diff options
Diffstat (limited to 'src/core/ngx_slab.c')
| -rw-r--r-- | src/core/ngx_slab.c | 685 |
1 files changed, 685 insertions, 0 deletions
diff --git a/src/core/ngx_slab.c b/src/core/ngx_slab.c new file mode 100644 index 000000000..e182b7a1a --- /dev/null +++ b/src/core/ngx_slab.c @@ -0,0 +1,685 @@ + +/* + * Copyright (C) Igor Sysoev + */ + +#include <ngx_config.h> +#include <ngx_core.h> + +/* + + 12 + 2048 2 11 + 1024 4 10 + 512 8 9 + 256 16 8 + + 128 32 4 32 7 + + 64 64 8 63 6 1 + 32 128 16 127 5 1 + 16 256 32 254 4 2 + 8 512 64 504 3 8 + + */ + + +#define NGX_SLAB_PAGE_MASK 3 +#define NGX_SLAB_PAGE 0 +#define NGX_SLAB_BIG 1 +#define NGX_SLAB_EXACT 2 +#define NGX_SLAB_SMALL 3 + +#if (NGX_PTR_SIZE == 4) + +#define NGX_SLAB_PAGE_FREE 0 +#define NGX_SLAB_PAGE_BUSY 0xffffffff +#define NGX_SLAB_PAGE_START 0x80000000 + +#define NGX_SLAB_SHIFT_MASK 0x0000000f +#define NGX_SLAB_MAP_MASK 0xffff0000 +#define NGX_SLAB_MAP_SHIFT 16 + +#define NGX_SLAB_BUSY 0xffffffff + +#else /* (NGX_PTR_SIZE == 8) */ + +#define NGX_SLAB_PAGE_FREE 0 +#define NGX_SLAB_PAGE_BUSY 0xffffffffffffffff +#define NGX_SLAB_PAGE_START 0x8000000000000000 + +#define NGX_SLAB_SHIFT_MASK 0x000000000000000f +#define NGX_SLAB_MAP_MASK 0xffffffff00000000 +#define NGX_SLAB_MAP_SHIFT 32 + +#define NGX_SLAB_BUSY 0xffffffffffffffff + +#endif + + +#if (NGX_DEBUG_MALLOC) +#define ngx_slab_junk(p, size) ngx_memset(p, 0xD0, size) +#else +#define ngx_slab_junk(p, size) +#endif + +static ngx_slab_page_t *ngx_slab_alloc_pages(ngx_slab_pool_t *pool, + ngx_uint_t pages); +static void ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page, + ngx_uint_t pages); + + +static ngx_uint_t ngx_slab_max_size; +static ngx_uint_t ngx_slab_exact_size; +static ngx_uint_t ngx_slab_exact_shift; + + +void +ngx_slab_init(ngx_slab_pool_t *pool) +{ + u_char *p; + size_t size; + ngx_int_t m; + ngx_uint_t i, n, pages; + ngx_slab_page_t *slots; + + /* STUB */ + if (ngx_slab_max_size == 0) { + ngx_slab_max_size = ngx_pagesize / 2; + ngx_slab_exact_size = ngx_pagesize / (8 * sizeof(uintptr_t)); + for (n = ngx_slab_exact_size; n >>= 1; ngx_slab_exact_shift++) { + /* void */ + } + } + /**/ + + pool->min_size = 1 << pool->min_shift; + + p = (u_char *) pool + sizeof(ngx_slab_pool_t); + size = pool->end - p; + + ngx_slab_junk(p, size); + + slots = (ngx_slab_page_t *) p; + n = ngx_pagesize_shift - pool->min_shift; + + for (i = 0; i < n; i++) { + slots[i].slab = 0; + slots[i].next = &slots[i]; + slots[i].prev = 0; + } + + p += n * sizeof(ngx_slab_page_t); + + /* STUB: possible overflow on 64-bit platform */ + pages = (ngx_uint_t) ((uint64_t) size * ngx_pagesize + / (ngx_pagesize + sizeof(ngx_slab_page_t)) + / ngx_pagesize); + + ngx_memzero(p, pages * sizeof(ngx_slab_page_t)); + + pool->pages = (ngx_slab_page_t *) p; + + pool->free.prev = 0; + pool->free.next = (ngx_slab_page_t *) p; + + pool->pages->slab = pages; + pool->pages->next = &pool->free; + pool->pages->prev = (uintptr_t) &pool->free; + + pool->start = (u_char *) + ngx_align((uintptr_t) p + pages * sizeof(ngx_slab_page_t), + ngx_pagesize); + + m = pages - (pool->end - pool->start) / ngx_pagesize; + if (m > 0) { + pages -= m; + pool->pages->slab = pages; + } + +#if 0 + ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0, "slab: %p, %p, %ui, %d", + pool, pool->start, pages, + (pool->end - pool->start) / ngx_pagesize - pages); +#endif +} + + +void * +ngx_slab_alloc(ngx_slab_pool_t *pool, size_t size) +{ + size_t s; + uintptr_t p, mask, *bitmap; + ngx_uint_t