lib/isc/taskpool.c

/*
 * Copyright (C) 2004, 2005, 2007, 2011-2013  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 1999-2001  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */

/* $Id$ */

/*! \file */

#include <config.h>

#include <isc/mem.h>
#include <isc/random.h>
#include <isc/taskpool.h>
#include <isc/util.h>

/***
 *** Types.
 ***/

struct isc_taskpool {
    isc_mem_t *         mctx;
    isc_taskmgr_t *         tmgr;
    unsigned int            ntasks;
    unsigned int            quantum;
    isc_task_t **           tasks;
};

/***
 *** Functions.
 ***/

static isc_result_t
alloc_pool(isc_taskmgr_t *tmgr, isc_mem_t *mctx, unsigned int ntasks,
       unsigned int quantum, isc_taskpool_t **poolp)
{
    isc_taskpool_t *pool;
    unsigned int i;

    pool = isc_mem_get(mctx, sizeof(*pool));
    if (pool == NULL)
        return (ISC_R_NOMEMORY);

    pool->mctx = NULL;
    isc_mem_attach(mctx, &pool->mctx);
    pool->ntasks = ntasks;
    pool->quantum = quantum;
    pool->tmgr = tmgr;
    pool->tasks = isc_mem_get(mctx, ntasks * sizeof(isc_task_t *));
    if (pool->tasks == NULL) {
        isc_mem_putanddetach(&pool->mctx, pool, sizeof(*pool));
        return (ISC_R_NOMEMORY);
    }
    for (i = 0; i < ntasks; i++)
        pool->tasks[i] = NULL;

    *poolp = pool;
    return (ISC_R_SUCCESS);
}

isc_result_t
isc_taskpool_create(isc_taskmgr_t *tmgr, isc_mem_t *mctx,
            unsigned int ntasks, unsigned int quantum,
            isc_taskpool_t **poolp)
{
    unsigned int i;
    isc_taskpool_t *pool = NULL;
    isc_result_t result;

    INSIST(ntasks > 0);

    /* Allocate the pool structure */
    result = alloc_pool(tmgr, mctx, ntasks, quantum, &pool);
    if (result != ISC_R_SUCCESS)
        return (result);

    /* Create the tasks */
    for (i = 0; i < ntasks; i++) {
        result = isc_task_create(tmgr, quantum, &pool->tasks[i]);
        if (result != ISC_R_SUCCESS) {
            isc_taskpool_destroy(&pool);
            return (result);
        }
        isc_task_setname(pool->tasks[i], "taskpool", NULL);
    }

    *poolp = pool;
    return (ISC_R_SUCCESS);
}

void
isc_taskpool_gettask(isc_taskpool_t *pool, isc_task_t **targetp) {
    isc_uint32_t i;
    isc_random_get(&i);
    isc_task_attach(pool->tasks[i % pool->ntasks], targetp);
}

int
isc_taskpool_size(isc_taskpool_t *pool) {
    REQUIRE(pool != NULL);
    return (pool->ntasks);
}

isc_result_t
isc_taskpool_expand(isc_taskpool_t **sourcep, unsigned int size,
            isc_taskpool_t **targetp)
{
    isc_result_t result;
    isc_taskpool_t *pool;

    REQUIRE(sourcep != NULL && *sourcep != NULL);
    REQUIRE(targetp != NULL && *targetp == NULL);

    pool = *sourcep;
    if (size > pool->ntasks) {
        isc_taskpool_t *newpool = NULL;
        unsigned int i;

        /* Allocate a new pool structure */
        result = alloc_pool(pool->tmgr, pool->mctx, size,
                    pool->quantum, &newpool);
        if (result != ISC_R_SUCCESS)
            return (result);

        /* Copy over the tasks from the old pool */
        for (i = 0; i < pool->ntasks; i++) {
            newpool->tasks[i] = pool->tasks[i];
            pool->tasks[i] = NULL;
        }

        /* Create new tasks */
        for (i = pool->ntasks; i < size; i++) {
            result = isc_task_create(pool->tmgr, pool->quantum,
                         &newpool->tasks[i]);
            if (result != ISC_R_SUCCESS) {
                isc_taskpool_destroy(&newpool);
                return (result);
            }
            isc_task_setname(newpool->tasks[i], "taskpool", NULL);
        }

        isc_taskpool_destroy(&pool);
        pool = newpool;
    }

    *sourcep = NULL;
    *targetp = pool;
    return (ISC_R_SUCCESS);
}

void
isc_taskpool_destroy(isc_taskpool_t **poolp) {
    unsigned int i;
    isc_taskpool_t *pool = *poolp;
    for (i = 0; i < pool->ntasks; i++) {
        if (pool->tasks[i] != NULL) {
            isc_task_detach(&pool->tasks[i]);
        }
    }
    isc_mem_put(pool->mctx, pool->tasks,
            pool->ntasks * sizeof(isc_task_t *));
    isc_mem_putanddetach(&pool->mctx, pool, sizeof(*pool));
    *poolp = NULL;
}