Ensure cached proxies metadata is reset on proxy changes

Author: fabiocav

src/WebJobs.Script/Host/ProxyMetadataManager.cs

@@ -7,33 +7,74 @@
 using System.Collections.ObjectModel;
 using System.IO;
 using System.Linq;
+using System.Reactive.Linq;
 using System.Text.RegularExpressions;
+using System.Threading;
 using Microsoft.Azure.AppService.Proxy.Client;
 using Microsoft.Azure.WebJobs.Logging;
 using Microsoft.Azure.WebJobs.Script.Description;
+using Microsoft.Azure.WebJobs.Script.Eventing;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using Newtonsoft.Json.Linq;
 
 namespace Microsoft.Azure.WebJobs.Script
 {
-    public class ProxyMetadataManager : IProxyMetadataManager
+    public class ProxyMetadataManager : IProxyMetadataManager, IDisposable
     {
         private static readonly Regex ProxyNameValidationRegex = new Regex(@"[^a-zA-Z0-9_-]", RegexOptions.Compiled | RegexOptions.IgnoreCase);
-        private readonly Lazy<ProxyMetadataInfo> _metadata;
+        private readonly ReaderWriterLockSlim _metadataLock = new ReaderWriterLockSlim();
         private readonly IOptionsMonitor<ScriptApplicationHostOptions> _applicationHostOptions;
         private readonly IEnvironment _environment;
         private readonly ILogger _logger;
+        private readonly IDisposable _fileChangeSubscription;
+        private Lazy<ProxyMetadataInfo> _metadata;
+        private bool _disposed = false;
 
-        public ProxyMetadataManager(IOptionsMonitor<ScriptApplicationHostOptions> applicationHostOptions, IEnvironment environment, ILoggerFactory loggerFactory)
+        public ProxyMetadataManager(IOptionsMonitor<ScriptApplicationHostOptions> applicationHostOptions, IEnvironment environment, IScriptEventManager eventManager, ILoggerFactory loggerFactory)
         {
             _applicationHostOptions = applicationHostOptions;
             _environment = environment;
             _logger = loggerFactory.CreateLogger(LogCategories.Startup);
             _metadata = new Lazy<ProxyMetadataInfo>(LoadFunctionMetadata);
+
+            _fileChangeSubscription = eventManager.OfType<FileEvent>()
+                       .Where(f => string.Equals(f.Source, EventSources.ScriptFiles, StringComparison.Ordinal) &&
+                       string.Equals(Path.GetFileName(f.FileChangeArguments.Name), ScriptConstants.ProxyMetadataFileName, StringComparison.OrdinalIgnoreCase))
+                       .Subscribe(e => HandleProxyFileChange());
         }
 
-        public ProxyMetadataInfo ProxyMetadata => _metadata.Value;
+        public ProxyMetadataInfo ProxyMetadata
+        {
+            get
+            {
+                _metadataLock.EnterReadLock();
+                try
+                {
+                    return _metadata.Value;
+                }
+                finally
+                {
+                    _metadataLock.ExitReadLock();
+                }
+            }
+        }
+
+        private void HandleProxyFileChange()
+        {
+            _metadataLock.EnterWriteLock();
+            try
+            {
+                if (_metadata.IsValueCreated)
+                {
+                    _metadata = new Lazy<ProxyMetadataInfo>(LoadFunctionMetadata);
+                }
+            }
+            finally
+            {
+                _metadataLock.ExitWriteLock();
+            }
+        }
 
         private ProxyMetadataInfo LoadFunctionMetadata()
         {
@@ -137,5 +178,23 @@ internal static string NormalizeProxyName(string name)
         {
             return ProxyNameValidationRegex.Replace(name, string.Empty);
         }
+
+        protected virtual void Dispose(bool disposing)
+        {
+            if (!_disposed)
+            {
+                if (disposing)
+                {
+                    _fileChangeSubscription?.Dispose();
+                }
+
+                _disposed = true;
+            }
+        }
+
+        public void Dispose()
+        {
+            Dispose(true);
+        }
     }
 }

test/WebJobs.Script.Tests/ProxyMetadataManagerTests.cs

@@ -0,0 +1,55 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+using Microsoft.Azure.WebJobs.Script.Eventing;
+using Microsoft.Extensions.Logging.Abstractions;
+using WebJobs.Script.Tests;
+using Xunit;
+
+namespace Microsoft.Azure.WebJobs.Script.Tests
+{
+    public class ProxyMetadataManagerTests
+    {
+        [Fact]
+        public void ProxyMetadata_WhenProxyFileChanges_IsRefreshed()
+        {
+            using (var tempDirectory = new TempDirectory())
+            {
+                var testProxiesPath = Path.Combine(Environment.CurrentDirectory, @"TestScripts\Proxies");
+                var monitor = new TestOptionsMonitor<ScriptApplicationHostOptions>(new ScriptApplicationHostOptions
+                {
+                    ScriptPath = tempDirectory.Path
+                });
+
+                var environment = new TestEnvironment();
+                var eventManager = new ScriptEventManager();
+
+                var manager = new ProxyMetadataManager(monitor, environment, eventManager, NullLoggerFactory.Instance);
+
+                // Get metadata before proxies exist
+                ProxyMetadataInfo proxyMetadata1 = manager.ProxyMetadata;
+                ProxyMetadataInfo proxyMetadata2 = manager.ProxyMetadata;
+
+                Assert.True(proxyMetadata2.Functions.IsDefaultOrEmpty);
+                Assert.Same(proxyMetadata1, proxyMetadata2);
+
+                // Update our proxies definition
+                FileUtility.CopyDirectory(testProxiesPath, tempDirectory.Path);
+
+                // Simulate a file change notification
+                eventManager.Publish(new FileEvent(EventSources.ScriptFiles,
+                    new FileSystemEventArgs(WatcherChangeTypes.Changed, tempDirectory.Path, ScriptConstants.ProxyMetadataFileName)));
+
+                ProxyMetadataInfo proxyMetadata3 = manager.ProxyMetadata;
+
+                Assert.NotSame(proxyMetadata1, proxyMetadata3);
+
+                Assert.Equal(16, proxyMetadata3.Functions.Length);
+            }
+        }
+    }
+}