/**
 * Licensed to the University Corporation for Advanced Internet
 * Development, Inc. (UCAID) under one or more contributor license
 * agreements. See the NOTICE file distributed with this work for
 * additional information regarding copyright ownership.
 *
 * UCAID 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.
 */

/**
 * @file xmltooling/util/Threads.h
 *
 * Thread and locking wrappers.
 */

#ifndef _xmltooling_threads_h
#define _xmltooling_threads_h

#include <xmltooling/exceptions.h>

#include <memory>
#include <boost/scoped_ptr.hpp>
#include <signal.h>

namespace xmltooling
{
    DECL_XMLTOOLING_EXCEPTION(ThreadingException,XMLTOOL_EXCEPTIONAPI(XMLTOOL_API),xmltooling,XMLToolingException,Exceptions during threading/locking operations);

    /**
     * A class for manual thread creation and synchronization.
     */
    class XMLTOOL_API Thread
    {
        MAKE_NONCOPYABLE(Thread);
    protected:
        Thread() {}
    public:
        virtual ~Thread() {}

        /**
         * Disassociate from the thread.
         *
         * @return 0 for success, non-zero for failure
         */
        virtual int detach()=0;

        /**
         * Join with the thread and wait for its completion.
         *
         * @param thread_return holds the return value of the thread routine
         * @return 0 for success, non-zero for failure
         */
        virtual int join(void** thread_return)=0;

        /**
         * Kill the thread.
         *
         * @param signo the signal to send to the thread
         * @return 0 for success, non-zero for failure
         */
        virtual int kill(int signo)=0;

        /**
         * Creates a new thread object to run the supplied start routine.
         *
         * @param start_routine the function to execute on the thread
         * @param arg           a parameter for the start routine
         * @param stacksize     size of stack to use, or 0 for default
         * @return  the created and running thread object
         */
        static Thread* create(void* (*start_routine)(void*), void* arg, size_t stacksize=0);

        /**
         * Exits a thread gracefully.
         *
         * @param return_val    the return value for the thread
         */
        static void exit(void* return_val);

        /**
         * Sleeps the current thread for the specified amount of time.
         *
         * @param seconds   time to sleep
         */
        static void sleep(int seconds);
#ifndef WIN32
        /**
         * Masks all signals from a thread.
         */
        static void mask_all_signals(void);

        /**
         * Masks specific signals from a thread.
         *
         * @param how
         * @param newmask   the new signal mask
         * @param oldmask   the old signal mask
         * @return 0 for success, non-zero for failure
         */
        static int mask_signals(int how, const sigset_t *newmask, sigset_t *oldmask);
#endif
    };

    /**
     * A class for managing Thread Local Storage values.
     */
    class XMLTOOL_API ThreadKey
    {
        MAKE_NONCOPYABLE(ThreadKey);
    protected:
        ThreadKey() {}
    public:
        virtual ~ThreadKey() {}

        /**
         * Sets the value for a TLS key.
         *
         * @param data  the value to set
         * @return 0 for success, non-zero for failure
         */
        virtual int setData(void* data)=0;

        /**
         * Returns the value for a TLS key.
         *
         * @return the value or nullptr
         */
        virtual void* getData() const=0;

        /**
         * Creates a new TLS key.
         *
         * @param destroy_fn    a functon to cleanup key values
         * @return the new key
         */
        static ThreadKey* create(void (*destroy_fn)(void*));

#ifdef WIN32
        /**
         * Allows system to notify TLS implementation when a thread completes.
         *
         * <p>Windows doesn't support TLS destructors, so only the DllMain detach
         * notification can be used to trigger per-thread cleanup.
         */
        static void onDetach();
#endif
    };

    /**
     * A class for managing exclusive access to resources.
     */
    class XMLTOOL_API Mutex
    {
        MAKE_NONCOPYABLE(Mutex);
    protected:
        Mutex() {}
    public:
        virtual ~Mutex() {}

        /**
         * Locks the mutex for exclusive access.
         *
         * @return 0 for success, non-zero for failure
         */
        virtual int lock()=0;

        /**
         * Unlocks the mutex for exclusive access.
         *
         * @return 0 for success, non-zero for failure
         */
        virtual int unlock()=0;

        /**
         * Creates a new mutex object.
         *
         * @return the new mutex
         */
        static Mutex* create();
    };

    /**
     * A class for managing shared and exclusive access to resources.
     */
    class XMLTOOL_API RWLock
    {
        MAKE_NONCOPYABLE(RWLock);
    protected:
        RWLock() {}
    public:
        virtual ~RWLock() {}