i, n, m, slot, shift, map; + ngx_slab_page_t *page, *prev, *slots; + + ngx_shmtx_lock(&pool->mutex); + + if (size >= ngx_slab_max_size) { + page = ngx_slab_alloc_pages(pool, (size + ngx_pagesize - 1) + >> ngx_pagesize_shift); + if (page) { + p = (page - pool->pages) << ngx_pagesize_shift; + p += (uintptr_t) pool->start; + + } else { + p = 0; + } + + goto done; + } + + if (size > pool->min_size) { + shift = 1; + for (s = size - 1; s >>= 1; shift++) { /* void */ } + slot = shift - pool->min_shift; + + } else { + size = pool->min_size; + shift = pool->min_shift; + slot = 0; + } + + ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, + "slab alloc: %uz slot: %ui", size, slot); + + slots = (ngx_slab_page_t *) ((u_char *) pool + sizeof(ngx_slab_pool_t)); + page = slots[slot].next; + +#if 0 + ngx_log_debug2(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, + "slab alloc: page %p next: %p", page, page->next); +#endif + + if (page->next != page) { + + if (size < ngx_slab_exact_size) { + + do { + p = (page - pool->pages) << ngx_pagesize_shift; + bitmap = (uintptr_t *) (pool->start + p); + + map = (1 << (ngx_pagesize_shift - shift)) + / (sizeof(uintptr_t) * 8); + + for (n = 0; n < map; n++) { + + if (bitmap[n] != NGX_SLAB_BUSY) { + + for (m = 1, i = 0; m; m <<= 1, i++) { + if ((bitmap[n] & m)) { + continue; + } + + bitmap[n] |= m; + i <<= shift; + + if (bitmap[n] == NGX_SLAB_BUSY) { + for (n = n + 1; n < map; n++) { + if (bitmap[n] != NGX_SLAB_BUSY) { + p = (uintptr_t) bitmap + i; + + goto done; + } + } + + prev = (ngx_slab_page_t *) + (page->prev & ~NGX_SLAB_PAGE_MASK); + prev->next = page->next; + page->next->prev = page->prev; + + page->next = NULL; + page->prev = NGX_SLAB_SMALL; + } + + p = (uintptr_t) bitmap + i; + + goto done; + } + } + } + + page = page->next; + + } while (page); + + } else if (size == ngx_slab_exact_size) { + + do { + if (page->slab != NGX_SLAB_BUSY) { + + for (m = 1, i = 0; m; m <<= 1, i++) { + if ((page->slab & m)) { + continue; + } + + page->slab |= m; + + if (page->slab == NGX_SLAB_BUSY) { + prev = (ngx_slab_page_t *) + (page->prev & ~NGX_SLAB_PAGE_MASK); + prev->next = page->next; + page->next->prev = page->prev; + + page->next = NULL; + page->prev = NGX_SLAB_EXACT; + } + + p = (page - pool->pages) << ngx_pagesize_shift; + p += i << shift; + p += (uintptr_t) pool->start; + + goto done; + } + } + + page = page->next; + + } while (page); + + } else { /* size < ngx_pagesize */ + + n = ngx_pagesize_shift - (page->slab & NGX_SLAB_SHIFT_MASK); + n = 1 << n; + n = (1 << n) - 1; + mask = n << NGX_SLAB_MAP_SHIFT; + + do { + if ((page->slab & NGX_SLAB_MAP_MASK) != mask) { + + for (m = 1 << NGX_SLAB_MAP_SHIFT, i = 0; + m & mask; + m <<= 1, i++) + { + if ((page->slab & m)) { + continue; + } + + page->slab |= m; + + if ((page->slab & NGX_SLAB_MAP_MASK) == mask) { + prev = (ngx_slab_page_t *) + (page->prev & ~NGX_SLAB_PAGE_MASK); + prev->next = page->next; + page->next->prev = page->prev; + + page->next = NULL; + page->prev = NGX_SLAB_BIG; + } + + p = (page - pool->pages) << ngx_pagesize_shift; + p += i << shift; + p += (uintptr_t) pool->start; + + goto done; + } + } + + page = page->next; + + } while (page); + } + } + + page = ngx_slab_alloc_pages(pool, 1); + + if (page) { + if (size < ngx_slab_exact_size) { + p = (page - pool->pages) << ngx_pagesize_shift; + bitmap = (uintptr_t *) (pool->start + p); + + s = 1 << shift; + n = (1 << (ngx_pagesize_shift - shift)) / 8 / s; + + if (n == 0) { + n = 