Refactoring Warmup to an HttpModule

--HG--
branch : dev

src/Orchard.Tests/Environment/WarmUp/WarmUpUtilityTests.cs

@@ -4,7 +4,7 @@ using Orchard.Environment.Warmup;
 
 namespace Orchard.Tests.Environment.Warmup {
     [TestFixture]
-    public class WarmUpUtilityTests {
+    public class WarmupUtilityTests {
 
         [Test]
         public void EmptyStringsAreNotAllowed() {

src/Orchard.Tests/Orchard.Framework.Tests.csproj

@@ -240,7 +240,7 @@
     <Compile Include="Environment\RunningShellTableTests.cs" />
     <Compile Include="Environment\StubHostEnvironment.cs" />
     <Compile Include="Environment\Utility\Build.cs" />
-    <Compile Include="Environment\WarmUp\WarmUpUtilityTests.cs" />
+    <Compile Include="Environment\Warmup\WarmupUtilityTests.cs" />
     <Compile Include="FileSystems\AppData\AppDataFolderTests.cs" />
     <Compile Include="Environment\Configuration\DefaultTenantManagerTests.cs" />
     <Compile Include="Environment\DefaultCompositionStrategyTests.cs" />

src/Orchard.Web/Global.asax.cs

@@ -1,22 +1,18 @@
 using System;
-using System.IO;
 using System.Threading;
 using System.Web;
-using System.Web.Hosting;
 using System.Web.Mvc;
 using System.Web.Routing;
 using Autofac;
 using Orchard.Environment;
-using Orchard.Environment.Warmup;
-using Orchard.Utility.Extensions;
 
 namespace Orchard.Web {
     // Note: For instructions on enabling IIS6 or IIS7 classic mode, 
     // visit http://go.microsoft.com/?LinkId=9394801
 
     public class MvcApplication : HttpApplication {
-        private static StartupResult _startupResult;
-        private static EventWaitHandle _waitHandle;
+        private static IOrchardHost _host;
+        private static Exception _error;
 
         public static void RegisterRoutes(RouteCollection routes) {
             routes.IgnoreRoute("{resource}.axd/{*pathInfo}");
@@ -26,77 +22,30 @@ namespace Orchard.Web {
             LaunchStartupThread();
         }
 
-        /// <summary>
-        /// Initializes Orchard's Host in a separate thread
-        /// </summary>
-        private static void LaunchStartupThread() {
-            _startupResult = new StartupResult();
-            _waitHandle = new AutoResetEvent(false);
-
-            ThreadPool.QueueUserWorkItem(
-                state => {
-                    try {
-                        RegisterRoutes(RouteTable.Routes);
-                        var host = OrchardStarter.CreateHost(MvcSingletons);
-                        host.Initialize();
-                        _startupResult.Host = host;
-                    }
-                    catch (Exception e) {
-                        _startupResult.Error = e;
-                    }
-                    finally {
-                        _waitHandle.Set();
-                    }
-                });
-        }
-
         protected void Application_BeginRequest() {
-            // Host is still starting up?
-            if (_startupResult.Host == null && _startupResult.Error == null) {
+            if (_error != null) {
+                // Host startup resulted in an error
 
-                // use the url as it was requested by the client
-                // the real url might be different if it has been translated (proxy, load balancing, ...)
-                var url = Request.ToUrlString();
-                var virtualFileCopy = "~/App_Data/WarmUp/" + WarmupUtility.EncodeUrl(url.Trim('/'));
-                var localCopy = HostingEnvironment.MapPath(virtualFileCopy);
-
-                if (File.Exists(localCopy)) {
-                    // result should not be cached, even on proxies
-                    Context.Response.Cache.SetExpires(DateTime.UtcNow.AddDays(-1));
-                    Context.Response.Cache.SetValidUntilExpires(false);
-                    Context.Response.Cache.SetRevalidation(HttpCacheRevalidation.AllCaches);
-                    Context.Response.Cache.SetCacheability(HttpCacheability.NoCache);
-                    Context.Response.Cache.SetNoStore();
-
-                    Context.Response.WriteFile(localCopy);
-                    Context.Response.End();
-                }
-                else if(!File.Exists(Request.PhysicalPath)) {
-                    // there is no local copy and the host is not running
-                    // wait for the host to initialize
-                    _waitHandle.WaitOne();
-                }
+                // Throw error once, and restart launch; machine state may have changed
+                // so we need to simulate a "restart".
+                var error = _error;
+                LaunchStartupThread();
+                throw error;
             }
-            else {
-                if (_startupResult.Error != null) {
-                    // Host startup resulted in an error
 
-                    // Throw error once, and restart launch (machine state may have changed
-                    // so we need to simulate a "restart".
-                    var error = _startupResult.Error;
-                    LaunchStartupThread();
-                    throw error;
-                }
-
-                Context.Items["originalHttpContext"] = Context;
-                _startupResult.Host.BeginRequest();
+            // Only notify if the host has started up
+            if (_host == null) {
+                return;
             }
+
+            Context.Items["originalHttpContext"] = Context;
+            _host.BeginRequest();
         }
 
         protected void Application_EndRequest() {
             // Only notify if the host has started up
-            if (_startupResult.Host != null) {
-                _startupResult.Host.EndRequest();
+            if (_host != null) {
+                _host.EndRequest();
             }
         }
 
