Rewrite AWH bits into ArchiCachable

ArchiSteamFarm/Helpers/ArchiCachable.cs

@@ -0,0 +1,141 @@
+//     _                _      _  ____   _                           _____
+//    / \    _ __  ___ | |__  (_)/ ___| | |_  ___   __ _  _ __ ___  |  ___|__ _  _ __  _ __ ___
+//   / _ \  | '__|/ __|| '_ \ | |\___ \ | __|/ _ \ / _` || '_ ` _ \ | |_  / _` || '__|| '_ ` _ \
+//  / ___ \ | |  | (__ | | | || | ___) || |_|  __/| (_| || | | | | ||  _|| (_| || |   | | | | | |
+// /_/   \_\|_|   \___||_| |_||_||____/  \__|\___| \__,_||_| |_| |_||_|   \__,_||_|   |_| |_| |_|
+// 
+// Copyright 2015-2018 Łukasz "JustArchi" Domeradzki
+// Contact: JustArchi@JustArchi.net
+// 
+// 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.
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace ArchiSteamFarm.Helpers {
+	internal sealed class ArchiCachable<T> : IDisposable {
+		private readonly TimeSpan CacheLifetime;
+		private readonly SemaphoreSlim InitSemaphore = new SemaphoreSlim(1, 1);
+		private readonly Func<Task<(bool Success, T Result)>> ResolveFunction;
+
+		private bool IsInitialized => InitializedAt > DateTime.MinValue;
+		private bool IsPermanentCache => CacheLifetime == Timeout.InfiniteTimeSpan;
+		private bool IsRecent => IsPermanentCache || (DateTime.UtcNow.Subtract(InitializedAt) < CacheLifetime);
+
+		// Purge should happen slightly after lifetime, to allow eventual refresh if the property is still used
+		private TimeSpan PurgeLifetime => CacheLifetime + TimeSpan.FromMinutes(1);
+
+		private DateTime InitializedAt;
+		private T InitializedValue;
+		private Timer MaintenanceTimer;
+
+		internal ArchiCachable(Func<Task<(bool Success, T Result)>> resolveFunction, TimeSpan? cacheLifetime = null) {
+			ResolveFunction = resolveFunction ?? throw new ArgumentNullException(nameof(resolveFunction));
+			CacheLifetime = cacheLifetime ?? Timeout.InfiniteTimeSpan;
+		}
+
+		public void Dispose() {
+			// Those are objects that are always being created if constructor doesn't throw exception
+			InitSemaphore.Dispose();
+
+			// Those are objects that might be null and the check should be in-place
+			MaintenanceTimer?.Dispose();
+		}
+
+		internal async Task<(bool Success, T Result)> GetValue() {
+			if (IsInitialized && IsRecent) {
+				return (true, InitializedValue);
+			}
+
+			await InitSemaphore.WaitAsync().ConfigureAwait(false);
+
+			try {
+				if (IsInitialized && IsRecent) {
+					return (true, InitializedValue);
+				}
+
+				(bool success, T result) = await ResolveFunction().ConfigureAwait(false);
+				if (!success) {
+					return (false, InitializedValue);
+				}
+
+				InitializedValue = result;
+				InitializedAt = DateTime.UtcNow;
+
+				if (!IsPermanentCache) {
+					if (MaintenanceTimer == null) {
+						MaintenanceTimer = new Timer(
+							async e => await SoftReset().ConfigureAwait(false),
+							null,
+							PurgeLifetime, // Delay
+							Timeout.InfiniteTimeSpan // Period
+						);
+					} else {
+						MaintenanceTimer.Change(PurgeLifetime, Timeout.InfiniteTimeSpan);
+					}
+				}
+
+				return (true, result);
+			} finally {
+				InitSemaphore.Release();
+			}
+		}
+
+		internal async Task Reset() {
+			if (!IsInitialized) {
+				return;
+			}
+
+			await InitSemaphore.WaitAsync().ConfigureAwait(false);
+
+			try {
+				if (!IsInitialized) {
+					return;
+				}
+
+				HardReset();
+			} finally {
+				InitSemaphore.Release();
+			}
+		}
+
+		private void HardReset() {
+			InitializedAt = DateTime.MinValue;
+			InitializedValue = default;
+
+			if (MaintenanceTimer != null) {
+				MaintenanceTimer.Dispose();
+				MaintenanceTimer = null;
+			}
+		}
+
+		private async Task SoftReset() {
+			if (!IsInitialized || IsRecent) {
+				return;
+			}
+
+			await InitSemaphore.WaitAsync().ConfigureAwait(false);
+
+			try {
+				if (!IsInitialized || IsRecent) {
+					return;
+				}
+
+				HardReset();
+			} finally {
+				InitSemaphore.Release();
+			}
+		}
+	}
+}