1 files changed, 123 insertions, 0 deletions
diff --git a/framework/src/onos/utils/misc/src/main/java/org/onlab/util/SharedExecutors.java b/framework/src/onos/utils/misc/src/main/java/org/onlab/util/SharedExecutors.java
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+++ b/framework/src/onos/utils/misc/src/main/java/org/onlab/util/SharedExecutors.java
@@ -0,0 +1,123 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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 org.onlab.util;
+
+import java.util.Timer;
+import java.util.concurrent.ExecutorService;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static java.util.concurrent.Executors.newFixedThreadPool;
+import static java.util.concurrent.Executors.newSingleThreadExecutor;
+import static org.onlab.util.Tools.groupedThreads;
+
+/**
+ * Utility for managing a set of shared execution resources, such as a timer,
+ * single thread executor and thread pool executor for use by various parts of
+ * the platform or by applications.
+ * <p>
+ * Whenever possible, use of these shared resources is encouraged over creating
+ * separate ones.
+ * </p>
+ */
+public final class SharedExecutors {
+
+    public static final int DEFAULT_POOL_SIZE = 30;
+
+    private static SharedExecutorService singleThreadExecutor =
+            new SharedExecutorService(
+                    newSingleThreadExecutor(groupedThreads("onos/shared",
+                                                           "onos-single-executor")));
+
+    private static SharedExecutorService poolThreadExecutor =
+            new SharedExecutorService(
+                    newFixedThreadPool(DEFAULT_POOL_SIZE,
+                                       groupedThreads("onos/shared",
+                                                      "onos-pool-executor-%d")));
+
+    private static SharedTimer sharedTimer = new SharedTimer();
+
+    // Ban public construction
+    private SharedExecutors() {
+    }
+
+    /**
+     * Returns the shared single thread executor.
+     *
+     * @return shared single thread executor
+     */
+    public static ExecutorService getSingleThreadExecutor() {
+        return singleThreadExecutor;
+    }
+
+    /**
+     * Returns the shared thread pool executor.
+     *
+     * @return shared executor pool
+     */
+    public static ExecutorService getPoolThreadExecutor() {
+        return poolThreadExecutor;
+    }
+
+    /**
+     * Returns the shared timer.
+     *
+     * @return shared timer
+     */
+    public static Timer getTimer() {
+        return sharedTimer;
+    }
+
+    /**
+     * Sets the shared thread pool size.
+     *
+     * @param poolSize new pool size
+     */
+    public static void setPoolSize(int poolSize) {
+        checkArgument(poolSize > 0, "Shared pool size size must be greater than 0");
+        poolThreadExecutor.setBackingExecutor(
+                newFixedThreadPool(poolSize, groupedThreads("onos/shared",
+                                                            "onos-pool-executor-%d")));
+    }
+
+    /**
+     * Shuts down all shared timers and executors and therefore should be
+     * called only by the framework.
+     */
+    public static void shutdown() {
+        sharedTimer.shutdown();
+        singleThreadExecutor.backingExecutor().shutdown();
+        poolThreadExecutor.backingExecutor().shutdown();
+    }
+
+    // Timer extension which does not allow outside cancel method.
+    private static class SharedTimer extends Timer {
+
+        public SharedTimer() {
+            super("onos-shared-timer");
+        }
+
+        @Override
+        public void cancel() {
+            throw new UnsupportedOperationException("Cancel of shared timer is not allowed");
+        }
+
+        private void shutdown() {
+            super.cancel();
+        }
+    }
+
+}