@@ -105,5 +54,31 @@ namespace Orchard.Web {
             builder.Register(ctx => ModelBinders.Binders).SingleInstance();
             builder.Register(ctx => ViewEngines.Engines).SingleInstance();
         }
+
+        /// <summary>
+        /// Initializes Orchard's Host in a separate thread
+        /// </summary>
+        private static void LaunchStartupThread() {
+            RegisterRoutes(RouteTable.Routes);
+
+            _host = null;
+            _error = null;
+
+            ThreadPool.QueueUserWorkItem(
+                state => {
+                    try {
+                        var host = OrchardStarter.CreateHost(MvcSingletons);
+                        host.Initialize();
+                        _host = host;
+                    }
+                    catch (Exception e) {
+                        _error = e;
+                    }
+                    finally {
+                        // Execute pending actions as the host is available
+                        WarmupHttpModule.Signal();
+                    }
+                });
+        }
     }
 }

src/Orchard.Web/Orchard.Web.csproj

@@ -127,6 +127,7 @@
     <Compile Include="Global.asax.cs">
       <DependentUpon>Global.asax</DependentUpon>
     </Compile>
+    <Compile Include="WarmupHttpModule.cs" />
     <Content Include="Config\log4net.config" />
     <Content Include="Config\Sample.HostComponents.config">
       <SubType>Designer</SubType>

src/Orchard.Web/WarmupHttpModule.cs

@@ -0,0 +1,170 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+using System.Threading;
+using System.Web;
+using System.Web.Hosting;
+
+namespace Orchard.Web {
+    public class WarmupHttpModule : IHttpModule {
+        private const string WarmupFilesPath = "~/App_Data/Warmup/";
+        private HttpApplication _context;
+
+        public void Init(HttpApplication context) {
+            _context = context;
+            context.AddOnBeginRequestAsync(BeginBeginRequest, EndBeginRequest, null);
+        }
+
+        static IList<Action> _awaiting = new List<Action>();
+
+        public static bool InWarmup() {
+            if (_awaiting == null) return false;
+            lock (_awaiting) {
+                return _awaiting != null;
+            }
+        }
+
+        public static void Signal() {
+            lock(typeof(WarmupHttpModule)) {
+                var awaiting = _awaiting;
+                _awaiting = null;
+                foreach (var action in awaiting) {
+                    action();
+                }
+            }
+        }
+
+        public static void Await(Action action) {
+            if (_awaiting == null) {
+                action();
+                return;
+            }
+
+            lock(typeof(WarmupHttpModule)) {
+                if (_awaiting == null) {
+                    action();
+                    return;
+                }
+                _awaiting.Add(action);
+            }
+        }
+
+        private IAsyncResult BeginBeginRequest(object sender, EventArgs e, AsyncCallback cb, object extradata) {
+            var asyncResult = new WarmupAsyncResult(cb);
+            
+            // host is available, process every requests, or file is processed
+            if (!InWarmup() || DoBeginRequest()) {
+                asyncResult.Done();
+            }
+            else {
+                // this is the "on hold" execution path
+                Await(asyncResult.Done);
+            }
+            
+            return asyncResult;
+        }
+
+        private void EndBeginRequest(IAsyncResult ar) {
+            ((WarmupAsyncResult)ar).Wait();
+        }
+
+        public void Dispose() {
+        }
+
+        /// <summary>
+        /// return true to put request on hold (until call to Signal()) - return false to allow pipeline to execute immediately
+        /// </summary>
+        /// <returns></returns>
+        private bool DoBeginRequest() {
+            // use the url as it was requested by the client
+            // the real url might be different if it has been translated (proxy, load balancing, ...)
+            var url = ToUrlString(_context.Request);
+            var virtualFileCopy = WarmupFilesPath + EncodeUrl(url.Trim('/'));
+            var localCopy = HostingEnvironment.MapPath(virtualFileCopy);
+
+            if (localCopy != null && File.Exists(localCopy)) {
+                // result should not be cached, even on proxies
+                _context.Response.Cache.SetExpires(DateTime.UtcNow.AddDays(-1));
+                _context.Response.Cache.SetValidUntilExpires(false);
+                _context.Response.Cache.SetRevalidation(HttpCacheRevalidation.AllCaches);
+                _context.Response.Cache.SetCacheability(HttpCacheability.NoCache);
+                _context.Response.Cache.SetNoStore();
+
+                _context.Response.WriteFile(localCopy);
+                _context.Response.End();
+                return true;
+            }
+
+            // there is no local copy and the file exists
+            // serve the static file
+            if (File.Exists(_context.Request.PhysicalPath)) {
+                return true;
+            }
+
+            return false;
+        }
+
+        public static string EncodeUrl(string url) {
+            if(String.IsNullOrWhiteSpace(url)) {
+                throw new ArgumentException("url can't be empty");
+            }
+
+            var sb = new StringBuilder();
+            foreach(var c in url.ToLowerInvariant()) {
+                // only accept alphanumeric chars
+                if((c >= 'a' && c <= 'z')  || (c >= '0' && c <= '9')) {
+                    sb.Append(c);
+                }
+                // otherwise encode them in UTF8
+                else {
+                    sb.Append("_");
+                    foreach(var b in Encoding.UTF8.GetBytes(new [] {c})) {
+                        sb.Append(b.ToString("X"));
+                    }
+                }
+            }
+
+            return sb.ToString();
+        }
+
+        public static string ToUrlString(HttpRequest request) {
+            return string.Format("{0}://{1}{2}", request.Url.Scheme, request.Headers["Host"], request.RawUrl);
+        }
+
+        private class WarmupAsyncResult : IAsyncResult {
+            readonly EventWaitHandle _eventWaitHandle = new AutoResetEvent(false);
+
+            private readonly AsyncCallback _cb;
+
+            public WarmupAsyncResult(AsyncCallback cb) {
+                _cb = cb;
+                IsCompleted = false;
+            }
+
+            public void Done() {
+                IsCompleted = true;
+                _eventWaitHandle.Set();
+                _cb(this);
+            }
+
+            public object AsyncState {
+                get { return null; }
+            }
+
+            public WaitHandle AsyncWaitHandle {
+                get { throw new NotImplementedException(); }
+            }
+
+            public bool CompletedSynchronously {
+                get { return true; }
+            }
+
+            public bool IsCompleted { get; private set; }
+
+            public void Wait() {
+                _eventWaitHandle.WaitOne();
+            }
+        }
+    }
+}

