Nginx之连接的建立
Posted 季末的天堂
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了Nginx之连接的建立相关的知识,希望对你有一定的参考价值。
1. 函数调用分析
在开启 master 的情况下,多进程模型的下的入口函数为 ngx_master_process_cycle,如下:
int mian()
{
...
if (ngx_process == NGX_PROCESS_SINGLE)
{
/* 单进程模型下的入口函数 */
ngx_single_process_cycle(cycle);
}
else
{
/* 多进程模型下的入口函数 */
ngx_master_process_cycle(cycle);
}
return 0;
}
1.1 ngx_master_process_cycle:
static ngx_cycle_t ngx_exit_cycle;
static ngx_log_t ngx_exit_log;
static ngx_open_file_t ngx_exit_log_file;
/*
* 参数意义:
* - cycle是当前进程ngx_cycle_t的结构体指针
*
* 执行意义:
* 进入master进程的工作循环
*/
void ngx_master_process_cycle(ngx_cycle_t *cycle)
{
char *title;
u_char *p;
size_t size;
ngx_int_t i;
ngx_uint_t n, sigio;
sigset_t set;
struct itimerval itv;
ngx_uint_t live;
ngx_msec_t delay;
ngx_listening_t *ls;
ngx_core_conf_t *ccf;
/* 将下列信号添加到 set 信号集中 */
sigemptyset(&set);
sigaddset(&set, SIGCHLD);
sigaddset(&set, SIGALRM);
sigaddset(&set, SIGIO);
sigaddset(&set, SIGINT);
sigaddset(&set, ngx_signal_value(NGX_RECONFIGURE_SIGNAL));
sigaddset(&set, ngx_signal_value(NGX_REOPEN_SIGNAL));
sigaddset(&set, ngx_signal_value(NGX_NOACCEPT_SIGNAL));
sigaddset(&set, ngx_signal_value(NGX_TERMINATE_SIGNAL));
sigaddset(&set, ngx_signal_value(NGX_SHUTDOWN_SIGNAL));
sigaddset(&set, ngx_signal_value(NGX_CHANGEBIN_SIGNAL));
/*
* sigprocmask(int how, const sigset_t *set, sigset_t *oldset);
* 函数既可以修改进程的信号掩码,又可获取现有掩码,或者两者皆可。
* - SIG_BLOCK:将set指向信号集内的指定信号添加到信号掩码中。换言之,将信号掩码
* 设置为其当前值和set的并集。
* - SIG_UNBLOCK:将set指向信号集中的指定信号从信号掩码中移除。即使要接触阻塞的信号当前
* 并未处于阻塞状态,也不会返回错误。
* - SIG_SETMASK:将set指向的信号集赋给信号掩码。
*/
/* 临时阻塞上面所示信号,防止其信号处理器将某些关键代码片段的执行中断,然后下面调用
* sigsuspend()解除对信号的阻塞,然后暂停执行,直至有信号到达. */
if (sigprocmask(SIG_BLOCK, &set, NULL) == -1) {
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"sigprocmask() failed");
}
sigemptyset(&set);
size = sizeof(master_process);
for (i = 0; i < ngx_argc; i++) {
size += ngx_strlen(ngx_argv[i]) + 1;
}
title = ngx_pnalloc(cycle->pool, size);
if (title == NULL) {
/* fatal */
exit(2);
}
p = ngx_cpymem(title, master_process, sizeof(master_process) - 1);
for (i = 0; i < ngx_argc; i++) {
*p++ = ‘ ‘;
p = ngx_cpystrn(p, (u_char *) ngx_argv[i], size);
}
/* 设置监控进程的名字 */
ngx_setproctitle(title);
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);
/* 该函数用于fork()产生子进程,该函数的主体是一个无限for( ;; )循环,持续不断地处理
* 客户端的服务请求,而主进程继续执行ngx_master_process_cycle()函数,也就是作为监控
* 进程执行主体for(;;)循环,这也是一个无限循环,直到进程终止才退出. */
ngx_start_worker_processes(cycle, ccf->worker_processes,
NGX_PROCESS_RESPAWN);
ngx_start_cache_manager_processes(cycle, 0);
ngx_new_binary = 0;
delay = 0;
sigio = 0;
live = 1;
for ( ;; ) {
if (delay) {
if (ngx_sigalrm) {
sigio = 0;
delay *= 2;
ngx_sigalrm = 0;
}
ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
"termination cycle: %M", delay);
itv.it_interval.tv_sec = 0;
itv.it_interval.tv_usec = 0;
itv.it_value.tv_sec = delay / 1000;
itv.it_value.tv_usec = (delay % 1000 ) * 1000;
if (setitimer(ITIMER_REAL, &itv, NULL) == -1) {
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"setitimer() failed");
}
}
ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "sigsuspend");
/*
* sigsuspend(const sigset_t *mask);
* 该函数将以mask所指向的信号集来替换进程的信号掩码,然后挂起进程的执行,
* 直到其捕获到信号,并从信号处理器中返回。一旦处理器返回,sigsuspend()
* 会将进程信号掩码恢复为调用前的值。
*/
/* 该函数使得监控进程的大部分时间都处于挂起等待状态,直到监控进程接收到信号为止。
* 当监控进程接收到信号时,信号处理函数ngx_signal_handler()就会被执行。*/
sigsuspend(&set);
ngx_time_update();
ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
"wake up, sigio %i", sigio);
/* 有子进程退出? */
if (ngx_reap) {
ngx_reap = 0;
ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "reap children");
live = ngx_reap_children(cycle);
}
/* 进程要退出或终止? */
if (!live && (ngx_terminate || ngx_quit)) {
ngx_master_process_exit(cycle);
}
/* 进程要终止?
