Migrate memory cache provider implementations to Polly v7.0.0

Author: reisenberger

src/Polly.Caching.Memory.NetStandard13/Polly.Caching.Memory.NetStandard13.csproj

@@ -29,7 +29,8 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Caching.Memory" Version="1.1.2" />
-    <PackageReference Include="Polly" Version="6.1.1" />
+    <PackageReference Include="Polly" Version="7.0.0" />
+    <PackageReference Include="System.ValueTuple" Version="4.5.0" />
   </ItemGroup>
   <Import Project="..\Polly.Caching.Memory.Shared\Polly.Caching.Memory.Shared.projitems" Label="Shared" />
 </Project>

src/Polly.Caching.Memory.NetStandard20/Polly.Caching.Memory.NetStandard20.csproj

@@ -29,7 +29,7 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.Extensions.Caching.Memory" Version="2.0.2" />
-    <PackageReference Include="Polly" Version="6.1.1" />
+    <PackageReference Include="Polly" Version="7.0.0" />
   </ItemGroup>
   <Import Project="..\Polly.Caching.Memory.Shared\Polly.Caching.Memory.Shared.projitems" Label="Shared" />
 </Project>

src/Polly.Caching.Memory.Shared/MemoryCacheProvider.cs

@@ -19,25 +19,23 @@ public class MemoryCacheProvider : ISyncCacheProvider, IAsyncCacheProvider
         /// <param name="memoryCache">The memory cache instance in which to store cached items.</param>
         public MemoryCacheProvider(IMemoryCache memoryCache)
         {
-            if (memoryCache == null) throw new ArgumentNullException(nameof(memoryCache));
-            _cache = memoryCache;
+            _cache = memoryCache ?? throw new ArgumentNullException(nameof(memoryCache));
         }
 
         /// <summary>
         /// Gets a value from cache.
         /// </summary>
         /// <param name="key">The cache key.</param>
-        /// <returns>The value from cache; or null, if none was found.</returns>
-        public object Get(String key)
+        /// <returns>
+        /// A tuple whose first element is a value indicating whether the key was found in the cache,
+        /// and whose second element is the value from the cache (null if not found).
+        /// </returns>
+        public (bool, object) TryGet(string key)
         {
-            object value;
-            if (_cache.TryGetValue(key, out value))
-            {
-                return value;
-            }
-            return null;
+            bool cacheHit = _cache.TryGetValue(key, out var value);
+            return (cacheHit, value);
         }
-        
+
         /// <summary>
         /// Puts the specified value in the cache.
         /// </summary>
@@ -59,7 +57,7 @@ public void Put(string key, object value, Ttl ttl)
                 {
                     options.AbsoluteExpiration = DateTimeOffset.MaxValue;
                 }
-else
+                else
                 {
                     options.AbsoluteExpirationRelativeToNow = ttl.Timespan < remaining ? ttl.Timespan : remaining;
                 }
@@ -69,17 +67,20 @@ public void Put(string key, object value, Ttl ttl)
         }
 
         /// <summary>
-        /// Gets a value from the memory cache as part of an asynchronous execution.  <para><remarks>The implementation is synchronous as there is no advantage to an asynchronous implementation for an in-memory cache.</remarks></para>
+        /// Gets a value from the cache asynchronously.
+        /// <para><remarks>The implementation is synchronous as there is no advantage to an asynchronous implementation for an in-memory cache.</remarks></para>
         /// </summary>
         /// <param name="key">The cache key.</param>
-        /// <param name="cancellationToken">The cancellation token.  </param>
-        /// <param name="continueOnCapturedContext">Whether async calls should continue on a captured synchronization context. <para><remarks>For <see cref="MemoryCacheProvider"/>, this parameter is irrelevant and is ignored, as the implementation is synchronous.</remarks></para></param>
-        /// <returns>A <see cref="Task{TResult}" /> promising as Result the value from cache; or null, if none was found.</returns>
-        public Task<object> GetAsync(string key, CancellationToken cancellationToken, bool continueOnCapturedContext)
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <param name="continueOnCapturedContext">Whether async calls should continue on a captured synchronization context. <para><remarks>Note: if the underlying cache's async API does not support controlling whether to continue on a captured context, async Policy executions with continueOnCapturedContext == true cannot be guaranteed to remain on the captured context.</remarks></para></param>
+        /// <returns>
+        /// A <see cref="Task{TResult}" /> promising as Result a tuple whose first element is a value indicating whether
+        /// the key was found in the cache, and whose second element is the value from the cache (null if not found).
+        /// </returns>
+        public Task<(bool, object)> TryGetAsync(string key, CancellationToken cancellationToken, bool continueOnCapturedContext)
         {
             cancellationToken.ThrowIfCancellationRequested();
-            return Task.FromResult(Get(key));
-            // (With C#7.0, a ValueTask<> approach would be preferred, but some of our tfms do not support that.  TO DO: Implement it, with preprocessor if/endif directives, for NetStandard)
+            return Task.FromResult(TryGet(key));
         }
 
         /// <summary>
@@ -97,7 +98,6 @@ public Task PutAsync(string key, object value, Ttl ttl, CancellationToken cancel
             cancellationToken.ThrowIfCancellationRequested();
             Put(key, value, ttl);
             return Task.CompletedTask;
-            // (With C#7.0, a ValueTask<> approach would be preferred, but some of our tfms do not support that. TO DO: Implement it, with preprocessor if/endif directives, for NetStandard)
         }
     }
 }

src/Polly.Caching.Memory.SharedSpecs/Integration/CacheProviderExtensions.cs

@@ -9,7 +9,6 @@
     <Import_RootNamespace>Polly.Caching.Memory.Specs</Import_RootNamespace>
   </PropertyGroup>
   <ItemGroup>
-    <Compile Include="$(MSBuildThisFileDirectory)Integration\CacheProviderExtensions.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Integration\CacheRoundTripspecsAsyncBase.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Integration\CacheRoundTripSpecsBase.cs" />
     <Compile Include="$(MSBuildThisFileDirectory)Integration\CacheRoundTripSpecsSyncBase.cs" />

src/Polly.Caching.Memory.SharedSpecs/Polly.Caching.Memory.SharedSpecs.projitems

@@ -42,28 +42,26 @@ public void Get_should_return_instance_previously_stored_in_cache()
 
             string key = Guid.NewGuid().ToString();
             object value = new object();
-#if PORTABLE
-            using (Microsoft.Extensions.Caching.Memory.ICacheEntry entry = memoryCache.CreateEntry(key)) { 
+            using (ICacheEntry entry = memoryCache.CreateEntry(key)) { 
                 entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(10);
                 entry.Value = value;
             }
-#else
-            memoryCache[key] = value;
-#endif
 
             MemoryCacheProvider provider = new MemoryCacheProvider(memoryCache);
-            object got = provider.Get(key);
-            got.Should().BeSameAs(value);
+            (bool cacheHit, object payload) = provider.TryGet(key);
+            cacheHit.Should().BeTrue();
+            payload.Should().BeSameAs(value);
         }
 
         [Fact]
-        public void Get_should_return_null_on_unknown_key()
+        public void Get_should_return_false_on_unknown_key()
         {
             IMemoryCache memoryCache = new MemoryCache(new MemoryCacheOptions());
 
             MemoryCacheProvider provider = new MemoryCacheProvider(memoryCache);
-            object got = provider.Get(Guid.NewGuid().ToString());
-            got.Should().BeNull();
+            (bool cacheHit, object payload) = provider.TryGet(Guid.NewGuid().ToString());
+            cacheHit.Should().BeFalse();
+            payload.Should().BeNull();
         }
 
         #endregion