Fix locking

Vocaluxe/Lib/Database/CCoverDB.cs

@@ -35,28 +35,29 @@ namespace Vocaluxe.Lib.Database
 {
     public class CCoverDB : CDatabaseBase
     {
-        //You have to lock all actions using cover connection or transaction, otherwhise order is not guaranted
-        private readonly object _CoverMutex = new object();
         private SQLiteTransaction _TransactionCover;
 
         public CCoverDB(string filePath) : base(filePath) {}
 
         public override bool Init()
         {
-            if (!base.Init())
-                return false;
+            lock (_Mutex)
+            {
+                if (!base.Init())
+                    return false;
 
-            if (_Version < 0)
-                return _CreateCoverDB();
-            if (_Version < CSettings.DatabaseCoverVersion)
-                throw new NotImplementedException("Upgrading of cover DB not implemented");
+                if (_Version < 0)
+                    return _CreateCoverDB();
+                if (_Version < CSettings.DatabaseCoverVersion)
+                    throw new NotImplementedException("Upgrading of cover DB not implemented");
+            }
             return true;
         }
 
         public override void Close()
         {
             //Do commit and close atomicly otherwhise we may loose changes
-            lock (_CoverMutex)
+            lock (_Mutex)
             {
                 _CommitCovers();
 
@@ -74,7 +75,7 @@ namespace Vocaluxe.Lib.Database
                 return false;
             }
 
-            lock (_CoverMutex)
+            lock (_Mutex)
             {
                 //Double check here because we may have just closed our connection
                 if (_Connection == null)
@@ -147,7 +148,7 @@ namespace Vocaluxe.Lib.Database
 
             tex = CDraw.EnqueueTexture(size.Width, size.Height, data);
 
-            lock (_CoverMutex)
+            lock (_Mutex)
             {
                 //Double check here because we may have just closed our connection
                 if (_Connection == null)
@@ -184,7 +185,7 @@ namespace Vocaluxe.Lib.Database
 
         public void CommitCovers()
         {
-            lock (_CoverMutex)
+            lock (_Mutex)
             {
                 _CommitCovers();
             }

Vocaluxe/Lib/Database/CDatabaseBase.cs

@@ -17,7 +17,6 @@
 
 using System;
 using System.IO;
-using Vocaluxe.Base;
 #if WIN
 using System.Data.SQLite;
 
@@ -27,61 +26,72 @@ using Mono.Data.Sqlite;
 
 namespace Vocaluxe.Lib.Database
 {
-    public class CDatabaseBase
+    public abstract class CDatabaseBase
     {
         protected readonly string _FilePath;
         protected SQLiteConnection _Connection;
 
+        //You have to lock all actions using connection or transaction, otherwhise order is not guaranted
+        protected readonly object _Mutex = new object();
+
         protected int _Version; //Version of the database (value of row "Value" in table "Version") or -1 if none
 
-        public CDatabaseBase(string filePath)
+        protected CDatabaseBase(string filePath)
         {
             _FilePath = filePath;
         }
 
         public virtual bool Init()
         {
-            _Connection = new SQLiteConnection("Data Source=" + _FilePath);
-            try
+            lock (_Mutex)
             {
-                _Connection.Open();
-            }
-            catch (Exception)
-            {
-                _Connection.Dispose();
-                _Connection = null;
-                return false;
-            }
-
-            using (var command = new SQLiteCommand(_Connection))
-            {
-                command.CommandText = "SELECT Value FROM Version";
-
-                SQLiteDataReader reader = null;
-
+                if (_Connection != null)
+                    return false;
+                _Connection = new SQLiteConnection("Data Source=" + _FilePath);
                 try
                 {
-                    reader = command.ExecuteReader();
+                    _Connection.Open();
+                }
+                catch (Exception)
+                {
+                    _Connection.Dispose();
+                    _Connection = null;
+                    return false;
                 }
-                catch (Exception) {}
 
-                if (reader == null || !reader.Read() || reader.FieldCount == 0)
-                    _Version = -1;
-                else
-                    _Version = reader.GetInt32(0);
+                using (var command = new SQLiteCommand(_Connection))
+                {
+                    command.CommandText = "SELECT Value FROM Version";
 
-                if (reader != null)
-                    reader.Dispose();
+                    SQLiteDataReader reader = null;
+
+                    try
+                    {
+                        reader = command.ExecuteReader();
+                    }
+                    catch (Exception) {}
+
+                    if (reader == null || !reader.Read() || reader.FieldCount == 0)
+                        _Version = -1;
+                    else
+                        _Version = reader.GetInt32(0);
+
+                    if (reader != null)
+                        reader.Dispose();
+                }
             }
             return true;
         }
 
         public virtual void Close()
         {
-            if (_Connection != null)
+            lock (_Mutex)
             {
-                _Connection.Dispose();
-                _Connection = null;
+                if (_Connection != null)
+                {
+                    _Connection.Dispose();
+                    _Connection = null;
+                }
             }
         }
 
@@ -92,6 +102,13 @@ namespace Vocaluxe.Lib.Database
             return t70.Ticks;
         }
 
+        /// <summary>
+        ///     Reads the contents of a field as a byte array <br />
+        ///     Assumes you did the locking!
+        /// </summary>
+        /// <param name="reader"></param>
+        /// <param name="field">Field number to read from (default=first)</param>
+        /// <returns></returns>
         protected static byte[] _GetBytes(SQLiteDataReader reader, int field = 0)
         {
             const int chunkSize = 2 * 1024;