shared_mutex.hpp

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/*
 * Copyright 2016, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in
 *       the documentation and/or other materials provided with the
 *       distribution.
 *
 *     * Neither the name of the copyright holder nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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 */

#ifndef PMEMOBJ_SHARED_MUTEX_HPP
#define PMEMOBJ_SHARED_MUTEX_HPP

#include "libpmemobj/thread.h"
#include "libpmemobj/tx_base.h"

namespace nvml
{

namespace obj
{

class shared_mutex {
public:
    typedef PMEMrwlock *native_handle_type;

    shared_mutex() noexcept = default;

    ~shared_mutex() = default;

    void
    lock()
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
        if (int ret = pmemobj_rwlock_wrlock(pop, &this->plock))
            throw lock_error(ret, std::system_category(),
                     "Failed to lock a "
                     "shared mutex.");
    }

    void
    lock_shared()
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
        if (int ret = pmemobj_rwlock_rdlock(pop, &this->plock))
            throw lock_error(ret, std::system_category(),
                     "Failed to shared lock a "
                     "shared mutex.");
    }

    bool
    try_lock()
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
        int ret = pmemobj_rwlock_trywrlock(pop, &this->plock);

        if (ret == 0)
            return true;
        else if (ret == EBUSY)
            return false;
        else
            throw lock_error(ret, std::system_category(),
                     "Failed to lock a"
                     " shared mutex.");
    }

    bool
    try_lock_shared()
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
        int ret = pmemobj_rwlock_tryrdlock(pop, &this->plock);

        if (ret == 0)
            return true;
        else if (ret == EBUSY)
            return false;
        else
            throw lock_error(ret, std::system_category(),
                     "Failed to lock a"
                     " shared mutex.");
    }

    void
    unlock()
    {
        PMEMobjpool *pop = pmemobj_pool_by_ptr(this);
        if (int ret = pmemobj_rwlock_unlock(pop, &this->plock))
            throw lock_error(ret, std::system_category(),
                     "Failed to unlock a"
                     " shared mutex.");
    }

    void
    unlock_shared()
    {
        this->unlock();
    }

    native_handle_type
    native_handle() noexcept
    {
        return &this->plock;
    }

    enum pobj_tx_lock
    lock_type() const noexcept
    {
        return TX_LOCK_RWLOCK;
    }

    shared_mutex &operator=(const shared_mutex &) = delete;

    shared_mutex(const shared_mutex &) = delete;

private:
    PMEMrwlock plock;
};

} /* namespace obj */

} /* namespace nvml */

#endif /* PMEMOBJ_SHARED_MUTEX_HPP */