IResponseCache adapter and support for vary by header

samples/ResponseCachingSample/Startup.cs

@@ -15,7 +15,7 @@ namespace ResponseCachingSample
     {
         public void ConfigureServices(IServiceCollection services)
         {
-            services.AddMemoryCache();
+            services.AddDistributedResponseCache();
         }
 
         public void Configure(IApplicationBuilder app)
@@ -23,11 +23,14 @@ namespace ResponseCachingSample
             app.UseResponseCaching();
             app.Run(async (context) =>
             {
+                // These settings should be configured by context.Response.Cache.*
                 context.Response.GetTypedHeaders().CacheControl = new CacheControlHeaderValue()
                 {
                     Public = true,
-                    MaxAge = TimeSpan.FromSeconds(10)                    
+                    MaxAge = TimeSpan.FromSeconds(10)
                 };
+                context.Response.Headers["Vary"] = new string[] { "Accept-Encoding", "Non-Existent" };
+
                 await context.Response.WriteAsync("Hello World! " + DateTime.UtcNow);
             });
         }

src/Microsoft.AspNetCore.ResponseCaching/IResponseCache.cs

@@ -0,0 +1,13 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.ResponseCaching
+{
+    public interface IResponseCache
+    {
+        object Get(string key);
+        // TODO: Set expiry policy in the underlying cache?
+        void Set(string key, object entry);
+        void Remove(string key);
+    }
+}

src/Microsoft.AspNetCore.ResponseCaching/Internal/CachedResponse.cs

@@ -3,12 +3,14 @@
 
 using Microsoft.AspNetCore.Http;
 
-namespace Microsoft.AspNetCore.ResponseCaching
+namespace Microsoft.AspNetCore.ResponseCaching.Internal
 {
-    internal class ResponseCachingEntry
+    internal class CachedResponse
     {
-        public int StatusCode { get; set; }
+        internal int StatusCode { get; set; }
+
         internal IHeaderDictionary Headers { get; set; } = new HeaderDictionary();
+
         internal byte[] Body { get; set; }
     }
 }

src/Microsoft.AspNetCore.ResponseCaching/Internal/CachedVaryBy.cs

@@ -0,0 +1,12 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.Extensions.Primitives;
+
+namespace Microsoft.AspNetCore.ResponseCaching.Internal
+{
+    internal class CachedVaryBy
+    {
+        internal StringValues Headers { get; set; }
+    }
+}

src/Microsoft.AspNetCore.ResponseCaching/Internal/DefaultResponseCacheEntrySerializer.cs

