src/cx/allocator.h

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2021 Mike Becker, 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.
 */
/**
 * @file allocator.h
 * Interface for custom allocators.
 */

#ifndef UCX_ALLOCATOR_H
#define UCX_ALLOCATOR_H

#include "common.h"

#ifdef __cplusplus
extern "C" {
#endif

/**
 * The class definition for an allocator.
 */
typedef struct {
    /**
     * The allocator's malloc() implementation.
     */
    void *(*malloc)(void *data, size_t n);

    /**
     * The allocator's realloc() implementation.
     */
    void *(*realloc)(void *data, void *mem, size_t n);

    /**
     * The allocator's calloc() implementation.
     */
    void *(*calloc)(void *data, size_t nmemb, size_t size);

    /**
     * The allocator's free() implementation.
     */
    void (*free)(void *data, void *mem);
} cx_allocator_class;

/**
 * Structure holding the data for an allocator.
 */
struct cx_allocator_s {
    /**
     * A pointer to the instance of the allocator class.
     */
    cx_allocator_class *cl;
    /**
     * A pointer to the data this allocator uses.
     */
    void *data;
};

/**
 * High-Level type alias for the allocator type.
 */
typedef struct cx_allocator_s CxAllocator;

/**
 * A pre-defined allocator using standard library malloc() etc.
 */
CX_EXPORT extern const CxAllocator * const cxStdlibAllocator;

/**
 * The default allocator that is used by UCX.
 * Initialized with cxStdlibAllocator, but you may change it.
 */
CX_EXPORT extern const CxAllocator * cxDefaultAllocator;

/**
 * Function pointer type for destructor functions.
 *
 * A destructor function deallocates possible contents and MAY free the memory
 * pointed to by @p memory. Read the documentation of the respective function
 * pointer to learn if a destructor SHALL, MAY, or MUST NOT free the memory in
 * that particular implementation.
 *
 * @param memory a pointer to the object to destruct
  */
typedef void (*cx_destructor_func)(void *memory);

/**
 * Function pointer type for destructor functions.
 *
 * A destructor function deallocates possible contents and MAY free the memory
 * pointed to by @p memory. Read the documentation of the respective function
 * pointer to learn if a destructor SHALL, MAY, or MUST NOT free the memory in
 * that particular implementation.
 *
 * @param data an optional pointer to custom data
 * @param memory a pointer to the object to destruct
  */
typedef void (*cx_destructor_func2)(void *data, void *memory);


/**
 * Function pointer type for clone functions.
 *
 * A clone function is supposed to create a deep copy of the memory pointed to
 * by the @p source pointer.
 * If the @p target pointer is non-null, the clone function is supposed to store
 * the copy into that memory region.
 * Otherwise, the clone function shall use the specified @p allocator to create
 * a new object.
 *
 * The return value of a clone function is always a pointer to the target
 * memory region, or @c NULL if any allocation failed.
 * A clone function SHOULD NOT fail for any other reason than an allocation
 * failure.
 *
 * @param target the target memory or @c NULL, if memory shall be allocated
 * @param source the source memory
 * @param allocator the allocator that shall be used
 * @param data optional additional data
 * @return either the specified @p target, a pointer to the allocated memory,
 * or @c NULL, if any error occurred
 */
typedef void*(*cx_clone_func)(void *target, const void *source,
                             const CxAllocator *allocator, void *data);

/**
 * Returns the system's memory page size.
 *
 * If the page size cannot be retrieved from the system,
 * a default of 4096 bytes is assumed.
 *
 * @return the system's memory page size in bytes
 */
cx_attr_nodiscard
CX_EXPORT unsigned long cx_system_page_size(void);

/**
 * Reallocate a previously allocated block.
 *
 * Internal function - do not use.
 *
 * @param mem pointer to the pointer to allocated block
 * @param n the new size in bytes
 * @retval zero success
 * @retval non-zero failure
 * @see cx_reallocatearray()
 */
cx_attr_nonnull cx_attr_nodiscard
CX_EXPORT int cx_reallocate_(void **mem, size_t n);

