| // pending merges, until it's empty: |
| while (true) |
| { |
| long startStallTime = 0; |
| while (writer.HasPendingMerges() && MergeThreadCount() >= MaxMergeCount) |
| { |
| // this means merging has fallen too far behind: we |
| // have already created maxMergeCount threads, and |
| // now there's at least one more merge pending. |
| // Note that only maxThreadCount of |
| // those created merge threads will actually be |
| // running; the rest will be paused (see |
| // updateMergeThreads). We stall this producer |
| // thread to prevent creation of new segments, |
| // until merging has caught up: |
| startStallTime = Environment.TickCount; |
| if (Verbose()) |
| { |
| Message(" too many merges; stalling..."); |
| } |
| |
| _manualResetEvent.Reset(); |
| _manualResetEvent.Wait(); |
| } |
| |
| if (Verbose()) |
| { |
| if (startStallTime != 0) |
| { |
| Message(" stalled for " + (Environment.TickCount - startStallTime) + " msec"); |
| } |
| } |
| |
| MergePolicy.OneMerge merge = writer.NextMerge; |
| if (merge == null) |
| { |
| if (Verbose()) |
| { |
| Message(" no more merges pending; now return"); |
| } |
| return; |
| } |
| |
| bool success = false; |
| try |
| { |
| if (Verbose()) |
| { |
| Message(" consider merge " + writer.SegString(merge.Segments)); |
| } |
| |
| // OK to spawn a new merge thread to handle this |
| // merge: |
| var merger = CreateTask(writer, merge); |
| |
| merger.MergeThreadCompleted += OnMergeThreadCompleted; |
| |
| _mergeThreads.Add(merger); |
| |
| if (Verbose()) |
| { |
| Message(" launch new thread [" + merger.Name + "]"); |
| } |
| |
| merger.Start(_taskScheduler); |
| |
| // Must call this after starting the thread else |
| // the new thread is removed from mergeThreads |
| // (since it's not alive yet): |
| UpdateMergeThreads(); |
| |
| success = true; |
| } |
| finally |
| { |
| if (!success) |
| { |
| writer.MergeFinish(merge); |
| } |
| } |
| } |
| } |
| } |
| |
| private void OnMergeThreadCompleted(object sender, EventArgs e) |
| { |
| var mergeThread = sender as MergeThread; |
| |
| if (mergeThread == null) |
| { |
| return; |
| } |
| |
| mergeThread.MergeThreadCompleted -= OnMergeThreadCompleted; |
| |
| using (_lock.Write()) |
| { |
| UpdateMergeThreads(); |
| } |
| } |
| |
| /// <summary> |
| /// Create and return a new MergeThread </summary> |
| private MergeThread CreateTask(IndexWriter writer, MergePolicy.OneMerge merge) |
| { |
| var count = Interlocked.Increment(ref _mergeThreadCount); |
| var name = string.Format("Lucene Merge Task #{0}", count); |
| |
| return new MergeThread(name, writer, merge, writer.infoStream, Verbose(), _manualResetEvent, HandleMergeException); |
| } |
| |
| /// <summary> |
| /// Called when an exception is hit in a background merge |
| /// thread |
| /// </summary> |
| protected internal virtual void HandleMergeException(Exception exc) |
| { |
| // suppressExceptions is normally only set during testing |
| if (SuppressExceptions) |
| { |
| return; |
| } |
| |
| try |
| { |
| // When an exception is hit during merge, IndexWriter |
| // removes any partial files and then allows another |
| // merge to run. If whatever caused the error is not |
| // transient then the exception will keep happening, |
| // so, we sleep here to avoid saturating CPU in such |
| // cases: |
| Thread.Sleep(250); |
| } |
| catch (ThreadInterruptedException ie) |
| { |
| throw new ThreadInterruptedException("Thread Interrupted Exception", ie); |
| } |
| throw new MergePolicy.MergeException(exc, _directory); |
| } |
| |
| private bool SuppressExceptions; |
| |
| /// <summary> |
| /// Used for testing </summary> |
| public virtual void SetSuppressExceptions() |
| { |
| SuppressExceptions = true; |
| } |
| |
| /// <summary> |
| /// Used for testing </summary> |
| public virtual void ClearSuppressExceptions() |
| { |
| SuppressExceptions = false; |
| } |
| |
| public override string ToString() |
| { |
| StringBuilder sb = new StringBuilder(this.GetType().Name + ": "); |
| sb.AppendFormat("maxThreadCount={0}, ", MaxThreadCount); |
| sb.AppendFormat("maxMergeCount={0}", MaxMergeCount); |
| return sb.ToString(); |
| } |
| |
| public override IMergeScheduler Clone() |
| { |
| TaskMergeScheduler clone = (TaskMergeScheduler)base.Clone(); |
| clone._writer = null; |
| clone._directory = null; |
| clone._mergeThreads.Clear(); |
| return clone; |
| } |
| |
| /// <summary> |
| /// Runs a merge thread, which may run one or more merges |
| /// in sequence. |
| /// </summary> |
| internal class MergeThread : IDisposable |
| { |
| public event EventHandler MergeThreadCompleted; |
| |
| private readonly CancellationTokenSource _cancellationTokenSource; |
| private readonly ReaderWriterLockSlim _lock = new ReaderWriterLockSlim(); |
| private readonly ManualResetEventSlim _resetEvent; |
| private readonly Action<Exception> _exceptionHandler; |
| private readonly InfoStream _logger; |
| private readonly IndexWriter _writer; |
| private readonly MergePolicy.OneMerge _startingMerge; |
