/*
* Copyright (C) Igor Sysoev
* Copyright (C) NGINX, Inc.
*/
#include <nxt_main.h>
/*
* A memory pool allocates memory in clusters of specified size and aligned
* to page_alignment. A cluster is divided on pages of specified size. Page
* size must be a power of 2. A page can be used entirely or can be divided
* on chunks of equal size. Chunk size must be a power of 2. Non-freeable
* memory is also allocated from pages. A cluster can contains a mix of pages
* with different chunk sizes and non-freeable pages. Cluster size must be
* a multiple of page size and may be not a power of 2. Allocations greater
* than page are allocated outside clusters. Start addresses and sizes of
* the clusters and large allocations are stored in rbtree blocks to find
* them on free operations. The rbtree nodes are sorted by start addresses.
* The rbtree is also used to destroy memory pool.
*/
typedef struct {
/*
* Used to link
* *) pages with free chunks in pool chunk pages lists,
* *) pages with free space for non-freeable allocations,
* *) free pages in clusters.
*/
nxt_queue_link_t link;
union {
/* Chunk bitmap. There can be no more than 32 chunks in a page. */
uint32_t map;
/* Size of taken non-freeable space. */
uint32_t taken;
} u;
/*
* Size of chunks or page shifted by pool->chunk_size_shift. Zero means
* that page is free, 0xFF means page with non-freeable allocations.
*/
uint8_t size;
/* Number of free chunks of a chunked page. */
uint8_t chunks;
/*
* Number of allocation fails due to free space insufficiency
* in non-freeable page.
*/
uint8_t fails;
/*
* Page number in page cluster.
* There can be no more than 256 pages in a cluster.
*/
uint8_t number;
} nxt_mp_page_t;
/*
* Some malloc implementations (e.g. jemalloc) allocates large enough
* blocks (e.g. greater than 4K) with 4K alignment. So if a block
* descriptor will be allocated together with the block it will take
* excessive 4K memory. So it is better to allocate the block descriptor
* apart.
*/
typedef enum {
/* Block of cluster. The block is allocated apart of the cluster. */
NXT_MP_CLUSTER_BLOCK = 0,
/*
* Block of large allocation.
* The block is allocated apart of the allocation.
*/
NXT_MP_DISCRETE_BLOCK,
/*
* Block of large allocation.
* The block is allocated just after of the allocation.
*/
NXT_MP_EMBEDDED_BLOCK,
} nxt_mp_block_type_t;
typedef struct {
NXT_RBTREE_NODE (node);
nxt_mp_block_type_t type:8;
/* Block size must be less than 4G. */
uint32_t size;
u_char *start;
nxt_mp_page_t pages[];
} nxt_mp_block_t;
struct nxt_mp_s {
/* rbtree of nxt_mp_block_t. */
nxt_rbtree_t blocks;
uint8_t chunk_size_shift;
uint8_t page_size_shift;
uint32_t page_size;
uint32_t page_alignment;
uint32_t cluster_size;
uint32_t retain;
/* Lists of nxt_mp_page_t. */
nxt_queue_t free_pages;
nxt_queue_t nget_pages;
nxt_queue_t get_pages;
nxt_queue_t chunk_pages[0];
};
#define nxt_mp_chunk_get_free(map) \
(__builtin_ffs(map) - 1)
#define nxt_mp_chunk_is_free(map, chunk) \
((map & (1 << chunk)) != 0)
#define nxt_mp_chunk_set_busy(map, chunk) \
map &= ~(1 << chunk)
#define nxt_mp_chunk_set_free(map, chunk) \
map |= (1 << chunk)
#define nxt_mp_free_junk(p, size) \
memset((p), 0x5A, size)
#if !(NXT_DEBUG_MEMORY)
static void *nxt_mp_alloc_small(nxt_mp_t *mp, size_t size);
