1 files changed, 69 insertions, 0 deletions
diff --git a/infrastructure/net.appjet.oui/synchronizer.scala b/infrastructure/net.appjet.oui/synchronizer.scala
new file mode 100644
index 0000000..2a6d9c1
--- /dev/null
+++ b/infrastructure/net.appjet.oui/synchronizer.scala
@@ -0,0 +1,69 @@
+/**
+ * Copyright 2009 Google Inc.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS-IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package net.appjet.oui;
+
+class Synchronizer {
+  import java.util.concurrent.locks.ReentrantLock;
+  import java.util.concurrent.ConcurrentHashMap;
+  
+  private val lockMap = new ConcurrentHashMap[Object, Lock];
+  private val monitor = new Object {};
+  
+  private class Lock {
+    var users = 0;
+    val impl = new ReentrantLock;
+  }
+
+  def acquire(key: Object) {
+    val lock = monitor.synchronized {
+      var lck = lockMap.get(key);
+      if (lck == null) {
+	lck = new Lock;
+	lockMap.put(key, lck);
+      }
+      lck.users += 1;
+      lck;
+    }
+    lock.impl.lock();
+  }
+
+  def isHeld(key: Object): Boolean = {
+    monitor.synchronized {
+      val lck = lockMap.get(key);
+      if (lck == null) {
+        false;
+      }
+      else {
+        lck.impl.isLocked;
+      }
+    }
+  }
+  
+  def release(key: Object) {
+    val lock = monitor.synchronized {
+      var lck = lockMap.get(key);
+      lck.users -= 1;
+      if (lck.users == 0) {
+	lockMap.remove(key);
+      }
+      lck;
+    }
+    lock.impl.unlock();
+  }
+}
+
+object GlobalSynchronizer extends Synchronizer;