* CachingFileStorage: Added more callbacks to provide user with more information what's going on

* Changed TestCacheSupervisor for easier use of the many callbacks
* Adapted tests for new callbacks

* GroupBaseActivity: Added sync menu command
* Preferences: Added option to enable/disable offline caching
* App: don't lock database when user wants to reload. This is done in PasswordActivity and should be done there after the password was filled into the pw field
* CheckDatabaseForChanges.cs: used when syncing a non-cached database

src/Kp2aBusinessLogic/Io/CachingFileStorage.cs

@@ -27,12 +27,29 @@ namespace keepass2android.Io
 		/// </summary>
 		void CouldntOpenFromRemote(IOConnectionInfo ioc, Exception ex);
 
+		/// <summary>
+		/// Called when the local file either didn't exist or was unmodified, so the remote file
+		/// was loaded and the cache was updated during the load operation.
+		/// </summary>
+		void UpdatedCachedFileOnLoad(IOConnectionInfo ioc);
+
+		/// <summary>
+		/// Called when the remote file either didn't exist or was unmodified, so the local file
+		/// was loaded and the remote file was updated during the load operation.
+		/// </summary>
+		void UpdatedRemoteFileOnLoad(IOConnectionInfo ioc);
+
 		/// <summary>
 		/// Called to notify the supervisor that the file described by ioc is opened from the cache because there's a conflict
 		/// with local and remote changes
 		/// </summary>
 		/// <param name="ioc"></param>
 		void NotifyOpenFromLocalDueToConflict(IOConnectionInfo ioc);
+
+		/// <summary>
+		/// Called when the load operation was performed and the remote file was identical with the local file
+		/// </summary>
+		void LoadedFromRemoteInSync(IOConnectionInfo ioc);
 	}
 
 	/// <summary>
@@ -148,7 +165,8 @@ namespace keepass2android.Io
 				//no changes in remote file -> upload
 				using (Stream localData = File.OpenRead(CachedFilePath(ioc)))
 				{
-					TryUpdateRemoteFile(localData, ioc, true, hash);
+					if (TryUpdateRemoteFile(localData, ioc, true, hash))
+						_cacheSupervisor.UpdatedRemoteFileOnLoad(ioc);
 				}
 			}
 			else
@@ -197,20 +215,34 @@ namespace keepass2android.Io
 					cachedFile.Close();
 					fileHash = MemUtil.ByteArrayToHexString(cachedFile.Hash);
 				}
+
+				//remember current hash
+				string previousHash = null;
+				string baseVersionFilePath = BaseVersionFilePath(ioc);
+				if (File.Exists(baseVersionFilePath))
+					previousHash = File.ReadAllText(baseVersionFilePath);
+
 				//save hash in cache files:
 				File.WriteAllText(VersionFilePath(ioc), fileHash);
-				File.WriteAllText(BaseVersionFilePath(ioc), fileHash);
+				File.WriteAllText(baseVersionFilePath, fileHash);
+
+				//notify supervisor what we did:
+				if (previousHash != fileHash)
+					_cacheSupervisor.UpdatedCachedFileOnLoad(ioc);
+				else
+					_cacheSupervisor.LoadedFromRemoteInSync(ioc);
 
 				return File.OpenRead(cachedFilePath);	
 			}
 			
 		}
 
-		private void TryUpdateRemoteFile(Stream cachedData, IOConnectionInfo ioc, bool useFileTransaction, string hash)
+		private bool TryUpdateRemoteFile(Stream cachedData, IOConnectionInfo ioc, bool useFileTransaction, string hash)
 		{
 			try
 			{
 				UpdateRemoteFile(cachedData, ioc, useFileTransaction, hash);
+				return true;
 			}
 			catch (Exception e)
 			{
@@ -218,6 +250,7 @@ namespace keepass2android.Io
 				Kp2aLog.Log(e.ToString());
 				//notify the supervisor so it might display a warning or schedule a retry
 				_cacheSupervisor.CouldntSaveToRemote(ioc, e);
+				return false;
 			}
 		}
 

src/Kp2aBusinessLogic/Kp2aBusinessLogic.csproj

@@ -51,6 +51,7 @@
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="database\CheckDatabaseForChanges.cs" />
     <Compile Include="database\SynchronizeCachedDatabase.cs" />
     <Compile Include="Io\BuiltInFileStorage.cs" />
     <Compile Include="Io\CachingFileStorage.cs" />

src/Kp2aBusinessLogic/UiStringKey.cs

@@ -40,6 +40,8 @@ namespace keepass2android
 		UploadingFile,
 		FilesInSync,
 		SynchronizedDatabaseSuccessfully,
-		RestoringRemoteFile
+		RestoringRemoteFile,
+		CheckingDatabaseForChanges,
+		RemoteDatabaseUnchanged
     }
 }

