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GeezerVison is showing github.com — HttpClient.Cache/src/HttpClient.Cache/Files/FileCache.cs at master · rmja/HttpClient.Cache Expand file tree/ Copy pathFileCache.csMore file actions 575 lines (500 loc) · 20.2 KB / Copy pathFileCache.csFile metadata and controls575 lines (500 loc) · 20.2 KB 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 using System.IO; using System.Net; using System.Reflection; namespace HttpClientCache.Files; /// <summary> /// Provides a file-based implementation of <see cref="IHttpCache"/> for persistent HTTP response caching on disk. /// </summary> public class FileCache : IHttpCache { private readonly DirectoryInfo _rootDirectory; private readonly DirectoryInfo _tempDirectory; private readonly ICacheKeyComputer _cacheKeyComputer; private readonly TimeProvider _timeProvider; private readonly ITimer _timer; public static FileCache Default { get; } = new(); public DirectoryInfo RootDirectory => _rootDirectory; /// <summary> /// Gets or sets the maximum number of cache entries allowed in the cache directory. /// Note that this is a soft limit, and the actual number of entries may exceed this value temporarily during purging. /// </summary> public int MaxEntries { get; set; } = 1000; /// <summary> /// The default duration for which a cached entry remains valid <i>after it is first seen</i> if no explicit expiration is set in the response. /// </summary> public TimeSpan DefaultInitialExpiration { get; set; } = TimeSpan.FromDays(2); /// <summary> /// The default duration for which a cached entry remains valid <i>when it is seen again</i> if no explicit expiration is set in the response. /// </summary> public TimeSpan DefaultRefreshExpiration { get; set; } = TimeSpan.FromDays(2); /// <summary> /// Creates a new instance of <see cref="FileCache"/> with the default root directory. /// </summary> public FileCache() : this(GetDefaultRootDirectory()) { } private static string GetDefaultRootDirectory() { // GetEntryAssembly() can return null when hosted by unmanaged code or some test runners, // so fall back to the executing assembly and finally to a constant name. var appName = Assembly.GetEntryAssembly()?.GetName().Name ?? Assembly.GetExecutingAssembly().GetName().Name ?? "HttpClient.Cache"; return Path.Combine(Path.GetTempPath(), "HttpClient.FileCache", appName); } /// <summary> /// Creates a new instance of <see cref="FileCache"/> with the specified root directory. /// </summary> /// <param name="rootDirectory">The directory where cache files are stored.</param> public FileCache(string rootDirectory) : this(rootDirectory, new CacheKeyComputer(), TimeProvider.System) { } /// <summary> /// Creates a new instance of <see cref="FileCache"/>. /// </summary> /// <param name="rootDirectory">The directory where cache files are stored</param> /// <param name="cacheKeyComputer">The mechanism used to provide cache keys for a given request</param> /// <param name="timeProvider">The time provider</param> public FileCache( string rootDirectory, ICacheKeyComputer cacheKeyComputer, TimeProvider timeProvider ) { _cacheKeyComputer = cacheKeyComputer; _timeProvider = timeProvider; _rootDirectory = new(rootDirectory); if (!_rootDirectory.Exists) { _rootDirectory.Create(); } // 1) Ensure temp directory is separate to avoid conflicts // 2) Let temp files be on the same file system for performance and atomicity during file moves // 3) Allow for easier cleanup as the temp directory can be traversed when recursively deleting files in the root directory _tempDirectory = new(Path.Combine(rootDirectory, "temp")); if (!_tempDirectory.Exists) { _tempDirectory.Create(); } _timer = timeProvider.CreateTimer( _ => Purge(), null, TimeSpan.FromMinutes(5), TimeSpan.FromMinutes(5) ); } public async ValueTask<HttpResponseMessage?> GetResponseAsync( HttpRequestMessage request, CancellationToken cancellationToken = default ) { var response = await GetResponseWithVariationAsync(request, cancellationToken); return response?.Response; } public async ValueTask<ResponseWithVariation?