static void *nxt_mp_get_small(nxt_mp_t *mp, nxt_queue_t *pages, size_t size);
static nxt_mp_page_t *nxt_mp_alloc_page(nxt_mp_t *mp);
static nxt_mp_block_t *nxt_mp_alloc_cluster(nxt_mp_t *mp);
#endif
static void *nxt_mp_alloc_large(nxt_mp_t *mp, size_t alignment, size_t size);
static intptr_t nxt_mp_rbtree_compare(nxt_rbtree_node_t *node1,
nxt_rbtree_node_t *node2);
static nxt_mp_block_t *nxt_mp_find_block(nxt_rbtree_t *tree, u_char *p);
static const char *nxt_mp_chunk_free(nxt_mp_t *mp, nxt_mp_block_t *cluster,
u_char *p);
nxt_mp_t *
nxt_mp_create(size_t cluster_size, size_t page_alignment, size_t page_size,
size_t min_chunk_size)
{
nxt_mp_t *mp;
nxt_uint_t pages, chunk_size;
nxt_queue_t *chunk_pages;
pages = 0;
chunk_size = page_size;
do {
pages++;
chunk_size /= 2;
} while (chunk_size > min_chunk_size);
mp = nxt_zalloc(sizeof(nxt_mp_t) + pages * sizeof(nxt_queue_t));
if (nxt_fast_path(mp != NULL)) {
mp->retain = 1;
mp->page_size = page_size;
mp->page_alignment = nxt_max(page_alignment, NXT_MAX_ALIGNMENT);
mp->cluster_size = cluster_size;
chunk_pages = mp->chunk_pages;
do {
nxt_queue_init(chunk_pages);
chunk_pages++;
chunk_size *= 2;
} while (chunk_size < page_size);
mp->chunk_size_shift = nxt_lg2(min_chunk_size);
mp->page_size_shift = nxt_lg2(page_size);
nxt_rbtree_init(&mp->blocks, nxt_mp_rbtree_compare);
nxt_queue_init(&mp->free_pages);
nxt_queue_init(&mp->nget_pages);
nxt_queue_init(&mp->get_pages);
}
return mp;
}
void
nxt_mp_destroy(nxt_mp_t *mp)
{
void *p;
nxt_mp_block_t *block;
nxt_rbtree_node_t *node, *next;
nxt_debug_alloc("mp destroy");
next = nxt_rbtree_root(&mp->blocks);
while (next != nxt_rbtree_sentinel(&mp->blocks)) {
node = nxt_rbtree_destroy_next(&mp->blocks, &next);
block = (nxt_mp_block_t *) node;
p = block->start;
if (block->type != NXT_MP_EMBEDDED_BLOCK) {
nxt_free(block);
}
nxt_free(p);
}
nxt_free(mp);
}
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_bool_t valid;
/* Alignment and sizes must be a power of 2. */
valid = nxt_expect(1, (nxt_is_power_of_two(page_alignment)
&& nxt_is_power_of_two(page_size)
&& nxt_is_power_of_two(min_chunk_size)));
if (!valid) {
return 0;
}
page_alignment = nxt_max(page_alignment, NXT_MAX_ALIGNMENT);
valid = nxt_expect(1, (page_size >= 64
&& page_size >= page_alignment
&& page_size >= min_chunk_size
&& min_chunk_size * 32 >= page_size
&& cluster_size >= page_size
&& cluster_size / page_size <= 256
&& cluster_size % page_size == 0));
if (!valid) {
return 0;
}
return 1;
}
nxt_bool_t
nxt_mp_is_empty(nxt_mp_t *mp)
{
return (nxt_rbtree_is_empty(&mp->blocks)
&& nxt_queue_is_empty(&mp->free_pages));
}
void *
nxt_mp_alloc(nxt_mp_t *mp, size_t size)
{
nxt_debug_alloc("mp alloc: %uz", size);
#if !(NXT_DEBUG_MEMORY)
if (size <= mp->page_size) {
return nxt_mp_alloc_small(mp, size);
}
#endif
return nxt_mp_alloc_large(mp, NXT_MAX_ALIGNMENT, size);
}
void *
nxt_mp_zalloc(nxt_mp_t *mp, size_t size)
{
void *p;
p = nxt_mp_alloc(mp, size);
if (nxt_fast_path(p != NULL)) {
memset(p, 0, size);
}
return p;
}
void *
nxt_mp_align(nxt_mp_t *mp, size_t alignment, size_t size)
{
nxt_debug_alloc("mp align: @%uz:%uz", alignment, size);
/* Alignment must be a power of 2. */
if (nxt_fast_path(nxt_is_power_of_two(alignment))) {
#if !(NXT_DEBUG_MEMORY)