/**
 * Reallocate a previously allocated block.
 *
 * Internal function - do not use.
 *
 * @param mem pointer to the pointer to allocated block
 * @param nmemb the number of elements
 * @param size the size of each element
 * @retval zero success
 * @retval non-zero failure
 * @see cx_reallocate()
 */
cx_attr_nonnull cx_attr_nodiscard
CX_EXPORT int cx_reallocatearray_(void **mem, size_t nmemb, size_t size);

/**
 * Reallocate a previously allocated block and changes the pointer in-place,
 * if necessary.
 *
 * @note This will use stdlib reallocate and @em not the cxDefaultAllocator.
 *
 * @par Error handling
 * @c errno will be set by realloc() on failure.
 *
 * @param mem (@c void**) pointer to the pointer to allocated block
 * @param n (@c size_t) the new size in bytes
 * @retval zero success
 * @retval non-zero failure
 * @see cx_reallocatearray()
 */
#define cx_reallocate(mem, n) cx_reallocate_((void**)(mem), n)

/**
 * Reallocate a previously allocated block and changes the pointer in-place,
 * if necessary.
 *
 * The size is calculated by multiplying @p nemb and @p size.
 *
 * @note This will use stdlib reallocate and @em not the cxDefaultAllocator.
 *
 * @par Error handling
 * @c errno will be set by realloc() on failure or when the multiplication of
 * @p nmemb and @p size overflows.
 *
 * @param mem (@c void**) pointer to the pointer to allocated block
 * @param nmemb (@c size_t) the number of elements
 * @param size (@c size_t) the size of each element
 * @retval zero success
 * @retval non-zero failure
 */
#define cx_reallocatearray(mem, nmemb, size) \
    cx_reallocatearray_((void**)(mem), nmemb, size)

/**
 * Allocates memory and sets every byte to zero.
 *
 * @param n (@c size_t) the number of bytes
 * @return (@c void*) a pointer to the allocated memory
 */
#define cx_zalloc(n) calloc(1, n)

/**
 * Free a block allocated by this allocator.
 *
 * @note Freeing a block of a different allocator is undefined.
 *
 * @param allocator the allocator
 * @param mem a pointer to the block to free
 */
cx_attr_nonnull_arg(1)
CX_EXPORT void cxFree(const CxAllocator *allocator, void *mem);

/**
 * Allocate @p n bytes of memory.
 *
 * @param allocator the allocator
 * @param n the number of bytes
 * @return a pointer to the allocated memory
 */
cx_attr_nodiscard cx_attr_nonnull
cx_attr_malloc cx_attr_dealloc_ucx cx_attr_allocsize(2)
CX_EXPORT void *cxMalloc(const CxAllocator *allocator, size_t n);

/**
 * Reallocate the previously allocated block in @p mem, making the new block
 * @p n bytes long.
 * This function may return the same pointer passed to it if moving
 * the memory was not necessary.
 *
 * @note Re-allocating a block allocated by a different allocator is undefined.
 *
 * @attention This function is bug-prone. Consider using cxReallocate().
 *
 * @param allocator the allocator
 * @param mem pointer to the previously allocated block
 * @param n the new size in bytes
 * @return a pointer to the reallocated memory
 */
cx_attr_nodiscard cx_attr_nonnull_arg(1)
cx_attr_dealloc_ucx cx_attr_allocsize(3)
CX_EXPORT void *cxRealloc(const CxAllocator *allocator, void *mem, size_t n);

/**
 * Reallocate the previously allocated block in @p mem.
 *
 * This function may return the same pointer passed to it if moving
 * the memory was not necessary.
 *
 * The size is calculated by multiplying @p nemb and @p size.
 * If that multiplication overflows, this function returns @c NULL, and @c errno
 * will be set.
 *
 * @note Re-allocating a block allocated by a different allocator is undefined.
 *
 * @attention This function is bug-prone. Consider using cxReallocateArray().
 *
 * @param allocator the allocator
 * @param mem pointer to the previously allocated block
 * @param nmemb the number of elements
 * @param size the size of each element
 * @return a pointer to the reallocated memory
 */
cx_attr_nodiscard cx_attr_nonnull_arg(1)
cx_attr_dealloc_ucx cx_attr_allocsize(3, 4)
CX_EXPORT void *cxReallocArray(const CxAllocator *allocator,
        void *mem, size_t nmemb, size_t size);

