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authorTavian Barnes <tavianator@tavianator.com>2014-08-19 17:10:03 -0400
committerTavian Barnes <tavianator@tavianator.com>2015-10-25 11:03:56 -0400
commit7b09710392d35fb55b52031d447a542d99fc6b4b (patch)
tree270eb927ee8c52ceeb99926ebf4843704775a610 /libdimension/base/pool.c
parent200c86b91ea7063d35be3bffc11c5da53c054653 (diff)
downloaddimension-7b09710392d35fb55b52031d447a542d99fc6b4b.tar.xz
Modularize the libdimension codebase.
Diffstat (limited to 'libdimension/base/pool.c')
-rw-r--r--libdimension/base/pool.c177
1 files changed, 177 insertions, 0 deletions
diff --git a/libdimension/base/pool.c b/libdimension/base/pool.c
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+/*************************************************************************
+ * 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);
+}