if (size <= mp->page_size && alignment <= mp->page_alignment) {
size = nxt_max(size, alignment);
if (size <= mp->page_size) {
return nxt_mp_alloc_small(mp, size);
}
}
#endif
return nxt_mp_alloc_large(mp, alignment, size);
}
return NULL;
}
void *
nxt_mp_zalign(nxt_mp_t *mp, size_t alignment, size_t size)
{
void *p;
p = nxt_mp_align(mp, alignment, size);
if (nxt_fast_path(p != NULL)) {
memset(p, 0, size);
}
return p;
}
nxt_inline nxt_uint_t
nxt_mp_chunk_pages_index(nxt_mp_t *mp, size_t size)
{
nxt_int_t n, index;
index = 0;
if (size > 1) {
n = nxt_lg2(size - 1) + 1 - mp->chunk_size_shift;
if (n > 0) {
index = n;
}
}
return index;
}
#if !(NXT_DEBUG_MEMORY)
nxt_inline u_char *
nxt_mp_page_addr(nxt_mp_t *mp, nxt_mp_page_t *page)
{
size_t page_offset;
nxt_mp_block_t *block;
page_offset = page->number * sizeof(nxt_mp_page_t)
+ offsetof(nxt_mp_block_t, pages);
block = (nxt_mp_block_t *) ((u_char *) page - page_offset);
return block->start + (page->number << mp->page_size_shift);
}
static void *
nxt_mp_alloc_small(nxt_mp_t *mp, size_t size)
{
u_char *p;
nxt_uint_t n, index;
nxt_queue_t *chunk_pages;
nxt_mp_page_t *page;
nxt_queue_link_t *link;
p = NULL;
if (size <= mp->page_size / 2) {
index = nxt_mp_chunk_pages_index(mp, size);
chunk_pages = &mp->chunk_pages[index];
if (nxt_fast_path(!nxt_queue_is_empty(chunk_pages))) {
link = nxt_queue_first(chunk_pages);
page = nxt_queue_link_data(link, nxt_mp_page_t, link);
p = nxt_mp_page_addr(mp, page);
n = nxt_mp_chunk_get_free(page->u.map);
nxt_mp_chunk_set_busy(page->u.map, n);
p += ((n << index) << mp->chunk_size_shift);
page->chunks--;
if (page->chunks == 0) {
/*
* Remove full page from the pool chunk pages list
* of pages with free chunks.
*/
nxt_queue_remove(&page->link);
}
} else {
page = nxt_mp_alloc_page(mp);
if (nxt_fast_path(page != NULL)) {
page->size = (1 << index);
n = mp->page_size_shift - (index + mp->chunk_size_shift);
page->chunks = (1 << n) - 1;
nxt_queue_insert_head(chunk_pages, &page->link);
/* Mark the first chunk as busy. */
page->u.map = 0xFFFFFFFE;
p = nxt_mp_page_addr(mp, page);
}
}
} else {
page = nxt_mp_alloc_page(mp);
if (nxt_fast_path(page != NULL)) {
page->size = mp->page_size >> mp->chunk_size_shift;
p = nxt_mp_page_addr(mp, page);
}
}
nxt_debug_alloc("mp chunk:%uz alloc: %p",
page->size << mp->chunk_size_shift, p);
return p;
}
static void *
nxt_mp_get_small(nxt_mp_t *mp, nxt_queue_t *pages, size_t size)
{
u_char *p;
uint32_t available;
nxt_mp_page_t *page;
nxt_queue_link_t *link, *next;
for (link = nxt_queue_first(pages);
link != nxt_queue_tail(pages);
link = next)
{
next = nxt_queue_next(link);
page = nxt_queue_link_data(link, nxt_mp_page_t, link);
available = mp->page_size - page->u.taken;
if (size <= available) {
goto found;
}
if (available == 0 || page->fails++ > 100) {
nxt_queue_remove(link);
}
}
page = nxt_mp_alloc_page(mp);
if (nxt_slow_path(page == NULL)) {
return page;
}
nxt_queue_insert_head(pages, &page->link);
page->size = 0xFF;
found:
p = nxt_mp_page_addr(mp, page);
p += page->u.taken;
page->u.taken += size;
nxt_debug_alloc("mp get: %p", p);
return p;
}
static nxt_mp_page_t *
nxt_mp_alloc_page(nxt_mp_t *mp)
{
nxt_mp_page_t *page;
nxt_mp_block_t *cluster;
nxt_queue_link_t *link;