src/Orchard.Web/Web.config

@@ -120,6 +120,10 @@
       <add path="*" verb="*" type="System.Web.HttpNotFoundHandler"/>
 
     </httpHandlers>
+
+    <httpModules>
+      <add name="WarmupHttpModule" type="Orchard.Web.WarmupHttpModule, Orchard.Web"/>
+    </httpModules>
   </system.web>
   <!-- 
         The system.webServer section is required for running ASP.NET AJAX under Internet
@@ -128,7 +132,10 @@
   <system.webServer>
 
     <validation validateIntegratedModeConfiguration="false" />
-    <modules runAllManagedModulesForAllRequests="true" />
+    <modules runAllManagedModulesForAllRequests="true">
+      <remove name="WarmupHttpModule" />
+      <add name="WarmupHttpModule" type="Orchard.Web.WarmupHttpModule, Orchard.Web"/>
+    </modules>
     <handlers accessPolicy="Script">
       <!-- clear all handlers, prevents executing code file extensions, prevents returning any file contents -->
       <clear/>

src/Orchard/Environment/Warmup/StartupResult.cs

@@ -1,8 +0,0 @@
-using System;
-
-namespace Orchard.Environment.Warmup {
-    public class StartupResult {
-        public IOrchardHost Host { get; set; }
-        public Exception Error { get; set; }
-    }
-}

src/Orchard/Environment/Warmup/WarmupUtility.cs

@@ -1,19 +1,29 @@
 using System;
-using System.Linq;
 using System.Text;
-using System.Text.RegularExpressions;
 
 namespace Orchard.Environment.Warmup {
     public static class WarmupUtility {
-        private const string EncodingPattern = "[^a-z0-9]";
-
         public static string EncodeUrl(string url) {
             if(String.IsNullOrWhiteSpace(url)) {
                 throw new ArgumentException("url can't be empty");
             }
 
-            return Regex.Replace(url.ToLower(), EncodingPattern, m => "_" + Encoding.UTF8.GetBytes(m.Value).Select(b => b.ToString("X")).Aggregate((a, b) => a + b));
-        }
+            var sb = new StringBuilder();
+            foreach (var c in url.ToLowerInvariant()) {
+                // only accept alphanumeric chars
+                if ((c >= 'a' && c <= 'z') || (c >= '0' && c <= '9')) {
+                    sb.Append(c);
+                }
+                // otherwise encode them in UTF8
+                else {
+                    sb.Append("_");
+                    foreach(var b in Encoding.UTF8.GetBytes(new [] {c})) {
+                        sb.Append(b.ToString("X"));
+                    }
+                }
+            }
 
+            return sb.ToString();
+        }
     }
 }

src/Orchard/Orchard.Framework.csproj

@@ -187,7 +187,6 @@
     <Compile Include="Environment\HostComponentsConfigModule.cs" />
     <Compile Include="Environment\IOrchardFrameworkAssemblies.cs" />
     <Compile Include="Environment\ViewsBackgroundCompilation.cs" />
-    <Compile Include="Environment\Warmup\StartupResult.cs" />
     <Compile Include="Environment\Warmup\WarmupUtility.cs" />
     <Compile Include="Environment\WorkContextImplementation.cs" />
     <Compile Include="Environment\WorkContextModule.cs" />