Merge pull request #1023 from github/feature/cache-versioning

Added a version to host cache.

Author: grokys

src/GitHub.App/Factories/HostCacheFactory.cs

@@ -1,17 +1,22 @@
 using System;
 using System.ComponentModel.Composition;
 using System.IO;
+using System.Reactive.Linq;
 using Akavache;
 using GitHub.Primitives;
 using Rothko;
 using GitHub.Extensions;
+using System.Threading.Tasks;
 
 namespace GitHub.Factories
 {
     [Export(typeof(IHostCacheFactory))]
     [PartCreationPolicy(CreationPolicy.Shared)]
     public class HostCacheFactory : IHostCacheFactory
     {
+        const int CacheVersion = 1;
+        const string CacheVersionKey = "cacheVersion";
+
         readonly Lazy<IBlobCacheFactory> blobCacheFactory;
         readonly Lazy<IOperatingSystem> operatingSystem;
 
@@ -22,7 +27,7 @@ public HostCacheFactory(Lazy<IBlobCacheFactory> blobCacheFactory, Lazy<IOperatin
             this.operatingSystem = operatingSystem;
         }
 
-        public IBlobCache Create(HostAddress hostAddress)
+        public async Task<IBlobCache> Create(HostAddress hostAddress)
         {
             var environment = OperatingSystem.Environment;
             // For GitHub.com, the cache file name should be "api.github.com.cache.db"
@@ -34,7 +39,17 @@ public IBlobCache Create(HostAddress hostAddress)
 
             // CreateDirectory is a noop if the directory already exists.
             OperatingSystem.Directory.CreateDirectory(Path.GetDirectoryName(userAccountPath));
-            return BlobCacheFactory.CreateBlobCache(userAccountPath);
+
+            var cache = BlobCacheFactory.CreateBlobCache(userAccountPath);
+            var version = await cache.GetOrCreateObject<int>(CacheVersionKey, () => 0);
+
+            if (version != CacheVersion)
+            {
+                await cache.InvalidateAll();
+                await cache.InsertObject(CacheVersionKey, CacheVersion);
+            }
+
+            return cache;
         }
 
         IOperatingSystem OperatingSystem { get { return operatingSystem.Value; } }

src/GitHub.App/Factories/IHostCacheFactory.cs

@@ -1,11 +1,12 @@
 using Akavache;
 using GitHub.Primitives;
 using System;
+using System.Threading.Tasks;
 
 namespace GitHub.Factories
 {
     public interface IHostCacheFactory : IDisposable
     {
-        IBlobCache Create(HostAddress hostAddress);
+        Task<IBlobCache> Create(HostAddress hostAddress);
     }
 }

src/GitHub.App/Factories/RepositoryHostFactory.cs

@@ -44,7 +44,7 @@ public RepositoryHostFactory(
         public async Task<IRepositoryHost> Create(HostAddress hostAddress)
         {
             var apiClient = await apiClientFactory.Create(hostAddress);
-            var hostCache = hostCacheFactory.Create(hostAddress);
+            var hostCache = await hostCacheFactory.Create(hostAddress);
             var modelService = new ModelService(apiClient, hostCache, avatarProvider);
             var host = new RepositoryHost(apiClient, modelService, loginManager, loginCache, usage);
             hosts.Add(host);