if (nxt_queue_is_empty(&mp->free_pages)) {
cluster = nxt_mp_alloc_cluster(mp);
if (nxt_slow_path(cluster == NULL)) {
return NULL;
}
}
link = nxt_queue_first(&mp->free_pages);
nxt_queue_remove(link);
page = nxt_queue_link_data(link, nxt_mp_page_t, link);
return page;
}
static nxt_mp_block_t *
nxt_mp_alloc_cluster(nxt_mp_t *mp)
{
nxt_uint_t n;
nxt_mp_block_t *cluster;
n = mp->cluster_size >> mp->page_size_shift;
cluster = nxt_zalloc(sizeof(nxt_mp_block_t) + n * sizeof(nxt_mp_page_t));
if (nxt_slow_path(cluster == NULL)) {
return NULL;
}
/* NXT_MP_CLUSTER_BLOCK type is zero. */
cluster->size = mp->cluster_size;
cluster->start = nxt_memalign(mp->page_alignment, mp->cluster_size);
if (nxt_slow_path(cluster->start == NULL)) {
nxt_free(cluster);
return NULL;
}
n--;
cluster->pages[n].number = n;
nxt_queue_insert_head(&mp->free_pages, &cluster->pages[n].link);
while (n != 0) {
n--;
cluster->pages[n].number = n;
nxt_queue_insert_before(&cluster->pages[n + 1].link,
&cluster->pages[n].link);
}
nxt_rbtree_insert(&mp->blocks, &cluster->node);
return cluster;
}
#endif
static void *
nxt_mp_alloc_large(nxt_mp_t *mp, size_t alignment, size_t size)
{
u_char *p;
size_t aligned_size;
uint8_t type;
nxt_mp_block_t *block;
/* Allocation must be less than 4G. */
if (nxt_slow_path(size >= 0xFFFFFFFF)) {
return NULL;
}
if (nxt_is_power_of_two(size)) {
block = nxt_malloc(sizeof(nxt_mp_block_t));
if (nxt_slow_path(block == NULL)) {
return NULL;
}
p = nxt_memalign(alignment, size);
if (nxt_slow_path(p == NULL)) {
nxt_free(block);
return NULL;
}
type = NXT_MP_DISCRETE_BLOCK;
} else {
aligned_size = nxt_align_size(size, sizeof(uintptr_t));
p = nxt_memalign(alignment, aligned_size + sizeof(nxt_mp_block_t));
if (nxt_slow_path(p == NULL)) {
return NULL;
}
block = (nxt_mp_block_t *) (p + aligned_size);
type = NXT_MP_EMBEDDED_BLOCK;
}
block->type = type;
block->size = size;
block->start = p;
nxt_rbtree_insert(&mp->blocks, &block->node);
return p;
}
static intptr_t
nxt_mp_rbtree_compare(nxt_rbtree_node_t *node1, nxt_rbtree_node_t *node2)
{
nxt_mp_block_t *block1, *block2;
block1 = (nxt_mp_block_t *) node1;
block2 = (nxt_mp_block_t *) node2;
return (uintptr_t) block1->start - (uintptr_t) block2->start;
}
void
nxt_mp_free(nxt_mp_t *mp, void *p)
{
const char *err;
nxt_thread_t *thread;
nxt_mp_block_t *block;
nxt_debug_alloc("mp free %p", p);
block = nxt_mp_find_block(&mp->blocks, p);
if (nxt_fast_path(block != NULL)) {
if (block->type == NXT_MP_CLUSTER_BLOCK) {
err = nxt_mp_chunk_free(mp, block, p);
if (nxt_fast_path(err == NULL)) {
return;
}
} else if (nxt_fast_path(p == block->start)) {
nxt_rbtree_delete(&mp->blocks, &block->node);
if (block->type == NXT_MP_DISCRETE_BLOCK) {
nxt_free(block);
}
nxt_free(p);
return;
} else {
err = "freed pointer points to middle of block: %p";
}
} else {
err = "freed pointer is out of pool: %p";
}
thread = nxt_thread();
nxt_log(thread->task, NXT_LOG_CRIT, err, p);
}
static nxt_mp_block_t *
nxt_mp_find_block(nxt_rbtree_t *tree, u_char *p)
{
nxt_mp_block_t *block;
nxt_rbtree_node_t *node, *sentinel;
node = nxt_rbtree_root(tree);
sentinel = nxt_rbtree_sentinel(tree);
while (node != sentinel) {
block = (nxt_mp_block_t *) node;
if (p < block->start) {
node = node->left;
} else if (p >= block->start + block->size) {
