Cache downstream swagger docs

README.md

@@ -570,6 +570,20 @@ services.AddSwaggerForOcelot(Configuration,
 
 Note, this does not affect nor checks the swagger document's `securityDefinitions` property.
 
+## Downstream Documentation Caching
+If your downstream documentation is too large, the response time may be slow. 
+To address this issue, you can enable caching of transformed documentation by setting the 
+`DownstreamDocsCacheExpire` parameter. If this parameter is not provided, the documentation won't be cached.
+If there is any change in the downstream documentation, the cache will be refreshed.
+
+```csharp
+services.AddSwaggerForOcelot(Configuration,
+            setup =>
+            {
+                setup.DownstreamDocsCacheExpire = TimeSpan.FromMinutes(10);
+            });
+```
+
 ## Limitation
 
 - Now, this library support only `{everything}` as a wildcard in routing definition. #68

src/MMLib.SwaggerForOcelot/Configuration/OcelotSwaggerGenOptions.cs

@@ -26,14 +26,22 @@ public class OcelotSwaggerGenOptions
         /// </value>
         public bool GenerateDocsForGatewayItSelf { get; set; } = false;
 
+        /// <summary>
+        /// Gets or sets a value indicating downstream docs cache expire duration in seconds.
+        /// </summary>
+        /// <value>
+        ///     <c>0</c> if it won't be cached; otherwise, cache expire duration in seconds.
+        /// </value>
+        public TimeSpan DownstreamDocsCacheExpire { get; set; } = TimeSpan.Zero;
+
         /// <summary>
         /// Generates docs for gateway it self with options.
         /// </summary>
         /// <param name="options">Gateway itself docs generation options.</param>
         public void GenerateDocsDocsForGatewayItSelf(Action<OcelotGatewayItSelfSwaggerGenOptions> options = null)
         {
             GenerateDocsForGatewayItSelf = true;
-           
+
             OcelotGatewayItSelfSwaggerGenOptions = new OcelotGatewayItSelfSwaggerGenOptions();
             options?.Invoke(OcelotGatewayItSelfSwaggerGenOptions);
 

src/MMLib.SwaggerForOcelot/Transformation/SwaggerJsonTransformer.cs

@@ -1,10 +1,14 @@
-using Kros.IO;
+using Kros.IO;
+using Microsoft.Extensions.Caching.Memory;
 using MMLib.SwaggerForOcelot.Configuration;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
+using System.Security.Cryptography;
+using System.Text;
 
 namespace MMLib.SwaggerForOcelot.Transformation
 {
@@ -15,14 +19,37 @@ namespace MMLib.SwaggerForOcelot.Transformation
     public class SwaggerJsonTransformer : ISwaggerJsonTransformer
     {
         private readonly OcelotSwaggerGenOptions _ocelotSwaggerGenOptions;
+        private readonly IMemoryCache _memoryCache;
 
-        public SwaggerJsonTransformer(OcelotSwaggerGenOptions ocelotSwaggerGenOptions)
+        public SwaggerJsonTransformer(OcelotSwaggerGenOptions ocelotSwaggerGenOptions, IMemoryCache memoryCache)
         {
             _ocelotSwaggerGenOptions = ocelotSwaggerGenOptions;
+            _memoryCache = memoryCache;
         }
 
         /// <inheritdoc/>
-        public string Transform(string swaggerJson,
+        public string Transform(
+            string swaggerJson,
+            IEnumerable<RouteOptions> routes,
+            string serverOverride,
+            SwaggerEndPointOptions endPointOptions)
+        {
+            if (_ocelotSwaggerGenOptions.DownstreamDocsCacheExpire == TimeSpan.Zero)
+            {
+                return TransformSwaggerOrOpenApi(swaggerJson, routes, serverOverride, endPointOptions);
+            }
+
+            return _memoryCache.GetOrCreate(
+                ComputeHash(swaggerJson),
+                entry =>
+                {
+                    entry.AbsoluteExpirationRelativeToNow = _ocelotSwaggerGenOptions.DownstreamDocsCacheExpire;
+                    return TransformSwaggerOrOpenApi(swaggerJson, routes, serverOverride, endPointOptions);
+                });
+        }
+
+        private string TransformSwaggerOrOpenApi(
+            string swaggerJson,
             IEnumerable<RouteOptions> routes,
             string serverOverride,
             SwaggerEndPointOptions endPointOptions)
@@ -327,5 +354,13 @@ private static void TransformServerPaths(JObject openApi, string serverOverride,
                 }
             }
         }
+
+        private static string ComputeHash(string input)
+        {
+            using var sha256 = SHA256.Create();
+            byte[] bytes = Encoding.UTF8.GetBytes(input);
+            byte[] hash = sha256.ComputeHash(bytes);
+            return Convert.ToBase64String(hash);
+        }
     }
 }

tests/MMLib.SwaggerForOcelot.BenchmarkTests/SwaggerJsonTransfromerBenchmark.cs

@@ -1,4 +1,6 @@
 using BenchmarkDotNet.Attributes;
+using Microsoft.Extensions.Caching.Memory;
+using Microsoft.Extensions.Options;
 using MMLib.SwaggerForOcelot.Configuration;
 using MMLib.SwaggerForOcelot.Transformation;
 using System.Collections.Generic;
@@ -14,6 +16,7 @@ public class SwaggerJsonTransfromerBenchmark
     private readonly string _swagger;
     private readonly SwaggerJsonTransformer _transformer;
     private readonly List<RouteOptions> _routeOptions;
+    private readonly IMemoryCache memoryCache = new MemoryCache(Options.Create(new MemoryCacheOptions()));
 
     public SwaggerJsonTransfromerBenchmark()
     {
@@ -40,7 +43,7 @@ public SwaggerJsonTransfromerBenchmark()
             }
         };
 
