| | | 1 | | #region Usings |
| | | 2 | | using System.Diagnostics; |
| | | 3 | | using System.Reflection; |
| | | 4 | | #endregion |
| | | 5 | | |
| | | 6 | | namespace ZhEaIsNsAaBn.DbSeeder.Design; |
| | | 7 | | |
| | | 8 | | /// <summary> |
| | | 9 | | /// The app's host, the way <c>dotnet ef</c> gets it: run the entry point on its own thread, catch the host when |
| | | 10 | | /// <c>Microsoft.Extensions.Hosting</c> reports <c>HostBuilt</c> (generic host, <c>Host.CreateApplicationBuilder</c>, |
| | | 11 | | /// <c>WebApplication</c>), then abort the entry point so the app never starts. Hosted services don't run. |
| | | 12 | | /// </summary> |
| | | 13 | | /// <remarks>Microsoft's <c>HostFactoryResolver.Sources</c> isn't on nuget.org, so this is the same mechanism, written h |
| | | 14 | | internal sealed class DesignTimeHost : IAsyncDisposable |
| | | 15 | | { |
| | | 16 | | private const string HostingListener = "Microsoft.Extensions.Hosting"; |
| | | 17 | | private const string HostBuiltEvent = "HostBuilt"; |
| | | 18 | | |
| | | 19 | | private readonly object _host; |
| | | 20 | | |
| | | 21 | | |
| | | 22 | | private DesignTimeHost( object host, IServiceProvider services ) |
| | | 23 | | { |
| | | 24 | | _host = host; |
| | | 25 | | Services = services; |
| | | 26 | | } |
| | | 27 | | |
| | | 28 | | |
| | | 29 | | public IServiceProvider Services { get; } |
| | | 30 | | |
| | | 31 | | |
| | | 32 | | /// <summary>The host, <see langword="null"/> without an entry point or when the entry point ends without building o |
| | | 33 | | /// <exception cref="InvalidOperationException">The entry point failed, or no host was built within <paramref name=" |
| | | 34 | | public static async Task<DesignTimeHost?> BuildAsync( Assembly assembly, string[] args, TimeSpan timeout ) |
| | | 35 | | { |
| | | 36 | | if ( assembly.EntryPoint is not { } entryPoint ) { return null; } |
| | | 37 | | |
| | | 38 | | |
| | | 39 | | var built = new TaskCompletionSource<object?>( TaskCreationOptions.RunContinuationsAsynchronously ); |
| | | 40 | | |
| | | 41 | | using var subscription = DiagnosticListener.AllListeners.Subscribe( new ListenerObserver( built ) ); |
| | | 42 | | |
| | | 43 | | var thread = new Thread( () => |
| | | 44 | | { |
| | | 45 | | try |
| | | 46 | | { |
| | | 47 | | entryPoint.Invoke( null, entryPoint.GetParameters().Length == 0 ? null : [ args ] ); |
| | | 48 | | built.TrySetResult( null ); // ended without a host (or the host was already caught: first result wins |
| | | 49 | | } |
| | | 50 | | catch ( TargetInvocationException exception ) when ( built.Task.IsCompleted || IsAbort( exception.InnerExcep |
| | | 51 | | { |
| | | 52 | | // our own abort, after HostBuilt |
| | | 53 | | } |
| | | 54 | | catch ( TargetInvocationException exception ) { built.TrySetException( exception.InnerException ?? exception |
| | | 55 | | } ) |
| | | 56 | | { |
| | | 57 | | IsBackground = true, |
| | | 58 | | Name = "dbseeder: app entry point" |
| | | 59 | | }; |
| | | 60 | | |
| | | 61 | | thread.Start(); |
| | | 62 | | |
| | | 63 | | if ( await Task.WhenAny( built.Task, Task.Delay( timeout ) ).ConfigureAwait( false ) != built.Task ) |
| | | 64 | | { |
| | | 65 | | throw new InvalidOperationException( $"The app built no host within {timeout.TotalSeconds:0} s." ); |
| | | 66 | | } |
| | | 67 | | |
| | | 68 | | object? host; |
| | | 69 | | |
| | | 70 | | try { host = await built.Task.ConfigureAwait( false ); } |
| | | 71 | | catch ( Exception exception ) when ( exception is not OperationCanceledException ) |
| | | 72 | | { |
