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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.Collections.Generic; |
| 6 | +using System.Diagnostics.CodeAnalysis; |
| 7 | +using System.Linq; |
| 8 | +using System.Threading; |
| 9 | +using Microsoft.AspNetCore.Http; |
| 10 | +using Microsoft.AspNetCore.Routing; |
| 11 | +using Microsoft.Azure.WebJobs.Rpc.Core.Internal; |
| 12 | +using Microsoft.Extensions.DependencyInjection; |
| 13 | +using Microsoft.Extensions.Primitives; |
| 14 | + |
| 15 | +namespace Microsoft.Azure.WebJobs.Script.Grpc |
| 16 | +{ |
| 17 | + /// <summary> |
| 18 | + /// Endpoint data source which composes all the WebJobs extension data sources together. |
| 19 | + /// </summary> |
| 20 | + /// <remarks> |
| 21 | + /// Implementation is adapted from <see cref="CompositeEndpointDataSource"/>. |
| 22 | + /// https://github.com/dotnet/aspnetcore/blob/main/src/Http/Routing/src/CompositeEndpointDataSource.cs. |
| 23 | + /// </remarks> |
| 24 | + internal sealed class ExtensionsCompositeEndpointDataSource : EndpointDataSource, IDisposable |
| 25 | + { |
| 26 | + private readonly object _lock = new(); |
| 27 | + private readonly List<EndpointDataSource> _dataSources = new(); |
| 28 | + private readonly IScriptHostManager _scriptHostManager; |
| 29 | + |
| 30 | + private IServiceProvider _extensionServices; |
| 31 | + private List<Endpoint> _endpoints; |
| 32 | + private IChangeToken _consumerChangeToken; |
| 33 | + private CancellationTokenSource _cts; |
| 34 | + private List<IDisposable> _changeTokenRegistrations; |
| 35 | + private bool _disposed; |
| 36 | + |
| 37 | + public ExtensionsCompositeEndpointDataSource(IScriptHostManager scriptHostManager) |
| 38 | + { |
| 39 | + _scriptHostManager = scriptHostManager; |
| 40 | + _scriptHostManager.ActiveHostChanged += OnHostChanged; |
| 41 | + } |
| 42 | + |
| 43 | + /// <inheritdoc /> |
| 44 | + public override IReadOnlyList<Endpoint> Endpoints |
| 45 | + { |
| 46 | + get |
| 47 | + { |
| 48 | + ThrowIfDisposed(); |
| 49 | + EnsureEndpointsInitialized(); |
| 50 | + return _endpoints; |
| 51 | + } |
| 52 | + } |
| 53 | + |
| 54 | + /// <inheritdoc /> |
| 55 | + public override IChangeToken GetChangeToken() |
| 56 | + { |
| 57 | + ThrowIfDisposed(); |
| 58 | + EnsureChangeTokenInitialized(); |
| 59 | + return _consumerChangeToken; |
| 60 | + } |
| 61 | + |
| 62 | + /// <inheritdoc /> |
| 63 | + public void Dispose() |
| 64 | + { |
| 65 | + List<IDisposable> disposables = null; |
| 66 | + lock (_lock) |
| 67 | + { |
| 68 | + if (_disposed) |
| 69 | + { |
| 70 | + return; |
| 71 | + } |
| 72 | + |
| 73 | + _scriptHostManager.ActiveHostChanged -= OnHostChanged; |
| 74 | + _disposed = true; |
| 75 | + if (_changeTokenRegistrations is { Count: > 0 }) |
| 76 | + { |
| 77 | + disposables ??= new List<IDisposable>(); |
| 78 | + disposables.AddRange(_changeTokenRegistrations); |
| 79 | + _changeTokenRegistrations = null; |
| 80 | + } |
| 81 | + } |
| 82 | + |
| 83 | + // Dispose everything outside of the lock in case a registration is blocking on HandleChange completing |
| 84 | + // on another thread or something. |
| 85 | + if (disposables is not null) |
| 86 | + { |
| 87 | + foreach (var disposable in disposables) |
| 88 | + { |
| 89 | + disposable.Dispose(); |
| 90 | + } |
| 91 | + } |
| 92 | + |
| 93 | + _cts?.Dispose(); |
| 94 | + } |
| 95 | + |
| 96 | + private Endpoint WrapEndpoint(Endpoint endpoint) |
| 97 | + { |
| 98 | + static RequestDelegate CreateDelegate(RequestDelegate next, IServiceProvider services) |
| 99 | + { |
| 100 | + // Incoming HttpContext has the gRPC script host services. Create a scope |
| 101 | + // for the JobHost services and swap out the contexts request services. |