* 结束比较粗暴,不过它通过使用SIGKILL信号能保证在一段
* 时间后必定被结束掉. */
if (ngx_terminate) {
if (delay == 0) {
delay = 50;
}
if (sigio) {
sigio--;
continue;
}
sigio = ccf->worker_processes + 2 /* cache processes */;
if (delay > 1000) {
ngx_signal_worker_processes(cycle, SIGKILL);
} else {
ngx_signal_worker_processes(cycle,
ngx_signal_value(NGX_TERMINATE_SIGNAL));
}
continue;
}
/* 进程要退出?
* 该结束比较优雅,会让nginx监控进程做一些清理工作且等待
* 子进程也完全清理并退出之后才终止. */
if (ngx_quit) {
ngx_signal_worker_processes(cycle,
ngx_signal_value(NGX_SHUTDOWN_SIGNAL));
ls = cycle->listening.elts;
for (n = 0; n < cycle->listening.nelts; n++) {
if (ngx_close_socket(ls[n].fd) == -1) {
ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_socket_errno,
ngx_close_socket_n " %V failed",
&ls[n].addr_text);
}
}
cycle->listening.nelts = 0;
continue;
}
/* 重新加载配置? */
if (ngx_reconfigure) {
ngx_reconfigure = 0;
if (ngx_new_binary) {
ngx_start_worker_processes(cycle, ccf->worker_processes,
NGX_PROCESS_RESPAWN);
ngx_start_cache_manager_processes(cycle, 0);
ngx_noaccepting = 0;
continue;
}
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "reconfiguring");
cycle = ngx_init_cycle(cycle);
if (cycle == NULL) {
cycle = (ngx_cycle_t *) ngx_cycle;
continue;
}
ngx_cycle = cycle;
ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx,
ngx_core_module);
ngx_start_worker_processes(cycle, ccf->worker_processes,
NGX_PROCESS_JUST_RESPAWN);
ngx_start_cache_manager_processes(cycle, 1);
/* allow new processes to start */
ngx_msleep(100);
live = 1;
ngx_signal_worker_processes(cycle,
ngx_signal_value(NGX_SHUTDOWN_SIGNAL));
}
if (ngx_restart) {
ngx_restart = 0;
ngx_start_worker_processes(cycle, ccf->worker_processes,
NGX_PROCESS_RESPAWN);
ngx_start_cache_manager_processes(cycle, 0);
live = 1;
}
if (ngx_reopen) {
ngx_reopen = 0;
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "reopening logs");
ngx_reopen_files(cycle, ccf->user);
ngx_signal_worker_processes(cycle,
ngx_signal_value(NGX_REOPEN_SIGNAL));
}
if (ngx_change_binary) {
ngx_change_binary = 0;
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "changing binary");
ngx_new_binary = ngx_exec_new_binary(cycle, ngx_argv);
}
if (ngx_noaccept) {
ngx_noaccept = 0;
ngx_noaccepting = 1;
ngx_signal_worker_processes(cycle,
ngx_signal_value(NGX_SHUTDOWN_SIGNAL));
}
}
}
1.2 ngx_start_worker_processes
/*
* 参数含义:
* - cycle: 是当前进程的ngx_cycle_t结构体指针
* - n: 是启动子进程的个数
* - type: 是启动方式,取值范围有以下5个:
* - NGX_PROCESS_RESPAWN
* - NGX_PROCESS_NORESPAWN
* - NGX_PROCESS_JUST_SPAWN
* - NGX_PROCESS_JUST_RESPAWN
* - NGX_PROCESS_DETACHED
* type的值将会影响ngx_process_t结构体的respawn、detached、just_spawn标志位的值.
