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| 1 | +// Copyright (c) .NET Foundation. All rights reserved. |
| 2 | +// Licensed under the MIT License. See License.txt in the project root for license information. |
| 3 | + |
| 4 | +using System; |
| 5 | +using System.Diagnostics; |
| 6 | +using System.Diagnostics.CodeAnalysis; |
| 7 | +using Microsoft.Azure.WebJobs.Script; |
| 8 | +using Microsoft.Extensions.DependencyInjection; |
| 9 | + |
| 10 | +#nullable enable |
| 11 | + |
| 12 | +namespace Microsoft.Extensions.Logging |
| 13 | +{ |
| 14 | + internal class ForwardingLogger : ILogger |
| 15 | + { |
| 16 | + // The service key to use for dependency injection to get forwarding loggers. |
| 17 | + public const string ServiceKey = "Forwarding"; |
| 18 | + |
| 19 | + private readonly string _categoryName; |
| 20 | + private readonly ILogger _fallback; |
| 21 | + private readonly IScriptHostManager _manager; |
| 22 | + |
| 23 | + // We use weak references so as to not keep a ScriptHost alive after it shuts down. |
| 24 | + private readonly WeakReference<ILogger> _current = new(null!); |
| 25 | + private readonly WeakReference<IServiceProvider> _services = new(null!); |
| 26 | + |
| 27 | + public ForwardingLogger(string categoryName, ILogger inner, IScriptHostManager manager) |
| 28 | + { |
| 29 | + ArgumentNullException.ThrowIfNull(inner); |
| 30 | + ArgumentNullException.ThrowIfNull(manager); |
| 31 | + _categoryName = categoryName; |
| 32 | + _fallback = inner; |
| 33 | + _manager = manager; |
| 34 | + } |
| 35 | + |
| 36 | + private ILogger Current |
| 37 | + { |
| 38 | + get |
| 39 | + { |
| 40 | + if (TryGetCurrentLogger(out ILogger? logger)) |
| 41 | + { |
| 42 | + return logger; |
| 43 | + } |
| 44 | + |
| 45 | + // No current ScriptHost logger, or the ScriptHost is gone. Use the fallback WebHost logger. |
| 46 | + return _fallback; |
| 47 | + } |
| 48 | + } |
| 49 | + |
| 50 | + public IDisposable? BeginScope<TState>(TState state) |
| 51 | + where TState : notnull |
| 52 | + => Current.BeginScope(state); |
| 53 | + |
| 54 | + public bool IsEnabled(LogLevel logLevel) => Current.IsEnabled(logLevel); |
| 55 | + |
| 56 | + public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter) |
| 57 | + => Current.Log(logLevel, eventId, state, exception, formatter); |
| 58 | + |
| 59 | + private bool TryGetCurrentLogger([NotNullWhen(true)] out ILogger? logger) |
| 60 | + { |
| 61 | + if (IsLoggerCurrent(out logger)) |
| 62 | + { |
| 63 | + return true; |
| 64 | + } |
| 65 | + else if (_manager.Services is { } services) |
| 66 | + { |
| 67 | + logger = services.GetRequiredService<ILoggerFactory>().CreateLogger(_categoryName); |
| 68 | + _services.SetTarget(services); |
| 69 | + _current.SetTarget(logger); |
| 70 | + return true; |
| 71 | + } |
| 72 | + |
| 73 | + logger = null; |
| 74 | + return false; |
| 75 | + } |
| 76 | + |
| 77 | + private bool IsLoggerCurrent([NotNullWhen(true)] out ILogger? logger) |
| 78 | + { |
| 79 | + // First check if the last IServiceProvider we used is still active. |
| 80 | + if (_services.TryGetTarget(out IServiceProvider? services) |
| 81 | + && ReferenceEquals(services, _manager.Services)) |
| 82 | + { |
| 83 | + // Service provider is still correct, so our logger is current. |
| 84 | + return _current.TryGetTarget(out logger); |
| 85 | + } |
| 86 | + |
| 87 | + logger = null; |
| 88 | + return false; |
| 89 | + } |
| 90 | + } |
| 91 | + |
| 92 | + [DebuggerDisplay("{_logger}")] |
| 93 | + internal class ForwardingLogger<T> : ILogger<T> |
| 94 | + { |
| 95 | + private readonly ILogger _logger; |
| 96 | + |
| 97 | + public ForwardingLogger([ForwardingLogger] ILoggerFactory factory) |
| 98 | + { |
| 99 | + ArgumentNullException.ThrowIfNull(factory); |
| 100 | + _logger = factory.CreateLogger<T>(); |
| 101 | + } |
| 102 | + |
| 103 | + IDisposable? ILogger.BeginScope<TState>(TState state) => _logger.BeginScope(state); |
| 104 | + |
| 105 | + bool ILogger.IsEnabled(LogLevel logLevel) => _logger.IsEnabled(logLevel); |
| 106 | + |
| 107 | + void ILogger.Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception? exception, Func<TState, Exception?, string> formatter) => |
| 108 | + _logger.Log(logLevel, eventId, state, exception, formatter); |
| 109 | + } |
| 110 | +} |
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