在nginx中,定时器是由红黑树来实现的。
有以下几个定时器的接口
init_timer
初始化定时器(初始化红黑树)
add_timer
添加定时器(红黑树左侧时间小,右侧时间大。当时间出现重复的时候,插入右侧)
del_timer
删除定时器
find_nearest_expire_timer
查找时间最近的定时器(红黑树中最左侧的节点)
expire_timer
到期的定时器(执行定时事件,并删除红黑树中对应的节点)
一、nignx中的定时器
rbt-timer.h
#ifndef _MARK_RBT_ #define _MARK_RBT_ #include <stdio.h> #include <stdint.h> // 整数 #include <unistd.h> // usleep #include <stdlib.h> // malloc 注意需要强转 #include <stddef.h> //offsetof #if defined(__APPLE__) #include <AvailabilityMacros.h> #include <sys/time.h> #include <mach/task.h> #include <mach/mach.h> #else #include <time.h> #endif #include "rbtree.h" ngx_rbtree_t timer; static ngx_rbtree_node_t sentinel;//哨兵节点 typedef struct timer_entry_s timer_entry_t; typedef void (*timer_handler_pt)(timer_entry_t *ev); struct timer_entry_s { ngx_rbtree_node_t rbnode; timer_handler_pt handler; }; static uint32_t current_time() { uint32_t t; #if !defined(__APPLE__) || defined(AVAILABLE_MAC_OS_X_VERSION_10_12_AND_LATER) struct timespec ti; clock_gettime(CLOCK_MONOTONIC, &ti); t = (uint32_t)ti.tv_sec * 1000; t += ti.tv_nsec / 1000000; #else struct timeval tv; gettimeofday(&tv, NULL); t = (uint32_t)tv.tv_sec * 1000; t += tv.tv_usec / 1000; #endif return t; } //初始化定时器(初始化红黑树) ngx_rbtree_t * init_timer() { ngx_rbtree_init(&timer, &sentinel, ngx_rbtree_insert_timer_value); return &timer; } //添加定时器(参数1:时间间隔 参数2:事件函数) void add_timer(uint32_t msec, timer_handler_pt func) { timer_entry_t *te = malloc(sizeof(timer_entry_t)); memset(te, 0, sizeof(timer_entry_t)); te->handler = func; msec += current_time(); printf("add_timer expire at msec = %u\n", msec); te->rbnode.key = msec;//把时间作为红黑树的key ngx_rbtree_insert(&timer, &te->rbnode);//rbtree中插入节点 } //删除定时器(删除红黑树节点) void del_timer(timer_entry_t *te) { ngx_rbtree_delete(&timer, &te->rbnode); free(te); } //找到时间最近的定时器(二叉树最左侧的节点) int find_nearest_expire_timer() { ngx_rbtree_node_t *node; if (timer.root == &sentinel) {//没有定时任务(如果红黑树根节点为哨兵节点,说明红黑树是空的,没有定时任务) return -1; } node = ngx_rbtree_min(timer.root, timer.sentinel); int diff = (int)node->key - (int)current_time();//时间差(事件还要等待多久,传给epoll_wait最后那个参数) return diff > 0 ? diff : 0; } void expire_timer() { timer_entry_t *te; ngx_rbtree_node_t *sentinel, *root, *node; sentinel = timer.sentinel; uint32_t now = current_time(); for (;;) { root = timer.root; if (root == sentinel) break;//空的红黑树,直接退出 node = ngx_rbtree_min(root, sentinel); if (node->key > now) break;//当前红黑树节点的时间大于当前时间,说明事件还没触发,直接退出 printf("touch timer expire time=%u, now = %u\n", node->key, now); te = (timer_entry_t *) ((char *) node - offsetof(timer_entry_t, rbnode));//将红黑树节点转化为该node的定时器事件 te->handler(te);//事件触发,直接调用事件函数 ngx_rbtree_delete(&timer, &te->rbnode); //删除红黑树节点 free(te); } } #endif
二、nignx中定时器测试
rbt-timer.c
#include <stdio.h> #include <string.h> #include <sys/epoll.h> #include "rbt-timer.h" void hello_world(timer_entry_t *te) { printf("hello world time = %u\n", te->rbnode.key); } int main() { init_timer(); add_timer(3000, hello_world); int epfd = epoll_create(1); struct epoll_event events[512]; for (;;) { int nearest = find_nearest_expire_timer(); int n = epoll_wait(epfd, events, 512, nearest); for (int i=0; i < n; i++) { // } expire_timer(); } return 0; }
通过rbt-timer.h、rbt-timer.c、以及附件中的rbtree.h、rbtree.c可以直接编译运行测试
三、附件
rbtree.h
