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GeezerVison is showing github.com — SimpleCache/DigitalRuby.SimpleCache/DistributedCache.cs at main · DigitalRuby/SimpleCache Expand file tree/ Copy pathDistributedCache.csMore file actions 387 lines (344 loc) · 11.4 KB / Copy pathDistributedCache.csFile metadata and controls387 lines (344 loc) · 11.4 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 namespace DigitalRuby.SimpleCache; /// <summary> /// Distributed cache item /// </summary> public readonly struct DistributedCacheItem { /// <summary> /// The item bytes or null if no item found /// </summary> public byte[]? Bytes { get; init; } /// <summary> /// The item expiration relative to now or null if none /// </summary> public TimeSpan? Expiry { get; init; } /// <summary> /// Whether there is an item /// </summary> [MemberNotNullWhen(true, nameof(Bytes))] [MemberNotNullWhen(true, nameof(Expiry))] public bool HasValue => Bytes is not null && Expiry is not null; } /// <summary> /// Distributed cache interface /// </summary> public interface IDistributedCache { /// <summary> /// Attempt to get an item from the cache /// </summary> /// <param name="key">Key</param> /// <param name="cancelToken">Cancel token</param> /// <returns>Task that returns the item</returns> Task<DistributedCacheItem> GetAsync(string key, CancellationToken cancelToken = default); /// <summary> /// Set an item in the cache /// </summary> /// <param name="key">Key</param> /// <param name="item">Item</param> /// <param name="cancelToken">Cancel token</param> /// <returns>Task</returns> Task SetAsync(string key, DistributedCacheItem item, CancellationToken cancelToken = default); /// <summary> /// Delete an item from the cache /// </summary> /// <param name="key">Key</param> /// <param name="cancelToken">Cancel token</param> /// <returns>Task</returns> Task DeleteAsync(string key, CancellationToken cancelToken = default); /// <summary> /// Key change event, get notified if a key changes outside of this machine /// </summary> event Action<string>? KeyChanged; } /// <summary> /// Null distributed cache that no-ops everything /// </summary> public sealed class NullDistributedCache : IDistributedCache, IDistributedLockFactory { #pragma warning disable CS0067 // never used /// <inheritdoc /> public event Action<string>? KeyChanged; #pragma warning restore /// <inheritdoc /> public Task DeleteAsync(string key, CancellationToken cancelToken = default) { return Task.CompletedTask; } /// <inheritdoc /> public Task<DistributedCacheItem> GetAsync(string key, CancellationToken cancelToken = default) { return Task.FromResult<DistributedCacheItem>(new DistributedCacheItem()); } /// <inheritdoc /> public Task SetAsync(string key, DistributedCacheItem item, CancellationToken cancelToken = default) { return Task.CompletedTask; } /// <inheritdoc /> public Task<IAsyncDisposable?> TryAcquireLockAsync(string key, TimeSpan lockTime, TimeSpan timeout, CancellationToken cancelToken) { return Task.FromResult<IAsyncDisposable?>(new DistributedMemoryCache.FakeDistributedLock()); } } /// <summary> /// Distributed cache but all in memory (for testing) /// </summary> /// <remarks> /// Constructor /// </remarks> /// <param name="clock">Clock</param> public sealed class DistributedMemoryCache(TimeProvider clock) : IDistributedCache, IDistributedLockFactory { private readonly TimeProvider clock = clock; internal sealed class FakeDistributedLock : IAsyncDisposable { public ValueTask DisposeAsync() { return new(); } } private readonly ConcurrentDictionary<string, (DateTimeOffset, byte[])> items = new(); /// <inheritdoc /> public event Action<string>? KeyChanged; /// <inheritdoc /> public Task DeleteAsync(string key, CancellationToken cancelToken = default) { if (items.TryRemove(key, out _)) { KeyChanged?.Invoke(key); } return Task.CompletedTask; } /// <inheritdoc /> public Task<DistributedCacheItem> GetAsync(string key, CancellationToken cancelToken = default) { if (items.TryGetValue(key, out var item) && item.Item1 > clock.GetUtcNow()) { return Task.FromResult(new DistributedCacheItem { Bytes = item.Item2, Expiry = item.Item1 - clock.GetUtcNow() }); } return Task.FromResult<DistributedCacheItem>(default); } /// <inheritdoc /> public Task SetAsync(string key, DistributedCacheItem item, CancellationToken cancelToken = default) { if (item.Bytes is not null) { DateTimeOffset expire = clock.GetUtcNow() + item.Expiry ?? throw new ArgumentException("Null expiry not allowed"); items[key] = new(expire, item.Bytes); } return Task.CompletedTask; } /// <inheritdoc /> public Task<IAsyncDisposable?> TryAcquireLockAsync(string key, TimeSpan lockTime, TimeSpan timeout, CancellationToken cancelToken) { if (items.TryAdd(key, new())) { return Task.FromResult<IAsyncDisposable?>(new FakeDistributedLock()); } return Task.FromResult<IAsyncDisposable?>(null); } } /// <summary> /// Distributed redis cache /// </summary> public sealed class DistributedRedisCache : BackgroundService, IDistributedCache, IDistributedLockFactory { private static readonly TimeSpan oneMinute = TimeSpan.FromMinutes(1.0); private readonly IConnectionMultiplexer connectionMultiplexer; private readonly string keyPrefix; private readonly ILogger<DistributedRedisCache> logger; private ISubscriber? changeQueue; /// <summary> /// Constructor /// </summary> /// <param name="options">Options</param> /// <param name="connectionMultiplexer">Connection multiplexer</param> /// <param name="logger">Logger</param> public DistributedRedisCache(DistributedRedisCacheOptions options, IConnectionMultiplexer connectionMultiplexer, ILogger<DistributedRedisCache> logger) { this.keyPrefix = string.IsNullOrWhiteSpace(options.KeyPrefix) ? string.Empty : options.KeyPrefix + ":"; this.connectionMultiplexer = connectionMultiplexer; this.logger = logger; // if we get a connection multiplexer that hasn't connected properly, log an error if (!connectionMultiplexer.IsConnected) { logger.LogError("Connection multiplexer has failed to connect"); } } /// <inheritdoc /> public Task DeleteAsync(string key, CancellationToken cancelToken = default) { return PerformOperation(async () => { await connectionMultiplexer.GetDatabase().KeyDeleteAsync(key); logger.LogDebug("Redis cache deleted {key}", key); return true; }); } /// <inheritdoc /> public Task<DistributedCacheItem> GetAsync(string key, CancellationToken cancelToken = default) { return PerformOperation(async () => { var item = await connectionMultiplexer.GetDatabase().StringGetWithExpiryAsync(key); if (item.Value.HasValue) { logger.LogDebug("Redis cache hit {key}", key); return new DistributedCacheItem { Bytes = item.Value, Expiry = item.Expiry }; } logger.LogDebug("Redis cache miss {key}", key); return default; }); } /// <inheritdoc /> public Task SetAsync(string key, DistributedCacheItem item, CancellationToken cancelToken = default) { if (!item.HasValue) { throw new ArgumentException("Cannot add a null item or null expiration to redis cache, key: " + key); } return PerformOperation(async () => { await connectionMultiplexer.GetDatabase().StringSetAsync(key, item.Bytes, expiry: item.Expiry); logger.LogDebug("Redis cache set {key}", key); return true; }); } /// <inheritdoc /> public event Action<string>? KeyChanged; private async Task<T?