> GetResponseWithVariationAsync( HttpRequestMessage request, CancellationToken cancellationToken = default ) { var responseKey = _cacheKeyComputer.ComputeKey(request, new(CacheType.Shared)); if (responseKey is null) { return null; } var fileInfo = FindJsonFile(responseKey); if (fileInfo is null) { return null; } var filename = FileName.FromFileInfo(fileInfo); if (filename.IsMetadataFile) { // A response was found directly from the response key without a variation var filePair = ResponseFilePair.FromMetadataFileInfo(fileInfo); var response = await filePair.GetResponseAsync(_timeProvider.GetUtcNow()); if (response is null) { // Response is expired filePair.TryDelete(); return null; } response.RequestMessage = request; return new(response, new Variation(CacheType.Shared)); } else if (filename.IsVariationFile) { // A variation file was found, so we need to read the variation to find the response var file = VariationFile.FromVariationFileInfo(fileInfo); // Indicate that we have used the variation file filename.Refresh(fileInfo, _timeProvider.GetUtcNow()); var variation = await file.GetVariationAsync(_timeProvider.GetUtcNow()); if (variation is null) { return null; } // Recompute the response key using the variation responseKey = _cacheKeyComputer.ComputeKey(request, variation); if (responseKey is null) { return null; } fileInfo = FindJsonFile(responseKey, filename.EtagHash); if (fileInfo is null) { return null; } filename = FileName.FromFileInfo(fileInfo); if (filename.IsMetadataFile) { var filePair = ResponseFilePair.FromMetadataFileInfo(fileInfo); var response = await filePair.GetResponseAsync(_timeProvider.GetUtcNow()); if (response is null) { // Response is expired filePair.TryDelete(); return null; } response.RequestMessage = request; return new(response, variation); } } return null; } public async ValueTask<HttpResponseMessage?> SetResponseAsync( HttpResponseMessage response, CancellationToken cancellationToken = default ) { var variation = Variation.FromResponseMessage(response); if (variation.CacheType == CacheType.None) { // Response is not cacheable return null; } var request = response.RequestMessage ?? throw new ArgumentNullException( nameof(response), "Response must have a RequestMessage set." ); var responseKey = _cacheKeyComputer.ComputeKey(request, new(CacheType.Shared)); if (responseKey is null) { // Response cannot be cached as the cache key could not be computed return null; } if (variation.CacheType == CacheType.Shared && variation.NormalizedVaryHeaders.Count == 0) { // No Vary header, cache the response directly in the shared cache using the entry key var now = _timeProvider.GetUtcNow(); var cachedResponse = await SetResponseImplAsync( responseKey, response, now, cancellationToken ); cachedResponse.RequestMessage = request; return cachedResponse; } else { // The response is private or has a Vary header, so we need to cache both the response and the variation // Let the computed response key be the key for the variation, // and compute a new response key using the variation var variationKey = responseKey; responseKey = _cacheKeyComputer.ComputeKey(request, variation); if (responseKey is null) { // Response cannot be cached as the variation key could not be computed return null; } var now = _timeProvider.GetUtcNow(); var modified = response.GetModified() ?? now; var expiration = response.GetExpiration(now) ?? (now + DefaultInitialExpiration); // Write the response var cachedResponse = await SetResponseImplAsync( responseKey, response, now, cancellationToken ); cachedResponse.RequestMessage = request; var variationFileName = FileName.Variation( variationKey, modified, response.Headers.ETag ); var variationFile = VariationFile.CreateTemp(_tempDirectory); await variationFile.WriteAsync(request.RequestUri!, variation); // Let the variation file have the same (possibly updated) expiration as the response