1; + } + + bitmap[0] = (2 << n) - 1; + + map = (1 << (ngx_pagesize_shift - shift)) / (sizeof(uintptr_t) * 8); + + for (i = 1; i < map; i++) { + bitmap[i] = 0; + } + + page->slab = shift; + page->next = &slots[slot]; + page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_SMALL; + + slots[slot].next = page; + + p = ((page - pool->pages) << ngx_pagesize_shift) + s * n; + p += (uintptr_t) pool->start; + + goto done; + + } else if (size == ngx_slab_exact_size) { + + page->slab = 1; + page->next = &slots[slot]; + page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_EXACT; + + slots[slot].next = page; + + p = (page - pool->pages) << ngx_pagesize_shift; + p += (uintptr_t) pool->start; + + goto done; + + } else { /* size < ngx_pagesize */ + + page->slab = (1 << NGX_SLAB_MAP_SHIFT) | shift; + page->next = &slots[slot]; + page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_BIG; + + slots[slot].next = page; + + p = (page - pool->pages) << ngx_pagesize_shift; + p += (uintptr_t) pool->start; + + goto done; + } + } + + p = 0; + +done: + + ngx_shmtx_unlock(&pool->mutex); + + ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab alloc: %p", p); + + return (void *) p; +} + + +void +ngx_slab_free(ngx_slab_pool_t *pool, void *p) +{ + size_t size; + uintptr_t slab, *bitmap; + ngx_uint_t n, m, type, slot, shift, map; + ngx_slab_page_t *slots, *page; + + ngx_log_debug1(NGX_LOG_DEBUG_ALLOC, ngx_cycle->log, 0, "slab free: %p", p); + + ngx_shmtx_lock(&pool->mutex); + + if ((u_char *) p < pool->start || (u_char *) p > pool->end) { + ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0, + "ngx_slab_free(): outside of pool"); + goto fail; + } + + n = ((u_char *) p - pool->start) >> ngx_pagesize_shift; + page = &pool->pages[n]; + slab = page->slab; + type = page->prev & NGX_SLAB_PAGE_MASK; + + switch (type) { + + case NGX_SLAB_SMALL: + + shift = slab & NGX_SLAB_SHIFT_MASK; + size = 1 << shift; + + if ((uintptr_t) p & (size - 1)) { + goto wrong_chunk; + } + + n = ((uintptr_t) p & (ngx_pagesize - 1)) >> shift; + m = 1 << (n & (sizeof(uintptr_t) * 8 - 1)); + n /= (sizeof(uintptr_t) * 8); + bitmap = (uintptr_t *) ((uintptr_t) p & ~(ngx_pagesize - 1)); + + if (bitmap[n] & m) { + + if (page->next == NULL) { + slots = (ngx_slab_page_t *) + ((u_char *) pool + sizeof(ngx_slab_pool_t)); + slot = shift - pool->min_shift; + + page->next = slots[slot].next; + slots[slot].next = page; + + page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_SMALL; + page->next->prev = (uintptr_t) page | NGX_SLAB_SMALL; + } + + bitmap[n] &= ~m; + + n = (1 << (ngx_pagesize_shift - shift)) / 8 / (1 << shift); + + if (n == 0) { + n = 1; + } + + if (bitmap[0] & ~((1 << n) - 1)) { + goto done; + } + + map = (1 << (ngx_pagesize_shift - shift)) / (sizeof(uintptr_t) * 8); + + for (n = 1; n < map; n++) { + if (bitmap[n]) { + goto done; + } + } + + ngx_slab_free_pages(pool, page, 1); + + goto done; + } + + goto chunk_already_free; + + case NGX_SLAB_EXACT: + + m = 1 << (((uintptr_t) p & (ngx_pagesize - 1)) >> ngx_slab_exact_shift); + size = ngx_slab_exact_size; + + if ((uintptr_t) p & (size - 1)) { + goto wrong_chunk; + } + + if (slab & m) { + if (slab == NGX_SLAB_BUSY) { + slots = (ngx_slab_page_t *) + ((u_char *) pool + sizeof(ngx_slab_pool_t)); + slot = ngx_slab_exact_shift - pool->min_shift; + + page->next = slots[slot].next; + slots[slot].next = page; + + page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_EXACT; + page->next->prev = (uintptr_t) page | NGX_SLAB_EXACT; + } + + page->slab &= ~m; + + if (page->slab) { + goto done; + } + + ngx_slab_free_pages(pool, page, 1); + + goto done; + } + + goto chunk_already_free; + + case NGX_SLAB_BIG: + + shift = slab & NGX_SLAB_SHIFT_MASK; + size = 1 << shift; + + if ((uintptr_t) p & (size - 1)) { + goto wrong_chunk; + } + + m = 1 << ((((uintptr_t) p & (ngx_pagesize - 1)) >> shift) + + NGX_SLAB_MAP_SHIFT); + + if (slab & m) { + + if (page->next == NULL) { + slots = (ngx_slab_page_t *) + ((u_char *) pool + sizeof(ngx_slab_pool_t)); + slot = shift - pool->min_shift; + + page->next = slots[slot].next; + slots[slot].next = page; + + page->prev = (uintptr_t) &slots[slot] | NGX_SLAB_BIG; + page->next->prev = (uintptr_t) page | NGX_SLAB_BIG; + } + + page->slab &= ~m; + + if (page->slab & NGX_SLAB_MAP_MASK) { + goto done; + } + + ngx_slab_free_pages(pool, page, 1); + + goto done; + } + + goto chunk_already_free; + + case NGX_SLAB_PAGE: + + if ((uintptr_t) p & (ngx_pagesize - 1)) { + goto wrong_chunk; + } + + if (slab == NGX_SLAB_PAGE_FREE) { + ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0, + "ngx_slab_free(): page is already free"); + goto fail; + } + + if (slab == NGX_SLAB_PAGE_BUSY) { + ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0, + "ngx_slab_free(): pointer to wrong page"); + goto fail; + } + + n = ((u_char *) p - pool->start) >> ngx_pagesize_shift; + size = slab & ~NGX_SLAB_PAGE_START; + + ngx_slab_free_pages(pool, &pool->pages[n], size); + + size <<= ngx_pagesize_shift; + + goto done; + } + + /* not reached */ + + return; + +done: + + ngx_slab_junk(p, size); + + ngx_shmtx_unlock(&pool->mutex); + + return; + +wrong_chunk: + + ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0, + "ngx_slab_free(): pointer to wrong chunk"); + + goto fail; + +chunk_already_free: + + ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0, + "ngx_slab_free(): chunk is already free"); + +fail: + + ngx_shmtx_unlock(&pool->mutex); + + return; +} + + +static ngx_slab_page_t * +ngx_slab_alloc_pages(ngx_slab_pool_t *pool, ngx_uint_t pages) +{ + ngx_slab_page_t *page, *p; + + for (page = pool->free.next; page != &pool->free; page = page->next) { + + if (page->slab >= pages) { + + if (page->slab > pages) { + page[pages].slab = page->slab - pages; + page[pages].next = page->next; + page[pages].prev = page->prev; + + p = (ngx_slab_page_t *) page->prev; + p->next = &page[pages]; + page->next->prev = (uintptr_t) &page[pages]; + + } else { + p = (ngx_slab_page_t *) page->prev; + p->next = page->next; + page->next->prev = page->prev; + } + + page->slab = pages | NGX_SLAB_PAGE_START; + +#if (NGX_DEBUG) + page->next = NULL; + page->prev = NGX_SLAB_PAGE; +#endif + + if (--pages == 0) { + return page; + } + + for (p = page + 1; pages; pages--) { + p->slab = NGX_SLAB_PAGE_BUSY; +#if (NGX_DEBUG) + p->next = NULL; + p->prev = NGX_SLAB_PAGE; +#endif + p++; + } + + return page; + } + } + + ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, NGX_ENOMEM, + "ngx_slab_alloc(): failed"); + return NULL; +} + + +static void +ngx_slab_free_pages(ngx_slab_pool_t *pool, ngx_slab_page_t *page, + ngx_uint_t pages) +{ + ngx_slab_page_t *prev; + + page->slab = pages--; + + if (pages) { + ngx_memzero(&page[1], pages * sizeof(ngx_slab_page_t)); + } + + prev = (ngx_slab_page_t *) (page->prev & ~NGX_SLAB_PAGE_MASK); + prev->next = page->next; + + page->next = pool->free.next; + pool->free.next = page; + + page->prev = page->next->prev; + page->next->prev = (uintptr_t) page; +} |