Mercurial > hg > nginx-quic
view src/core/ngx_rbtree.c @ 4311:45272aab5eea
Unlock of shared memory zones on process crash.
If process exited abnormally while holding lock on some shared memory zone -
unlock it. It may be not safe thing to do (as crash with lock held may
result in corrupted shared memory structure, and other processes will
subsequently crash while trying to access shared data), therefore complain
loudly if unlock succeeds.
author | Maxim Dounin <mdounin@mdounin.ru> |
---|---|
date | Wed, 23 Nov 2011 14:09:19 +0000 |
parents | bead8ca82404 |
children | d620f497c50f |
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/* * Copyright (C) Igor Sysoev */ #include <ngx_config.h> #include <ngx_core.h> /* * The red-black tree code is based on the algorithm described in * the "Introduction to Algorithms" by Cormen, Leiserson and Rivest. */ static ngx_inline void ngx_rbtree_left_rotate(ngx_rbtree_node_t **root, ngx_rbtree_node_t *sentinel, ngx_rbtree_node_t *node); static ngx_inline void ngx_rbtree_right_rotate(ngx_rbtree_node_t **root, ngx_rbtree_node_t *sentinel, ngx_rbtree_node_t *node); void ngx_rbtree_insert(ngx_thread_volatile ngx_rbtree_t *tree, ngx_rbtree_node_t *node) { ngx_rbtree_node_t **root, *temp, *sentinel; /* a binary tree insert */ root = (ngx_rbtree_node_t **) &tree->root; sentinel = tree->sentinel; if (*root == sentinel) { node->parent = NULL; node->left = sentinel; node->right = sentinel; ngx_rbt_black(node); *root = node; return; } tree->insert(*root, node, sentinel); /* re-balance tree */ while (node != *root && ngx_rbt_is_red(node->parent)) { if (node->parent == node->parent->parent->left) { temp = node->parent->parent->right; if (ngx_rbt_is_red(temp)) { ngx_rbt_black(node->parent); ngx_rbt_black(temp); ngx_rbt_red(node->parent->parent); node = node->parent->parent; } else { if (node == node->parent->right) { node = node->parent; ngx_rbtree_left_rotate(root, sentinel, node); } ngx_rbt_black(node->parent); ngx_rbt_red(node->parent->parent); ngx_rbtree_right_rotate(root, sentinel, node->parent->parent); } } else { temp = node->parent->parent->left; if (ngx_rbt_is_red(temp)) { ngx_rbt_black(node->parent); ngx_rbt_black(temp); ngx_rbt_red(node->parent->parent); node = node->parent->parent; } else { if (node == node->parent->left) { node = node->parent; ngx_rbtree_right_rotate(root, sentinel, node); } ngx_rbt_black(node->parent); ngx_rbt_red(node->parent->parent); ngx_rbtree_left_rotate(root, sentinel, node->parent->parent); } } } ngx_rbt_black(*root); } void ngx_rbtree_insert_value(ngx_rbtree_node_t *temp, ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel) { ngx_rbtree_node_t **p; for ( ;; ) { p = (node->key < temp->key) ? &temp->left : &temp->right; if (*p == sentinel) { break; } temp = *p; } *p = node; node->parent = temp; node->left = sentinel; node->right = sentinel; ngx_rbt_red(node); } void ngx_rbtree_insert_timer_value(ngx_rbtree_node_t *temp, ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel) { ngx_rbtree_node_t **p; for ( ;; ) { /* * Timer values * 1) are spread in small range, usually several minutes, * 2) and overflow each 49 days, if milliseconds are stored in 32 bits. * The comparison takes into account that overflow. */ /* node->key < temp->key */ p = ((ngx_rbtree_key_int_t) node->key - (ngx_rbtree_key_int_t) temp->key < 0) ? &temp->left : &temp->right; if (*p == sentinel) { break; } temp = *p; } *p = node; node->parent = temp; node->left = sentinel; node->right = sentinel; ngx_rbt_red(node); } void ngx_rbtree_delete(ngx_thread_volatile ngx_rbtree_t *tree, ngx_rbtree_node_t *node) { ngx_uint_t red; ngx_rbtree_node_t **root, *sentinel, *subst, *temp, *w; /* a binary tree delete */ root = (ngx_rbtree_node_t **) &tree->root; sentinel = tree->sentinel; if (node->left == sentinel) { temp = node->right; subst = node; } else if (node->right == sentinel) { temp = node->left; subst = node; } else { subst = ngx_rbtree_min(node->right, sentinel); if (subst->left != sentinel) { temp = subst->left; } else { temp = subst->right; } } if (subst == *root) { *root = temp; ngx_rbt_black(temp); /* DEBUG stuff */ node->left = NULL; node->right = NULL; node->parent = NULL; node->key = 0; return; } red = ngx_rbt_is_red(subst); if (subst == subst->parent->left) { subst->parent->left = temp; } else { subst->parent->right = temp; } if (subst == node) { temp->parent = subst->parent; } else { if (subst->parent == node) { temp->parent = subst; } else { temp->parent = subst->parent; } subst->left = node->left; subst->right = node->right; subst->parent = node->parent; ngx_rbt_copy_color(subst, node); if (node == *root) { *root = subst; } else { if (node == node->parent->left) { node->parent->left = subst; } else { node->parent->right = subst; } } if (subst->left != sentinel) { subst->left->parent = subst; } if (subst->right != sentinel) { subst->right->parent = subst; } } /* DEBUG stuff */ node->left = NULL; node->right = NULL; node->parent = NULL; node->key = 0; if (red) { return; } /* a delete fixup */ while (temp != *root && ngx_rbt_is_black(temp)) { if (temp == temp->parent->left) { w = temp->parent->right; if (ngx_rbt_is_red(w)) { ngx_rbt_black(w); ngx_rbt_red(temp->parent); ngx_rbtree_left_rotate(root, sentinel, temp->parent); w = temp->parent->right; } if (ngx_rbt_is_black(w->left) && ngx_rbt_is_black(w->right)) { ngx_rbt_red(w); temp = temp->parent; } else { if (ngx_rbt_is_black(w->right)) { ngx_rbt_black(w->left); ngx_rbt_red(w); ngx_rbtree_right_rotate(root, sentinel, w); w = temp->parent->right; } ngx_rbt_copy_color(w, temp->parent); ngx_rbt_black(temp->parent); ngx_rbt_black(w->right); ngx_rbtree_left_rotate(root, sentinel, temp->parent); temp = *root; } } else { w = temp->parent->left; if (ngx_rbt_is_red(w)) { ngx_rbt_black(w); ngx_rbt_red(temp->parent); ngx_rbtree_right_rotate(root, sentinel, temp->parent); w = temp->parent->left; } if (ngx_rbt_is_black(w->left) && ngx_rbt_is_black(w->right)) { ngx_rbt_red(w); temp = temp->parent; } else { if (ngx_rbt_is_black(w->left)) { ngx_rbt_black(w->right); ngx_rbt_red(w); ngx_rbtree_left_rotate(root, sentinel, w); w = temp->parent->left; } ngx_rbt_copy_color(w, temp->parent); ngx_rbt_black(temp->parent); ngx_rbt_black(w->left); ngx_rbtree_right_rotate(root, sentinel, temp->parent); temp = *root; } } } ngx_rbt_black(temp); } static ngx_inline void ngx_rbtree_left_rotate(ngx_rbtree_node_t **root, ngx_rbtree_node_t *sentinel, ngx_rbtree_node_t *node) { ngx_rbtree_node_t *temp; temp = node->right; node->right = temp->left; if (temp->left != sentinel) { temp->left->parent = node; } temp->parent = node->parent; if (node == *root) { *root = temp; } else if (node == node->parent->left) { node->parent->left = temp; } else { node->parent->right = temp; } temp->left = node; node->parent = temp; } static ngx_inline void ngx_rbtree_right_rotate(ngx_rbtree_node_t **root, ngx_rbtree_node_t *sentinel, ngx_rbtree_node_t *node) { ngx_rbtree_node_t *temp; temp = node->left; node->left = temp->right; if (temp->right != sentinel) { temp->right->parent = node; } temp->parent = node->parent; if (node == *root) { *root = temp; } else if (node == node->parent->right) { node->parent->right = temp; } else { node->parent->left = temp; } temp->right = node; node->parent = temp; }