| private readonly bool _isLoggingEnabled; |
| |
| private Task _task; |
| private MergePolicy.OneMerge _runningMerge; |
| private volatile bool _isDisposed = false; |
| private volatile bool _isDone; |
| |
| /// <summary> |
| /// Sole constructor. </summary> |
| public MergeThread(string name, IndexWriter writer, MergePolicy.OneMerge startMerge, |
| InfoStream logger, bool isLoggingEnabled, |
| ManualResetEventSlim resetEvent, Action<Exception> exceptionHandler) |
| { |
| Name = name; |
| _cancellationTokenSource = new CancellationTokenSource(); |
| _writer = writer; |
| _startingMerge = startMerge; |
| _logger = logger; |
| _isLoggingEnabled = isLoggingEnabled; |
| _resetEvent = resetEvent; |
| _exceptionHandler = exceptionHandler; |
| } |
| |
| public string Name { get; private set; } |
| |
| public Task Instance |
| { |
| get |
| { |
| using (_lock.Read()) |
| { |
| return _task; |
| } |
| } |
| } |
| |
| /// <summary> |
| /// Record the currently running merge. </summary> |
| public virtual MergePolicy.OneMerge RunningMerge |
| { |
| set |
| { |
| Interlocked.Exchange(ref _runningMerge, value); |
| } |
| get |
| { |
| using (_lock.Read()) |
| { |
| return _runningMerge; |
| } |
| } |
| } |
| |
| /// <summary> |
| /// Return the current merge, or null if this {@code |
| /// MergeThread} is done. |
| /// </summary> |
| public virtual MergePolicy.OneMerge CurrentMerge |
| { |
| get |
| { |
| using (_lock.Read()) |
| { |
| if (_isDone) |
| { |
| return null; |
| } |
| |
| return _runningMerge ?? _startingMerge; |
| } |
| } |
| } |
| |
| public bool IsAlive |
| { |
| get |
| { |
| if (_isDisposed || _isDone) |
| { |
| return false; |
| } |
| |
| using (_lock.Read()) |
| { |
| return _task != null |
| && (_task.Status != TaskStatus.Canceled |
| || _task.Status != TaskStatus.Faulted |
| || _task.Status != TaskStatus.RanToCompletion); |
| } |
| } |
| } |
| |
| public void Start(TaskScheduler taskScheduler) |
| { |
| using (_lock.Write()) |
| { |
| if (_task == null && !_cancellationTokenSource.IsCancellationRequested) |
| { |
| _task = Task.Factory.StartNew(() => Run(_cancellationTokenSource.Token), _cancellationTokenSource.Token, TaskCreationOptions.None, taskScheduler); |
| } |
| } |
| } |
| |
| public void Wait() |
| { |
| if (!IsAlive) |
| { |
| return; |
| } |
| |
| _task.Wait(_cancellationTokenSource.Token); |
| } |
| |
| public void Cancel() |
| { |
| if (!IsAlive) |
| { |
| return; |
| } |
| |
| using (_lock.Write()) |
| { |
| if (!_cancellationTokenSource.IsCancellationRequested) |
| { |
| _cancellationTokenSource.Cancel(); |
| } |
| } |
| } |
| |
| private void Run(CancellationToken cancellationToken) |
| { |
| // First time through the while loop we do the merge |
| // that we were started with: |
| MergePolicy.OneMerge merge = _startingMerge; |
| |
| try |
| { |
| if (_isLoggingEnabled) |
| { |
| _logger.Message(COMPONENT_NAME, " merge thread: start"); |
| } |
| |
| while (true && !cancellationToken.IsCancellationRequested) |
| { |
| RunningMerge = merge; |
| _writer.Merge(merge); |
| |
| // Subsequent times through the loop we do any new |
| // merge that writer says is necessary: |
| merge = _writer.NextMerge; |
| |
| // Notify here in case any threads were stalled; |
| // they will notice that the pending merge has |
| // been pulled and possibly resume: |
| _resetEvent.Set(); |
| |
| if (merge != null) |
| { |
| if (_isLoggingEnabled) |
| { |
| _logger.Message(COMPONENT_NAME, " merge thread: do another merge " + _writer.SegString(merge.Segments)); |
| } |
| } |
| else |
| { |
| break; |
| } |
| } |
| |
| if (_isLoggingEnabled) |
| { |
| _logger.Message(COMPONENT_NAME, " merge thread: done"); |
| } |
| } |
| catch (Exception exc) |
| { |
| // Ignore the exception if it was due to abort: |
| if (!(exc is MergePolicy.MergeAbortedException)) |
| { |
| //System.out.println(Thread.currentThread().getName() + ": CMS: exc"); |
| //exc.printStackTrace(System.out) |
| _exceptionHandler(exc); |
| } |
| } |
| finally |
| { |
| _isDone = true; |
| |
| if (MergeThreadCompleted != null) |
| { |
| MergeThreadCompleted(this, EventArgs.Empty); |
| } |
| } |
| } |
| |
| public void Dispose() |
| { |
| if (_isDisposed) |
| { |
| return; |
| } |
| |
| _isDisposed = true; |
| _lock.Dispose(); |
| _cancellationTokenSource.Dispose(); |
| } |
| |
| public override string ToString() |
| { |
| return _task == null |
| ? string.Format("Task[{0}], Task has not been started yet.", Name) |
| : string.Format("Task[{0}], Id[{1}], Status[{2}]", Name, _task.Id, _task.Status); |
| } |
| |
| public override bool Equals(object obj) |
| { |
| var compared = obj as MergeThread; |
| |
| if (compared == null |
| || (Instance == null && compared.Instance != null) |
| || (Instance != null && compared.Instance == null)) |
| { |
| return false; |
| } |
| |
| return Instance.Id == compared.Instance.Id; |
| } |
| |
| public override int GetHashCode() |
| { |
| return Instance == null |
| ? base.GetHashCode() |
| : Instance.GetHashCode(); |
| } |
| } |
| } |
| } |