valuetask (#162)

* test

* valuetask

* proj

* dead code

Author: bitfaster

BitFaster.Caching.Benchmarks/Lru/LruAsyncGet.cs

@@ -0,0 +1,43 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Jobs;
+using BitFaster.Caching.Lru;
+
+namespace BitFaster.Caching.Benchmarks.Lru
+{
+    /// <summary>
+    /// Verify 0 allocs for GetOrAddAsync cache hits.
+    /// </summary>
+    [SimpleJob(RuntimeMoniker.Net48)]
+    [SimpleJob(RuntimeMoniker.Net60)]
+    [DisassemblyDiagnoser(printSource: true, maxDepth: 5)]
+    [MemoryDiagnoser]
+    public class LruAsyncGet
+    {
+        // if the cache value is a value type, value task has no effect - so use string to repro.
+        private static readonly IAsyncCache<int, string> concurrentLru = new ConcurrentLruBuilder<int, string>().AsAsyncCache().Build();
+        private static readonly IAsyncCache<int, string> atomicConcurrentLru = new ConcurrentLruBuilder<int, string>().AsAsyncCache().WithAtomicCreate().Build();
+
+        private static Task<string> returnTask = Task.FromResult("1");
+
+        [Benchmark()]
+        public async ValueTask<string> GetOrAddAsync()
+        {
+            Func<int, Task<string>> func = x => returnTask;
+
+            return await concurrentLru.GetOrAddAsync(1, func);
+        }
+
+        [Benchmark()]
+        public async ValueTask<string> AtomicGetOrAddAsync()
+        {
+            Func<int, Task<string>> func = x => returnTask;
+
+            return await atomicConcurrentLru.GetOrAddAsync(1, func);
+        }
+    }
+}

BitFaster.Caching.UnitTests/Synchronized/AsyncAtomicFactoryTests.cs

@@ -70,7 +70,7 @@ public async Task WhenCallersRunConcurrentlyResultIsFromWinner()
             var result = 0;
             var winnerCount = 0;
 
-            Task<int> first = atomicFactory.GetValueAsync(1, async k =>
+            var first = atomicFactory.GetValueAsync(1, async k =>
             {
                 enter.SetResult(true);
                 await resume.Task;
@@ -80,7 +80,7 @@ public async Task WhenCallersRunConcurrentlyResultIsFromWinner()
                 return 1;
             });
 
-            Task<int> second = atomicFactory.GetValueAsync(1, async k =>
+            var second = atomicFactory.GetValueAsync(1, async k =>
             {
                 enter.SetResult(true);
                 await resume.Task;

BitFaster.Caching.UnitTests/Synchronized/AtomicFactoryCacheTests.cs

@@ -106,14 +106,6 @@ public void WhenKeyDoesNotExistGetOrAddAddsValue()
             value.Should().Be(1);
         }
 
-        [Fact]
-        public async Task GetOrAddAsyncThrows()
-        {
-            Func<Task> getOrAdd = async () => { await this.cache.GetOrAddAsync(1, k => Task.FromResult(k)); };
-
-            await getOrAdd.Should().ThrowAsync<NotImplementedException>();
-        }
-
         [Fact]
         public void WhenCacheContainsValuesTrim1RemovesColdestValue()
         {

BitFaster.Caching.UnitTests/Synchronized/ScopedAsyncAtomicFactoryTests.cs

@@ -98,7 +98,7 @@ public async Task WhenCallersRunConcurrentlyResultIsFromWinner()
             var winningNumber = 0;
             var winnerCount = 0;
 
-            Task<(bool r, Lifetime<IntHolder> l)> first = atomicFactory.TryCreateLifetimeAsync(1, async k =>
+            ValueTask<(bool r, Lifetime<IntHolder> l)> first = atomicFactory.TryCreateLifetimeAsync(1, async k =>
             {
                 enter.SetResult(true);
                 await resume.Task;
@@ -108,7 +108,7 @@ public async Task WhenCallersRunConcurrentlyResultIsFromWinner()
                 return new Scoped<IntHolder>(new IntHolder() { actualNumber = 1 });
             });
 
-            Task<(bool r, Lifetime<IntHolder> l)> second = atomicFactory.TryCreateLifetimeAsync(1, async k =>
+            ValueTask<(bool r, Lifetime<IntHolder> l)> second = atomicFactory.TryCreateLifetimeAsync(1, async k =>
             {
                 enter.SetResult(true);
                 await resume.Task;
@@ -142,7 +142,7 @@ public async Task WhenDisposedWhileInitResultIsDisposed()
             var atomicFactory = new ScopedAsyncAtomicFactory<int, IntHolder>();
             var holder = new IntHolder() { actualNumber = 1 };
 