variationFileName.SetExpiration(variationFile.Info, expiration); variationFile.TryMakePermanent(_rootDirectory, variationFileName); return cachedResponse; } } private async Task<HttpResponseMessage> SetResponseImplAsync( string responseKey, HttpResponseMessage response, DateTimeOffset now, CancellationToken cancellationToken ) { var modified = response.GetModified() ?? now; var expiration = response.GetExpiration(now) ?? (now + DefaultInitialExpiration); var metadata = new MetadataModel() { Url = response.RequestMessage!.RequestUri!, Version = response.Version, StatusCode = response.StatusCode, ReasonPhrase = response.ReasonPhrase, ResponseHeaders = response .Headers.Select(x => new KeyValuePair<string, List<string>>( x.Key, x.Value.ToList() )) .ToList(), ContentHeaders = response .Content.Headers.Select(x => new KeyValuePair<string, List<string>>( x.Key, x.Value.ToList() )) .ToList(), TrailingHeaders = response .TrailingHeaders.Select(x => new KeyValuePair<string, List<string>>( x.Key, x.Value.ToList() )) .ToList(), }; var metadataFileName = FileName.Metadata(responseKey, modified, response.Headers.ETag); var filePair = ResponseFilePair.CreateTemp(_tempDirectory); await using (var responseFile = filePair.ResponseInfo.OpenWrite()) { // Generate the cached response from the response await using var httpStream = await response.Content.ReadAsStreamAsync( cancellationToken ); await httpStream.CopyToAsync(responseFile, cancellationToken); } await filePair.WriteMetadataAsync(metadata); // Set the expiration on the metadata file metadataFileName.SetExpiration(filePair.MetadataInfo, expiration); // Try and make the file pair permanent // If it fails then it really does not matter, as we will then just serve the temporary file and clean up later filePair.TryMakePermanent(_rootDirectory, metadataFileName); // Allow expired responses to be returned in case that the expiration was immediate var cachedResponse = await filePair.GetResponseAsync(now, allowExpired: true); return cachedResponse!; } public ValueTask RefreshResponseAsync( HttpResponseMessage cachedResponse, CancellationToken cancellationToken = default ) { var now = _timeProvider.GetUtcNow(); RefreshResponseImpl(cachedResponse, now, expiration: now + DefaultRefreshExpiration); return ValueTask.CompletedTask; } public ValueTask RefreshResponseAsync( HttpResponseMessage cachedResponse, HttpResponseMessage notModifiedResponse, CancellationToken cancellationToken = default ) { if (notModifiedResponse.StatusCode != HttpStatusCode.NotModified) { throw new ArgumentException( "The response must be a 304 NOT MODIFIED response.", nameof(notModifiedResponse) ); } var now = _timeProvider.GetUtcNow(); var expiration = notModifiedResponse.GetExpiration(now) ?? (now + DefaultRefreshExpiration); RefreshResponseImpl(cachedResponse, now, expiration); return ValueTask.CompletedTask; } private void RefreshResponseImpl( HttpResponseMessage cachedResponse, DateTimeOffset now, DateTimeOffset expiration ) { var request = cachedResponse.RequestMessage!; var responseKey = _cacheKeyComputer.ComputeKey(request, new(CacheType.Shared)); if (responseKey is null) { return; } var fileInfo = FindJsonFile(responseKey); if (fileInfo is null) { return; } var filename = FileName.FromFileInfo(fileInfo); filename.Refresh(fileInfo, now); filename.SetExpiration(fileInfo, expiration); if (filename.IsVariationFile) { // If the file is a variation file, we need to refresh the actual response as well var variation = Variation.FromResponseMessage(cachedResponse); responseKey = _cacheKeyComputer.ComputeKey(request, variation); if (responseKey is null) { return; } fileInfo = FindJsonFile(responseKey, filename.EtagHash); if (fileInfo is null) { return; } filename = FileName.FromFileInfo(fileInfo); if (!filename.IsMetadataFile) { return; } filename.Refresh(fileInfo, now); filename.SetExpiration(fileInfo, expiration); } } private FileInfo? FindJsonFile(string key) { var hash = Hash.ComputeHash(key); // Rely on that the file name includes the "modified" timestamp right after the hash return _rootDirectory.EnumerateFiles($"{hash}_*.json").MaxBy(x => x.Name); } private FileInfo? FindJsonFile(string key, string? etagHash) { var hash = Hash.ComputeHash(key); // Rely on that the file name includes the "modified" timestamp right after the hash return _rootDirectory .EnumerateFiles($"{hash}_*_{etagHash ?? ""}.