Memory pools refactoring.

src/nxt_mp.h

@@ -0,0 +1,112 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ * Copyright (C) NGINX, Inc.
+ */
+
+#ifndef _NXT_MP_H_INCLUDED_
+#define _NXT_MP_H_INCLUDED_
+
+
+/*
+ * Memory pool keeps track of all allocations so they can be freed at once
+ * on pool destruction.  A memory pool is not thread safe, so only one thread
+ * must work with the pool.  If an allocation should be passed to another
+ * thread, it should be allocated with nxt_mp_retain() and then should be
+ * freed with nxt_mp_release().  These functions updates pool retention
+ * counter.  Memory pools decrease number of malloc() and free() calls and
+ * thus reduces thread contention on locks in malloc library.  Memory pools
+ * allow to make both freeable and non-freeable allocations.  The freeable
+ * memory is allocated in fixed size chunks to decrease memory fragmentaiton
+ * on reallocations.  The non-freeable memory is intended to allocate
+ * structures and other items which should be available until memory pool
+ * destruction.  Due to allocation strategy described in nxt_mp.c memory pools
+ * may also improve data cache locality.
+ */
+
+typedef struct nxt_mp_s  nxt_mp_t;
+
+
+/*
+ * nxt_mp_create() creates a memory pool and sets the pool's retention
+ * counter to 1.
+ */
+NXT_EXPORT nxt_mp_t *nxt_mp_create(size_t cluster_size, size_t page_alignment,
+    size_t page_size, size_t min_chunk_size)
+    NXT_MALLOC_LIKE;
+
+/*
+ * nxt_mp_destroy() destroys memory pool in spite of the pool's retention
+ * counter.
+ */
+NXT_EXPORT void nxt_mp_destroy(nxt_mp_t *mp);
+
+/* nxt_mp_test_sizes() tests validity of memory pool parameters. */
+NXT_EXPORT nxt_bool_t nxt_mp_test_sizes(size_t cluster_size,
+    size_t page_alignment, size_t page_size, size_t min_chunk_size);
+
+/* nxt_mp_is_empty() tests that pool is empty. */
+NXT_EXPORT nxt_bool_t nxt_mp_is_empty(nxt_mp_t *mp);
+
+
+/*
+ * nxt_mp_alloc() returns aligned freeable memory.
+ * The alignment is sutiable to allocate structures.
+ */
+NXT_EXPORT void *nxt_mp_alloc(nxt_mp_t *mp, size_t size)
+    NXT_MALLOC_LIKE;
+
+
+/*
+ * nxt_mp_zalloc() returns zeroed aligned freeable memory.
+ * The alignment is sutiable to allocate structures.
+ */
+NXT_EXPORT void *nxt_mp_zalloc(nxt_mp_t *mp, size_t size)
+    NXT_MALLOC_LIKE;
+
+/* nxt_mp_align() returns aligned freeable memory. */
+NXT_EXPORT void *nxt_mp_align(nxt_mp_t *mp, size_t alignment, size_t size)
+    NXT_MALLOC_LIKE;
+
+/* nxt_mp_zalign() returns zeroed aligned freeable memory. */
+NXT_EXPORT void *nxt_mp_zalign(nxt_mp_t *mp, size_t alignment, size_t size)
+    NXT_MALLOC_LIKE;
+
+/* nxt_mp_free() frees freeable memory. */
+NXT_EXPORT void nxt_mp_free(nxt_mp_t *mp, void *p);
+
+
+/*
+ * nxt_mp_retain() returns aligned freeable memory and increases memory
+ * pool retention counter.
+ */
+NXT_EXPORT void *nxt_mp_retain(nxt_mp_t *mp, size_t size)
+    NXT_MALLOC_LIKE;
+
+/*
+ * nxt_mp_release() returns freeable memory and decreases memory pool
+ * retention counter.  If the counter becomes zero the pool is destroyed.
+ */
+NXT_EXPORT void nxt_mp_release(nxt_mp_t *mp, void *p);
+
+
+/* nxt_mp_nget() returns non-aligned non-freeable memory. */
+NXT_EXPORT void *nxt_mp_nget(nxt_mp_t *mp, size_t size)
+    NXT_MALLOC_LIKE;
+
+/*
+ * nxt_mp_get() returns aligned non-freeable memory.
+ * The alignment is sutiable to allocate structures.
+ */
+NXT_EXPORT void *nxt_mp_get(nxt_mp_t *mp, size_t size)
+    NXT_MALLOC_LIKE;
+
+/*
+ * nxt_mp_zget() returns zeroed aligned non-freeable memory.
+ * The alignment is sutiable to allocate structures.
+ */
+NXT_EXPORT void *nxt_mp_zget(nxt_mp_t *mp, size_t size)
+    NXT_MALLOC_LIKE;
+
+
+#endif /* _NXT_MP_H_INCLUDED_ */