| 102 | + return async context => |
| 103 | + { |
| 104 | + if (next is null) |
| 105 | + { |
| 106 | + return; |
| 107 | + } |
| 108 | + |
| 109 | + IServiceProvider original = context.RequestServices; |
| 110 | + |
| 111 | + try |
| 112 | + { |
| 113 | + await using AsyncServiceScope scope = services.CreateAsyncScope(); |
| 114 | + context.RequestServices = scope.ServiceProvider; |
| 115 | + await next(context); |
| 116 | + } |
| 117 | + finally |
| 118 | + { |
| 119 | + context.RequestServices = original; |
| 120 | + } |
| 121 | + }; |
| 122 | + } |
| 123 | + |
| 124 | + if (endpoint is not RouteEndpoint route) |
| 125 | + { |
| 126 | + // We only wrap URL-routeable endpoints (ie: RouteEndpoint). |
| 127 | + return endpoint; |
| 128 | + } |
| 129 | + |
| 130 | + IServiceProvider services = _extensionServices |
| 131 | + ?? throw new InvalidOperationException( |
| 132 | + "Trying to register extension endpoints, but no extension IServiceProvider available."); |
| 133 | + |
| 134 | + return new RouteEndpoint( |
| 135 | + CreateDelegate(route.RequestDelegate, services), |
| 136 | + route.RoutePattern, |
| 137 | + route.Order, |
| 138 | + route.Metadata, |
| 139 | + route.DisplayName); |
| 140 | + } |
| 141 | + |
| 142 | + [MemberNotNull(nameof(_consumerChangeToken))] |
| 143 | + private void EnsureChangeTokenInitialized() |
| 144 | + { |
| 145 | + if (_consumerChangeToken is not null) |
| 146 | + { |
| 147 | + return; |
| 148 | + } |
| 149 | + |
| 150 | + lock (_lock) |
| 151 | + { |
| 152 | + if (_consumerChangeToken is not null) |
| 153 | + { |
| 154 | + return; |
| 155 | + } |
| 156 | + |
| 157 | + // This is our first time initializing the change token, so the collection has "changed" from nothing. |
| 158 | + CreateChangeTokenUnsynchronized(collectionChanged: true); |
| 159 | + } |
| 160 | + } |
| 161 | + |
| 162 | + [MemberNotNull(nameof(_consumerChangeToken))] |
| 163 | + private void CreateChangeTokenUnsynchronized(bool collectionChanged) |
| 164 | + { |
| 165 | + CancellationTokenSource cts = new(); |
| 166 | + |
| 167 | + if (collectionChanged) |
| 168 | + { |
| 169 | + _changeTokenRegistrations = new(); |
| 170 | + foreach (var dataSource in _dataSources) |
| 171 | + { |
| 172 | + _changeTokenRegistrations.Add(ChangeToken.OnChange( |
| 173 | + dataSource.GetChangeToken, |
| 174 | + () => OnEndpointsChange(collectionChanged: false))); |
| 175 | + } |
| 176 | + } |
| 177 | + |
| 178 | + _cts = cts; |
| 179 | + _consumerChangeToken = new CancellationChangeToken(cts.Token); |
| 180 | + } |
| 181 | + |
| 182 | + private void OnHostChanged(object sender, ActiveHostChangedEventArgs args) |
| 183 | + { |
| 184 | + lock (_lock) |
| 185 | + { |
| 186 | + _dataSources.Clear(); |
| 187 | + if (args?.NewHost?.Services is { } services) |
| 188 | + { |
| 189 | + _extensionServices = services; |
| 190 | + IEnumerable<WebJobsRpcEndpointDataSource> sources = services |
| 191 | + .GetService<IEnumerable<WebJobsRpcEndpointDataSource>>() |
| 192 | + ?? Enumerable.Empty<WebJobsRpcEndpointDataSource>(); |
| 193 | + _dataSources.AddRange(sources); |
| 194 | + } |
| 195 | + else |
| 196 | + { |
| 197 | + _extensionServices = null; |
| 198 | + } |
| 199 | + } |
| 200 | + |
| 201 | + OnEndpointsChange(collectionChanged: true); |
| 202 | + } |
| 203 | + |
| 204 | + private void OnEndpointsChange(bool collectionChanged) |
| 205 | + { |
| 206 | + CancellationTokenSource oldTokenSource = null; |
| 207 | + List<IDisposable> oldChangeTokenRegistrations = null; |
| 208 | + |
| 209 | + lock (_lock) |
| 210 | + { |
| 211 | + if (_disposed) |
| 212 | + { |
| 213 | + return; |
| 214 | + } |
| 215 | + |