src/Kp2aBusinessLogic/database/CheckDatabaseForChanges.cs

@@ -0,0 +1,74 @@
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Security.Cryptography;
+using System.Text;
+using Android.App;
+using Android.Content;
+using KeePassLib.Cryptography;
+using KeePassLib.Serialization;
+using KeePassLib.Utility;
+using keepass2android.Io;
+
+namespace keepass2android
+{
+	public class CheckDatabaseForChanges: RunnableOnFinish
+	{
+		private readonly Context _context;
+		private readonly IKp2aApp _app;
+
+
+		public CheckDatabaseForChanges(Context context, IKp2aApp app, OnFinish finish)
+			: base(finish)
+		{
+			_context = context;
+			_app = app;
+		}
+
+		public override void Run()
+		{
+			try
+			{
+				IOConnectionInfo ioc = _app.GetDb().Ioc;
+				IFileStorage fileStorage = _app.GetFileStorage(ioc);
+				if (fileStorage is CachingFileStorage)
+				{
+					throw new Exception("Cannot sync a cached database!");
+				}
+				StatusLogger.UpdateMessage(UiStringKey.CheckingDatabaseForChanges);
+				
+				//download file from remote location and calculate hash:
+				StatusLogger.UpdateSubMessage(_app.GetResourceString(UiStringKey.DownloadingRemoteFile));
+				
+
+				MemoryStream remoteData = new MemoryStream();
+				using (
+					HashingStreamEx hashingRemoteStream = new HashingStreamEx(fileStorage.OpenFileForRead(ioc), false,
+																				new SHA256Managed()))
+				{
+					hashingRemoteStream.CopyTo(remoteData);
+					hashingRemoteStream.Close();
+					
+					if (!MemUtil.ArraysEqual(_app.GetDb().KpDatabase.HashOfFileOnDisk, hashingRemoteStream.Hash))
+					{
+						_app.TriggerReload(_context);
+						Finish(true);
+					}
+					else
+					{
+						Finish(true, _app.GetResourceString(UiStringKey.RemoteDatabaseUnchanged));
+					}
+				}
+			
+				
+				
+			}
+			catch (Exception e)
+			{
+				Finish(false, e.Message);
+			}
+
+		}
+
+	}
+}

src/Kp2aBusinessLogic/database/edit/LoadDB.cs

@@ -48,7 +48,8 @@ namespace keepass2android
 			try
 			{
 				StatusLogger.UpdateMessage(UiStringKey.loading_database);
-				_app.LoadDatabase(_ioc, _databaseData == null ? null : _databaseData.Result, _pass, _key, StatusLogger);
+				MemoryStream memoryStream = _databaseData == null ? null : _databaseData.Result;
+				_app.LoadDatabase(_ioc, memoryStream, _pass, _key, StatusLogger);
 				SaveFileData (_ioc, _key);
 				
 			} catch (KeyFileException) {
@@ -56,7 +57,7 @@ namespace keepass2android
 				Finish(false, /*TODO Localize: use Keepass error text KPRes.KeyFileError (including "or invalid format")*/ _app.GetResourceString(UiStringKey.keyfile_does_not_exist));
 			}
 			catch (Exception e) {
-				Kp2aLog.Log("Exception: " + e.Message);
+				Kp2aLog.Log("Exception: " + e);
 				Finish(false, "An error occured: " + e.Message);
 				return;
 			} 

src/Kp2aKeyboardBinding/Kp2aKeyboardBinding.csproj

@@ -51,9 +51,11 @@
     <Compile Include="Properties\AssemblyInfo.cs" />
   </ItemGroup>
   <ItemGroup>
+    <LibraryProjectZip Include="..\java\KP2ASoftKeyboard\project.zip">
+      <Link>project.zip</Link>
+    </LibraryProjectZip>
     <None Include="Additions\AboutAdditions.txt" />
     <None Include="Jars\AboutJars.txt" />
-    <LibraryProjectZip Include="project.zip" />
   </ItemGroup>
   <ItemGroup>
     <TransformFile Include="Transforms\EnumFields.xml" />

src/Kp2aUnitTests/MainActivity.cs

@@ -19,7 +19,7 @@ namespace Kp2aUnitTests
             TestRunner runner = new TestRunner();
             // Run all tests from this assembly
             runner.AddTests(Assembly.GetExecutingAssembly());
-			//runner.AddTests(new List<Type> { typeof(TestSaveDbCached) });
+			//runner.AddTests(new List<Type> { typeof(TestSynchronizeCachedDatabase) });
 			//runner.AddTests(typeof(TestSaveDbCached).GetMethod("TestLoadEditSaveWhenModified"));
 			
 			//runner.AddTests(new List<Type> { typeof(TestSaveDb) });

src/Kp2aUnitTests/TestBase.cs

@@ -66,7 +66,7 @@ namespace Kp2aUnitTests
 			var app = CreateTestKp2aApp();
 			app.CreateNewDatabase();
 			bool loadSuccesful = false;
-			LoadDb task = new LoadDb(app, new IOConnectionInfo() { Path = filename }, password, keyfile, new ActionOnFinish((success, message) =>
+			LoadDb task = new LoadDb(app, new IOConnectionInfo() { Path = filename }, null, password, keyfile, new ActionOnFinish((success, message) =>
 				{
 					if (!success)
 						Kp2aLog.Log(message);

src/Kp2aUnitTests/TestCacheSupervisor.cs

@@ -1,29 +1,78 @@
 using System;
+using System.Collections.Generic;
+using System.Linq;
 using KeePassLib.Serialization;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
 using keepass2android.Io;
 
 namespace Kp2aUnitTests
 {
 	class TestCacheSupervisor: ICacheSupervisor
 	{
-		public bool CouldntOpenFromRemoteCalled { get; set; }
-		public bool CouldntSaveToRemoteCalled { get; set; }
-		public bool NotifyOpenFromLocalDueToConflictCalled { get; set; }
+		public const string CouldntOpenFromRemoteId = "CouldntOpenFromRemote";
+		public const string CouldntSaveToRemoteId = "CouldntSaveToRemote";
+		public const string NotifyOpenFromLocalDueToConflictId = "CouldntSaveToRemote";
+		public const string UpdatedCachedFileOnLoadId = "UpdatedCachedFileOnLoad";
+		public const string LoadedFromRemoteInSyncId = "LoadedFromRemoteInSync";
+		public const string UpdatedRemoteFileOnLoadId = "UpdatedRemoteFileOnLoad";
 