@@ -0,0 +1,157 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.IO;
+using Microsoft.AspNetCore.Http;
+
+namespace Microsoft.AspNetCore.ResponseCaching.Internal
+{
+    internal static class DefaultResponseCacheSerializer
+    {
+        private const int FormatVersion = 1;
+
+        public static object Deserialize(byte[] serializedEntry)
+        {
+            using (var memory = new MemoryStream(serializedEntry))
+            {
+                using (var reader = new BinaryReader(memory))
+                {
+                    return Read(reader);
+                }
+            }
+        }
+
+        public static byte[] Serialize(object entry)
+        {
+            using (var memory = new MemoryStream())
+            {
+                using (var writer = new BinaryWriter(memory))
+                {
+                    Write(writer, entry);
+                    writer.Flush();
+                    return memory.ToArray();
+                }
+            }
+        }
+
+        // Serialization Format
+        // Format version (int)
+        // Type (string)
+        // Type-dependent data (see CachedResponse and CachedVaryBy)
+        public static object Read(BinaryReader reader)
+        {
+            if (reader == null)
+            {
+                throw new ArgumentNullException(nameof(reader));
+            }
+
+            if (reader.ReadInt32() != FormatVersion)
+            {
+                return null;
+            }
+
+            var type = reader.ReadString();
+
+            if (string.Equals(nameof(CachedResponse), type))
+            {
+                var cachedResponse = ReadCachedResponse(reader);
+                return cachedResponse;
+            }
+            else if (string.Equals(nameof(CachedVaryBy), type))
+            {
+                var cachedResponse = ReadCachedVaryBy(reader);
+                return cachedResponse;
+            }
+
+            // Unable to read as CachedResponse or CachedVaryBy
+            return null;
+        }
+
+        // Serialization Format
+        // Status code (int)
+        // Header count (int)
+        // Header(s)
+        //   Key (string)
+        //   Value (string)
+        // Body length (int)
+        // Body (byte[])
+        private static CachedResponse ReadCachedResponse(BinaryReader reader)
+        {
+            var statusCode = reader.ReadInt32();
+            var headerCount = reader.ReadInt32();
+            var headers = new HeaderDictionary();
+            for (var index = 0; index < headerCount; index++)
+            {
+                var key = reader.ReadString();
+                var value = reader.ReadString();
+                headers[key] = value;
+            }
+            var bodyLength = reader.ReadInt32();
+            var body = reader.ReadBytes(bodyLength);
+
+            return new CachedResponse { StatusCode = statusCode, Headers = headers, Body = body };
+        }
+
+        // Serialization Format
+        // Headers (comma separated string)
+        private static CachedVaryBy ReadCachedVaryBy(BinaryReader reader)
+        {
+            var headers = reader.ReadString().Split(',');
+
+            return new CachedVaryBy { Headers = headers };
+        }
+
+        // See serialization format above
+        public static void Write(BinaryWriter writer, object entry)
+        {
+            if (writer == null)
+            {
+                throw new ArgumentNullException(nameof(writer));
+            }
+
+            if (entry == null)
+            {
+                throw new ArgumentNullException(nameof(entry));
+            }
+
+            writer.Write(FormatVersion);
+            
+            if (entry is CachedResponse)
+            {
+                WriteCachedResponse(writer, entry as CachedResponse);
+            }
+            else if (entry is CachedVaryBy)
+            {
+                WriteCachedVaryBy(writer, entry as CachedVaryBy);
+            }
+            else
+            {
+                throw new NotSupportedException($"Unrecognized entry format for {nameof(entry)}.");
+            }
+        }
+
+        // See serialization format above
+        private static void WriteCachedResponse(BinaryWriter writer, CachedResponse entry)
+        {
+            writer.Write(nameof(CachedResponse));
+            writer.Write(entry.StatusCode);
+            writer.Write(entry.Headers.Count);
+            foreach (var header in entry.Headers)
+            {
+                writer.Write(header.Key);
+                writer.Write(header.Value);
+            }
+
+            writer.Write(entry.Body.Length);
+            writer.Write(entry.Body);
+        }
+
+        // See serialization format above
+        private static void WriteCachedVaryBy(BinaryWriter writer, CachedVaryBy entry)
+        {
+            writer.Write(nameof(CachedVaryBy));
+            writer.Write(entry.Headers);
+        }
+    }
+}

src/Microsoft.AspNetCore.ResponseCaching/Internal/DistributedResponseCache.cs

@@ -0,0 +1,60 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.Extensions.Caching.Distributed;
+
+namespace Microsoft.AspNetCore.ResponseCaching.Internal
+{
+    internal class DistributedResponseCache : IResponseCache
+    {
+        private readonly IDistributedCache _cache;
+
+        public DistributedResponseCache(IDistributedCache cache)
+        {
+            if (cache == null)
+            {
+                throw new ArgumentNullException(nameof(cache));
+            }
+
+            _cache = cache;
+        }
+
+        public object Get(string key)
+        {
+            try
+            {
+                return DefaultResponseCacheSerializer.Deserialize(_cache.Get(key));
+            }
+            catch
+            {
+                // TODO: Log error
+                return null;
+            }
+        }
+
+        public void Remove(string key)
+        {
+            try
+            {
+                _cache.Remove(key);
+            }
+            catch
+            {
+                // TODO: Log error
+            }
+        }
+
+        public void Set(string key, object entry)
+        {
+            try
+            {
+                _cache.Set(key, DefaultResponseCacheSerializer.Serialize(entry));
+            }
+            catch
+            {
+                // TODO: Log error
+            }
+        }
+    }
+}

src/Microsoft.AspNetCore.ResponseCaching/Internal/MemoryResponseCache.cs

@@ -0,0 +1,38 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.Extensions.Caching.Memory;
+
+namespace Microsoft.AspNetCore.ResponseCaching.Internal
+{
+    internal class MemoryResponseCache : IResponseCache
+    {
+        private readonly IMemoryCache _cache;
+
+        public MemoryResponseCache(IMemoryCache cache)
+        {
+            if (cache == null)
+            {
+                throw new ArgumentNullException(nameof(cache));
+            }
+
+            _cache = cache;
+        }
+
+        public object Get(string key)
+        {
+            return _cache.Get(key);
+        }
+
+        public void Remove(string key)
+        {
+            _cache.Remove(key);
+        }
+
+        public void Set(string key, object entry)
+        {
+            _cache.Set(key, entry);
+        }
+    }
+}

src/Microsoft.AspNetCore.ResponseCaching/ResponseCachingContext.cs

@@ -3,9 +3,11 @@
 
 using System;
 using System.IO;
+using System.Text;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
-using Microsoft.Extensions.Caching.Memory;
+using Microsoft.AspNetCore.ResponseCaching.Internal;
+using Microsoft.Extensions.Primitives;
 
 namespace Microsoft.AspNetCore.ResponseCaching
 {
@@ -13,15 +15,25 @@ namespace Microsoft.AspNetCore.ResponseCaching
     {
         private string _cacheKey;
 
