thread_pool.c

Go to the documentation of this file.

/* -*- 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/trace.h"
#include "lib/thread_pool.h"
#include "lib/memory.h"
#include "lib/assert.h"
#include "lib/errno.h"

enum  m0_parallel_pool_state {
        PPS_IDLE = 1,
        PPS_BUSY,
        PPS_TERMINATING,
        PPS_TERMINATED,
};

/* queue */


struct m0_parallel_queue_link {
        struct m0_queue_link  ql_link;
        int                   ql_rc;
        void                 *ql_item;
};

struct m0_parallel_queue {
        struct m0_queue pq_queue;
        struct m0_mutex pq_lock;
};

static struct m0_parallel_queue_link *
parallel_queue_get(struct m0_parallel_queue *queue)
{
        struct m0_parallel_queue_link *link;

        m0_mutex_lock(&queue->pq_lock);
        link = (struct m0_parallel_queue_link *)m0_queue_get(&queue->pq_queue);
        m0_mutex_unlock(&queue->pq_lock);

        return link;
}

static void parallel_queue_add(struct m0_parallel_queue *queue,
                               struct m0_parallel_queue_link *link)
{
        m0_mutex_lock(&queue->pq_lock);
        m0_queue_put(&queue->pq_queue, &link->ql_link);
        m0_mutex_unlock(&queue->pq_lock);
}

static void parallel_queue_init(struct m0_parallel_queue *queue)
{
        m0_queue_init(&queue->pq_queue);
        m0_mutex_init(&queue->pq_lock);
}

static void parallel_queue_fini(struct m0_parallel_queue *queue)
{
        m0_mutex_fini(&queue->pq_lock);
        m0_queue_fini(&queue->pq_queue);
}

static void parallel_queue_link_init(struct m0_parallel_queue_link *l)
{
        m0_queue_link_init(&l->ql_link);
        l->ql_item = NULL;
}

/* pool */


static void pool_thread(struct m0_parallel_pool *pool)
{
        struct m0_parallel_queue_link *qlink;
        void                          *item;

        while (true) {
                m0_semaphore_down(&pool->pp_ready);

                M0_PRE(M0_IN(pool->pp_state, (PPS_BUSY, PPS_TERMINATING)));
                if (pool->pp_done)
                        break;

                while (true) {
                        qlink = parallel_queue_get(pool->pp_queue);
                        if (qlink == NULL)
                                break;

                        item = qlink->ql_item;
                        qlink->ql_rc = pool->pp_process(item);
                        M0_LOG(M0_DEBUG, "job: %p, ql_rc: %d", item,
                               qlink->ql_rc);
                }

                m0_semaphore_up(&pool->pp_sync);
        }
}

static void pool_threads_fini(struct m0_parallel_pool *pool, bool join)
{
        int i;

        for (i = 0; i < pool->pp_thread_nr; ++i) {
                if (join)
                        m0_thread_join(&pool->pp_threads[i]);
                m0_thread_fini(&pool->pp_threads[i]);
        }

        parallel_queue_fini(pool->pp_queue);
        m0_free(pool->pp_threads);
        m0_free(pool->pp_qlinks);
        m0_free(pool->pp_queue);
}

static void parallel_pool_fini(struct m0_parallel_pool *pool, bool join)
{
        pool_threads_fini(pool, join);
        m0_semaphore_fini(&pool->pp_sync);
        m0_semaphore_fini(&pool->pp_ready);
}

static int pool_threads_init(struct m0_parallel_pool *pool,
                             int thread_nr, int qlink_nr)
{
        int i;
        int result = thread_nr > 0 && qlink_nr > 0 ? 0 : -EINVAL;

        if (result != 0)
                return result;

        M0_ALLOC_ARR(pool->pp_threads, thread_nr);
        M0_ALLOC_ARR(pool->pp_qlinks,  qlink_nr);
        M0_ALLOC_PTR(pool->pp_queue);
        if (pool->pp_threads == NULL || pool->pp_qlinks == NULL ||
            pool->pp_queue == NULL) {
                m0_free(pool->pp_threads);
                m0_free(pool->pp_qlinks);
                m0_free(pool->pp_queue);
                return -ENOMEM;
        }

        parallel_queue_init(pool->pp_queue);

        for (i = 0; i < qlink_nr; ++i)
                parallel_queue_link_init(&pool->pp_qlinks[i]);