+		private HashSet<string> _callsMade = new HashSet<string>();
+		
+		public void Reset()
+		{
+			_callsMade.Clear();
+		}
+
+		public void AssertNoCall()
+		{
+			string allCalls = _callsMade.Aggregate("", (current, s) => current + s + ",");
+			Assert.AreEqual("", allCalls);
+		}
+
+		public void AssertSingleCall(string id)
+		{
+			if ((_callsMade.Count == 1)
+			    && _callsMade.Single() == id)
+			{
+				Reset();
+				return;
+			}
+				
+
+			Assert.Fail("expected only "+id+", but received: "+_callsMade.Aggregate("", (current, s) => current + s + ","));
+
+		}
 
 		public void CouldntSaveToRemote(IOConnectionInfo ioc, Exception e)
 		{
-			CouldntSaveToRemoteCalled = true;
+			_callsMade.Add(CouldntSaveToRemoteId);
 		}
 
 		public void CouldntOpenFromRemote(IOConnectionInfo ioc, Exception ex)
 		{
-			CouldntOpenFromRemoteCalled = true;
+			_callsMade.Add(CouldntOpenFromRemoteId);
+		}
+
+		public void UpdatedCachedFileOnLoad(IOConnectionInfo ioc)
+		{
+			_callsMade.Add(UpdatedCachedFileOnLoadId);
+		}
+
+		public void UpdatedRemoteFileOnLoad(IOConnectionInfo ioc)
+		{
+			_callsMade.Add(UpdatedRemoteFileOnLoadId);
 		}
 
 		public void NotifyOpenFromLocalDueToConflict(IOConnectionInfo ioc)
 		{
-			NotifyOpenFromLocalDueToConflictCalled = true;
+			_callsMade.Add(NotifyOpenFromLocalDueToConflictId);
 		}
+
+		public void LoadedFromRemoteInSync(IOConnectionInfo ioc)
+		{
+			_callsMade.Add(LoadedFromRemoteInSyncId);
+		}
+
+		
 	}
 }

src/Kp2aUnitTests/TestCachingFileStorage.cs

@@ -30,6 +30,8 @@ namespace Kp2aUnitTests
 			//read the file once. Should now be in the cache.
 			MemoryStream fileContents = ReadToMemoryStream(_fileStorage, CachingTestFile);
 
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.UpdatedCachedFileOnLoadId);
+
 			//check it's the correct data:
 			Assert.AreEqual(MemoryStreamToString(fileContents), _defaultCacheFileContents);
 
@@ -41,8 +43,7 @@ namespace Kp2aUnitTests
 
 			AssertEqual(fileContents, fileContents2);
 
-			Assert.IsTrue(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.CouldntOpenFromRemoteId);
 			
 
 		}
@@ -67,8 +68,7 @@ namespace Kp2aUnitTests
 			//read the file once. Should now be in the cache.
 			ReadToMemoryStream(_fileStorage, CachingTestFile);
 
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.UpdatedCachedFileOnLoadId);
 
 			//let the base file storage go offline:
 			_testFileStorage.Offline = true;
@@ -77,16 +77,13 @@ namespace Kp2aUnitTests
 			string newContent = "new content";
 			WriteContentToCacheFile(newContent);
 
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsTrue(_testCacheSupervisor.CouldntSaveToRemoteCalled);
-			_testCacheSupervisor.CouldntSaveToRemoteCalled = false;
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.CouldntSaveToRemoteId);
 
 			//now try to read the file again:
 			MemoryStream fileContents2 = ReadToMemoryStream(_fileStorage, CachingTestFile);
 
-			Assert.IsTrue(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
-			_testCacheSupervisor.CouldntOpenFromRemoteCalled = false;
+
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.CouldntOpenFromRemoteId);
 
 			//should return the written content:
 			Assert.AreEqual(MemoryStreamToString(fileContents2), newContent);
@@ -96,8 +93,7 @@ namespace Kp2aUnitTests
 			MemoryStream fileContents3 = ReadToMemoryStream(_fileStorage, CachingTestFile);
 			Assert.AreEqual(MemoryStreamToString(fileContents3), newContent);
 
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.UpdatedRemoteFileOnLoadId);
 
 			//ensure the data on the remote was synced:
 			MemoryStream fileContents4 = ReadToMemoryStream(_testFileStorage, CachingTestFile);
@@ -115,8 +111,7 @@ namespace Kp2aUnitTests
 			//read the file once. Should now be in the cache.
 			ReadToMemoryStream(_fileStorage, CachingTestFile);
 
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.UpdatedCachedFileOnLoadId);
 
 			//let the base file storage go offline:
 			_testFileStorage.Offline = true;
@@ -125,9 +120,7 @@ namespace Kp2aUnitTests
 			string newLocalContent = "new local content";
 			WriteContentToCacheFile(newLocalContent);
 