-        public ResponseCachingContext(HttpContext httpContext, IMemoryCache cache)
+        public ResponseCachingContext(HttpContext httpContext, IResponseCache cache)
         {
+            if (cache == null)
+            {
+                throw new ArgumentNullException(nameof(cache));
+            }
+
+            if (httpContext == null)
+            {
+                throw new ArgumentNullException(nameof(httpContext));
+            }
+
             HttpContext = httpContext;
             Cache = cache;
         }
 
         private HttpContext HttpContext { get; }
 
-        private IMemoryCache Cache { get; }
+        private IResponseCache Cache { get; }
 
         private Stream OriginalResponseStream { get; set; }
 
@@ -46,38 +58,81 @@ namespace Microsoft.AspNetCore.ResponseCaching
         }
 
         // Only QueryString is treated as case sensitive
-        // GET;HTTP://MYDOMAIN.COM:80/PATHBASE/PATH?QueryString
+        // GET;/PATH;VaryBy
         private string CreateCacheKey()
+        {
+            return CreateCacheKey(varyBy: null);
+        }
+
+        private string CreateCacheKey(CachedVaryBy varyBy)
         {
             var request = HttpContext.Request;
-            return request.Method.ToUpperInvariant()
-                + ";"
-                + request.Scheme.ToUpperInvariant()
-                + "://"
-                + request.Host.Value.ToUpperInvariant()
-                + request.PathBase.Value.ToUpperInvariant()
-                + request.Path.Value.ToUpperInvariant()
-                + request.QueryString;
+            var builder = new StringBuilder()
+                .Append(request.Method.ToUpperInvariant())
+                .Append(";")
+                .Append(request.Path.Value.ToUpperInvariant())
+                .Append(CreateVaryByCacheKey(varyBy));
+
+            return builder.ToString();
+        }
+
+        private string CreateVaryByCacheKey(CachedVaryBy varyBy)
+        {
+            // TODO: resolve key format and delimiters
+            if (varyBy == null)
+            {
+                return string.Empty;
+            }
+
+            var request = HttpContext.Request;
+            var builder = new StringBuilder(";");
+
+            foreach (var header in varyBy.Headers)
+            {
+                var value = request.Headers[header].ToString();
+                // null vs Empty?
+                if (string.IsNullOrEmpty(value))
+                {
+                    value = "null";
+                }
+
+                builder.Append(header)
+                    .Append("=")
+                    .Append(value)
+                    .Append(";");
+            }
+
+            // Parse querystring params
+
+            return builder.ToString();
         }
 
         internal async Task<bool> TryServeFromCacheAsync()
         {
             _cacheKey = CreateCacheKey();
-            ResponseCachingEntry cacheEntry;
-            if (Cache.TryGetValue(_cacheKey, out cacheEntry))
+            var cacheEntry = Cache.Get(_cacheKey);
+
+            if (cacheEntry is CachedVaryBy)
+            {
+                // Request contains VaryBy rules, recompute key and try again
+                _cacheKey = CreateCacheKey(cacheEntry as CachedVaryBy);
+                cacheEntry = Cache.Get(_cacheKey);
+            }
+
+            if (cacheEntry is CachedResponse)
             {
                 // TODO: Compare cached request headers
 
-                // TODO: Evaluate Vary-By and select the most appropriate response
-
                 // TODO: Content negotiation if there are multiple cached response formats?
 
                 // TODO: Verify content freshness, or else re-validate the data?
 
