| | | 1 | | using System; |
| | | 2 | | using System.Collections.Concurrent; |
| | | 3 | | using System.Collections.Generic; |
| | | 4 | | using System.Diagnostics; |
| | | 5 | | using System.Linq; |
| | | 6 | | using System.Threading; |
| | | 7 | | using System.Threading.Channels; |
| | | 8 | | using System.Threading.Tasks; |
| | | 9 | | using MediaBrowser.Controller.Configuration; |
| | | 10 | | using Microsoft.Extensions.Hosting; |
| | | 11 | | using Microsoft.Extensions.Logging; |
| | | 12 | | |
| | | 13 | | namespace MediaBrowser.Controller.LibraryTaskScheduler; |
| | | 14 | | |
| | | 15 | | /// <summary> |
| | | 16 | | /// Provides Parallel action interface to process tasks with a set concurrency level. |
| | | 17 | | /// </summary> |
| | | 18 | | public sealed class LimitedConcurrencyLibraryScheduler : ILimitedConcurrencyLibraryScheduler, IAsyncDisposable |
| | | 19 | | { |
| | | 20 | | private const int CleanupGracePeriod = 60; |
| | | 21 | | private readonly IHostApplicationLifetime _hostApplicationLifetime; |
| | | 22 | | private readonly ILogger<LimitedConcurrencyLibraryScheduler> _logger; |
| | | 23 | | private readonly IServerConfigurationManager _serverConfigurationManager; |
| | 21 | 24 | | private readonly Dictionary<CancellationTokenSource, Task> _taskRunners = new(); |
| | | 25 | | |
| | 0 | 26 | | private static readonly AsyncLocal<CancellationTokenSource> _deadlockDetector = new(); |
| | | 27 | | |
| | | 28 | | /// <summary> |
| | | 29 | | /// Gets used to lock all operations on the Tasks queue and creating workers. |
| | | 30 | | /// </summary> |
| | 21 | 31 | | private readonly Lock _taskLock = new(); |
| | | 32 | | |
| | 21 | 33 | | private readonly Channel<TaskQueueItem> _tasks = Channel.CreateUnbounded<TaskQueueItem>(); |
| | | 34 | | |
| | | 35 | | private volatile int _workCounter; |
| | | 36 | | private Task? _cleanupTask; |
| | | 37 | | private bool _disposed; |
| | | 38 | | |
| | | 39 | | /// <summary> |
| | | 40 | | /// Initializes a new instance of the <see cref="LimitedConcurrencyLibraryScheduler"/> class. |
| | | 41 | | /// </summary> |
| | | 42 | | /// <param name="hostApplicationLifetime">The hosting lifetime.</param> |
| | | 43 | | /// <param name="logger">The logger.</param> |
| | | 44 | | /// <param name="serverConfigurationManager">The server configuration manager.</param> |
| | | 45 | | public LimitedConcurrencyLibraryScheduler( |
| | | 46 | | IHostApplicationLifetime hostApplicationLifetime, |
| | | 47 | | ILogger<LimitedConcurrencyLibraryScheduler> logger, |
| | | 48 | | IServerConfigurationManager serverConfigurationManager) |
| | | 49 | | { |
| | 21 | 50 | | _hostApplicationLifetime = hostApplicationLifetime; |
| | 21 | 51 | | _logger = logger; |
| | 21 | 52 | | _serverConfigurationManager = serverConfigurationManager; |
| | 21 | 53 | | } |
| | | 54 | | |
| | | 55 | | private void ScheduleTaskCleanup() |
| | 0 | 56 | | { |
| | | 57 | | lock (_taskLock) |
| | | 58 | | { |
| | 0 | 59 | | if (_cleanupTask is not null) |
| | | 60 | | { |
| | 0 | 61 | | _logger.LogDebug("Cleanup task already scheduled."); |
| | | 62 | | // cleanup task is already running. |
| | 0 | 63 | | return; |
| | | 64 | | } |
| | | 65 | | |
| | 0 | 66 | | _cleanupTask = RunCleanupTask(); |
| | 0 | 67 | | } |
| | | 68 | | |
| | | 69 | | async Task RunCleanupTask() |
| | | 70 | | { |