-            Task<(bool r, Lifetime<IntHolder> l)> first = atomicFactory.TryCreateLifetimeAsync(1, async k =>
+            ValueTask<(bool r, Lifetime<IntHolder> l)> first = atomicFactory.TryCreateLifetimeAsync(1, async k =>
             {
                 enter.SetResult(true);
                 await resume.Task;
@@ -171,7 +171,7 @@ public async Task WhenDisposedWhileThrowingNextInitIsDisposed()
             var atomicFactory = new ScopedAsyncAtomicFactory<int, IntHolder>();
             var holder = new IntHolder() { actualNumber = 1 };
 
-            Task<(bool r, Lifetime<IntHolder> l)> first = atomicFactory.TryCreateLifetimeAsync(1, async k =>
+            ValueTask<(bool r, Lifetime<IntHolder> l)> first = atomicFactory.TryCreateLifetimeAsync(1, async k =>
             {
                 enter.SetResult(true);
                 await resume.Task;

BitFaster.Caching/BitFaster.Caching.csproj

@@ -39,4 +39,8 @@
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.1.1" PrivateAssets="All" />
   </ItemGroup>
 
+  <ItemGroup Condition=" '$(TargetFramework)' == 'net472' or '$(TargetFramework)' == 'net48' or '$(TargetFramework)' == 'netstandard2.0'">
+     <PackageReference Include="System.Threading.Tasks.Extensions" Version="4.5.4" />
+  </ItemGroup>
+
 </Project>

BitFaster.Caching/IAsyncCache.cs

@@ -48,7 +48,7 @@ public interface IAsyncCache<K, V>
         /// <param name="key">The key of the element to add.</param>
         /// <param name="valueFactory">The factory function used to asynchronously generate a value for the key.</param>
         /// <returns>A task that represents the asynchronous GetOrAdd operation.</returns>
-        Task<V> GetOrAddAsync(K key, Func<K, Task<V>> valueFactory);
+        ValueTask<V> GetOrAddAsync(K key, Func<K, Task<V>> valueFactory);
 
         /// <summary>
         /// Attempts to remove the value that has the specified key.

BitFaster.Caching/IScopedAsyncCache.cs

@@ -53,7 +53,7 @@ public interface IScopedAsyncCache<K, V> where V : IDisposable
         /// <param name="key">The key of the element to add.</param>
         /// <param name="valueFactory">The factory function used to asynchronously generate a scoped value for the key.</param>
         /// <returns>A task that represents the asynchronous ScopedGetOrAdd operation.</returns>
-        Task<Lifetime<V>> ScopedGetOrAddAsync(K key, Func<K, Task<Scoped<V>>> valueFactory);
+        ValueTask<Lifetime<V>> ScopedGetOrAddAsync(K key, Func<K, Task<Scoped<V>>> valueFactory);
 
         /// <summary>
         /// Attempts to remove the value that has the specified key.

BitFaster.Caching/Lru/ClassicLru.cs

@@ -149,7 +149,7 @@ public V GetOrAdd(K key, Func<K, V> valueFactory)
         }
 
         ///<inheritdoc/>
-        public async Task<V> GetOrAddAsync(K key, Func<K, Task<V>> valueFactory)
+        public async ValueTask<V> GetOrAddAsync(K key, Func<K, Task<V>> valueFactory)
         {
             if (this.TryGet(key, out var value))
             {

BitFaster.Caching/Lru/TemplateConcurrentLru.cs

@@ -184,7 +184,7 @@ public V GetOrAdd(K key, Func<K, V> valueFactory)
         }
 
         ///<inheritdoc/>
-        public async Task<V> GetOrAddAsync(K key, Func<K, Task<V>> valueFactory)
+        public async ValueTask<V> GetOrAddAsync(K key, Func<K, Task<V>> valueFactory)
         {
             while (true)
             {

BitFaster.Caching/ScopedAsyncCache.cs

@@ -53,7 +53,7 @@ public void Clear()
         }
 
         ///<inheritdoc/>
-        public async Task<Lifetime<V>> ScopedGetOrAddAsync(K key, Func<K, Task<Scoped<V>>> valueFactory)
+        public async ValueTask<Lifetime<V>> ScopedGetOrAddAsync(K key, Func<K, Task<Scoped<V>>> valueFactory)
         {
             int c = 0;
             var spinwait = new SpinWait();