        /**
         * Obtains a shared lock.
         *
         * @return 0 for success, non-zero for failure
         */
        virtual int rdlock()=0;

        /**
         * Obtains an exclusive lock.
         *
         * @return 0 for success, non-zero for failure
         */
        virtual int wrlock()=0;

        /**
         * Unlocks the lock.
         *
         * @return 0 for success, non-zero for failure
         */
        virtual int unlock()=0;

        /**
         * Creates a new read/write lock.
         *
         * @return the new lock
         */
        static RWLock* create();
    };

    /**
     * A class for establishing queues on a mutex based on a periodic condition.
     */
    class XMLTOOL_API CondWait
    {
        MAKE_NONCOPYABLE(CondWait);
    protected:
        CondWait() {}
    public:
        virtual ~CondWait() {}

        /**
         * Waits for a condition variable using the supplied mutex as a queue.
         *
         * @param lock  mutex to queue on
         * @return 0 for success, non-zero for failure
         */
        virtual int wait(Mutex* lock)=0;

        /**
         * Waits for a condition variable using the supplied mutex as a queue,
         * but only for a certain time limit.
         *
         * @param lock          mutex to queue on
         * @param delay_seconds maximum time to wait before waking up
         * @return 0 for success, non-zero for failure
         */
        virtual int timedwait(Mutex* lock, long delay_seconds)=0;

        /**
         * Signal a single thread to wake up if a condition changes.
         *
         * @return 0 for success, non-zero for failure
         */
        virtual int signal()=0;

        /**
         * Signal all threads to wake up if a condition changes.
         *
         * @return 0 for success, non-zero for failure
         */
        virtual int broadcast()=0;

        /**
         * Creates a new condition variable.
         *
         * @return the new condition variable
         */
        static CondWait* create();
    };

    /**
     * RAII wrapper for a mutex lock.
     */
    class XMLTOOL_API Lock {
        MAKE_NONCOPYABLE(Lock);
    public:
        /**
         * Locks and wraps the designated mutex.
         *
         * @param mtx mutex to lock
         */
        Lock(Mutex* mtx) : mutex(mtx) {
            if (mutex)
                mutex->lock();
        }

        /**
         * Locks and wraps the designated mutex.
         *
         * @param mtx mutex to lock
         */
        Lock(Mutex& mtx) : mutex(&mtx) {
            mtx.lock();
        }

        /**
         * Locks and wraps the designated mutex.
         *
         * @param mtx mutex to lock
         */
        Lock(const boost::scoped_ptr<Mutex>& mtx) : mutex(mtx.get()) {
            if (mutex)
                mutex->lock();
        }

        /**
         * Unlocks the wrapped mutex, if any.
         */
        ~Lock() {
            if (mutex)
                mutex->unlock();
        }

        /**
         * Releases control of the original Mutex and returns it without unlocking it.
         *
         * @return the original, locked Mutex
         */
        Mutex* release() {
            Mutex* ret = mutex;
            mutex = nullptr;
            return ret;
        }

    private:
        Mutex* mutex;
    };

    /**
     * RAII wrapper for a shared lock.
     */
    class XMLTOOL_API SharedLock {
        MAKE_NONCOPYABLE(SharedLock);
    public:
        /**
         * Locks and wraps the designated shared lock.
         *
         * @param lock      lock to acquire
         * @param lockit    true if the lock should be acquired here, false if already acquired
         */
        SharedLock(RWLock* lock, bool lockit=true) : rwlock(lock) {
            if (rwlock && lockit)
                rwlock->rdlock();
        }

        /**
         * Locks and wraps the designated shared lock.
         *
         * @param lock      lock to acquire
         * @param lockit    true if the lock should be acquired here, false if already acquired
         */
        SharedLock(const boost::scoped_ptr<RWLock>& lock, bool lockit=true) : rwlock(lock.get()) {
            if (rwlock && lockit)
                rwlock->rdlock();
        }

        /**
         * Unlocks the wrapped shared lock, if any.
         */
        ~SharedLock() {
            if (rwlock)
                rwlock->unlock();
        }

        /**
         * Releases control of the original shared lock and returns it without unlocking it.
         *
         * @return the original shared lock
         */
        RWLock* release() {
            RWLock* ret = rwlock;
            rwlock = nullptr;
            return ret;
        }

    private:
        RWLock* rwlock;
    };

}

#endif /* _xmltooling_threads_h */
