Mercurial > hg > nginx
view src/core/ngx_radix_tree.c @ 4309:3f6040cd731e
Added shmtx interface to forcibly unlock mutexes.
It is currently used from master process on abnormal worker termination to
unlock accept mutex (unlocking of accept mutex was broken in 1.0.2). It is
expected to be used in the future to unlock other mutexes as well.
Shared mutex code was rewritten to make this possible in a safe way, i.e.
with a check if lock was actually held by the exited process. We again use
pid to lock mutex, and use separate atomic variable for a count of processes
waiting in sem_wait().
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Wed, 23 Nov 2011 13:55:38 +0000 |
parents | 3aa4fd0e7dc5 |
children | 62be1c4edfba d620f497c50f |
line wrap: on
line source
/* * Copyright (C) Igor Sysoev */ #include <ngx_config.h> #include <ngx_core.h> static void *ngx_radix_alloc(ngx_radix_tree_t *tree); ngx_radix_tree_t * ngx_radix_tree_create(ngx_pool_t *pool, ngx_int_t preallocate) { uint32_t key, mask, inc; ngx_radix_tree_t *tree; tree = ngx_palloc(pool, sizeof(ngx_radix_tree_t)); if (tree == NULL) { return NULL; } tree->pool = pool; tree->free = NULL; tree->start = NULL; tree->size = 0; tree->root = ngx_radix_alloc(tree); if (tree->root == NULL) { return NULL; } tree->root->right = NULL; tree->root->left = NULL; tree->root->parent = NULL; tree->root->value = NGX_RADIX_NO_VALUE; if (preallocate == 0) { return tree; } /* * Preallocation of first nodes : 0, 1, 00, 01, 10, 11, 000, 001, etc. * increases TLB hits even if for first lookup iterations. * On 32-bit platforms the 7 preallocated bits takes continuous 4K, * 8 - 8K, 9 - 16K, etc. On 64-bit platforms the 6 preallocated bits * takes continuous 4K, 7 - 8K, 8 - 16K, etc. There is no sense to * to preallocate more than one page, because further preallocation * distributes the only bit per page. Instead, a random insertion * may distribute several bits per page. * * Thus, by default we preallocate maximum * 6 bits on amd64 (64-bit platform and 4K pages) * 7 bits on i386 (32-bit platform and 4K pages) * 7 bits on sparc64 in 64-bit mode (8K pages) * 8 bits on sparc64 in 32-bit mode (8K pages) */ if (preallocate == -1) { switch (ngx_pagesize / sizeof(ngx_radix_tree_t)) { /* amd64 */ case 128: preallocate = 6; break; /* i386, sparc64 */ case 256: preallocate = 7; break; /* sparc64 in 32-bit mode */ default: preallocate = 8; } } mask = 0; inc = 0x80000000; while (preallocate--) { key = 0; mask >>= 1; mask |= 0x80000000; do { if (ngx_radix32tree_insert(tree, key, mask, NGX_RADIX_NO_VALUE) != NGX_OK) { return NULL; } key += inc; } while (key); inc >>= 1; } return tree; } ngx_int_t ngx_radix32tree_insert(ngx_radix_tree_t *tree, uint32_t key, uint32_t mask, uintptr_t value) { uint32_t bit; ngx_radix_node_t *node, *next; bit = 0x80000000; node = tree->root; next = tree->root; while (bit & mask) { if (key & bit) { next = node->right; } else { next = node->left; } if (next == NULL) { break; } bit >>= 1; node = next; } if (next) { if (node->value != NGX_RADIX_NO_VALUE) { return NGX_BUSY; } node->value = value; return NGX_OK; } while (bit & mask) { next = ngx_radix_alloc(tree); if (next == NULL) { return NGX_ERROR; } next->right = NULL; next->left = NULL; next->parent = node; next->value = NGX_RADIX_NO_VALUE; if (key & bit) { node->right = next; } else { node->left = next; } bit >>= 1; node = next; } node->value = value; return NGX_OK; } ngx_int_t ngx_radix32tree_delete(ngx_radix_tree_t *tree, uint32_t key, uint32_t mask) { uint32_t bit; ngx_radix_node_t *node; bit = 0x80000000; node = tree->root; while (node && (bit & mask)) { if (key & bit) { node = node->right; } else { node = node->left; } bit >>= 1; } if (node == NULL) { return NGX_ERROR; } if (node->right || node->left) { if (node->value != NGX_RADIX_NO_VALUE) { node->value = NGX_RADIX_NO_VALUE; return NGX_OK; } return NGX_ERROR; } for ( ;; ) { if (node->parent->right == node) { node->parent->right = NULL; } else { node->parent->left = NULL; } node->right = tree->free; tree->free = node; node = node->parent; if (node->right || node->left) { break; } if (node->value != NGX_RADIX_NO_VALUE) { break; } if (node->parent == NULL) { break; } } return NGX_OK; } uintptr_t ngx_radix32tree_find(ngx_radix_tree_t *tree, uint32_t key) { uint32_t bit; uintptr_t value; ngx_radix_node_t *node; bit = 0x80000000; value = NGX_RADIX_NO_VALUE; node = tree->root; while (node) { if (node->value != NGX_RADIX_NO_VALUE) { value = node->value; } if (key & bit) { node = node->right; } else { node = node->left; } bit >>= 1; } return value; } static void * ngx_radix_alloc(ngx_radix_tree_t *tree) { char *p; if (tree->free) { p = (char *) tree->free; tree->free = tree->free->right; return p; } if (tree->size < sizeof(ngx_radix_node_t)) { tree->start = ngx_pmemalign(tree->pool, ngx_pagesize, ngx_pagesize); if (tree->start == NULL) { return NULL; } tree->size = ngx_pagesize; } p = tree->start; tree->start += sizeof(ngx_radix_node_t); tree->size -= sizeof(ngx_radix_node_t); return p; }