dmmlib/src/custom_realloc.c

/*
 *   Copyright 2011 Institute of Communication and Computer Systems (ICCS) 
 *
 *   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.
 *
 */

/**
 * \file    custom_realloc.c
 * \author  Ioannis Koutras (joko@microlab.ntua.gr)
 * \date    January, 2012
 *
 * \brief   Implementation of a function to change the size of an allocated
 * block.
 */

#include <dmmlib/custom_realloc.h>
#include <dmmlib/initialize_allocator.h>
#include "block_header.h"
#ifndef WITH_MEMORY_SPACE_AWARENESS
#include "other.h"
#endif /* WITH_MEMORY_SPACE_AWARENESS */
#if defined (SPLITTING_FIXED) || defined (SPLITTING_VARIABLE)
#include "split.h"
#endif /* SPLITTING_FIXED || SPLITTING_VARIABLE */

/**
 * Allocates a new block and copies the contents of the old block to the new
 * block. No check is done if there is an old block!
 */
void * clean_realloc(allocator_t *allocator, heap_t *heap, void *ptr,
        size_t size);
/**
 * Copy a memory area
 */
static void custom_memcpy(void* dest, const void* src, size_t n) {
    char *dst8, *src8;
    
    dst8 = (char *) dest + HEADER_SIZE;
    src8 = (char *) src + HEADER_SIZE;
    
    while(n--) {
        *dst8++ = *src8++;
    }
}

void * clean_realloc(allocator_t *allocator, heap_t *heap, void *ptr, 
        size_t size) {
    size_t old_size;
    void *new_ptr;

    old_size = get_size(ptr);
    new_ptr = custom_ahmalloc(allocator, heap, size);
    custom_memcpy(new_ptr, ptr, old_size);
    custom_ahfree(allocator, heap, ptr);

    return new_ptr;
}

/**
 * \details The realloc() function tries to change the size of the allocation
 * pointed to by ptr to size, and returns ptr. realloc() creates a new
 * allocation, copies as much of the old data pointed to by ptr as will fit to
 * the new allocation, frees the old allocation and returns a pointer to the
 * allocated memory. If ptr is NULL, realloc() is identical to a call to
 * malloc() for size bytes.
 */
void * custom_ahrealloc(allocator_t *allocator, heap_t *heap, void *ptr, size_t size) {
    void *next_block;
    size_t old_size;

#if defined (SPLITTING_FIXED) || defined (SPLITTING_VARIABLE)
    size_t min_split_size;
#endif /* (SPLITTING_FIXED) || (SPLITTING_VARIABLE) */

#ifndef WITH_MEMORY_SPACE_AWARENESS
    int heap_id;

    /* Go to the system allocator if none was given */
    if(allocator == NULL) {
        allocator = &systemallocator;
        if(allocator->initialized != true) {
            initialize_allocator(allocator);
        }
    }

    if(heap == NULL) {
        heap_id = map_thread_heap();
        heap = &allocator->heaps[heap_id];
    }

#endif /* WITH_MEMORY_SPACE_AWARENESS */

    if(ptr != NULL) {
        old_size = get_size(ptr);
        if(old_size > size) {
            /* The old size is bigger than the new, use the old block */

            /* Try to split the currently allocated block */
#if defined (SPLITTING_FIXED) || defined (SPLITTING_VARIABLE)
#ifdef SPLITTING_FIXED
            min_split_size = MIN_SPLITTING_SIZE;
#endif /* SPLITTING_FIXED */
#ifdef SPLITTING_VARIABLE
            min_split_size = heap->dmm_knobs.min_split_size;
#endif /* SPLITTING_VARIABLE */

            if(old_size - size - HEADER_SIZE >= min_split_size) {
                split(allocator, heap, ptr, size);
            }
#endif /* (SPLITTING_FIXED) || (SPLITTING_VARIABLE) */
            return ptr;
        } else {
            /* The new size can't fit in the old box */

            /* Check if the block next to the original as in the data layout
             * can be used.
             */
            next_block = get_dlnext(allocator, ptr);
            if(next_block != NULL) {
#ifndef WITH_OWNERSHIP
                if(is_free(next_block) == true) {
#else /* WITH_OWNERSHIP */
                if(is_free(next_block) == true
                        && get_owner(next_block) == get_owner(ptr)) {
#endif /* WITH_OWNERSHIP */
                    if(size < old_size + get_size(next_block) + HEADER_SIZE) {
                        remove_block_from_lists(&next_block, heap);
                        if(allocator->border_ptr == next_block) {
                            allocator->border_ptr = ptr;
                        }
                        set_size_and_used(allocator,
                                ptr,
                                old_size + get_size(next_block) + HEADER_SIZE);

#if defined (SPLITTING_FIXED) || defined (SPLITTING_VARIABLE)
#ifdef SPLITTING_FIXED
                        min_split_size = MIN_SPLITTING_SIZE;
#endif /* SPLITTING_FIXED */
#ifdef SPLITTING_VARIABLE
                        min_split_size = heap->dmm_knobs.min_split_size;
#endif /* SPLITTING_VARIABLE */

                        if(get_size(ptr) - size >= min_split_size) {
                            split(allocator, heap, ptr, size);
                        }
#endif /* (SPLITTING_FIXED) || (SPLITTING_VARIABLE) */

                        return ptr;
                    } else {
                        return clean_realloc(allocator, heap, ptr, size);
                    }
                } else {
                    return clean_realloc(allocator, heap, ptr, size);
                }
            } else {
                return clean_realloc(allocator, heap, ptr, size);
            }
        }
    } else {
        /* ptr is NULL, call malloc() */
        return custom_ahmalloc(allocator, heap, size);
    }
}

#ifndef WITH_MEMORY_SPACE_AWARENESS
void * custom_realloc(void *ptr, size_t size) {
    return custom_ahrealloc(NULL, NULL, ptr, size);
}
#endif /* WITH_MEMORY_SPACE_AWARENESS */