| | | 71 | | _logger.LogDebug("Schedule cleanup task in {CleanupGracePerioid} sec.", CleanupGracePeriod); |
| | | 72 | | await Task.Delay(TimeSpan.FromSeconds(CleanupGracePeriod)).ConfigureAwait(false); |
| | | 73 | | if (_disposed) |
| | | 74 | | { |
| | | 75 | | _logger.LogDebug("Abort cleaning up, already disposed."); |
| | | 76 | | return; |
| | | 77 | | } |
| | | 78 | | |
| | | 79 | | lock (_taskLock) |
| | | 80 | | { |
| | | 81 | | if (_tasks.Reader.Count > 0 || _workCounter > 0) |
| | | 82 | | { |
| | | 83 | | _logger.LogDebug("Delay cleanup task, operations still running."); |
| | | 84 | | // tasks are still there so its still in use. Reschedule cleanup task. |
| | | 85 | | // we cannot just exit here and rely on the other invoker because there is a considerable timeframe |
| | | 86 | | _cleanupTask = RunCleanupTask(); |
| | | 87 | | return; |
| | | 88 | | } |
| | | 89 | | } |
| | | 90 | | |
| | | 91 | | _logger.LogDebug("Cleanup runners."); |
| | | 92 | | foreach (var item in _taskRunners.ToArray()) |
| | | 93 | | { |
| | | 94 | | await item.Key.CancelAsync().ConfigureAwait(false); |
| | | 95 | | _taskRunners.Remove(item.Key); |
| | | 96 | | } |
| | | 97 | | } |
| | 0 | 98 | | } |
| | | 99 | | |
| | | 100 | | private bool ShouldForceSequentialOperation() |
| | | 101 | | { |
| | | 102 | | // if the user either set the setting to 1 or it's unset and we have fewer than 4 cores it's better to run seque |
| | 6 | 103 | | var fanoutSetting = _serverConfigurationManager.Configuration.LibraryScanFanoutConcurrency; |
| | 6 | 104 | | return fanoutSetting == 1 || (fanoutSetting <= 0 && Environment.ProcessorCount <= 3); |
| | | 105 | | } |
| | | 106 | | |
| | | 107 | | private int CalculateScanConcurrencyLimit() |
| | | 108 | | { |
| | | 109 | | // when this is invoked, we already checked ShouldForceSequentialOperation for the sequential check. |
| | 0 | 110 | | var fanoutConcurrency = _serverConfigurationManager.Configuration.LibraryScanFanoutConcurrency; |
| | 0 | 111 | | if (fanoutConcurrency <= 0) |
| | | 112 | | { |
| | | 113 | | // in case the user did not set a limit manually, we can assume he has 3 or more cores as already checked by |
| | 0 | 114 | | return Environment.ProcessorCount - 3; |
| | | 115 | | } |
| | | 116 | | |
| | 0 | 117 | | return fanoutConcurrency; |
| | | 118 | | } |
| | | 119 | | |
| | | 120 | | private void Worker() |
| | 0 | 121 | | { |
| | | 122 | | lock (_taskLock) |
| | | 123 | | { |
| | 0 | 124 | | var operationFanout = Math.Max(0, CalculateScanConcurrencyLimit() - _taskRunners.Count); |
| | 0 | 125 | | _logger.LogDebug("Spawn {NumberRunners} new runners.", operationFanout); |
| | 0 | 126 | | for (int i = 0; i < operationFanout; i++) |
| | | 127 | | { |
| | 0 | 128 | | var stopToken = new CancellationTokenSource(); |
| | 0 | 129 | | var combinedSource = CancellationTokenSource.CreateLinkedTokenSource(stopToken.Token, _hostApplicationLi |
| | 0 | 130 | | _taskRunners.Add( |
| | 0 | 131 | | combinedSource, |
| | 0 | 132 | | Task.Factory.StartNew( |
| | 0 | 133 | | ItemWorker, |
| | 0 | 134 | | (combinedSource, stopToken), |
| | 0 | 135 | | combinedSource.Token, |
| | 0 | 136 | | TaskCreationOptions.PreferFairness, |
| | 0 | 137 | | TaskScheduler.Default)); |
| | | 138 | | } |
| | 0 | 139 | | } |
| | 0 | 140 | | } |
| | | 141 | | |