*.json") .MaxBy(x => x.Name); } public void Clear() { foreach (var fileInfo in _rootDirectory.GetFiles("*.json", SearchOption.AllDirectories)) { var fileName = FileName.FromFileInfo(fileInfo); if (fileName.IsMetadataFile) { var filePair = ResponseFilePair.FromMetadataFileInfo(fileInfo); filePair.TryDelete(); } else if (fileName.IsVariationFile) { var variationFile = VariationFile.FromVariationFileInfo(fileInfo); variationFile.TryDelete(); } } RemoveOrphanedResponseFiles(force: true); } public void Purge() { // Only sweep temp files that are old enough that they cannot still be part of an in-flight // SetResponse/MakePermanent operation. Without this guard the timer could delete a temp file // while it is being written or moved into place. var staleTempBefore = _timeProvider.GetUtcNow().AddMinutes(-30).UtcDateTime; var files = Enumerable.Concat( _rootDirectory .GetFiles("*.json") .OrderByDescending(x => x.LastAccessTimeUtc) .Skip(MaxEntries), _tempDirectory.GetFiles("*.json").Where(x => x.CreationTimeUtc < staleTempBefore) ); foreach (var fileInfo in files) { var fileName = FileName.FromFileInfo(fileInfo); if (fileName.IsMetadataFile) { var filePair = ResponseFilePair.FromMetadataFileInfo(fileInfo); filePair.TryDelete(); } else if (fileName.IsVariationFile) { var variationFile = VariationFile.FromVariationFileInfo(fileInfo); variationFile.TryDelete(); } } RemoveOrphanedResponseFiles(force: false); } private void RemoveOrphanedResponseFiles(bool force) { var removeBefore = force ? DateTime.MaxValue : _timeProvider.GetUtcNow().AddMinutes(-30); // Track unpaired files: response FileName -> (metadataFileInfo, responseFileInfo) // When a metadata file is seen first, we store (metadataFileInfo, null). // When a response file is seen first, we store (null, responseFileInfo). // When the pair is matched, the entry is removed. var unpaired = new Dictionary<FileName, (FileInfo? MetadataFileInfo, FileInfo? ResponseFileInfo)>(); foreach (var fileInfo in _rootDirectory.GetFiles("*.*", SearchOption.AllDirectories)) { var fileName = FileName.FromFileInfo(fileInfo); if (fileName.IsMetadataFile) { var responseFileName = fileName.ToResponseFileName(); if ( unpaired.TryGetValue(responseFileName, out var existing) && existing.ResponseFileInfo is not null ) { // Response file was already iterated - pair is complete unpaired.Remove(responseFileName); } else { // Response file is not yet iterated unpaired[responseFileName] = (fileInfo, null); } } else if (fileName.IsResponseFile) { if ( unpaired.TryGetValue(fileName, out var existing) && existing.MetadataFileInfo is not null ) { // Metadata file was already iterated - pair is complete unpaired.Remove(fileName); } else { unpaired[fileName] = (null, fileInfo); } } } foreach (var (metadataFileInfo, responseFileInfo) in unpaired.Values) { // It may be that we have just moved the response from temp to here, and that the // metadata is about to follow, see ResponseFilePair.TryMakePermanent(). // In that case, we must not consider the file as orphaned if it was created recently. var fileInfo = metadataFileInfo ?? responseFileInfo!; if (fileInfo.CreationTimeUtc >= removeBefore) { continue; } try { if (responseFileInfo is not null) { responseFileInfo.Delete(); } else if (metadataFileInfo is not null) { // Metadata file exists without its response file - clean it up var filePair = ResponseFilePair.FromMetadataFileInfo(metadataFileInfo); filePair.TryDelete(); } } catch { } } } public virtual ValueTask DisposeAsync() { GC.SuppressFinalize(this); return _timer.DisposeAsync(); } public virtual void Dispose() { GC.SuppressFinalize(this); _timer.Dispose(); } } |
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