node = node->right;
} else {
return block;
}
}
return NULL;
}
static const char *
nxt_mp_chunk_free(nxt_mp_t *mp, nxt_mp_block_t *cluster, u_char *p)
{
u_char *start;
uintptr_t offset;
nxt_uint_t n, size, chunk;
nxt_queue_t *chunk_pages;
nxt_mp_page_t *page;
n = (p - cluster->start) >> mp->page_size_shift;
start = cluster->start + (n << mp->page_size_shift);
page = &cluster->pages[n];
if (nxt_slow_path(page->size == 0)) {
return "freed pointer points to already free page: %p";
}
if (nxt_slow_path(page->size == 0xFF)) {
return "freed pointer points to non-freeble page: %p";
}
size = page->size << mp->chunk_size_shift;
if (size != mp->page_size) {
offset = (uintptr_t) (p - start) & (mp->page_size - 1);
chunk = offset / size;
if (nxt_slow_path(offset != chunk * size)) {
return "freed pointer points to wrong chunk: %p";
}
if (nxt_slow_path(nxt_mp_chunk_is_free(page->u.map, chunk))) {
return "freed pointer points to already free chunk: %p";
}
nxt_mp_chunk_set_free(page->u.map, chunk);
if (page->u.map != 0xFFFFFFFF) {
page->chunks++;
if (page->chunks == 1) {
/*
* Add the page to the head of pool chunk pages list
* of pages with free chunks.
*/
n = nxt_mp_chunk_pages_index(mp, size);
chunk_pages = &mp->chunk_pages[n];
nxt_queue_insert_head(chunk_pages, &page->link);
}
nxt_mp_free_junk(p, size);
return NULL;
} else {
/*
* All chunks are free, remove the page from pool
* chunk pages list of pages with free chunks.
*/
nxt_queue_remove(&page->link);
}
} else if (nxt_slow_path(p != start)) {
return "invalid pointer to chunk: %p";
}
/* Add the free page to the pool's free pages tree. */
page->size = 0;
nxt_queue_insert_head(&mp->free_pages, &page->link);
nxt_mp_free_junk(p, size);
/* Test if all pages in the cluster are free. */
n = mp->cluster_size >> mp->page_size_shift;
page = cluster->pages;
do {
if (page->size != 0) {
return NULL;
}
page++;
n--;
} while (n != 0);
/* Free cluster. */
n = mp->cluster_size >> mp->page_size_shift;
page = cluster->pages;
do {
nxt_queue_remove(&page->link);
page++;
n--;
} while (n != 0);
nxt_rbtree_delete(&mp->blocks, &cluster->node);
p = cluster->start;
nxt_free(cluster);
nxt_free(p);
return NULL;
}
void *
nxt_mp_retain(nxt_mp_t *mp, size_t size)
{
void *p;
p = nxt_mp_alloc(mp, size);
if (nxt_fast_path(p != NULL)) {
mp->retain++;
nxt_debug_alloc("mp retain: %uD", mp->retain);
}
return p;
}
void
nxt_mp_release(nxt_mp_t *mp, void *p)
{
nxt_mp_free(mp, p);
mp->retain--;
nxt_debug_alloc("mp release: %uD", mp->retain);
if (mp->retain == 0) {
nxt_mp_destroy(mp);
}
}
void *
nxt_mp_nget(nxt_mp_t *mp, size_t size)
{
nxt_debug_alloc("mp nget: %uz", size);
#if !(NXT_DEBUG_MEMORY)
if (size <= mp->page_size) {
return nxt_mp_get_small(mp, &mp->nget_pages, size);
}
#endif
return nxt_mp_alloc_large(mp, NXT_MAX_ALIGNMENT, size);
}
void *
nxt_mp_get(nxt_mp_t *mp, size_t size)
{
nxt_debug_alloc("mp get: %uz", size);
#if !(NXT_DEBUG_MEMORY)
if (size <= mp->page_size) {
size = nxt_max(size, NXT_MAX_ALIGNMENT);
return nxt_mp_get_small(mp, &mp->get_pages, size);
}
#endif
return nxt_mp_alloc_large(mp, NXT_MAX_ALIGNMENT, size);
}
void *
nxt_mp_zget(nxt_mp_t *mp, size_t size)
{
void *p;
p = nxt_mp_get(mp, size);
if (nxt_fast_path(p != NULL)) {
memset(p, 0, size);
}
return p;
}