| | | 142 | | private async Task ItemWorker(object? obj) |
| | | 143 | | { |
| | | 144 | | var stopToken = ((CancellationTokenSource TaskStop, CancellationTokenSource GlobalStop))obj!; |
| | | 145 | | _deadlockDetector.Value = stopToken.TaskStop; |
| | | 146 | | try |
| | | 147 | | { |
| | | 148 | | while (!stopToken.GlobalStop.Token.IsCancellationRequested) |
| | | 149 | | { |
| | | 150 | | var item = await _tasks.Reader.ReadAsync(stopToken.GlobalStop.Token).ConfigureAwait(false); |
| | | 151 | | try |
| | | 152 | | { |
| | | 153 | | var newWorkerLimit = Interlocked.Increment(ref _workCounter) > 0; |
| | | 154 | | Debug.Assert(newWorkerLimit, "_workCounter > 0"); |
| | | 155 | | _logger.LogDebug("Process new item '{Data}'.", item.Data); |
| | | 156 | | await ProcessItem(item).ConfigureAwait(false); |
| | | 157 | | } |
| | | 158 | | finally |
| | | 159 | | { |
| | | 160 | | var newWorkerLimit = Interlocked.Decrement(ref _workCounter) >= 0; |
| | | 161 | | Debug.Assert(newWorkerLimit, "_workCounter > 0"); |
| | | 162 | | } |
| | | 163 | | } |
| | | 164 | | } |
| | | 165 | | catch (OperationCanceledException) when (stopToken.TaskStop.IsCancellationRequested) |
| | | 166 | | { |
| | | 167 | | // thats how you do it, interupt the waiter thread. There is nothing to do here when it was on purpose. |
| | | 168 | | } |
| | | 169 | | finally |
| | | 170 | | { |
| | | 171 | | _logger.LogDebug("Cleanup Runner'."); |
| | | 172 | | _deadlockDetector.Value = default!; |
| | | 173 | | _taskRunners.Remove(stopToken.TaskStop); |
| | | 174 | | stopToken.GlobalStop.Dispose(); |
| | | 175 | | stopToken.TaskStop.Dispose(); |
| | | 176 | | } |
| | | 177 | | } |
| | | 178 | | |
| | | 179 | | private async Task ProcessItem(TaskQueueItem item) |
| | | 180 | | { |
| | | 181 | | try |
| | | 182 | | { |
| | | 183 | | if (item.CancellationToken.IsCancellationRequested) |
| | | 184 | | { |
| | | 185 | | // if item is cancelled, just skip it |
| | | 186 | | return; |
| | | 187 | | } |
| | | 188 | | |
| | | 189 | | await item.Worker(item.Data).ConfigureAwait(true); |
| | | 190 | | } |
| | | 191 | | catch (System.Exception ex) |
| | | 192 | | { |
| | | 193 | | _logger.LogError(ex, "Error while performing a library operation"); |
| | | 194 | | } |
| | | 195 | | finally |
| | | 196 | | { |
| | | 197 | | item.Progress.Report(100); |
| | | 198 | | item.Done.SetResult(); |
| | | 199 | | } |
| | | 200 | | } |
| | | 201 | | |
| | | 202 | | /// <inheritdoc/> |
| | | 203 | | public async Task Enqueue<T>(T[] data, Func<T, IProgress<double>, Task> worker, IProgress<double> progress, Cancella |
| | | 204 | | { |
| | | 205 | | if (_disposed) |
| | | 206 | | { |
| | | 207 | | return; |
| | | 208 | | } |
| | | 209 | | |
| | | 210 | | if (data.Length == 0 || cancellationToken.IsCancellationRequested) |
| | | 211 | | { |
| | | 212 | | progress.Report(100); |
| | | 213 | | return; |
| | | 214 | | } |
| | | 215 | | |
| | | 216 | | _logger.LogDebug("Enqueue new Workset of {NoItems} items.", data.Length); |
| | | 217 | | |
| | | 218 | | TaskQueueItem[] workItems = null!; |
| | | 219 | | |
| | | 220 | | void UpdateProgress() |
| | | 221 | | { |
| | | 222 | | progress.Report(workItems.Select(e => e.ProgressValue).Average()); |
| | | 223 | | } |
| | | 224 | | |
| | | 225 | | workItems = data.Select(item => |
| | | 226 | | { |
| | | 227 | | TaskQueueItem queueItem = null!; |
