Modularize the libdimension codebase.

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);
+}