/**
 * Reallocate a previously allocated block.
 *
 * Internal function - do not use.
 *
 * @param allocator the allocator
 * @param mem pointer to the pointer to allocated block
 * @param n the new size in bytes
 * @retval zero success
 * @retval non-zero failure
 */
cx_attr_nodiscard cx_attr_nonnull
CX_EXPORT int cxReallocate_(const CxAllocator *allocator, void **mem, size_t n);

/**
 * Reallocate a previously allocated block and changes the pointer in-place,
 * if necessary.
 * This function acts like cxRealloc() using the pointer pointed to by @p mem.
 *
 * @note Re-allocating a block allocated by a different allocator is undefined.
 *
 * @par Error handling
 * @c errno will be set if the underlying realloc function does so.
 *
 * @param allocator (@c CxAllocator*) the allocator
 * @param mem (@c void**) pointer to the pointer to allocated block
 * @param n (@c size_t) the new size in bytes
 * @retval zero success
 * @retval non-zero failure
 */
#define cxReallocate(allocator, mem, n) \
    cxReallocate_(allocator, (void**)(mem), n)

/**
 * Reallocate a previously allocated block.
 *
 * Internal function - do not use.
 *
 * @param allocator the allocator
 * @param mem pointer to the pointer to allocated block
 * @param nmemb the number of elements
 * @param size the size of each element
 * @retval zero success
 * @retval non-zero on failure
 */
cx_attr_nodiscard cx_attr_nonnull
CX_EXPORT int cxReallocateArray_(const CxAllocator *allocator,
        void **mem, size_t nmemb, size_t size);

/**
 * Reallocate a previously allocated block and changes the pointer in-place,
 * if necessary.
 * This function acts like cxReallocArray() using the pointer pointed to
 * by @p mem.
 *
 * @note Re-allocating a block allocated by a different allocator is undefined.
 *
 * @par Error handling
 * @c errno will be set, if the underlying realloc function does so or the
 * multiplication of @p nmemb and @p size overflows.
 *
 * @param allocator (@c CxAllocator*) the allocator
 * @param mem (@c void**) pointer to the pointer to allocated block
 * @param nmemb (@c size_t) the number of elements
 * @param size (@c size_t) the size of each element
 * @retval zero success
 * @retval non-zero failure
 */
#define cxReallocateArray(allocator, mem, nmemb, size) \
        cxReallocateArray_(allocator, (void**) (mem), nmemb, size)

/**
 * Allocate @p nmemb elements of @p size bytes each, all initialized to zero.
 *
 * @param allocator the allocator
 * @param nmemb the number of elements
 * @param size the size of each element in bytes
 * @return a pointer to the allocated memory
 */
cx_attr_nonnull_arg(1) cx_attr_nodiscard
cx_attr_malloc cx_attr_dealloc_ucx cx_attr_allocsize(2, 3)
CX_EXPORT void *cxCalloc(const CxAllocator *allocator, size_t nmemb, size_t size);

/**
 * Allocate @p n bytes of memory and sets every byte to zero.
 *
 * @param allocator the allocator
 * @param n the number of bytes
 * @return a pointer to the allocated memory
 */
cx_attr_nodiscard cx_attr_nonnull
cx_attr_malloc cx_attr_dealloc_ucx cx_attr_allocsize(2)
CX_EXPORT void *cxZalloc(const CxAllocator *allocator, size_t n);

/**
 * Allocate @p n bytes of memory.
 *
 * Convenience macro that invokes cxMalloc() with the cxDefaultAllocator.
 *
 * @param n (@c size_t) the number of bytes
 * @return (@c void*) a pointer to the allocated memory
 */
#define cxMallocDefault(n) cxMalloc(cxDefaultAllocator, n)