| | | 228 | | return queueItem = new TaskQueueItem() |
| | | 229 | | { |
| | | 230 | | Data = item!, |
| | | 231 | | Progress = new Progress<double>(innerPercent => |
| | | 232 | | { |
| | | 233 | | // round the percent and only update progress if it changed to prevent excessive UpdateProgress |
| | | 234 | | var innerPercentRounded = Math.Round(innerPercent); |
| | | 235 | | if (queueItem.ProgressValue != innerPercentRounded) |
| | | 236 | | { |
| | | 237 | | queueItem.ProgressValue = innerPercentRounded; |
| | | 238 | | UpdateProgress(); |
| | | 239 | | } |
| | | 240 | | }), |
| | | 241 | | Worker = (val) => worker((T)val, queueItem.Progress), |
| | | 242 | | CancellationToken = cancellationToken |
| | | 243 | | }; |
| | | 244 | | }).ToArray(); |
| | | 245 | | |
| | | 246 | | if (ShouldForceSequentialOperation() || _deadlockDetector.Value is not null) |
| | | 247 | | { |
| | | 248 | | _logger.LogDebug("Process sequentially."); |
| | | 249 | | try |
| | | 250 | | { |
| | | 251 | | foreach (var item in workItems) |
| | | 252 | | { |
| | | 253 | | await ProcessItem(item).ConfigureAwait(false); |
| | | 254 | | } |
| | | 255 | | } |
| | | 256 | | catch (OperationCanceledException) when (cancellationToken.IsCancellationRequested) |
| | | 257 | | { |
| | | 258 | | // operation is cancelled. Do nothing. |
| | | 259 | | } |
| | | 260 | | |
| | | 261 | | _logger.LogDebug("Process sequentially done."); |
| | | 262 | | return; |
| | | 263 | | } |
| | | 264 | | |
| | | 265 | | for (var i = 0; i < workItems.Length; i++) |
| | | 266 | | { |
| | | 267 | | var item = workItems[i]!; |
| | | 268 | | await _tasks.Writer.WriteAsync(item, CancellationToken.None).ConfigureAwait(false); |
| | | 269 | | } |
| | | 270 | | |
| | | 271 | | Worker(); |
| | | 272 | | _logger.LogDebug("Wait for {NoWorkers} to complete.", workItems.Length); |
| | | 273 | | await Task.WhenAll([.. workItems.Select(f => f.Done.Task)]).ConfigureAwait(false); |
| | | 274 | | _logger.LogDebug("{NoWorkers} completed.", workItems.Length); |
| | | 275 | | ScheduleTaskCleanup(); |
| | | 276 | | } |
| | | 277 | | |
| | | 278 | | /// <inheritdoc/> |
| | | 279 | | public async ValueTask DisposeAsync() |
| | | 280 | | { |
| | | 281 | | if (_disposed) |
| | | 282 | | { |
| | | 283 | | return; |
| | | 284 | | } |
| | | 285 | | |
| | | 286 | | _disposed = true; |
| | | 287 | | _tasks.Writer.Complete(); |
| | | 288 | | foreach (var item in _taskRunners) |
| | | 289 | | { |
| | | 290 | | await item.Key.CancelAsync().ConfigureAwait(false); |
| | | 291 | | } |
| | | 292 | | |
| | | 293 | | if (_cleanupTask is not null) |
| | | 294 | | { |
| | | 295 | | await _cleanupTask.ConfigureAwait(false); |
| | | 296 | | _cleanupTask?.Dispose(); |
| | | 297 | | } |
| | | 298 | | } |
| | | 299 | | |
| | | 300 | | private class TaskQueueItem |
| | | 301 | | { |
| | | 302 | | public required object Data { get; init; } |
| | | 303 | | |
| | | 304 | | public double ProgressValue { get; set; } |
| | | 305 | | |
| | | 306 | | public required Func<object, Task> Worker { get; init; } |
| | | 307 | | |
| | | 308 | | public required IProgress<double> Progress { get; init; } |
| | | 309 | | |
| | | 310 | | public TaskCompletionSource Done { get; } = new(); |
| | | 311 | | |
| | | 312 | | public CancellationToken CancellationToken { get; init; } |
| | | 313 | | } |
| | | 314 | | } |