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsTrue(_testCacheSupervisor.CouldntSaveToRemoteCalled);
-			_testCacheSupervisor.CouldntSaveToRemoteCalled = false;
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.CouldntSaveToRemoteId);
 
 			//write something to the remote file:
 			File.WriteAllText(CachingTestFile, "new remote content");
@@ -142,12 +135,7 @@ namespace Kp2aUnitTests
 			Assert.AreEqual(MemoryStreamToString(fileContents2), newLocalContent);
 
 			//but a notification about the conflict should be made:
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
-			Assert.IsTrue(_testCacheSupervisor.NotifyOpenFromLocalDueToConflictCalled);
-			_testCacheSupervisor.NotifyOpenFromLocalDueToConflictCalled = false;
-
-			
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.NotifyOpenFromLocalDueToConflictId);
 
 		}
 
@@ -160,13 +148,13 @@ namespace Kp2aUnitTests
 
 			//read the file once. Should now be in the cache.
 			ReadToMemoryStream(_fileStorage, CachingTestFile);
+			_testCacheSupervisor.Reset();
 
 			//write something to the cache:
 			string newContent = "new content";
 			WriteContentToCacheFile(newContent);
 
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
+			_testCacheSupervisor.AssertNoCall();
 
 			Assert.AreEqual(newContent, File.ReadAllText(CachingTestFile));			
 		}
@@ -180,17 +168,19 @@ namespace Kp2aUnitTests
 			//read the file once. Should now be in the cache.
 			ReadToMemoryStream(_fileStorage, CachingTestFile);
 
+			_testCacheSupervisor.Reset();
+
 			//delete remote file:
 			_testFileStorage.DeleteFile(IocForCacheFile);
 
+
 			//read again. shouldn't throw and give the same result:
 			var memStream = ReadToMemoryStream(_fileStorage, CachingTestFile);
 
 			//check if we received the correct content:
 			Assert.AreEqual(_defaultCacheFileContents, MemoryStreamToString(memStream));
 
-			Assert.IsTrue(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.CouldntOpenFromRemoteId);
 			
 		}
 
@@ -216,7 +206,8 @@ namespace Kp2aUnitTests
 		{
 			_testFileStorage = new TestFileStorage();
 			_testCacheSupervisor = new TestCacheSupervisor();
-			_fileStorage = new CachingFileStorage(_testFileStorage, Application.Context.CacheDir.Path, _testCacheSupervisor);
+			//_fileStorage = new CachingFileStorage(_testFileStorage, Application.Context.CacheDir.Path, _testCacheSupervisor);
+			_fileStorage = new CachingFileStorage(_testFileStorage, "/mnt/sdcard/kp2atest_cache", _testCacheSupervisor);
 			_fileStorage.ClearCache();
 			File.WriteAllText(CachingTestFile, _defaultCacheFileContents);
 		}

src/Kp2aUnitTests/TestKp2aApp.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.IO;
 using Android.App;
 using Android.Content;
 using Android.OS;
@@ -29,6 +30,18 @@ namespace Kp2aUnitTests
 			
 		}
 
+		public void LockDatabase(bool allowQuickUnlock = true)
+		{
+			throw new NotImplementedException();
+		}
+
+		public void LoadDatabase(IOConnectionInfo ioConnectionInfo, MemoryStream memoryStream, string password, string keyFile,
+		                         ProgressDialogStatusLogger statusLogger)
+		{
+			_db.LoadData(this, ioConnectionInfo, memoryStream, password, keyFile, statusLogger);
+			
+		}
+
 		public Database GetDb()
 		{
 			return _db;

src/Kp2aUnitTests/TestLoadDb.cs

@@ -21,7 +21,7 @@ namespace Kp2aUnitTests
 			IKp2aApp app = new TestKp2aApp();
 			app.CreateNewDatabase();
 			bool loadSuccesful = false;
-			LoadDb task = new LoadDb(app, new IOConnectionInfo() { Path = TestDbDirectory+filenameWithoutDir },
+			LoadDb task = new LoadDb(app, new IOConnectionInfo() { Path = TestDbDirectory+filenameWithoutDir }, null,
 				password, keyfile, new ActionOnFinish((success, message) =>
 					{
 						if (!success)
@@ -78,7 +78,7 @@ namespace Kp2aUnitTests
 			app.CreateNewDatabase();
 			
 			bool loadSuccesful = false;
-			LoadDb task = new LoadDb(app, ioc, "a", null, new ActionOnFinish((success, message) =>
+			LoadDb task = new LoadDb(app, ioc, null, "a", null, new ActionOnFinish((success, message) =>
 				{
 					if (!success)
 						Android.Util.Log.Debug("KP2ATest", "error loading db: " + message);
@@ -102,7 +102,7 @@ namespace Kp2aUnitTests
 			app.CreateNewDatabase();
 			
 			bool loadSuccesful = false;
-			LoadDb task = new LoadDb(app, ioc, "test", null, new ActionOnFinish((success, message) =>
+			LoadDb task = new LoadDb(app, ioc, null, "test", null, new ActionOnFinish((success, message) =>
 				{
 					if (!success)
 						Android.Util.Log.Debug("KP2ATest", "error loading db: " + message);
@@ -128,7 +128,7 @@ namespace Kp2aUnitTests
 
