Executors.h

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/*
 * 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_EXECUTORS_H_
#define _DECAF_UTIL_CONCURRENT_EXECUTORS_H_

#include <decaf/util/Config.h>

#include <decaf/lang/Thread.h>
#include <decaf/lang/Runnable.h>
#include <decaf/util/concurrent/Callable.h>

#include <decaf/lang/exceptions/NullPointerException.h>

namespace decaf {
namespace util {
namespace concurrent {

    class ThreadFactory;
    class ExecutorService;

    class DECAF_API Executors {
    private:

        Executors();
        Executors(const Executors&);
        Executors& operator= (const Executors&);

    private:

        template<typename E>
        class RunnableAdapter : public decaf::util::concurrent::Callable<E> {
        private:

            decaf::lang::Runnable* task;
            bool owns;
            E result;

        private:

            RunnableAdapter(const RunnableAdapter&);
            RunnableAdapter operator= (const RunnableAdapter&);

        public:

            RunnableAdapter(decaf::lang::Runnable* task, bool owns, const E& result) :
                decaf::util::concurrent::Callable<E>(), task(task), owns(owns), result(result) {
            }

            virtual ~RunnableAdapter() {
                try{
                    if (owns) {
                        delete this->task;
                    }
                }
                DECAF_CATCHALL_NOTHROW()
            }

            virtual E call() {
                this->task->run();
                return result;
            }
        };

    public:

        virtual ~Executors();

        static ThreadFactory* getDefaultThreadFactory();

        static ExecutorService* newFixedThreadPool(int nThreads);

        static ExecutorService* newFixedThreadPool(int nThreads, ThreadFactory* threadFactory);

        static ExecutorService* newSingleThreadExecutor();

        static ExecutorService* newSingleThreadExecutor(ThreadFactory* threadFactory);

        static ExecutorService* unconfigurableExecutorService(ExecutorService* executor);

    public:

        template<typename E>
        static Callable<E>* callable(decaf::lang::Runnable* task, bool owns = true) {

            if (task == NULL) {
                throw decaf::lang::exceptions::NullPointerException(__FILE__, __LINE__,
                    "The Runnable task argument cannot be NULL");
            }

            return new RunnableAdapter<E>(task, owns, E());
        }

        template<typename E>
        static Callable<E>* callable(decaf::lang::Runnable* task, const E& result, bool owns = true) {

            if (task == NULL) {
                throw decaf::lang::exceptions::NullPointerException(__FILE__, __LINE__,
                    "The Runnable task argument cannot be NULL");
            }

            return new RunnableAdapter<E>(task, owns, result);
        }

    private:

        static void initialize();
        static void shutdown();

        friend class decaf::internal::util::concurrent::Threading;

    };

}}}

#endif /* _DECAF_UTIL_CONCURRENT_EXECUTORS_H_ */