+                var cachedResponse = cacheEntry as CachedResponse;
+
                 var response = HttpContext.Response;
                 // Copy the cached status code and response headers
-                response.StatusCode = cacheEntry.StatusCode;
-                foreach (var pair in cacheEntry.Headers)
+                response.StatusCode = cachedResponse.StatusCode;
+                foreach (var pair in cachedResponse.Headers)
                 {
                     response.Headers[pair.Key] = pair.Value;
                 }
@@ -86,7 +141,7 @@ namespace Microsoft.AspNetCore.ResponseCaching
                 response.Headers["Served_From_Cache"] = DateTime.Now.ToString();
 
                 // Copy the cached response body
-                var body = cacheEntry.Body;
+                var body = cachedResponse.Body;
                 if (body.Length > 0)
                 {
                     await response.Body.WriteAsync(body, 0, body.Length);
@@ -120,15 +175,34 @@ namespace Microsoft.AspNetCore.ResponseCaching
         {
             if (CacheResponse)
             {
-                // Store the buffer to cache
-                var cacheEntry = new ResponseCachingEntry();
-                cacheEntry.StatusCode = HttpContext.Response.StatusCode;
+                var response = HttpContext.Response;
+                var varyHeaderValue = response.Headers["Vary"];
+
+                // Check if any VaryBy rules exist
+                if (!StringValues.IsNullOrEmpty(varyHeaderValue))
+                {
+                    var cachedVaryBy = new CachedVaryBy
+                    {
+                        // Only vary by headers for now
+                        Headers = varyHeaderValue
+                    };
+
+                    Cache.Set(_cacheKey, cachedVaryBy);
+                    _cacheKey = CreateCacheKey(cachedVaryBy);
+                }
+
+                // Store the response to cache
+                var cachedResponse = new CachedResponse
+                {
+                    StatusCode = HttpContext.Response.StatusCode,
+                    Body = Buffer.ToArray()
+                };
                 foreach (var pair in HttpContext.Response.Headers)
                 {
-                    cacheEntry.Headers[pair.Key] = pair.Value;
+                    cachedResponse.Headers[pair.Key] = pair.Value;
                 }
-                cacheEntry.Body = Buffer.ToArray();
-                Cache.Set(_cacheKey, cacheEntry); // TODO: Timeouts
+
+                Cache.Set(_cacheKey, cachedResponse); // TODO: Timeouts
             }
 
             // TODO: TEMP, flush the buffer to the client

src/Microsoft.AspNetCore.ResponseCaching/ResponseCachingMiddleware.cs

@@ -1,9 +1,9 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
-using Microsoft.Extensions.Caching.Memory;
 
 namespace Microsoft.AspNetCore.ResponseCaching
 {
@@ -11,10 +11,20 @@ namespace Microsoft.AspNetCore.ResponseCaching
     public class ResponseCachingMiddleware
     {
         private readonly RequestDelegate _next;
-        private readonly IMemoryCache _cache;
+        private readonly IResponseCache _cache;
 
-        public ResponseCachingMiddleware(RequestDelegate next, IMemoryCache cache)
+        public ResponseCachingMiddleware(RequestDelegate next, IResponseCache cache)
         {
+            if (cache == null)
+            {
+                throw new ArgumentNullException(nameof(cache));
+            }
+
+            if (next == null)
+            {
+                throw new ArgumentNullException(nameof(next));
+            }
+
             _next = next;
             _cache = cache;
         }

src/Microsoft.AspNetCore.ResponseCaching/ResponseCachingServiceCollectionExtensions.cs

@@ -0,0 +1,39 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using Microsoft.AspNetCore.ResponseCaching;
+using Microsoft.AspNetCore.ResponseCaching.Internal;
+using Microsoft.Extensions.DependencyInjection.Extensions;
+
+namespace Microsoft.Extensions.DependencyInjection
+{
+    public static class ResponseCachingServiceCollectionExtensions
+    {
+        public static IServiceCollection AddMemoryResponseCache(this IServiceCollection services)
+        {
+            if (services == null)
+            {
+                throw new ArgumentNullException(nameof(services));
+            }
+            
+            services.AddMemoryCache();
+            services.TryAdd(ServiceDescriptor.Singleton<IResponseCache, MemoryResponseCache>());
+
+            return services;
+        }
+
+        public static IServiceCollection AddDistributedResponseCache(this IServiceCollection services)
+        {
+            if (services == null)
+            {
+                throw new ArgumentNullException(nameof(services));
+            }
+            
+            services.AddDistributedMemoryCache();
+            services.TryAdd(ServiceDescriptor.Singleton<IResponseCache, DistributedResponseCache>());
+
+            return services;
+        }
+    }
+}

src/Microsoft.AspNetCore.ResponseCaching/project.json

@@ -22,7 +22,7 @@
   },
   "dependencies": {
     "Microsoft.AspNetCore.Http": "1.1.0-*",
-    "Microsoft.Extensions.Caching.Abstractions": "1.1.0-*"
+    "Microsoft.Extensions.Caching.Memory": "1.1.0-*"
   },
   "frameworks": {
     "net451": {},

test/Microsoft.AspNetCore.ResponseCaching.Tests/Microsoft.AspNetCore.ResponseCaching.Tests.xproj

