ucx/allocator.h

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2016 Olaf Wintermann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
/**
 * Allocator for custom memory management.
 * 
 * A UCX allocator consists of a pointer to the memory area / pool and four
 * function pointers to memory management functions operating on this memory
 * area / pool. These functions shall behave equivalent to the standard libc
 * functions <code>malloc(), calloc(), realloc()</code> and <code>free()</code>.
 * 
 * The signature of the memory management functions is based on the signature
 * of the respective libc function but each of them takes the pointer to the
 * memory area / pool as first argument.
 * 
 * As the pointer to the memory area / pool can be arbitrarily chosen, any data
 * can be provided to the memory management functions. A UcxMempool is just
 * one example.
 * 
 * @see mempool.h
 * @see UcxMap
 * 
 * @file   allocator.h
 * @author Mike Becker
 * @author Olaf Wintermann
 */

#ifndef UCX_ALLOCATOR_H
#define	UCX_ALLOCATOR_H

#include "ucx.h"

#ifdef	__cplusplus
extern "C" {
#endif

/**
 * A function pointer to the allocators <code>malloc()</code> function.
 * @see UcxAllocator
 */
typedef void*(*ucx_allocator_malloc)(void *pool, size_t n);

/**
 * A function pointer to the allocators <code>calloc()</code> function.
 * @see UcxAllocator
 */
typedef void*(*ucx_allocator_calloc)(void *pool, size_t n, size_t size);

/**
 * A function pointer to the allocators <code>realloc()</code> function.
 * @see UcxAllocator
 */
typedef void*(*ucx_allocator_realloc)(void *pool, void *data, size_t n);

/**
 * A function pointer to the allocators <code>free()</code> function.
 * @see UcxAllocator
 */
typedef void(*ucx_allocator_free)(void *pool, void *data);

/**
 * UCX allocator data structure containing memory management functions.
 */
typedef struct {
    /** Pointer to an area of memory or a complex memory pool.
     * This pointer will be passed to any memory management function as first
     * argument.
     */
    void *pool;
    /**
     * The <code>malloc()</code> function for this allocator.
     */
    ucx_allocator_malloc  malloc;
    /**
     * The <code>calloc()</code> function for this allocator.
     */
    ucx_allocator_calloc  calloc;
    /**
     * The <code>realloc()</code> function for this allocator.
     */
    ucx_allocator_realloc realloc;
    /**
     * The <code>free()</code> function for this allocator.
     */
    ucx_allocator_free    free;
} UcxAllocator;

/**
 * Returns a pointer to the default allocator.
 * 
 * The default allocator contains wrappers to the standard libc memory
 * management functions. Use this function to get a pointer to a globally
 * available allocator. You may also define an own UcxAllocator by assigning
 * #UCX_ALLOCATOR_DEFAULT to a variable and pass the address of this variable
 * to any function that takes a UcxAllocator as argument. Note that using
 * this function is the recommended way of passing a default allocator, thus
 * it never runs out of scope.
 * 
 * @return a pointer to the default allocator
 * 
 * @see UCX_ALLOCATOR_DEFAULT
 */
UcxAllocator *ucx_default_allocator();

/**
 * A wrapper for the standard libc <code>malloc()</code> function.
 * @param ignore ignored (may be used by allocators for pooled memory)
 * @param n argument passed to <code>malloc()</code>
 * @return return value of <code>malloc()</code>
 */
void *ucx_default_malloc(void *ignore, size_t n);
/**
 * A wrapper for the standard libc <code>calloc()</code> function.
 * @param ignore ignored (may be used by allocators for pooled memory)
 * @param n argument passed to <code>calloc()</code>
 * @param size  argument passed to <code>calloc()</code>
 * @return return value of <code>calloc()</code>
 */
void *ucx_default_calloc(void *ignore, size_t n, size_t size);
/**
 * A wrapper for the standard libc <code>realloc()</code> function.
 * @param ignore ignored (may be used by allocators for pooled memory)
 * @param data argumend passed to <code>realloc()</code>
 * @param n argument passed to <code>realloc()</code>
 * @return return value of <code>realloc()</code>
 */
void *ucx_default_realloc(void *ignore, void *data, size_t n);
/**
 * A wrapper for the standard libc <code>free()</code> function.
 * @param ignore ignored (may be used by allocators for pooled memory)
 * @param data argument passed to <code>free()</code>
 */
void ucx_default_free(void *ignore, void *data);

/**
 * Shorthand for calling an allocators malloc function.
 * @param allocator the allocator to use
 * @param n size of space to allocate
 * @return a pointer to the allocated memory area
 */
#define almalloc(allocator, n) ((allocator)->malloc((allocator)->pool, n))

/**
 * Shorthand for calling an allocators calloc function.
 * @param allocator the allocator to use
 * @param n the count of elements the space should be allocated for
 * @param size the size of each element
 * @return a pointer to the allocated memory area
 */
#define alcalloc(allocator, n, size) \
        ((allocator)->calloc((allocator)->pool, n, size))

/**
 * Shorthand for calling an allocators realloc function.
 * @param allocator the allocator to use
 * @param ptr the pointer to the memory area that shall be reallocated
 * @param n the new size of the allocated memory area
 * @return a pointer to the reallocated memory area
 */
#define alrealloc(allocator, ptr, n) \
        ((allocator)->realloc((allocator)->pool, ptr, n))

/**
 * Shorthand for calling an allocators free function.
 * @param allocator the allocator to use
 * @param ptr the pointer to the memory area that shall be freed
 */
#define alfree(allocator, ptr) ((allocator)->free((allocator)->pool, ptr))

/**
 * Convenient macro for a default allocator <code>struct</code> definition.
 */
#define UCX_ALLOCATOR_DEFAULT {NULL, \
        ucx_default_malloc, ucx_default_calloc, ucx_default_realloc, \
        ucx_default_free }

#ifdef	__cplusplus
}
#endif

#endif	/* UCX_ALLOCATOR_H */