 			bool loadSuccesful = false;
 			bool gotError = false;
-			LoadDb task = new LoadDb(app, ioc, "test", null, new ActionOnFinish((success, message) =>
+			LoadDb task = new LoadDb(app, ioc, null, "test", null, new ActionOnFinish((success, message) =>
 			{
 				if (!success)
 				{
@@ -156,7 +156,7 @@ namespace Kp2aUnitTests
 
 			bool loadSuccesful = false;
 			bool gotError = false;
-			LoadDb task = new LoadDb(app, ioc, "test", null, new ActionOnFinish((success, message) =>
+			LoadDb task = new LoadDb(app, ioc, null, "test", null, new ActionOnFinish((success, message) =>
 			{
 				if (!success)
 				{

src/Kp2aUnitTests/TestSaveDbCached.cs

@@ -39,14 +39,15 @@ namespace Kp2aUnitTests
 			IOConnection.DeleteFile(new IOConnectionInfo { Path = DefaultFilename });
 			//save it and reload it so we have a base version
 			SaveDatabase(app);
+			_testCacheSupervisor.AssertNoCall();
 			app = LoadDatabase(DefaultFilename, DefaultPassword, DefaultKeyfile);
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.LoadedFromRemoteInSyncId);
 			//modify the database by adding a group:
 			app.GetDb().KpDatabase.RootGroup.AddGroup(new PwGroup(true, true, "TestGroup", PwIcon.Apple), true);
 			//save the database again:
 			SaveDatabase(app);
 			Assert.IsNull(((TestKp2aApp)app).LastYesNoCancelQuestionTitle);
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
+			_testCacheSupervisor.AssertNoCall();
 
 			//load database to a new app instance:
 			IKp2aApp resultApp = LoadDatabase(DefaultFilename, DefaultPassword, DefaultKeyfile);
@@ -71,10 +72,10 @@ namespace Kp2aUnitTests
 			//modify the database by adding a group:
 			app.GetDb().KpDatabase.RootGroup.AddGroup(new PwGroup(true, true, "TestGroup", PwIcon.Apple), true);
 			//save the database again:
+			_testCacheSupervisor.Reset();
 			SaveDatabase(app);
 			Assert.IsNull(((TestKp2aApp) app).LastYesNoCancelQuestionTitle);
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
+			_testCacheSupervisor.AssertNoCall();
 
 			//load database to a new app instance:
 			IKp2aApp resultApp = LoadDatabase(DefaultFilename, DefaultPassword, DefaultKeyfile);
@@ -109,11 +110,12 @@ namespace Kp2aUnitTests
 
 			SaveDatabase(app2);
 
+			_testCacheSupervisor.Reset();
+
 			foreach (var group in app.GetDb().KpDatabase.RootGroup.Groups)
 				Kp2aLog.Log("app d: " + group.Name);
 			Assert.IsNull(((TestKp2aApp)app).LastYesNoCancelQuestionTitle);
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
+			_testCacheSupervisor.AssertNoCall();
 
 			//modify the database by adding a group:
 			PwGroup group1 = new PwGroup(true, true, "TestGroup", PwIcon.Apple);
@@ -124,10 +126,10 @@ namespace Kp2aUnitTests
 
 
 			//save the database again:
+			_testCacheSupervisor.Reset();
 			SaveDatabase(app);
 			Assert.AreEqual(((TestKp2aApp)app).LastYesNoCancelQuestionTitle, UiStringKey.TitleSyncQuestion);
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
-			Assert.IsFalse(_testCacheSupervisor.CouldntSaveToRemoteCalled);
+			_testCacheSupervisor.AssertNoCall();
 			
 
 			//load database to a new app instance:

src/Kp2aUnitTests/TestSynchronizeCachedDatabase.cs

@@ -47,6 +47,7 @@ namespace Kp2aUnitTests
 			//save it and reload it so we have a base version ("remote" and in the cache)
 			SaveDatabase(app);
 			app = LoadDatabase(DefaultFilename, DefaultPassword, DefaultKeyfile);
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.LoadedFromRemoteInSyncId);
 		
 			string resultMessage;
 			bool wasSuccessful;
@@ -68,8 +69,8 @@ namespace Kp2aUnitTests
 			app.GetDb().KpDatabase.RootGroup.AddGroup(new PwGroup(true, true, "TestGroup", PwIcon.Apple), true);
 			//save the database again (will be saved locally only)
 			SaveDatabase(app);
-			Assert.IsTrue(_testCacheSupervisor.CouldntSaveToRemoteCalled);
-			_testCacheSupervisor.CouldntSaveToRemoteCalled = false;
+
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.CouldntSaveToRemoteId);
 
 			//go online again:
 			_testFileStorage.Offline = false;
@@ -82,10 +83,10 @@ namespace Kp2aUnitTests
 			//ensure both files are identical and up to date now:
 			_testFileStorage.Offline = true;
 			var appOfflineLoaded = LoadDatabase(DefaultFilename, DefaultPassword, DefaultKeyfile);
-			_testCacheSupervisor.CouldntOpenFromRemoteCalled = false;
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.CouldntOpenFromRemoteId);
 			_testFileStorage.Offline = false;
 			var appRemoteLoaded = LoadDatabase(DefaultFilename, DefaultPassword, DefaultKeyfile);
-			Assert.IsFalse(_testCacheSupervisor.CouldntOpenFromRemoteCalled);
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.LoadedFromRemoteInSyncId);
 
