lib/isc/pool.c

/*
 * Copyright (C) 2013, 2015, 2016  Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */

/* $Id$ */

/*! \file */

#include <config.h>

#include <string.h>

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

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

struct isc_pool {
    isc_mem_t *         mctx;
    unsigned int            count;
    isc_pooldeallocator_t       free;
    isc_poolinitializer_t       init;
    void *              initarg;
    void **             pool;
};

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

static isc_result_t
alloc_pool(isc_mem_t *mctx, unsigned int count, isc_pool_t **poolp) {
    isc_pool_t *pool;

    pool = isc_mem_get(mctx, sizeof(*pool));
    if (pool == NULL)
        return (ISC_R_NOMEMORY);
    pool->count = count;
    pool->free = NULL;
    pool->init = NULL;
    pool->initarg = NULL;
    pool->mctx = NULL;
    isc_mem_attach(mctx, &pool->mctx);
    pool->pool = isc_mem_get(mctx, count * sizeof(void *));
    if (pool->pool == NULL) {
        isc_mem_put(mctx, pool, sizeof(*pool));
        return (ISC_R_NOMEMORY);
    }
    memset(pool->pool, 0, count * sizeof(void *));

    *poolp = pool;
    return (ISC_R_SUCCESS);
}

isc_result_t
isc_pool_create(isc_mem_t *mctx, unsigned int count,
           isc_pooldeallocator_t release,
           isc_poolinitializer_t init, void *initarg,
           isc_pool_t **poolp)
{
    isc_pool_t *pool = NULL;
    isc_result_t result;
    unsigned int i;

    INSIST(count > 0);

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

    pool->free = release;
    pool->init = init;
    pool->initarg = initarg;

    /* Populate the pool */
    for (i = 0; i < count; i++) {
        result = init(&pool->pool[i], initarg);
        if (result != ISC_R_SUCCESS) {
            isc_pool_destroy(&pool);
            return (result);
        }
    }

    *poolp = pool;
    return (ISC_R_SUCCESS);
}

void *
isc_pool_get(isc_pool_t *pool) {
    isc_uint32_t i;
    isc_random_get(&i);
    return (pool->pool[i % pool->count]);
}

int
isc_pool_count(isc_pool_t *pool) {
    REQUIRE(pool != NULL);
    return (pool->count);
}

isc_result_t
isc_pool_expand(isc_pool_t **sourcep, unsigned int count,
           isc_pool_t **targetp)
{
    isc_result_t result;
    isc_pool_t *pool;

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

    pool = *sourcep;
    if (count > pool->count) {
        isc_pool_t *newpool = NULL;
        unsigned int i;

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

        newpool->free = pool->free;
        newpool->init = pool->init;
        newpool->initarg = pool->initarg;

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

        /* Populate the new entries */
        for (i = pool->count; i < count; i++) {
            result = pool->init(&newpool->pool[i], pool->initarg);
            if (result != ISC_R_SUCCESS) {
                isc_pool_destroy(&pool);
                return (result);
            }
        }

        isc_pool_destroy(&pool);
        pool = newpool;
    }

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

void
isc_pool_destroy(isc_pool_t **poolp) {
    unsigned int i;
    isc_pool_t *pool = *poolp;
    for (i = 0; i < pool->count; i++) {
        if (pool->free != NULL && pool->pool[i] != NULL)
            pool->free(&pool->pool[i]);
    }
    isc_mem_put(pool->mctx, pool->pool, pool->count * sizeof(void *));
    isc_mem_putanddetach(&pool->mctx, pool, sizeof(*pool));
    *poolp = NULL;
}