/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #ifndef _NGX_RBTREE_H_INCLUDED_ #define _NGX_RBTREE_H_INCLUDED_ typedef unsigned int ngx_rbtree_key_t; typedef unsigned int ngx_uint_t; typedef int ngx_rbtree_key_int_t; typedef unsigned char u_char; #ifndef NULL #define NULL ((void*)0) #endif typedef struct ngx_rbtree_node_s ngx_rbtree_node_t; struct ngx_rbtree_node_s { ngx_rbtree_key_t key; ngx_rbtree_node_t *left; ngx_rbtree_node_t *right; ngx_rbtree_node_t *parent; u_char color; u_char data; }; typedef struct ngx_rbtree_s ngx_rbtree_t; typedef void (*ngx_rbtree_insert_pt) (ngx_rbtree_node_t *root, ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel); struct ngx_rbtree_s { ngx_rbtree_node_t *root; ngx_rbtree_node_t *sentinel; ngx_rbtree_insert_pt insert; }; #define ngx_rbtree_init(tree, s, i) \ ngx_rbtree_sentinel_init(s); \ (tree)->root = s; \ (tree)->sentinel = s; \ (tree)->insert = i void ngx_rbtree_insert(ngx_rbtree_t *tree, ngx_rbtree_node_t *node); void ngx_rbtree_delete(ngx_rbtree_t *tree, ngx_rbtree_node_t *node); void ngx_rbtree_insert_value(ngx_rbtree_node_t *root, ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel); void ngx_rbtree_insert_timer_value(ngx_rbtree_node_t *root, ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel); ngx_rbtree_node_t * ngx_rbtree_next(ngx_rbtree_t *tree, ngx_rbtree_node_t *node); #define ngx_rbt_red(node) ((node)->color = 1) #define ngx_rbt_black(node) ((node)->color = 0) #define ngx_rbt_is_red(node) ((node)->color) #define ngx_rbt_is_black(node) (!ngx_rbt_is_red(node)) #define ngx_rbt_copy_color(n1, n2) (n1->color = n2->color) /* a sentinel must be black */ #define ngx_rbtree_sentinel_init(node) ngx_rbt_black(node) static ngx_rbtree_node_t * ngx_rbtree_min(ngx_rbtree_node_t *node, ngx_rbtree_node_t *sentinel) { while (node->left != sentinel) { node = node->left; } return node; } #endif /* _NGX_RBTREE_H_INCLUDED_ */
rbtree.c
/* * Copyright (C) Igor Sysoev * Copyright (C) Nginx, Inc. */ #include "rbtree.h" /* * The red-black tree code is based on the algorithm described in * the "Introduction to Algorithms" by Cormen, Leiserson and Rivest. */ static inline void ngx_rbtree_left_rotate(ngx_rbtree_node_t **root, ngx_rbtree_node_t *sentinel, ngx_rbtree_node_t *node); static 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_rbtree_t *tree, ngx_rbtree_node_t *node) { ngx_rbtree_node_t **root, *temp, *sentinel; /* a binary tree insert */ root = &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 */ //node 是要插入的节点,temp是树的节点,如果相等,就插入到右边.(也就是说,如果定时器的时间相等的话,定时事件后加入的就后触发) p = ((ngx_rbtree_key_int_t) (node->key - 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_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 = &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 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 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; } ngx_rbtree_node_t * ngx_rbtree_next(ngx_rbtree_t *tree, ngx_rbtree_node_t *node) { ngx_rbtree_node_t *root, *sentinel, *parent; sentinel = tree->sentinel; if (node->right != sentinel) { return ngx_rbtree_min(node->right, sentinel); } root = tree->root; for ( ;; ) { parent = node->parent; if (node == root) { return NULL; } if (node == parent->left) { return parent; } node = parent; } }