-        _transformer = new SwaggerJsonTransformer(new OcelotSwaggerGenOptions());
+        _transformer = new SwaggerJsonTransformer(new OcelotSwaggerGenOptions(), memoryCache);
     }
 
     [Benchmark]

tests/MMLib.SwaggerForOcelot.Tests/SwaggerForOcelotMiddlewareShould.cs

@@ -10,6 +10,7 @@
 using JsonDiffPatchDotNet;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Http.Extensions;
+using Microsoft.Extensions.Caching.Memory;
 using Microsoft.Extensions.Options;
 using MMLib.SwaggerForOcelot.Configuration;
 using MMLib.SwaggerForOcelot.Middleware;
@@ -23,6 +24,7 @@
 using Swashbuckle.AspNetCore.Swagger;
 using Xunit;
 using Xunit.Sdk;
+using Options = Microsoft.Extensions.Options.Options;
 
 namespace MMLib.SwaggerForOcelot.Tests
 {
@@ -35,6 +37,7 @@ public async Task AllowVersionPlaceholder()
             const string version = "v1";
             const string key = "projects";
             HttpContext httpContext = GetHttpContext(requestPath: $"/{version}/{key}");
+            IMemoryCache memoryCache = new MemoryCache(Options.Create(new MemoryCacheOptions()));
 
             var next = new TestRequestDelegate();
 
@@ -82,7 +85,7 @@ public async Task AllowVersionPlaceholder()
                     string swaggerJson,
                     IEnumerable<RouteOptions> routeOptions,
                     string serverOverride,
-                    SwaggerEndPointOptions options) => new SwaggerJsonTransformer(OcelotSwaggerGenOptions.Default)
+                    SwaggerEndPointOptions options) => new SwaggerJsonTransformer(OcelotSwaggerGenOptions.Default, memoryCache)
                     .Transform(swaggerJson, routeOptions, serverOverride, options));
             var swaggerForOcelotMiddleware = new SwaggerForOcelotMiddleware(
                 next.Invoke,
@@ -167,6 +170,7 @@ public async Task RespectDownstreamHttpVersionRouteSetting()
             const string version = "v1";
             const string key = "projects";
             HttpContext httpContext = GetHttpContext(requestPath: $"/{version}/{key}");
+            IMemoryCache memoryCache = new MemoryCache(Options.Create(new MemoryCacheOptions()));
 
             var next = new TestRequestDelegate();
 
@@ -200,7 +204,7 @@ public async Task RespectDownstreamHttpVersionRouteSetting()
                     string swaggerJson,
                     IEnumerable<RouteOptions> routeOptions,
                     string serverOverride,
-                    SwaggerEndPointOptions options) => new SwaggerJsonTransformer(OcelotSwaggerGenOptions.Default)
+                    SwaggerEndPointOptions options) => new SwaggerJsonTransformer(OcelotSwaggerGenOptions.Default, memoryCache)
                     .Transform(swaggerJson, routeOptions, serverOverride, options));
             var swaggerForOcelotMiddleware = new SwaggerForOcelotMiddleware(
                 next.Invoke,

tests/MMLib.SwaggerForOcelot.Tests/SwaggerForOcelotShould.cs

@@ -1,4 +1,5 @@
 using JsonDiffPatchDotNet;
+using Microsoft.Extensions.Caching.Memory;
 using MMLib.SwaggerForOcelot.Configuration;
 using MMLib.SwaggerForOcelot.Transformation;
 using Newtonsoft.Json.Linq;
@@ -19,22 +20,22 @@ public class SwaggerForOcelotShould
         public void TransferDownstreamSwaggerToUpstreamFormat(TestCase testData)
         {
             var options = new OcelotSwaggerGenOptions();
+            IMemoryCache memoryCache = new MemoryCache(Microsoft.Extensions.Options.Options.Create(new MemoryCacheOptions()));
 
             foreach ((string key, string value) in testData.AuthenticationProviderKeyMap)
             {
                 options.AuthenticationProviderKeyMap.Add(key, value);
             }
 
-            var transformer = new SwaggerJsonTransformer(options);
+            var transformer = new SwaggerJsonTransformer(options, memoryCache);
 
             string transformed = transformer.Transform(
                 testData.DownstreamSwagger.ToString(),
                 testData.Routes,
                 testData.HostOverride,
                 new SwaggerEndPointOptions()
                 {
-                    TakeServersFromDownstreamService = testData.TakeServersFromDownstreamService,
-                    RemoveUnusedComponentsFromScheme = testData.RemoveUnusedComponentsFromScheme
+                    TakeServersFromDownstreamService = testData.TakeServersFromDownstreamService, RemoveUnusedComponentsFromScheme = testData.RemoveUnusedComponentsFromScheme
                 });
 
             AreEqual(transformed, testData.ExpectedTransformedSwagger, testData.FileName);