@@ -14,5 +14,8 @@
   <PropertyGroup>
     <SchemaVersion>2.0</SchemaVersion>
   </PropertyGroup>
+  <ItemGroup>
+    <Service Include="{82a7f48d-3b50-4b1e-b82e-3ada8210c358}" />
+  </ItemGroup>
   <Import Project="$(VSToolsPath)\DotNet\Microsoft.DotNet.targets" Condition="'$(VSToolsPath)' != ''" />
 </Project>

test/Microsoft.AspNetCore.ResponseCaching.Tests/ResponseCachingContextTests.cs

@@ -1,11 +1,12 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.Caching.Memory;
 using Xunit;
 
-namespace Microsoft.AspNetCore.ResponseCaching
+namespace Microsoft.AspNetCore.ResponseCaching.Tests
 {
     public class ResponseCachingContextTests
     {
@@ -14,7 +15,7 @@ namespace Microsoft.AspNetCore.ResponseCaching
         {
             var httpContext = new DefaultHttpContext();
             httpContext.Request.Method = "GET";
-            var context = new ResponseCachingContext(httpContext, new MemoryCache(new MemoryCacheOptions()));
+            var context = new ResponseCachingContext(httpContext, new TestResponseCache());
 
             Assert.True(context.CheckRequestAllowsCaching());
         }
@@ -25,9 +26,25 @@ namespace Microsoft.AspNetCore.ResponseCaching
         {
             var httpContext = new DefaultHttpContext();
             httpContext.Request.Method = method;
-            var context = new ResponseCachingContext(httpContext, new MemoryCache(new MemoryCacheOptions()));
+            var context = new ResponseCachingContext(httpContext, new TestResponseCache());
 
             Assert.False(context.CheckRequestAllowsCaching());
         }
+
+        private class TestResponseCache : IResponseCache
+        {
+            public object Get(string key)
+            {
+                return null;
+            }
+
+            public void Remove(string key)
+            {
+            }
+
+            public void Set(string key, object entry)
+            {
+            }
+        }
     }
 }

test/Microsoft.AspNetCore.ResponseCaching.Tests/ResponseCachingTests.cs

@@ -0,0 +1,50 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.TestHost;
+using Microsoft.Extensions.DependencyInjection;
+using System;
+using Xunit;
+
+namespace Microsoft.AspNetCore.ResponseCaching.Tests
+{
+    public class ResponseCachingTests
+    {
+        [Fact]
+        public async void ServesCachedContentIfAvailable()
+        {
+            var builder = new WebHostBuilder()
+                .ConfigureServices(services =>
+                {
+                    services.AddDistributedResponseCache();
+                })
+                .Configure(app =>
+                {
+                    app.UseResponseCaching();
+                    app.Run(async (context) =>
+                    {
+                        context.Response.Headers["Cache-Control"] = "public";
+                        await context.Response.WriteAsync(DateTime.UtcNow.ToString());
+                    });
+                });
+
+            using (var server = new TestServer(builder))
+            {
+                var client = server.CreateClient();
+                var initialResponse = await client.GetAsync("");
+                var subsequentResponse = await client.GetAsync("");
+
+                initialResponse.EnsureSuccessStatusCode();
+                subsequentResponse.EnsureSuccessStatusCode();
+
+                // TODO: Check for the appropriate headers once we actually set them
+                Assert.False(initialResponse.Headers.Contains("Served_From_Cache"));
+                Assert.True(subsequentResponse.Headers.Contains("Served_From_Cache"));
+                Assert.Equal(await initialResponse.Content.ReadAsStringAsync(), await subsequentResponse.Content.ReadAsStringAsync());
+            }
+        }
+    }
+}

test/Microsoft.AspNetCore.ResponseCaching.Tests/project.json

@@ -5,9 +5,8 @@
   },
   "dependencies": {
     "dotnet-test-xunit": "2.2.0-*",
-    "Microsoft.AspNetCore.Http": "1.1.0-*",
     "Microsoft.AspNetCore.ResponseCaching": "0.1.0-*",
-    "Microsoft.Extensions.Caching.Memory": "1.1.0-*",
+    "Microsoft.AspNetCore.TestHost": "1.1.0-*",
     "xunit": "2.2.0-*"
   },
   "frameworks": {