 			AssertDatabasesAreEqual(app.GetDb().KpDatabase, appOfflineLoaded.GetDb().KpDatabase);
 			AssertDatabasesAreEqual(app.GetDb().KpDatabase, appRemoteLoaded.GetDb().KpDatabase);
@@ -101,6 +102,7 @@ namespace Kp2aUnitTests
 			//save it and reload it so we have a base version ("remote" and in the cache)
 			SaveDatabase(app);
 			app = LoadDatabase(DefaultFilename, DefaultPassword, DefaultKeyfile);
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.LoadedFromRemoteInSyncId);
 
 			//delete remote:
 			IOConnection.DeleteFile(new IOConnectionInfo { Path = DefaultFilename });
@@ -128,8 +130,11 @@ namespace Kp2aUnitTests
 			//save it and reload it so we have a base version ("remote" and in the cache)
 			SaveDatabase(app);
 			app = LoadDatabase(DefaultFilename, DefaultPassword, DefaultKeyfile);
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.LoadedFromRemoteInSyncId);
+
 			var app2 = LoadDatabase(DefaultFilename, DefaultPassword, DefaultKeyfile);
 			app2.FileStorage = _testFileStorage; //give app2 direct access to the remote file
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.LoadedFromRemoteInSyncId);
 
 			//go offline:
 			_testFileStorage.Offline = true;
@@ -145,8 +150,7 @@ namespace Kp2aUnitTests
 			app2.GetDb().KpDatabase.RootGroup.AddGroup(newGroup2, true);
 			//save the database again (will be saved locally only for "app")
 			SaveDatabase(app);
-			Assert.IsTrue(_testCacheSupervisor.CouldntSaveToRemoteCalled);
-			_testCacheSupervisor.CouldntSaveToRemoteCalled = false;
+			_testCacheSupervisor.AssertSingleCall(TestCacheSupervisor.CouldntSaveToRemoteId);
 
 			//go online again:
 			_testFileStorage.Offline = false;

src/keepass2android/GroupBaseActivity.cs

@@ -24,6 +24,7 @@ using Android.Views;
 using Android.Widget;
 using KeePassLib;
 using Android.Preferences;
+using keepass2android.Io;
 using keepass2android.view;
 using Android.Graphics.Drawables;
 
@@ -201,6 +202,14 @@ namespace keepass2android
 
 				searchView.SetSearchableInfo(searchManager.GetSearchableInfo(ComponentName));
 			}
+			var item = menu.FindItem(Resource.Id.menu_sync);
+			if (item != null)
+			{
+				if (App.Kp2a.GetDb().Ioc.IsLocalFile())
+					item.SetVisible(false);
+				else
+					item.SetVisible(true);
+			}
 			return true;
 		}
 		
@@ -256,6 +265,10 @@ namespace keepass2android
 				SetPassword();
 				return true;
 
+			case Resource.Id.menu_sync:
+				Synchronize();
+				return true;
+				
 			case Resource.Id.menu_sort:
 				ToggleSort();
 				return true;
@@ -293,6 +306,30 @@ namespace keepass2android
 			return base.OnOptionsItemSelected(item);
 		}
 
+		private void Synchronize()
+		{
+			var filestorage = App.Kp2a.GetFileStorage(App.Kp2a.GetDb().Ioc);
+			RunnableOnFinish task;
+			ActionOnFinish onFinishShowMessage = new ActionOnFinish((success, message) =>
+			{
+				if (!String.IsNullOrEmpty(message))
+					Toast.MakeText(this, message, ToastLength.Long).Show();
+			});
+			if (filestorage is CachingFileStorage)
+			{
+				
+				task = new SynchronizeCachedDatabase(this, App.Kp2a, onFinishShowMessage);
+			}
+			else
+			{
+
+				task = new CheckDatabaseForChanges(this, App.Kp2a, onFinishShowMessage);
+			}
+			var progressTask = new ProgressTask(App.Kp2a, this, task);
+			progressTask.Run();
+
+		}
+
 		private void ToggleSort() {
 			// Toggle setting
 			String sortKey = GetString(Resource.String.sort_key);

src/keepass2android/Resources/menu-v11/group.xml

@@ -41,11 +41,17 @@
         android:title="@string/menu_app_settings"
         android:showAsAction="ifRoom"
     />
-    <item android:id="@+id/menu_change_master_key"
+	<item android:id="@+id/menu_change_master_key"
         android:title="@string/menu_change_key"
         android:showAsAction="never"
     />
-    <item android:id="@+id/menu_sort"
+	<item android:id="@+id/menu_sync"
+		  android:icon="@android:drawable/ic_popup_sync"
+			android:title="@string/synchronize_database_menu"
+			android:showAsAction="never"
+    />
+
+	<item android:id="@+id/menu_sort"
         android:icon="@android:drawable/ic_menu_sort_by_size"
         android:title="@string/sort_name"
         android:showAsAction="never"
@@ -56,11 +62,6 @@
         android:title="@string/suggest_improvements"
         android:showAsAction="never"
     />
-    <item android:id="@+id/menu_rate"
-        android:icon="@android:drawable/star_off"
-        android:title="@string/rate_app"
-        android:showAsAction="never"
-    />
     <item android:id="@+id/menu_translate"
         android:title="@string/translate_app"
         android:showAsAction="never"

src/keepass2android/Resources/menu/group.xml

@@ -38,6 +38,9 @@
     <item android:id="@+id/menu_change_master_key"
         android:icon="@android:drawable/ic_menu_manage"
         android:title="@string/menu_change_key"
+    />
+	<item android:id="@+id/menu_sync"
+			android:title="@string/synchronize_database_menu"
     />
     <item android:id="@+id/menu_sort"
         android:icon="@android:drawable/ic_menu_sort_by_size"
@@ -47,10 +50,6 @@
         android:icon="@android:drawable/ic_menu_directions"
         android:title="@string/suggest_improvements"
     />
-    <item android:id="@+id/menu_rate"
-        android:icon="@android:drawable/star_off"
-        android:title="@string/rate_app"
-    />
     <item android:id="@+id/menu_translate"
         android:title="@string/translate_app"
        />

src/keepass2android/Resources/values/config.xml

@@ -63,6 +63,7 @@
 	<string name="LastInfoVersionCode_key">LastInfoVersion</string>
 	
