Changeset 1134 for trunk/sources/HeuristicLab.Hive.Server.ADODataAccess/DataAdapterBase.cs

Timestamp:

01/15/09 15:04:50 (16 years ago)

Author:

svonolfe

Message:

Further improved locking mechanism (avoid race conditions, performance) (#372)

File:

• trunk/sources/HeuristicLab.Hive.Server.ADODataAccess/DataAdapterBase.cs (modified) (7 diffs)

trunk/sources/HeuristicLab.Hive.Server.ADODataAccess/DataAdapterBase.cs

@@ -26 +26 @@
 using System.Text;
 using HeuristicLab.Hive.Contracts.BusinessObjects;
-using System.Runtime.CompilerServices;
+using System.Threading;
 
 namespace HeuristicLab.Hive.Server.ADODataAccess {
@@ -33 +33 @@
     where RowT : System.Data.DataRow
     where ObjT : IHiveObject, new() {
+
+    private static Mutex lockersMutex =
+      new Mutex();
+
+    private static IDictionary<long, Mutex> lockers =
+      new Dictionary<long, Mutex>();
+
+    private static IDictionary<long, int> lockCount =
+      new Dictionary<long, int>();
+
+    protected void LockRow(long id) {
+      Mutex rowLock = null;
+
+      /////begin critical section////
+      lockersMutex.WaitOne();
+
+      if (!lockers.ContainsKey(id)) {
+        lockers[id] = new Mutex();
+        lockCount[id] = 0;
+      }
+      rowLock = lockers[id];
+      lockCount[id]++;
+      
+      lockersMutex.ReleaseMutex();
+      /////end critical section////
+
+      rowLock.WaitOne();
+    }
+
+    protected void UnlockRow(long id) {
+      Mutex rowLock = lockers[id];
+      rowLock.ReleaseMutex();
+
+      /////begin critical section////
+      lockersMutex.WaitOne();
+
+      lockCount[id]--;
+      if (lockCount[id] == 0)
+        lockers.Remove(id);
+
+      lockersMutex.ReleaseMutex();
+      /////end critical section////
+    }
+    
     protected AdapterT Adapter {
       get {
@@ -44 +88 @@
     protected abstract ObjT ConvertRow(RowT row, ObjT obj);
 
-    [MethodImpl(MethodImplOptions.Synchronized)]
     protected abstract RowT InsertNewRow(ObjT obj);
 
-    [MethodImpl(MethodImplOptions.Synchronized)]
     protected abstract void UpdateRow(RowT row);
 
@@ -119 +161 @@
     }
 
-    [MethodImpl(MethodImplOptions.Synchronized)]
     public virtual void Update(ObjT obj) {
       if (obj != null) {
@@ -127 +168 @@
         if (row == null) {
           row = InsertNewRow(obj);
+          UpdateRow(row);
         }
 
+        obj.Id = (long)row[row.Table.PrimaryKey[0]];
+        LockRow(obj.Id);
+
         ConvertObj(obj, row);
-
         UpdateRow(row);
 
-        obj.Id = (long)row[row.Table.PrimaryKey[0]];
+        UnlockRow(obj.Id);
       }
     }
@@ -149 +193 @@
     }
 
-    [MethodImpl(MethodImplOptions.Synchronized)]
     public virtual bool Delete(ObjT obj) {
+      bool success = false;
+      
       if (obj != null) {
+        LockRow(obj.Id);
+
         RowT row =
           GetRowById(obj.Id);
@@ -159 +206 @@
           UpdateRow(row);
 
-          return true;
+          success = true;
         }
-      }
-
-      return false;
+
+        UnlockRow(obj.Id);
+      }
+
+      return success;
     }
   }