> PerformOperation<T>(Func<Task<T>> operation) { T? returnValue = default; await PerformOperationInternal(async () => returnValue = await operation()); return returnValue; } private async Task PerformOperationInternal(Func<Task> operation) { try { await operation(); } catch (RedisCommandException ex) { // handle replica going down and then coming back alive if (ex.Message.Contains("replica", StringComparison.OrdinalIgnoreCase)) { logger.LogError(ex, "Command failure on replica, re-init connection multiplexer and trying again..."); connectionMultiplexer.Configure(); RegisterChangeQueue(); await operation(); return; } // some other error, fail throw; } } private void RegisterChangeQueue() { try { const string keyspace = "__keyspace@0__:"; var queue = changeQueue; changeQueue = null; queue?.UnsubscribeAll(); var namespaceForSubscribe = $"{keyspace}{keyPrefix}*"; var namespaceForSubscribeFlushAll = $"{keyspace}__flushall__*"; queue = connectionMultiplexer.GetSubscriber(); #pragma warning disable CS0618 // Type or member is obsolete queue.Subscribe(namespaceForSubscribe, (channel, value) => { string key = channel.ToString()[keyspace.Length..]; KeyChanged?.Invoke(key); }); queue.Subscribe(namespaceForSubscribeFlushAll, (channel, value) => { if (value == "set") { string key = channel.ToString()[keyspace.Length..]; KeyChanged?.Invoke(key); } }); #pragma warning restore CS0618 // Type or member is obsolete changeQueue = queue; } catch (Exception ex) { logger.LogError(ex, "Error registering change queue"); } } private class DistributedLock(IConnectionMultiplexer connection, string lockKey, string lockToken) : IAsyncDisposable { private readonly IConnectionMultiplexer connection = connection; private readonly string lockKey = lockKey; private readonly string lockToken = lockToken; public async ValueTask DisposeAsync() { await connection.GetDatabase().LockReleaseAsync(lockKey, lockToken); } } private static readonly TimeSpan distributedLockSleepTime = TimeSpan.FromMilliseconds(100.0); /// <inheritdoc /> public async Task<IAsyncDisposable?> TryAcquireLockAsync(string key, TimeSpan lockTime, TimeSpan timeout, CancellationToken cancelToken) { var db = connectionMultiplexer.GetDatabase(); Stopwatch timer = Stopwatch.StartNew(); string lockKey = "DistributedLock_" + key; string lockToken = Guid.NewGuid().ToString("N"); lockTime = lockTime.Ticks == 0 ? oneMinute : lockTime; do { if (await db.LockTakeAsync(lockKey, lockToken, lockTime)) { logger.LogDebug("Acquired redis cache distributed lock {lockKey}", lockKey); return new DistributedLock(connectionMultiplexer, lockKey, lockToken); } if (timeout > distributedLockSleepTime) { await Task.Delay(distributedLockSleepTime, cancelToken); } } while (!cancelToken.IsCancellationRequested && timer.Elapsed < timeout); return null; } /// <inheritdoc /> protected override async Task ExecuteAsync(CancellationToken stoppingToken) { while (!stoppingToken.IsCancellationRequested) { // make sure pub/sub is up if (changeQueue is null) { RegisterChangeQueue(); } await Task.Delay(10000, stoppingToken); } } } /// <summary> /// Distributed redis cache options /// </summary> public sealed class DistributedRedisCacheOptions { /// <summary> /// Key prefix /// </summary> public string KeyPrefix { get; set; } = string.Empty; } /// <summary> /// Interface for distributed locks /// </summary> public interface IDistributedLockFactory { /// <summary> /// Attempt to acquire a distributed lock /// </summary> /// <param name="key">Lock key</param> /// <param name="lockTime">Duration to hold the lock before it auto-expires. Set this to the maximum possible duration you think your code might hold the lock. Default is 1 minute.</param> /// <param name="timeout">Time out to acquire the lock or default to only make one attempt to acquire the lock</param> /// <param name="cancelToken">Cancel token</param> /// <returns>The lock or null if the lock could not be acquired</returns> Task<IAsyncDisposable?> TryAcquireLockAsync(string key, TimeSpan lockTime = default, TimeSpan timeout = default, CancellationToken cancelToken = default); } |
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