 	<string name="UseFileTransactions_key">UseFileTransactions</string>
+	<string name="UseOfflineCache_key">UseOfflineCache</string>
 	<string name="CheckForFileChangesOnSave_key">CheckForFileChangesOnSave</string>
 
 	<string name="MarketURL">market://details?id=</string>

src/keepass2android/Resources/values/strings.xml

@@ -224,6 +224,10 @@
   <string name="credentials_dialog_title">Enter server credentials</string>
   <string name="UseFileTransactions_title">File transactions</string>
   <string name="UseFileTransactions_summary">Use file transactions for writing databases</string>
+	<string name="UseOfflineCache_title">Database caching</string>
+	<string name="UseOfflineCache_summary">Keep a copy of remote database files in the application cache directory. This allows to use remote databases even when offline.</string>
+	<string name="ClearOfflineCache_title">Clear cache?</string>
+	<string name="ClearOfflineCache_question">This will delete all cached database files. Any changes you made while being offline which have not yet been synchronized will be lost! Continue?</string>
   <string name="CheckForFileChangesOnSave_title">Check for modifications</string>
   <string name="CheckForFileChangesOnSave_summary">Check whether the file was modified externally before saving changes.</string>
 	
@@ -272,12 +276,23 @@
 	<string name="YesSynchronize">Yes, merge</string>
 	<string name="NoOverwrite">No, overwrite</string>
 
-	<string name="SynchronizingCachedDatabase">Synchronizing cached database...</string>
-	<string name="DownloadingRemoteFile">Downloading remote file...</string>
-	<string name="UploadingFile">Uploading file...</string>
-	<string name="RestoringRemoteFile">Restoring remote file...</string>
+	<string name="SynchronizingCachedDatabase">Synchronizing cached database…</string>
+	<string name="DownloadingRemoteFile">Downloading remote file…</string>
+	<string name="UploadingFile">Uploading file…</string>
+	<string name="RestoringRemoteFile">Restoring remote file…</string>
 	<string name="FilesInSync">Files are in sync.</string>
 	<string name="SynchronizedDatabaseSuccessfully">Database synchronized successfully!</string>
+	<string name="CheckingDatabaseForChanges">Checking database for changes…</string>
+
+	<string name="CouldNotSaveToRemote">Could not save to remote: %1$s. Save again or use the Synchronize menu when remote connection is available again.</string>
+	<string name="CouldNotLoadFromRemote">Could not open from remote: %1$s. Loaded file from local cache. You can still make changes in the database and synchronize them later.</string>
+	<string name="UpdatedRemoteFileOnLoad">Updated remote file.</string>
+	<string name="NotifyOpenFromLocalDueToConflict">Opened local file due to conflict with changes in remote file. Use Synchronize menu to merge.</string>
+	<string name="LoadedFromRemoteInSync">Remote file and cache are synchronized.</string>
+	<string name="UpdatedCachedFileOnLoad">Updated local cache copy of database.</string>
+	<string name="RemoteDatabaseUnchanged">No changes detected.</string>
+
+	<string name="synchronize_database_menu">Synchronize database…</string>
 
 		<string name="ChangeLog_title">Change log</string>
 	<string name="ChangeLog_0_8_4">

src/keepass2android/Resources/xml/preferences.xml

@@ -156,6 +156,14 @@
 			  android:defaultValue="true"
 			  android:title="@string/UseFileTransactions_title"
 			  android:key="@string/UseFileTransactions_key" />
+		<CheckBoxPreference
+			  android:enabled="true"
+			  android:persistent="true"
+			  android:summary="@string/UseOfflineCache_summary"
+			  android:defaultValue="true"
+			  android:title="@string/UseOfflineCache_title"
+			  android:key="@string/UseOfflineCache_key" />
+
 		<CheckBoxPreference
 		  android:key="@string/RememberRecentFiles_key"
 		  android:title="@string/RememberRecentFiles_title"

src/keepass2android/app/App.cs

@@ -218,7 +218,6 @@ namespace keepass2android
 				(dlgSender, dlgEvt) =>
 				{
 					_db.ReloadRequested = true;
-					LockDatabase(false);
 					activity.SetResult(KeePass.ExitReloadDb);
 					activity.Finish();
 
