mutex.c

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/* -*- C -*- */
/*
 * Copyright (c) 2015-2020 Seagate Technology LLC and/or its Affiliates
 *
 * 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.
 *
 * For any questions about this software or licensing,
 * please email opensource@seagate.com or cortx-questions@seagate.com.
 *
 */



#define M0_TRACE_SUBSYSTEM M0_TRACE_SUBSYS_LIB
#include "lib/mutex.h"
#include "lib/thread.h"               /* m0_thread_self */
#include "lib/misc.h"                 /* M0_IS0 */

M0_INTERNAL void m0_mutex_init(struct m0_mutex *mutex)
{
        M0_SET0(mutex);
        m0_arch_mutex_init(&mutex->m_arch);
}
M0_EXPORTED(m0_mutex_init);

M0_INTERNAL void m0_mutex_fini(struct m0_mutex *mutex)
{
        M0_PRE(mutex->m_owner == NULL);
        m0_arch_mutex_fini(&mutex->m_arch);
}
M0_EXPORTED(m0_mutex_fini);

M0_INTERNAL void m0_mutex_lock(struct m0_mutex *mutex)
{
        struct m0_mutex_addb2 *ma = mutex->m_addb2;

        M0_PRE(m0_mutex_is_not_locked(mutex));
        if (ma == NULL)
                m0_arch_mutex_lock(&mutex->m_arch);
        else {
                M0_ADDB2_HIST(ma->ma_id, &ma->ma_wait, m0_ptr_wrap(mutex),
                              m0_arch_mutex_lock(&mutex->m_arch));
                ma->ma_taken = m0_time_now();
        }
        M0_ASSERT(mutex->m_owner == NULL);
        mutex->m_owner = m0_thread_self();
}
M0_EXPORTED(m0_mutex_lock);

M0_INTERNAL void m0_mutex_unlock(struct m0_mutex *mutex)
{
        struct m0_mutex_addb2 *ma = mutex->m_addb2;

        M0_PRE(m0_mutex_is_locked(mutex));
        mutex->m_owner = NULL;
        if (ma != NULL) {
                m0_time_t hold  = m0_time_now() - ma->ma_taken;
                uint64_t  datum = m0_ptr_wrap(mutex);

                m0_addb2_hist_mod_with(&ma->ma_hold, hold, datum);
                if (ma->ma_id != 0)
                        M0_ADDB2_ADD(ma->ma_id + 1, hold, datum);
        }
        m0_arch_mutex_unlock(&mutex->m_arch);
}
M0_EXPORTED(m0_mutex_unlock);

M0_INTERNAL int m0_mutex_trylock(struct m0_mutex *mutex)
{
        int try = m0_arch_mutex_trylock(&mutex->m_arch);
        if (try == 0) {
                M0_ASSERT(mutex->m_owner == NULL);
                mutex->m_owner = m0_thread_self();
        }
        return try;
}
M0_EXPORTED(m0_mutex_trylock);

M0_INTERNAL bool m0_mutex_is_locked(const struct m0_mutex *mutex)
{
        return mutex->m_owner == m0_thread_self();
}
M0_EXPORTED(m0_mutex_is_locked);

M0_INTERNAL bool m0_mutex_is_not_locked(const struct m0_mutex *mutex)
{
        return mutex->m_owner != m0_thread_self();
}
M0_EXPORTED(m0_mutex_is_not_locked);

#undef M0_TRACE_SUBSYSTEM

/*
 *  Local variables:
 *  c-indentation-style: "K&R"
 *  c-basic-offset: 8
 *  tab-width: 8
 *  fill-column: 80
 *  scroll-step: 1
 *  End:
 */
/*
 * vim: tabstop=8 shiftwidth=8 noexpandtab textwidth=80 nowrap
 */