*
* 执行意义:
* 启动n个worker子进程,并设置好每个子进程与master父进程之间使用socketpair系统调用
* 建立起来的socket句柄通信机制.
*/
static void ngx_start_worker_processes(ngx_cycle_t *cycle, ngx_int_t n, ngx_int_t type)
{
ngx_int_t i;
ngx_channel_t ch;
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "start worker processes");
ngx_memzero(&ch, sizeof(ngx_channel_t));
ch.command = NGX_CMD_OPEN_CHANNEL;
for (i = 0; i < n; i++) {
ngx_spawn_process(cycle, ngx_worker_process_cycle,
(void *) (intptr_t) i, "worker process", type);
ch.pid = ngx_processes[ngx_process_slot].pid; // 子进程的id号
ch.slot = ngx_process_slot; // 子进程的相关信息在全局数组ngx_processes中的下标
// 父进程使用的socket描述符
ch.fd = ngx_processes[ngx_process_slot].channel[0];
/* 父进程fork()生成一个新子进程后,就会立即调用该函数ngx_pass_open_channel()
* 把这个子进程的相关信息告知给其前面已生成的子进程. */
ngx_pass_open_channel(cycle, &ch);
}
}
1.3 ngx_spawn_process
ngx_pid_t ngx_spawn_process(ngx_cycle_t *cycle, ngx_spawn_proc_pt proc, void *data,
char *name, ngx_int_t respawn)
{
u_long on;
ngx_pid_t pid;
ngx_int_t s;
if (respawn >= 0)
{
s = respawn;
}
else
{
/* 遍历所有存活的子进程,找到一个空闲的下标值 */
for (s = 0; s < ngx_last_process; s++)
{
if (ngx_processes[s].pid == -1)
{
break;
}
}
if (s == NGX_MAX_PROCESSES)
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, 0,
"no more than %d processes can be spawned",
NGX_MAX_PROCESSES);
return NGX_INVALID_PID;
}
}
if (respawn != NGX_PROCESS_DETACHED)
{
/* Solaris 9 still has no AF_LOCAL */
/* 采用socketpair()函数创造一对未命名的UNIX域套接字来进行Linux下具有
* 亲缘关系的进程之间的双向通信. */
/*
* 在fork()之前,先调用了socketpair()创建了一对socket描述符存放在变量
* ngx_processes[s].channel内(其中s标志在ngx_processes数组内第一个可用
* 元素的下标,比如最开始产生第一个工作进程时,可用元素的下标s为0),而
* 在fork()之后,由于子进程继承了父进程的资源,那么父子进程就都有了这一对
* socket描述符,而Nginx将channel[0]给父进程使用,channel[1]给子进程使用,
* 这样分别错开地使用不同socket描述符,即可以实现父子进程之间的双向通信.
*/
if (socketpair(AF_UNIX, SOCK_STREAM, 0, ngx_processes[s].channel) == -1)
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"socketpair() failed while spawning \"%s\"", name);
return NGX_INVALID_PID;
}
ngx_log_debug2(NGX_LOG_DEBUG_CORE, cycle->log, 0,
"channel: master socket:%d, worker socket:%d",
ngx_processes[s].channel[0],
ngx_processes[s].channel[1]);
if (ngx_nonblocking(ngx_processes[s].channel[0]) == -1)
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
ngx_nonblocking_n " failed while spawning \"%s\"",
name);
ngx_close_channel(ngx_processes[s].channel, cycle->log);
return NGX_INVALID_PID;
}
if (ngx_nonblocking(ngx_processes[s].channel[1]) == -1)
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
ngx_nonblocking_n " failed while spawning \"%s\"",
name);
ngx_close_channel(ngx_processes[s].channel, cycle->log);
return NGX_INVALID_PID;
}
on = 1;
if (ioctl(ngx_processes[s].channel[0], FIOASYNC, &on) == -1)
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"ioctl(FIOASYNC) failed while spawning \"%s\"", name);
ngx_close_channel(ngx_processes[s].channel, cycle->log);
return NGX_INVALID_PID;
}
if (fcntl(ngx_processes[s].channel[0], F_SETOWN, ngx_pid) == -1)
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"fcntl(F_SETOWN) failed while spawning \"%s\"", name);
ngx_close_channel(ngx_processes[s].channel, cycle->log);
return NGX_INVALID_PID;
}
if (fcntl(ngx_processes[s].channel[0], F_SETFD, FD_CLOEXEC) == -1)
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"fcntl(FD_CLOEXEC) failed while spawning \"%s\"", name);