@@ -334,14 +333,25 @@ namespace keepass2android
 				return new BuiltInFileStorage();
 			else
 			{
-				//todo: check if desired
-				return new CachingFileStorage(new BuiltInFileStorage(), Application.Context.CacheDir.Path, this);
+				var prefs = PreferenceManager.GetDefaultSharedPreferences(Application.Context);
+				if (prefs.GetBoolean(Application.Context.Resources.GetString(Resource.String.UseOfflineCache_key), true))
+				{
+					return new CachingFileStorage(new BuiltInFileStorage(), Application.Context.CacheDir.Path, this);	
+				}
+				else
+				{
+					return new BuiltInFileStorage();
+				}
 			}
 		}
 
 		public void TriggerReload(Context ctx)
 		{
-			AskForReload((Activity)ctx);
+			Handler handler = new Handler(Looper.MainLooper);
+			handler.Post(() =>
+				{
+					AskForReload((Activity) ctx);
+				});
 		}
 
 
@@ -386,21 +396,38 @@ namespace keepass2android
 
 		public void CouldntSaveToRemote(IOConnectionInfo ioc, Exception e)
 		{
-			//TODO use resource strings
-			ShowToast("Couldn't save to remote: "+e.Message+". Save again or use Sync menu when remote connection is available again.");
+			ShowToast(Application.Context.GetString(Resource.String.CouldNotSaveToRemote, e.Message));
 		}
 
-		//todo: test changes in SaveDb with Cache: Save without conflict, save with conflict
-		//add test?
 		
 		public void CouldntOpenFromRemote(IOConnectionInfo ioc, Exception ex)
 		{
-			ShowToast("Couldn't open from remote: " + ex.Message+". Loaded file from local cache. You can still make changes in the database and sync them later.");
+			ShowToast(Application.Context.GetString(Resource.String.CouldNotLoadFromRemote, ex.Message));
+		}
+
+		public void UpdatedCachedFileOnLoad(IOConnectionInfo ioc)
+		{
+			ShowToast(Application.Context.GetString(Resource.String.UpdatedCachedFileOnLoad));
+		}
+
+		public void UpdatedRemoteFileOnLoad(IOConnectionInfo ioc)
+		{
+			ShowToast(Application.Context.GetString(Resource.String.UpdatedRemoteFileOnLoad));
 		}
 
 		public void NotifyOpenFromLocalDueToConflict(IOConnectionInfo ioc)
 		{
-			ShowToast("Opened local file due to conflict with changes in remote file. Use Synchronize menu to merge.");
+			ShowToast(Application.Context.GetString(Resource.String.NotifyOpenFromLocalDueToConflict));
+		}
+
+		public void LoadedFromRemoteInSync(IOConnectionInfo ioc)
+		{
+			ShowToast(Application.Context.GetString(Resource.String.LoadedFromRemoteInSync));
+		}
+
+		public void ClearOfflineCache()
+		{
+			new CachingFileStorage(new BuiltInFileStorage(), Application.Context.CacheDir.Path, this).ClearCache();
 		}
 	}
 
@@ -408,6 +435,7 @@ namespace keepass2android
     ///Application class for Keepass2Android: Contains static Database variable to be used by all components.
 #if NoNet
 	[Application(Debuggable=false, Label=AppNames.AppName)]
+	todo: remove caching preference
 #else
 #if RELEASE 
 	[Application(Debuggable=false, Label=AppNames.AppName)] 

src/keepass2android/settings/AppSettingsActivity.cs

@@ -20,6 +20,8 @@ using Android.App;
 using Android.Content;
 using Android.OS;
 using Android.Preferences;
+using Android.Widget;
+using keepass2android.Io;
 
 namespace keepass2android
 {
@@ -42,10 +44,50 @@ namespace keepass2android
 			
 			FindPreference(GetString(Resource.String.keyfile_key)).PreferenceChange += OnRememberKeyFileHistoryChanged;
 			FindPreference(GetString(Resource.String.ShowUnlockedNotification_key)).PreferenceChange += OnShowUnlockedNotificationChanged;;
+			FindPreference(GetString(Resource.String.UseOfflineCache_key)).PreferenceChange += OnUseOfflineCacheChanged;
 
 			FindPreference(GetString(Resource.String.db_key)).Enabled = false;
 		}
 
+		private void OnUseOfflineCacheChanged(object sender, Preference.PreferenceChangeEventArgs e)
+		{
+			//ensure the user gets a matching database
+			if (App.Kp2a.GetDb().Loaded && !App.Kp2a.GetDb().Ioc.IsLocalFile())
+				App.Kp2a.LockDatabase(false);
+
+			if (!(bool)e.NewValue)
+			{
+				AlertDialog.Builder builder = new AlertDialog.Builder(this);
+				builder.SetTitle(GetString(Resource.String.ClearOfflineCache_title));
+
+				builder.SetMessage(GetString(Resource.String.ClearOfflineCache_question));
+
+				builder.SetPositiveButton(App.Kp2a.GetResourceString(UiStringKey.yes), (o, args) =>
+					 {
+						 try
+						 {
+							 App.Kp2a.ClearOfflineCache();
+						 }
+						 catch (Exception ex)
+						 {
+							 Kp2aLog.Log(ex.ToString());
+							 Toast.MakeText(Application.Context, ex.Message, ToastLength.Long).Show();
+						 }
+					 }
+					);
+
+				builder.SetNegativeButton(App.Kp2a.GetResourceString(UiStringKey.no), (o, args) =>
+				{
+				}
+				);
+
+				Dialog dialog = builder.Create();
+				dialog.Show();
+
+				
+			}
+		}
+
 		internal static void OnRememberKeyFileHistoryChanged(object sender, Preference.PreferenceChangeEventArgs eventArgs)
 		{
 			if (!(bool)eventArgs.NewValue)