From 250f2d1f8aba530397c2d492c7a72f203249f192 Mon Sep 17 00:00:00 2001
From: Halil ibrahim Kalkan <hi_kalkan@yahoo.com>
Date: Sat, 21 Jul 2018 20:09:44 +0300
Subject: [PATCH] Add GetOrAddAsync to DistributedCache.

---
 .../Volo/Abp/Caching/DistributedCache.cs      | 52 ++++++++++++++++++-
 .../Volo/Abp/Caching/IDistributedCache.cs     | 14 ++++-
 .../Volo/Abp/Localization/LanguageInfo.cs     |  6 +++
 .../Abp/Caching/DistributedCache_Tests.cs     | 37 +++++++++++++
 4 files changed, 107 insertions(+), 2 deletions(-)

diff --git a/framework/src/Volo.Abp.Caching/Volo/Abp/Caching/DistributedCache.cs b/framework/src/Volo.Abp.Caching/Volo/Abp/Caching/DistributedCache.cs
index 26d2b1f24b..b8b897068f 100644
--- a/framework/src/Volo.Abp.Caching/Volo/Abp/Caching/DistributedCache.cs
+++ b/framework/src/Volo.Abp.Caching/Volo/Abp/Caching/DistributedCache.cs
@@ -3,6 +3,7 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Extensions.Caching.Distributed;
+using Nito.AsyncEx;
 using Volo.Abp.MultiTenancy;
 using Volo.Abp.Serialization;
 using Volo.Abp.Threading;
@@ -24,10 +25,12 @@ namespace Volo.Abp.Caching
 
         protected ICurrentTenant CurrentTenant { get; }
 
+        protected AsyncLock AsyncLock { get; } = new AsyncLock();
+
         public DistributedCache(
             IDistributedCache cache,
             ICancellationTokenProvider cancellationTokenProvider,
-            IObjectSerializer objectSerializer, 
+            IObjectSerializer objectSerializer,
             ICurrentTenant currentTenant)
         {
             Cache = cache;
@@ -60,6 +63,53 @@ namespace Volo.Abp.Caching
             return ObjectSerializer.Deserialize<TCacheItem>(cachedBytes);
         }
 
+        public TCacheItem GetOrAdd(string key, Func<TCacheItem> factory)
+        {
+            var value = Get(key);
+            if (value != null)
+            {
+                return value;
+            }
+
+            using (AsyncLock.Lock())
+            {
+                value = Get(key);
+                if (value != null)
+                {
+                    return value;
+                }
+
+                value = factory();
+                Set(key, value);
+
+            }
+
+            return value;
+        }
+
+        public async Task<TCacheItem> GetOrAddAsync(string key, Func<Task<TCacheItem>> factory, CancellationToken token = default)
+        {
+            var value = await GetAsync(key, token);
+            if (value != null)
+            {
+                return value;
+            }
+
+            using (await AsyncLock.LockAsync(token))
+            {
+                value = await GetAsync(key, token);
+                if (value != null)
+                {
+                    return value;
+                }
+
+                value = await factory();
+                await SetAsync(key, value, token: token);
+            }
+
+            return value;
+        }
+
         public virtual void Set(string key, TCacheItem value, DistributedCacheEntryOptions options = null)
         {
             Cache.Set(
diff --git a/framework/src/Volo.Abp.Caching/Volo/Abp/Caching/IDistributedCache.cs b/framework/src/Volo.Abp.Caching/Volo/Abp/Caching/IDistributedCache.cs
index 805e721b0c..5fd6d2d84f 100644
--- a/framework/src/Volo.Abp.Caching/Volo/Abp/Caching/IDistributedCache.cs
+++ b/framework/src/Volo.Abp.Caching/Volo/Abp/Caching/IDistributedCache.cs
@@ -1,4 +1,5 @@
-using System.Threading;
+using System;
+using System.Threading;
 using System.Threading.Tasks;
 using JetBrains.Annotations;
 using Microsoft.Extensions.Caching.Distributed;
@@ -17,6 +18,17 @@ namespace Volo.Abp.Caching
             CancellationToken token = default
         );
 
+        TCacheItem GetOrAdd(
+            string key,
+            Func<TCacheItem> factory
+        );
+
+        Task<TCacheItem> GetOrAddAsync(
+            [NotNull] string key,
+            Func<Task<TCacheItem>> factory,
+            CancellationToken token = default
+        );
+
         void Set(
             string key,
             TCacheItem value,
diff --git a/framework/src/Volo.Abp.Localization/Volo/Abp/Localization/LanguageInfo.cs b/framework/src/Volo.Abp.Localization/Volo/Abp/Localization/LanguageInfo.cs
index 05c243f92c..7084e7205c 100644
--- a/framework/src/Volo.Abp.Localization/Volo/Abp/Localization/LanguageInfo.cs
+++ b/framework/src/Volo.Abp.Localization/Volo/Abp/Localization/LanguageInfo.cs
@@ -3,6 +3,7 @@ using JetBrains.Annotations;
 
 namespace Volo.Abp.Localization
 {
+    [Serializable]
     public class LanguageInfo
     {
         [NotNull]
@@ -17,6 +18,11 @@ namespace Volo.Abp.Localization
         [CanBeNull]
         public virtual string FlagIcon { get; set; }
 
+        protected LanguageInfo()
+        {
+            
+        }
+
         public LanguageInfo(
             string cultureName,
             string uiCultureName = null,
diff --git a/framework/test/Volo.Abp.Caching.Tests/Volo/Abp/Caching/DistributedCache_Tests.cs b/framework/test/Volo.Abp.Caching.Tests/Volo/Abp/Caching/DistributedCache_Tests.cs
index 23169eb240..4beca1f32b 100644
--- a/framework/test/Volo.Abp.Caching.Tests/Volo/Abp/Caching/DistributedCache_Tests.cs
+++ b/framework/test/Volo.Abp.Caching.Tests/Volo/Abp/Caching/DistributedCache_Tests.cs
@@ -35,5 +35,42 @@ namespace Volo.Abp.Caching
             cacheItem = await personCache.GetAsync(cacheKey);
             cacheItem.ShouldBeNull();
         }
+
+        [Fact]
+        public async Task GetOrAddAsync()
+        {
+            var personCache = GetRequiredService<IDistributedCache<PersonCacheItem>>();
+
+            var cacheKey = Guid.NewGuid().ToString();
+            const string personName = "john nash";
+
+            //Will execute the factory method to create the cache item
+
+            bool factoryExecuted = false;
+
+            var cacheItem = await personCache.GetOrAddAsync(cacheKey,
+                async () =>
+                {
+                    factoryExecuted = true;
+                    return new PersonCacheItem(personName);
+                });
+
+            factoryExecuted.ShouldBeTrue();
+            cacheItem.Name.ShouldBe(personName);
+
+            //This time, it will not execute the factory
+
+            factoryExecuted = false;
+
+            cacheItem = await personCache.GetOrAddAsync(cacheKey,
+                async () =>
+                {
+                    factoryExecuted = true;
+                    return new PersonCacheItem(personName);
+                });
+
+            factoryExecuted.ShouldBeFalse();
+            cacheItem.Name.ShouldBe(personName);
+        }
     }
 }