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From tab...@apache.org
Subject svn commit: r692895 - /activemq/activemq-cpp/trunk/src/main/decaf/util/concurrent/Future.h
Date Sun, 07 Sep 2008 16:32:02 GMT
Author: tabish
Date: Sun Sep  7 09:32:01 2008
New Revision: 692895

URL: http://svn.apache.org/viewvc?rev=692895&view=rev
Log:
First cut of the Future interface

Added:
    activemq/activemq-cpp/trunk/src/main/decaf/util/concurrent/Future.h

Added: activemq/activemq-cpp/trunk/src/main/decaf/util/concurrent/Future.h
URL: http://svn.apache.org/viewvc/activemq/activemq-cpp/trunk/src/main/decaf/util/concurrent/Future.h?rev=692895&view=auto
==============================================================================
--- activemq/activemq-cpp/trunk/src/main/decaf/util/concurrent/Future.h (added)
+++ activemq/activemq-cpp/trunk/src/main/decaf/util/concurrent/Future.h Sun Sep  7 09:32:01
2008
@@ -0,0 +1,105 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.
+ */
+
+#ifndef _DECAF_UTIL_CONCURRENT_FUTURE_H_
+#define _DECAF_UTIL_CONCURRENT_FUTURE_H_
+
+namespace decaf {
+namespace util {
+namespace concurrent {
+
+    /**
+     * A Future represents the result of an asynchronous computation. Methods
+     * are provided to check if the computation is complete, to wait for its
+     * completion, and to retrieve the result of the computation. The result
+     * can only be retrieved using method get when the computation has
+     * completed, blocking if necessary until it is ready. Cancellation is
+     * performed by the cancel method. Additional methods are provided to
+     * determine if the task completed normally or was canceled. Once a
+     * computation has completed, the computation cannot be canceled. If you
+     * would like to use a Future for the sake of cancellability but not
+     * provide a usable result, you can declare types of the form Future<void*>
+     * and return null as a result of the underlying task.
+     */
+    template<typename V>
+    class Future {
+    public:
+
+        virtual ~Future() {}
+
+        /**
+         * Attempts to cancel execution of this task. This attempt will fail if the
+         * task has already completed, has already been canceled, or could not be
+         * canceled for some other reason. If successful, and this task has not
+         * started when cancel is called, this task should never run. If the task
+         * has already started, then the mayInterruptIfRunning parameter determines
+         * whether the thread executing this task should be interrupted in an attempt
+         * to stop the task.
+         * <p>
+         * After this method returns, subsequent calls to isDone() will always return
+         * true. Subsequent calls to isCancelled() will always return true if this
+         * method returned true.
+         * <p>
+         * @param mayInterruptIfRunning - true if the thread executing this task should
+         * be interrupted; otherwise, in-progress tasks are allowed to complete.
+         * @returns false if the task could not be canceled, typically because it has
+         * already completed normally; true otherwise
+         */
+        bool cancel( bool mayInterruptIfRunning ) = 0;
+
+        /**
+         * Returns true if this task was canceled before it completed normally.
+         * @returns true if this task was canceled before it completed
+         */
+        bool isCancelled() const = 0;
+
+        /**
+         * Returns true if this task completed. Completion may be due to normal termination,
+         * an exception, or cancellation -- in all of these cases, this method will return
+         * true.
+         * @returns true if this task completed
+         */
+        bool isDone() const = 0;
+
+        /**
+         * Waits if necessary for the computation to complete, and then retrieves its result.
+         * @returns the computed result.
+         * @throws CancellationException - if the computation was canceled
+         * @throws ExecutionException - if the computation threw an exception
+         * @throws InterruptedException - if the current thread was interrupted while waiting
+         */
+        V get() throw( CancellationException, InterruptedException, ExecutionException )
= 0;
+
+        /**
+         * Waits if necessary for at most the given time for the computation to complete,
and
+         * then retrieves its result, if available.
+         * @param timeout - the maximum time to wait
+         * @param unit - the time unit of the timeout argument
+         * @returns the computed result
+         * @throws CancellationException - if the computation was canceled
+         * @throws ExecutionException - if the computation threw an exception
+         * @throws InterruptedException - if the current thread was interrupted while waiting
+         * @throws TimeoutException - if the wait timed out
+         */
+        V get( long long timeout, TimeUnit unit)
+            throw( InterruptedException, ExecutionException, TimeoutException ) = 0;
+
+    };
+
+}}}
+
+#endif /*_DECAF_UTIL_CONCURRENT_FUTURE_H_*/



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