Implement Servant.CreateSingletonsAsync.

point-platform · Aug 21, 2016 · 9ff24c3 · 9ff24c3
1 parent ed1c315
commit 9ff24c3
Show file tree

Hide file tree

Showing 2 changed files with 39 additions and 7 deletions.
diff --git a/Servant.Tests/ServantTests.cs b/Servant.Tests/ServantTests.cs
@@ -296,6 +296,29 @@ public async Task Add_FuncReturningNullInstanceThrows()
             Assert.Equal($"Instance for type \"{typeof(Test1)}\" cannot be null.", exception.Message);
         }
 
+        [Fact]
+        public async Task CreateSingletonsAsync()
+        {
+            var servant = new Servant();
+
+            var callCount = 0;
+            servant.AddSingleton(() =>
+            {
+                callCount++;
+                return new Test1();
+            });
+
+            Assert.Equal(0, callCount);
+
+            await servant.CreateSingletonsAsync();
+
+            Assert.Equal(1, callCount);
+
+            await servant.ServeAsync<Test1>();
+
+            Assert.Equal(1, callCount);
+        }
+
         #region Differing instance/declared types
 
         private interface IBase { }

diff --git a/Servant/Servant.cs b/Servant/Servant.cs
@@ -25,6 +25,7 @@
 using System;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
+using System.Diagnostics.CodeAnalysis;
 using System.Linq;
 using System.Threading.Tasks;
 using JetBrains.Annotations;
@@ -61,10 +62,10 @@ public TypeEntry(Type declaredType)
 
     internal sealed class TypeProvider
     {
+        public Lifestyle Lifestyle { get; }
         public IReadOnlyList<TypeEntry> Dependencies { get; }
 
         private readonly Func<object[], Task<object>> _factory;
-        private readonly Lifestyle _lifestyle;
         private readonly Type _declaredType;
 
         [CanBeNull] private object _singletonInstance;
@@ -73,15 +74,15 @@ public TypeProvider(Func<object[], Task<object>> factory, Type declaredType, Lif
         {
             _factory = factory;
             _declaredType = declaredType;
-            _lifestyle = lifestyle;
+            Lifestyle = lifestyle;
             Dependencies = dependencies;
         }
 
         public async Task<object> GetAsync()
         {
             // TODO make concurrency-safe here to avoid double-allocation of singleton
 
-            if (_lifestyle == Lifestyle.Singleton && _singletonInstance != null)
+            if (Lifestyle == Lifestyle.Singleton && _singletonInstance != null)
                 return _singletonInstance;
 
             // find arguments
@@ -103,7 +104,7 @@ public async Task<object> GetAsync()
             if (!_declaredType.IsInstanceOfType(instance))
                 throw new ServantException($"Instance produced for type \"{_declaredType}\" is not an instance of that type.");
 
-            if (_lifestyle == Lifestyle.Singleton)
+            if (Lifestyle == Lifestyle.Singleton)
                 _singletonInstance = instance;
 
             return instance;
@@ -179,11 +180,19 @@ private static bool DependsUpon(TypeEntry dependant, Type dependent)
         /// <summary>
         /// Eagerly initialises all types registered as having <see cref="Lifestyle.Singleton"/> lifestyle.
         /// </summary>
-        /// <remarks>If all singletons are already instantiated, calling this method has no effect.</remarks>
-        /// <returns></returns>
+        /// <remarks>
+        /// Calling this method is optional. If not used, singletons will be initialised lazily, when first requested.
+        /// <para />
+        /// If all singletons are already instantiated, calling this method has no effect.
+        /// </remarks>
+        /// <returns>A task that completes when singleton initialisation has finished.</returns>
         public Task CreateSingletonsAsync()
         {
-            throw new NotImplementedException();
+            return Task.WhenAll(
+                from typeEntry in _entryByType.Values
+                let provider = typeEntry.Provider
+                where provider?.Lifestyle == Lifestyle.Singleton
+                select provider.GetAsync());
         }
 
         /// <summary>