        for (i = 0; i < thread_nr; ++i) {
                result = M0_THREAD_INIT(&pool->pp_threads[pool->pp_thread_nr],
                                        struct m0_parallel_pool*, NULL,
                                        &pool_thread, pool,
                                        "pool_thread%d", pool->pp_thread_nr);
                if (result != 0) {
                        parallel_pool_fini(pool, true);
                        break;
                }
                pool->pp_thread_nr++;
        }

        return result;
}

M0_INTERNAL int m0_parallel_pool_init(struct m0_parallel_pool *pool,
                                      int thread_nr, int qlinks_nr)
{
        pool->pp_state     = PPS_IDLE;
        pool->pp_done      = false;
        pool->pp_process   = NULL;
        pool->pp_thread_nr = 0;
        pool->pp_qlinks_nr = qlinks_nr;

        m0_semaphore_init(&pool->pp_ready, 0);
        m0_semaphore_init(&pool->pp_sync, 0);

        return pool_threads_init(pool, thread_nr, qlinks_nr);
}

M0_INTERNAL void m0_parallel_pool_fini(struct m0_parallel_pool *pool)
{
        M0_PRE(pool->pp_state == PPS_TERMINATED);
        parallel_pool_fini(pool, false);
}

M0_INTERNAL void m0_parallel_pool_start(struct m0_parallel_pool *pool,
                                        int (*process)(void *item))
{
        int i;

        M0_PRE(pool->pp_state == PPS_IDLE);
        M0_PRE(pool->pp_process == NULL);

        pool->pp_state = PPS_BUSY;
        pool->pp_process = process;
        pool->pp_next_rc = 0;
        for (i = 0; i < pool->pp_qlinks_nr; ++i)
                pool->pp_qlinks[i].ql_rc = 0;


        for (i = 0; i < pool->pp_thread_nr; ++i)
                m0_semaphore_up(&pool->pp_ready);
}

M0_INTERNAL int m0_parallel_pool_wait(struct m0_parallel_pool *pool)
{
        int i;

        M0_PRE(pool->pp_state == PPS_BUSY);
        M0_PRE(pool->pp_process != NULL);

        for (i = 0; i < pool->pp_thread_nr; ++i)
                m0_semaphore_down(&pool->pp_sync);

        M0_ASSERT(pool->pp_process != NULL);
        pool->pp_state = PPS_IDLE;
        pool->pp_process = NULL;

        return m0_forall(i, pool->pp_qlinks_nr,
                         pool->pp_qlinks[i].ql_rc == 0) ? 0 : M0_ERR(-EINTR);
}

M0_INTERNAL void m0_parallel_pool_terminate_wait(struct m0_parallel_pool *pool)
{
        int i;

        M0_PRE(pool->pp_state == PPS_IDLE);
        pool->pp_state = PPS_TERMINATING;

        pool->pp_done = true;
        for (i = 0; i < pool->pp_thread_nr; ++i)
                m0_semaphore_up(&pool->pp_ready);

        for (i = 0; i < pool->pp_thread_nr; ++i)
                m0_thread_join(&pool->pp_threads[i]);

        pool->pp_state = PPS_TERMINATED;
}

M0_INTERNAL int m0_parallel_pool_job_add(struct m0_parallel_pool *pool,
                                         void *item)
{
        int pos;

        M0_PRE(pool->pp_state == PPS_IDLE);

        pos = m0_queue_length(&pool->pp_queue->pq_queue);
        if (pos < pool->pp_qlinks_nr) {
                pool->pp_qlinks[pos].ql_item = item;
                parallel_queue_add(pool->pp_queue, &pool->pp_qlinks[pos]);
                return 0;
        }

        return M0_ERR(-EFBIG);
}

M0_INTERNAL int m0_parallel_pool_rc_next(struct m0_parallel_pool *pool,
                                         void **job, int *rc)
{
        int i;

        M0_PRE(pool->pp_state == PPS_IDLE);

        for (i = pool->pp_next_rc; i < pool->pp_qlinks_nr; ++i) {
                if (pool->pp_qlinks[i].ql_rc != 0) {
                        *job = pool->pp_qlinks[i].ql_item;
                        *rc  = pool->pp_qlinks[i].ql_rc;
                        pool->pp_next_rc = ++i;
                        return +1;
                }
        }

        return 0;
}


#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
 */