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Diffstat (limited to 'libdimension/base/pool.c')
| -rw-r--r-- | libdimension/base/pool.c | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/libdimension/base/pool.c b/libdimension/base/pool.c new file mode 100644 index 0000000..4bfdd7d --- /dev/null +++ b/libdimension/base/pool.c @@ -0,0 +1,177 @@ +/************************************************************************* + * Copyright (C) 2014 Tavian Barnes <tavianator@tavianator.com> * + * * + * This file is part of The Dimension Library. * + * * + * The Dimension 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 3 of the * + * License, or (at your option) any later version. * + * * + * The Dimension 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 program. If not, see * + * <http://www.gnu.org/licenses/>. * + *************************************************************************/ + +/** + * @file + * Memory pool implementation. + */ + +#include "internal.h" +#include "internal/concurrency.h" +#include <stdatomic.h> + +/// Number of pointers per block, we want a block to fit in a single page. +#define DMNSN_POOL_BLOCK_SIZE (4096/sizeof(void *) - 4) +/// Number of pointers per tidy block +#define DMNSN_TIDY_BLOCK_SIZE ((4096 - 4*sizeof(void *))/(sizeof(void *) + sizeof(dmnsn_callback_fn *))) + +/// A single block in a thread-specific pool. +typedef struct dmnsn_pool_block { + /// Current index into allocs[]. + size_t i; + /// All allocations in the current block. + void *allocs[DMNSN_POOL_BLOCK_SIZE]; + /// Tail pointer to the previous block in the global chain. + struct dmnsn_pool_block *prev; +} dmnsn_pool_block; + +/// A single tidy block in a thread-specific pool. +typedef struct dmnsn_tidy_block { + /// Current index into allocs[]. + size_t i; + /// All allocations in the current block. + void *allocs[DMNSN_TIDY_BLOCK_SIZE]; + /// All cleanup callbacks in the current block. + dmnsn_callback_fn *cleanup_fns[DMNSN_TIDY_BLOCK_SIZE]; + /// Tail pointer to the previous tidy block in the global chain. + struct dmnsn_tidy_block *prev; +} dmnsn_tidy_block; + +/// dmnsn_pool implementation. +struct dmnsn_pool { + /// Thread-local regular block. + pthread_key_t thread_block; + /// Thread-local tidy block. + pthread_key_t thread_tidy_block; + + /// Global chain of regular blocks. + atomic(dmnsn_pool_block *) chain; + /// Global chain of tidy blocks. + atomic(dmnsn_tidy_block *) tidy_chain; +}; + +dmnsn_pool * +dmnsn_new_pool(void) +{ + dmnsn_pool *pool = DMNSN_MALLOC(dmnsn_pool); + + dmnsn_key_create(&pool->thread_block, NULL); + dmnsn_key_create(&pool->thread_tidy_block, NULL); + + atomic_store_explicit(&pool->chain, NULL, memory_order_relaxed); + atomic_store_explicit(&pool->tidy_chain, NULL, memory_order_relaxed); + + return pool; +} + +void * +dmnsn_palloc(dmnsn_pool *pool, size_t size) +{ + dmnsn_pool_block *old_block = pthread_getspecific(pool->thread_block); + + dmnsn_pool_block *new_block = old_block; + if (dmnsn_unlikely(!old_block || old_block->i == DMNSN_POOL_BLOCK_SIZE)) { + new_block = DMNSN_MALLOC(dmnsn_pool_block); + new_block->i = 0; + } + + void *result = dmnsn_malloc(size); + new_block->allocs[new_block->i++] = result; + + if (dmnsn_unlikely(new_block != old_block)) { + dmnsn_setspecific(pool->thread_block, new_block); + + // Atomically update pool->chain + dmnsn_pool_block *old_chain = atomic_exchange(&pool->chain, new_block); + new_block->prev = old_chain; + } + + return result; +} + +void * +dmnsn_palloc_tidy(dmnsn_pool *pool, size_t size, dmnsn_callback_fn *cleanup_fn) +{ + dmnsn_assert(cleanup_fn != NULL, "NULL cleanup_fn"); + + dmnsn_tidy_block *old_block = pthread_getspecific(pool->thread_tidy_block); + + dmnsn_tidy_block *new_block = old_block; + if (dmnsn_unlikely(!old_block || old_block->i == DMNSN_TIDY_BLOCK_SIZE)) { + new_block = DMNSN_MALLOC(dmnsn_tidy_block); + new_block->i = 0; + } + + void *result = dmnsn_malloc(size); + + size_t i = new_block->i; + new_block->allocs[i] = result; + new_block->cleanup_fns[i] = cleanup_fn; + ++new_block->i; + + if (dmnsn_unlikely(new_block != old_block)) { + dmnsn_setspecific(pool->thread_tidy_block, new_block); + + // Atomically update pool->tidy_chain + dmnsn_tidy_block *old_chain = atomic_exchange(&pool->tidy_chain, new_block); + new_block->prev = old_chain; + } + + return result; +} + +void +dmnsn_delete_pool(dmnsn_pool *pool) +{ + if (!pool) { + return; + } + + dmnsn_pool_block *block = atomic_load_explicit(&pool->chain, memory_order_relaxed); + while (block) { + // Free all the allocations + for (size_t i = block->i; i-- > 0;) { + dmnsn_free(block->allocs[i]); + } + + // Free the block itself and go to the previous one + dmnsn_pool_block *saved = block; + block = block->prev; + dmnsn_free(saved); + } + + dmnsn_tidy_block *tidy_block = atomic_load_explicit(&pool->tidy_chain, memory_order_relaxed); + while (tidy_block) { + // Free all the allocations + for (size_t i = tidy_block->i; i-- > 0;) { + void *ptr = tidy_block->allocs[i]; + tidy_block->cleanup_fns[i](ptr); + dmnsn_free(ptr); + } + + // Free the block itself and go to the previous one + dmnsn_tidy_block *saved = tidy_block; + tidy_block = tidy_block->prev; + dmnsn_free(saved); + } + + dmnsn_key_delete(pool->thread_tidy_block); + dmnsn_free(pool); +} |