ngx_close_channel(ngx_processes[s].channel, cycle->log);
return NGX_INVALID_PID;
}
if (fcntl(ngx_processes[s].channel[1], F_SETFD, FD_CLOEXEC) == -1)
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"fcntl(FD_CLOEXEC) failed while spawning \"%s\"", name);
ngx_close_channel(ngx_processes[s].channel, cycle->log);
return NGX_INVALID_PID;
}
/* 记录子进程使用的socket描述符 */
ngx_channel = ngx_processes[s].channel[1];
}
else
{
ngx_processes[s].channel[0] = -1;
ngx_processes[s].channel[1] = -1;
}
/* 记录该子进程的相关信息在全局数组中的下标 */
ngx_process_slot = s;
pid = fork();
switch (pid)
{
case -1:
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"fork() failed while spawning \"%s\"", name);
ngx_close_channel(ngx_processes[s].channel, cycle->log);
return NGX_INVALID_PID;
case 0:
ngx_pid = ngx_getpid(); // 获取该子进程的进程id号
proc(cycle, data);
break;
default:
break;
}
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "start child %s pid:%P", name, pid);
ngx_processes[s].pid = pid; // 记录子进程的pid
ngx_processes[s].exited = 0;
if (respawn >= 0)
{
return pid;
}
ngx_processes[s].proc = proc;
ngx_processes[s].data = data;
ngx_processes[s].name = name;
ngx_processes[s].exiting = 0;
switch (respawn)
{
case NGX_PROCESS_NORESPAWN:
ngx_processes[s].respawn = 0;
ngx_processes[s].just_spawn = 0;
ngx_processes[s].detached = 0;
break;
case NGX_PROCESS_JUST_SPAWN:
ngx_processes[s].respawn = 0;
ngx_processes[s].just_spawn = 1;
ngx_processes[s].detached = 0;
break;
case NGX_PROCESS_RESPAWN:
ngx_processes[s].respawn = 1;
ngx_processes[s].just_spawn = 0;
ngx_processes[s].detached = 0;
break;
case NGX_PROCESS_JUST_RESPAWN:
ngx_processes[s].respawn = 1;
ngx_processes[s].just_spawn = 1;
ngx_processes[s].detached = 0;
break;
case NGX_PROCESS_DETACHED:
ngx_processes[s].respawn = 0;
ngx_processes[s].just_spawn = 0;
ngx_processes[s].detached = 1;
break;
}
if (s == ngx_last_process)
{
ngx_last_process++;
}
return pid;
}
1.4 ngx_worker_process_cycle
/*
* 参数意义:
* - cycle是当前进程的ngx_cycle_t结构体指针,这里还未开始使用data参数,所以data一般为NULL
*
* 执行意义:
* 进入worker进程工作的循环
*/
static void ngx_worker_process_cycle(ngx_cycle_t *cycle, void *data)
{
ngx_int_t worker = (intptr_t) data;
ngx_process = NGX_PROCESS_WORKER;
ngx_worker = worker;
/* 子进程的启动初始化函数 */
ngx_worker_process_init(cycle, worker);
/* 设置子进程的进程名 */
ngx_setproctitle("worker process");
for ( ;; ) {
if (ngx_exiting) {
if (ngx_event_no_timers_left() == NGX_OK) {
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "exiting");
ngx_worker_process_exit(cycle);
}
}
ngx_log_debug0(NGX_LOG_DEBUG_EVENT, cycle->log, 0, "worker cycle");
/* 最重要的函数:监听并处理事件 */
ngx_process_events_and_timers(cycle);
if (ngx_terminate) {
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "exiting");
ngx_worker_process_exit(cycle);
}
if (ngx_quit) {
ngx_quit = 0;
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0,
"gracefully shutting down");
ngx_setproctitle("worker process is shutting down");
if (!ngx_exiting) {
ngx_exiting = 1;
ngx_set_shutdown_timer(cycle);
ngx_close_listening_sockets(cycle);
ngx_close_idle_connections(cycle);
}
}
if (ngx_reopen) {
ngx_reopen = 0;
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "reopening logs");
ngx_reopen_files(cycle, -1);
}
}
}
1.5 ngx_event_accept
每个监听待连接事件的回调函数都是 ngx_event_accept,一旦监听到客户端发来的连接请求,就会调用该回调方法。
致此,就完成了一个连接的建立.
以上是关于Nginx之连接的建立的主要内容,如果未能解决你的问题,请参考以下文章