| | | 73 | | throw new InvalidOperationException( exception.Message, exception ); |
| | | 74 | | } |
| | | 75 | | |
| | | 76 | | if ( host is null ) { return null; } |
| | | 77 | | |
| | | 78 | | |
| | | 79 | | var services = host.GetType().GetInterfaces().FirstOrDefault( i => i.FullName == "Microsoft.Extensions.Hosting.I |
| | | 80 | | as IServiceProvider |
| | | 81 | | ?? throw new InvalidOperationException( $"The host ({host.GetType().FullName}) has no services." ); |
| | | 82 | | |
| | | 83 | | return new DesignTimeHost( host, services ); |
| | | 84 | | } |
| | | 85 | | |
| | | 86 | | public async ValueTask DisposeAsync() |
| | | 87 | | { |
| | | 88 | | switch ( _host ) |
| | | 89 | | { |
| | | 90 | | case IAsyncDisposable asyncDisposable: await asyncDisposable.DisposeAsync().ConfigureAwait( false ); break; |
| | | 91 | | case IDisposable disposable: disposable.Dispose(); break; |
| | | 92 | | } |
| | | 93 | | } |
| | | 94 | | |
| | | 95 | | |
| | | 96 | | /// Hosting's own HostAbortedException when it's there (apps' catch-all logging skips it), else ours. |
| | | 97 | | private static Exception Abort() |
| | | 98 | | => Type.GetType( "Microsoft.Extensions.Hosting.HostAbortedException, Microsoft.Extensions.Hosting.Abstractions", |
| | | 99 | | && Activator.CreateInstance( type ) is Exception hosting |
| | | 100 | | ? hosting |
| | | 101 | | : new DesignTimeHostAbortedException(); |
| | | 102 | | |
| | | 103 | | private static bool IsAbort( Exception? exception ) |
| | | 104 | | => exception is DesignTimeHostAbortedException || exception?.GetType().FullName == "Microsoft.Extensions.Hosting |
| | | 105 | | |
| | | 106 | | |
| | | 107 | | private sealed class ListenerObserver : IObserver<DiagnosticListener> |
| | | 108 | | { |
| | | 109 | | private readonly TaskCompletionSource<object?> _built; |
| | | 110 | | |
| | | 111 | | |
| | | 112 | | public ListenerObserver( TaskCompletionSource<object?> built ) => _built = built; |
| | | 113 | | |
| | | 114 | | |
| | | 115 | | public void OnNext( DiagnosticListener value ) |
| | | 116 | | { |
| | | 117 | | if ( value.Name == HostingListener ) { value.Subscribe( new EventObserver( _built ) ); } |
| | | 118 | | } |
| | | 119 | | |
| | | 120 | | public void OnCompleted() { } |
| | | 121 | | |
| | | 122 | | public void OnError( Exception error ) { } |
| | | 123 | | } |
| | | 124 | | |
| | | 125 | | private sealed class EventObserver : IObserver<KeyValuePair<string, object?>> |
| | | 126 | | { |
| | | 127 | | private readonly TaskCompletionSource<object?> _built; |
| | | 128 | | |
| | | 129 | | |
| | | 130 | | public EventObserver( TaskCompletionSource<object?> built ) => _built = built; |
| | | 131 | | |
| | | 132 | | |
| | | 133 | | public void OnNext( KeyValuePair<string, object?> value ) |
| | | 134 | | { |
| | | 135 | | if ( value.Key != HostBuiltEvent || !_built.TrySetResult( value.Value ) ) { return; } |
| | | 136 | | |
| | | 137 | | // Stop the entry point before it runs the app (thrown out of the app's Build()). |
| | | 138 | | throw Abort(); |
| | | 139 | | } |
| | | 140 | | |
| | | 141 | | public void OnCompleted() { } |
| | | 142 | | |
| | | 143 | | public void OnError( Exception error ) { } |
| | | 144 | | } |
| | | 145 | | } |
| | | 146 | | |
| | | 147 | | /// Thrown out of the app's <c>Build()</c> when Hosting has no <c>HostAbortedException</c>. |
| | | 148 | | internal sealed class DesignTimeHostAbortedException : Exception |
| | | 149 | | { |
| | 0 | 150 | | public DesignTimeHostAbortedException() : base( "dotnet dbseeder stopped the app after its host was built." ) { } |
| | | 151 | | } |