/**
 * Allocate @p n bytes of memory and sets every byte to zero.
 *
 * Convenience macro that invokes cxZalloc() with the cxDefaultAllocator.
 *
 * @param n (@c size_t) the number of bytes
 * @return (@c void*) a pointer to the allocated memory
 */
#define cxZallocDefault(n) cxZalloc(cxDefaultAllocator, n)

/**
 * Allocate @p nmemb elements of @p size bytes each, all initialized to zero.
 *
 * Convenience macro that invokes cxCalloc() with the cxDefaultAllocator.
 *
 * @param nmemb (@c size_t) the number of elements
 * @param size (@c size_t) the size of each element in bytes
 * @return (@c void*) a pointer to the allocated memory
 */
#define cxCallocDefault(nmemb, size) cxCalloc(cxDefaultAllocator, nmemb, size)

/**
 * Reallocate the previously allocated block in @p mem.
 *
 * This function may return the same pointer passed to it if moving
 * the memory was not necessary.
 *
 * Convenience macro that invokes cxRealloc() with the cxDefaultAllocator.
 *
 * @attention This function is bug-prone. Consider using cxReallocateDefault().
 *
 * @param mem (@c void*) pointer to the previously allocated block
 * @param n (@c size_t) the new size in bytes
 * @return (@c void*) a pointer to the reallocated memory
 */
#define cxReallocDefault(mem, n) cxRealloc(cxDefaultAllocator, mem, n)

/**
 * Reallocate a previously allocated block and changes the pointer in-place,
 * if necessary.
 * This function acts like cxRealloc() using the pointer pointed to by @p mem.
 *
 * Convenience macro that invokes cxReallocate() with the cxDefaultAllocator.
 *
 * @note Re-allocating a block allocated by a different allocator is undefined.
 *
 * @par Error handling
 * @c errno will be set if the underlying realloc function does so.
 *
 * @param mem (@c void**) pointer to the pointer to allocated block
 * @param n (@c size_t) the new size in bytes
 * @retval zero success
 * @retval non-zero failure
 */
#define cxReallocateDefault(mem, n) cxReallocate(cxDefaultAllocator, mem, n)

/**
 * Reallocate a previously allocated block and changes the pointer in-place,
 * if necessary.
 * This function acts like cxReallocArray() using the pointer pointed to
 * by @p mem.
 *
 * Convenience macro that invokes cxReallocateArray() with the cxDefaultAllocator.
 *
 * @note Re-allocating a block allocated by a different allocator is undefined.
 *
 * @par Error handling
 * @c errno will be set, if the underlying realloc function does so or the
 * multiplication of @p nmemb and @p size overflows.
 *
 * @param mem (@c void**) pointer to the pointer to allocated block
 * @param nmemb (@c size_t) the number of elements
 * @param size (@c size_t) the size of each element
 * @retval zero success
 * @retval non-zero failure
 */
#define cxReallocateArrayDefault(mem, nmemb, size) \
        cxReallocateArray(cxDefaultAllocator, mem, nmemb, size)

/**
 * Reallocate the previously allocated block in @p mem.
 *
 * Convenience macro that invokes cxReallocArray() with the cxDefaultAllocator.
 *
 * This function may return the same pointer passed to it if moving
 * the memory was not necessary.
 *
 * The size is calculated by multiplying @p nemb and @p size.
 * If that multiplication overflows, this function returns @c NULL, and @c errno
 * will be set.
 *
 * @note Re-allocating a block allocated by a different allocator is undefined.
 *
 * @attention This function is bug-prone. Consider using cxReallocateArrayDefault().
 *
 * @param mem (@c void*) pointer to the previously allocated block
 * @param nmemb (@c size_t) the number of elements
 * @param size (@c size_t) the size of each element
 * @return (@c void*) a pointer to the reallocated memory
 */
#define cxReallocArrayDefault(mem, nmemb, size) cxReallocArray(cxDefaultAllocator, mem, nmemb, size)

/**
 * Free a block of memory.
 *
 * Convenience function that invokes cxFree() with the cxDefaultAllocator.
 *
 * @param mem the memory to deallocate
 */
CX_EXPORT void cxFreeDefault(void *mem);

#ifdef __cplusplus
} // extern "C"
#endif

#endif // UCX_ALLOCATOR_H