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/*
This file is part of libmicrohttpd
Copyright (C) 2007--2019 Daniel Pittman, Christian Grothoff and
Karlson2k (Evgeny Grin)
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file memorypool.h
* @brief memory pool; mostly used for efficient (de)allocation
* for each connection and bounding memory use for each
* request
* @author Christian Grothoff
* @author Karlson2k (Evgeny Grin)
*/
#ifndef MEMORYPOOL_H
#define MEMORYPOOL_H
#include "mhd_options.h"
#ifdef HAVE_STDDEF_H
#include <stddef.h>
#endif /* HAVE_STDDEF_H */
#ifdef HAVE_STDBOOL_H
#include <stdbool.h>
#endif
/**
* Opaque handle for a memory pool.
* Pools are not reentrant and must not be used
* by multiple threads.
*/
struct MemoryPool;
/**
* Initialize values for memory pools
*/
void
MHD_init_mem_pools_ (void);
/**
* Create a memory pool.
*
* @param max maximum size of the pool
* @return NULL on error
*/
struct MemoryPool *
MHD_pool_create (size_t max);
/**
* Destroy a memory pool.
*
* @param pool memory pool to destroy
*/
void
MHD_pool_destroy (struct MemoryPool *pool);
/**
* Allocate size bytes from the pool.
*
* @param pool memory pool to use for the operation
* @param size number of bytes to allocate
* @param from_end allocate from end of pool (set to 'true');
* use this for small, persistent allocations that
* will never be reallocated
* @return NULL if the pool cannot support size more
* bytes
*/
void *
MHD_pool_allocate (struct MemoryPool *pool,
size_t size,
bool from_end);
/**
* Try to allocate @a size bytes memory area from the @a pool.
*
* If allocation fails, @a required_bytes is updated with size required to be
* freed in the @a pool from relocatable area to allocate requested number
* of bytes.
* Allocated memory area is always not rellocatable ("from end").
*
* @param pool memory pool to use for the operation
* @param size the size of memory in bytes to allocate
* @param[out] required_bytes the pointer to variable to be updated with
* the size of the required additional free
* memory area, not updated if function succeed.
* Cannot be NULL.
* @return the pointer to allocated memory area if succeed,
* NULL if the pool doesn't have enough space, required_bytes is updated
* with amount of space needed to be freed in relocatable area or
* set to SIZE_MAX if requested size is too large for the pool.
*/
void *
MHD_pool_try_alloc (struct MemoryPool *pool,
size_t size,
size_t *required_bytes);
/**
* Reallocate a block of memory obtained from the pool.
* This is particularly efficient when growing or
* shrinking the block that was last (re)allocated.
* If the given block is not the most recently
* (re)allocated block, the memory of the previous
* allocation may be leaked until the pool is
* destroyed or reset.
*
* @param pool memory pool to use for the operation
* @param old the existing block
* @param old_size the size of the existing block
* @param new_size the new size of the block
* @return new address of the block, or
* NULL if the pool cannot support @a new_size
* bytes (old continues to be valid for @a old_size)
*/
void *
MHD_pool_reallocate (struct MemoryPool *pool,
void *old,
size_t old_size,
size_t new_size);
/**
* Check how much memory is left in the @a pool
*
* @param pool pool to check
* @return number of bytes still available in @a pool
*/
size_t
MHD_pool_get_free (struct MemoryPool *pool);
/**
* Clear all entries from the memory pool except
* for @a keep of the given @a copy_bytes. The pointer
* returned should be a buffer of @a new_size where
* the first @a copy_bytes are from @a keep.
*
* @param pool memory pool to use for the operation
* @param keep pointer to the entry to keep (maybe NULL)
* @param copy_bytes how many bytes need to be kept at this address
* @param new_size how many bytes should the allocation we return have?
* (should be larger or equal to @a copy_bytes)
* @return addr new address of @a keep (if it had to change)
*/
void *
MHD_pool_reset (struct MemoryPool *pool,
void *keep,
size_t copy_bytes,
size_t new_size);
#endif
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