| 216 | + // Prevent consumers from re-registering callback to in-flight events as that can |
| 217 | + // cause a stack overflow. |
| 218 | + // Example: |
| 219 | + // 1. B registers A. |
| 220 | + // 2. A fires event causing B's callback to get called. |
| 221 | + // 3. B executes some code in its callback, but needs to re-register callback |
| 222 | + // in the same callback. |
| 223 | + oldTokenSource = _cts; |
| 224 | + oldChangeTokenRegistrations = _changeTokenRegistrations; |
| 225 | + |
| 226 | + // Don't create a new change token if no one is listening. |
| 227 | + if (oldTokenSource is not null) |
| 228 | + { |
| 229 | + // We have to hook to any OnChange callbacks before caching endpoints, |
| 230 | + // otherwise we might miss changes that occurred to one of the _dataSources after caching. |
| 231 | + CreateChangeTokenUnsynchronized(collectionChanged); |
| 232 | + } |
| 233 | + |
| 234 | + // Don't update endpoints if no one has read them yet. |
| 235 | + if (_endpoints is not null) |
| 236 | + { |
| 237 | + // Refresh the endpoints from data source so that callbacks can get the latest endpoints. |
| 238 | + CreateEndpointsUnsynchronized(); |
| 239 | + } |
| 240 | + } |
| 241 | + |
| 242 | + // Disposing registrations can block on user defined code on running on other threads that could try to acquire the _lock. |
| 243 | + if (collectionChanged && oldChangeTokenRegistrations is not null) |
| 244 | + { |
| 245 | + foreach (var registration in oldChangeTokenRegistrations) |
| 246 | + { |
| 247 | + registration.Dispose(); |
| 248 | + } |
| 249 | + } |
| 250 | + |
| 251 | + // Raise consumer callbacks. Any new callback registration would happen on the new token created in earlier step. |
| 252 | + // Avoid raising callbacks inside a lock. |
| 253 | + oldTokenSource?.Cancel(); |
| 254 | + } |
| 255 | + |
| 256 | + [MemberNotNull(nameof(_endpoints))] |
| 257 | + private void CreateEndpointsUnsynchronized() |
| 258 | + { |
| 259 | + var endpoints = new List<Endpoint>(); |
| 260 | + |
| 261 | + foreach (var dataSource in _dataSources) |
| 262 | + { |
| 263 | + endpoints.AddRange(dataSource.Endpoints.Select(WrapEndpoint)); |
| 264 | + } |
| 265 | + |
| 266 | + // Only cache _endpoints after everything succeeds without throwing. |
| 267 | + // We don't want to create a negative cache which would cause 404s when there should be 500s. |
| 268 | + _endpoints = endpoints; |
| 269 | + } |
| 270 | + |
| 271 | + // Defer initialization to avoid doing lots of reflection on startup. |
| 272 | + [MemberNotNull(nameof(_endpoints))] |
| 273 | + private void EnsureEndpointsInitialized() |
| 274 | + { |
| 275 | + if (_endpoints is not null) |
| 276 | + { |
| 277 | + return; |
| 278 | + } |
| 279 | + |
| 280 | + lock (_lock) |
| 281 | + { |
| 282 | + if (_endpoints is not null) |
| 283 | + { |
| 284 | + return; |
| 285 | + } |
| 286 | + |
| 287 | + // Now that we're caching the _enpoints, we're responsible for keeping them up-to-date even if the caller |
| 288 | + // hasn't started listening for changes themselves yet. |
| 289 | + EnsureChangeTokenInitialized(); |
| 290 | + |
| 291 | + // Note: we can't use DataSourceDependentCache here because we also need to handle a list of change |
| 292 | + // tokens, which is a complication most of our code doesn't have. |
| 293 | + CreateEndpointsUnsynchronized(); |
| 294 | + } |
| 295 | + } |
| 296 | + |
| 297 | + private void ThrowIfDisposed() |
| 298 | + { |
| 299 | + if (_disposed) |
| 300 | + { |
| 301 | + throw new ObjectDisposedException(nameof(ExtensionsCompositeEndpointDataSource)); |
| 302 | + } |
| 303 | + } |
| 304 | + } |
| 305 | +} |
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