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/*

 * Copyright (c) 2007 Intel Corporation. All Rights Reserved.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the

 * "Software"), to deal in the Software without restriction, including

 * without limitation the rights to use, copy, modify, merge, publish,

 * distribute, sub license, and/or sell copies of the Software, and to

 * permit persons to whom the Software is furnished to do so, subject to

 * the following conditions:

 *

 * The above copyright notice and this permission notice (including the

 * next paragraph) shall be included in all copies or substantial portions

 * of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF

 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.

 * IN NO EVENT SHALL PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR

 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,

 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE

 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 */

#include 

#include 

#include "object_heap.h"

#define ASSERT  assert

#define LAST_FREE   -1

#define ALLOCATED   -2

/*

 * Expands the heap

 * Return 0 on success, -1 on error

 */

static int

object_heap_expand(object_heap_p heap)

{

    int i;

    void *new_heap_index;

    int next_free;

    int new_heap_size = heap->heap_size + heap->heap_increment;

    int bucket_index = new_heap_size / heap->heap_increment - 1;

    if (bucket_index >= heap->num_buckets) {

        int new_num_buckets = heap->num_buckets + 8;

        void **new_bucket;

        new_bucket = realloc(heap->bucket, new_num_buckets * sizeof(void *));

        if (NULL == new_bucket) {

            return -1;

        }

        heap->num_buckets = new_num_buckets;

        heap->bucket = new_bucket;

    }

    new_heap_index = (void *) malloc(heap->heap_increment * heap->object_size);

    if (NULL == new_heap_index) {

        return -1; /* Out of memory */

    }

    heap->bucket[bucket_index] = new_heap_index;

    next_free = heap->next_free;

    for (i = new_heap_size; i-- > heap->heap_size;) {

        object_base_p obj = (object_base_p)(new_heap_index + (i - heap->heap_size) * heap->object_size);

        obj->id = i + heap->id_offset;

        obj->next_free = next_free;

        next_free = i;

    }

    heap->next_free = next_free;

    heap->heap_size = new_heap_size;

    return 0; /* Success */

}

/*

 * Return 0 on success, -1 on error

 */

int

object_heap_init(object_heap_p heap, int object_size, int id_offset)

{

    pthread_mutex_init(&heap->mutex, NULL);

    heap->object_size = object_size;

    heap->id_offset = id_offset & OBJECT_HEAP_OFFSET_MASK;

    heap->heap_size = 0;

    heap->heap_increment = 16;

    heap->next_free = LAST_FREE;

    heap->num_buckets = 0;

    heap->bucket = NULL;

    return object_heap_expand(heap);

}

/*

 * Allocates an object

 * Returns the object ID on success, returns -1 on error

 */

static int

object_heap_allocate_unlocked(object_heap_p heap)

{

    object_base_p obj;

    int bucket_index, obj_index;

    if (LAST_FREE == heap->next_free) {

        if (-1 == object_heap_expand(heap)) {

            return -1; /* Out of memory */

        }

    }

    ASSERT(heap->next_free >= 0);

    bucket_index = heap->next_free / heap->heap_increment;

    obj_index = heap->next_free % heap->heap_increment;

    obj = (object_base_p)(heap->bucket[bucket_index] + obj_index * heap->object_size);

    heap->next_free = obj->next_free;

    obj->next_free = ALLOCATED;

    return obj->id;

}

int

object_heap_allocate(object_heap_p heap)

{

    int ret;

    pthread_mutex_lock(&heap->mutex);

    ret = object_heap_allocate_unlocked(heap);

    pthread_mutex_unlock(&heap->mutex);

    return ret;

}

/*

 * Lookup an object by object ID

 * Returns a pointer to the object on success, returns NULL on error

 */

static object_base_p

object_heap_lookup_unlocked(object_heap_p heap, int id)

{

    object_base_p obj;

    int bucket_index, obj_index;

    if ((id < heap->id_offset) || (id > (heap->heap_size + heap->id_offset))) {

        return NULL;

    }

    id &= OBJECT_HEAP_ID_MASK;

    bucket_index = id / heap->heap_increment;

    obj_index = id % heap->heap_increment;

    obj = (object_base_p)(heap->bucket[bucket_index] + obj_index * heap->object_size);

    /* Check if the object has in fact been allocated */

    if (obj->next_free != ALLOCATED) {

        return NULL;

    }

    return obj;

}

object_base_p

object_heap_lookup(object_heap_p heap, int id)

{

    object_base_p obj;

    pthread_mutex_lock(&heap->mutex);

    obj = object_heap_lookup_unlocked(heap, id);

    pthread_mutex_unlock(&heap->mutex);

    return obj;

}

/*

 * Iterate over all objects in the heap.

 * Returns a pointer to the first object on the heap, returns NULL if heap is empty.

 */

object_base_p

object_heap_first(object_heap_p heap, object_heap_iterator *iter)

{

    *iter = -1;

    return object_heap_next(heap, iter);

}

/*

 * Iterate over all objects in the heap.

 * Returns a pointer to the next object on the heap, returns NULL if heap is empty.

 */

static object_base_p

object_heap_next_unlocked(object_heap_p heap, object_heap_iterator *iter)

{

    object_base_p obj;

    int bucket_index, obj_index;

    int i = *iter + 1;

    while (i < heap->heap_size) {

        bucket_index = i / heap->heap_increment;

        obj_index = i % heap->heap_increment;

        obj = (object_base_p)(heap->bucket[bucket_index] + obj_index * heap->object_size);

        if (obj->next_free == ALLOCATED) {

            *iter = i;

            return obj;

        }

        i++;

    }

    *iter = i;

    return NULL;

}

object_base_p

object_heap_next(object_heap_p heap, object_heap_iterator *iter)

{

    object_base_p obj;

    pthread_mutex_lock(&heap->mutex);

    obj = object_heap_next_unlocked(heap, iter);

    pthread_mutex_unlock(&heap->mutex);

    return obj;

}

/*

 * Frees an object

 */

static void

object_heap_free_unlocked(object_heap_p heap, object_base_p obj)

{

    /* Check if the object has in fact been allocated */

    ASSERT(obj->next_free == ALLOCATED);

    obj->next_free = heap->next_free;

    heap->next_free = obj->id & OBJECT_HEAP_ID_MASK;

}

void

object_heap_free(object_heap_p heap, object_base_p obj)

{

    if (!obj)

        return;

    pthread_mutex_lock(&heap->mutex);

    object_heap_free_unlocked(heap, obj);

    pthread_mutex_unlock(&heap->mutex);

}

/*

 * Destroys a heap, the heap must be empty.

 */

void

object_heap_destroy(object_heap_p heap)

{

    object_base_p obj;

    int bucket_index, obj_index, i;

    /* Check if heap is empty */

    for (i = 0; i < heap->heap_size; i++) {

        /* Check if object is not still allocated */

        bucket_index = i / heap->heap_increment;

        obj_index = i % heap->heap_increment;

        obj = (object_base_p)(heap->bucket[bucket_index] + obj_index * heap->object_size);

        ASSERT(obj->next_free != ALLOCATED);

    }

    for (i = 0; i < heap->heap_size / heap->heap_increment; i++) {

        free(heap->bucket[i]);

    }

    pthread_mutex_destroy(&heap->mutex);

    free(heap->bucket);

    heap->bucket = NULL;

    heap->heap_size = 0;

    heap->next_free = LAST_FREE;

}