Migrated source code from Simantics SVN

[simantics/platform.git] / bundles / org.simantics.utils.thread / src / org / simantics / utils / threads / ua / SerialExecutor.java

diff --git a/bundles/org.simantics.utils.thread/src/org/simantics/utils/threads/ua/SerialExecutor.java b/bundles/org.simantics.utils.thread/src/org/simantics/utils/threads/ua/SerialExecutor.java
new file mode 100644 (file)
index 0000000..fe70514
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+++ b/bundles/org.simantics.utils.thread/src/org/simantics/utils/threads/ua/SerialExecutor.java
@@ -0,0 +1,55 @@
+/*******************************************************************************\r
+ * Copyright (c) 2007, 2010 Association for Decentralized Information Management\r
+ * in Industry THTH ry.\r
+ * All rights reserved. This program and the accompanying materials\r
+ * are made available under the terms of the Eclipse Public License v1.0\r
+ * which accompanies this distribution, and is available at\r
+ * http://www.eclipse.org/legal/epl-v10.html\r
+ *\r
+ * Contributors:\r
+ *     VTT Technical Research Centre of Finland - initial API and implementation\r
+ *******************************************************************************/\r
+\r
+package org.simantics.utils.threads.ua;\r
+\r
+import java.util.ArrayDeque;\r
+import java.util.Queue;\r
+import java.util.concurrent.Executor;\r
+\r
+/**\r
+ * The executor serializes the submission of tasks to a second executor,\r
+ * illustrating a composite executor.\r
+ * \r
+ * (This code is copied from the example in {@link Executor})\r
+ */\r
+public class SerialExecutor implements Executor {\r
+    final Queue<Runnable> tasks = new ArrayDeque<Runnable>();\r
+    final Executor executor;\r
+    Runnable active;\r
+                \r
+    public SerialExecutor(Executor executor) {\r
+        this.executor = executor;\r
+    }\r
+                \r
+    public synchronized void execute(final Runnable r) {\r
+        tasks.offer(new Runnable() {\r
+            public void run() {\r
+                try {\r
+                    r.run();\r
+                } finally {\r
+                    scheduleNext();\r
+                }\r
+            }\r
+        });\r
+        if (active == null) {\r
+            scheduleNext();\r
+        }\r
+    }\r
+                \r
+    protected synchronized void scheduleNext() {\r
+        if ((active = tasks.poll()) != null) {\r
+            executor.execute(active);\r
+        }\r
+    }\r
+       \r
+}\r