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ngx_process.c
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ngx_process.c
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// annotated by chrono since 2016
//
// * ngx_debug_point
// * ngx_spawn_process
// * ngx_signal_handler
// * ngx_init_signals
// * ngx_process_get_status
/*
* Copyright (C) Igor Sysoev
* Copyright (C) Nginx, Inc.
*/
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>
#include <ngx_channel.h>
// 标记unix信号,handler=ngx_signal_handler
typedef struct {
int signo;
char *signame;
char *name;
// 原接口:void (*handler)(int signo);
// 1.13.0 变动了函数接口
// 可以多获取一些信号的信息
void (*handler)(int signo, siginfo_t *siginfo, void *ucontext);
} ngx_signal_t;
static void ngx_execute_proc(ngx_cycle_t *cycle, void *data);
// 1.13.0 变动了函数接口
// 原接口:static void ngx_signal_handler(int signo);
//
// 处理unix信号
// 收到信号后设置ngx_quit/ngx_sigalrm/ngx_reconfigue等全局变量
// 由进程里的无限循环检查这些变量再处理
// 检查子进程结束,设置进程数组ngx_processes里的状态
static void ngx_signal_handler(int signo, siginfo_t *siginfo, void *ucontext);
// 检查子进程结束,设置进程数组ngx_processes里的状态
static void ngx_process_get_status(void);
// 解除子进程相关的共享内存锁
static void ngx_unlock_mutexes(ngx_pid_t pid);
// 在core/nginx.c ngx_save_argv()里存储命令行参数
int ngx_argc;
char **ngx_argv;
char **ngx_os_argv;
// 全局变量,用于传出创建的进程索引号
// 用在ngx_start_worker_processes()里
ngx_int_t ngx_process_slot;
// 进程间通信的channel
ngx_socket_t ngx_channel;
// 产生进程的计数器,初始值为0
// 标记数组ngx_processes的最后使用的位置,遍历用
ngx_int_t ngx_last_process;
// 创建的进程都在ngx_processes数组里
// 此数组主要在master进程里使用
// worker进程也用来维护其他worker进程的状态信息
ngx_process_t ngx_processes[NGX_MAX_PROCESSES];
// 命令行-s参数关联数组
// 所有信号都用ngx_signal_handler处理
ngx_signal_t signals[] = {
// #define NGX_RECONFIGURE_SIGNAL HUP
// 即sighup
{ ngx_signal_value(NGX_RECONFIGURE_SIGNAL),
"SIG" ngx_value(NGX_RECONFIGURE_SIGNAL),
"reload",
ngx_signal_handler },
// #define NGX_REOPEN_SIGNAL USR1
// 即sigusr1
{ ngx_signal_value(NGX_REOPEN_SIGNAL),
"SIG" ngx_value(NGX_REOPEN_SIGNAL),
"reopen",
ngx_signal_handler },
{ ngx_signal_value(NGX_NOACCEPT_SIGNAL),
"SIG" ngx_value(NGX_NOACCEPT_SIGNAL),
"",
ngx_signal_handler },
// #define NGX_TERMINATE_SIGNAL TERM
// sigterm
{ ngx_signal_value(NGX_TERMINATE_SIGNAL),
"SIG" ngx_value(NGX_TERMINATE_SIGNAL),
"stop",
ngx_signal_handler },
// #define NGX_SHUTDOWN_SIGNAL QUIT
// sigquit
{ ngx_signal_value(NGX_SHUTDOWN_SIGNAL),
"SIG" ngx_value(NGX_SHUTDOWN_SIGNAL),
"quit",
ngx_signal_handler },
// ngx_config.h
// #define NGX_CHANGEBIN_SIGNAL USR2
// hot upgrade, kill -s SIGUSR2 masterpid
{ ngx_signal_value(NGX_CHANGEBIN_SIGNAL),
"SIG" ngx_value(NGX_CHANGEBIN_SIGNAL),
"",
ngx_signal_handler },
{ SIGALRM, "SIGALRM", "", ngx_signal_handler },
{ SIGINT, "SIGINT", "", ngx_signal_handler },
{ SIGIO, "SIGIO", "", ngx_signal_handler },
{ SIGCHLD, "SIGCHLD", "", ngx_signal_handler },
{ SIGSYS, "SIGSYS, SIG_IGN", "", NULL },
{ SIGPIPE, "SIGPIPE, SIG_IGN", "", NULL },
{ 0, NULL, "", NULL }
};
// 被ngx_start_worker_processes()调用,产生worker进程
// 参数proc = ngx_worker_process_cycle
// data = (void *) (intptr_t) i,即worker id
// name = "worker process"
// respawn = NGX_PROCESS_RESPAWN 即-3
// #define NGX_PROCESS_JUST_SPAWN -2
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;
// 决定进程在ngx_processes数组里的位置
// 产生新进程时respawn < 0
if (respawn >= 0) {
s = respawn;
} else {
// 遍历进程数组,找到第一个“空”的位置,也就是pid无效的
for (s = 0; s < ngx_last_process; s++) {
if (ngx_processes[s].pid == -1) {
break;
}
}
// 序号不能超过nginx的最大值,即1024
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;
}
}
// 创建进程间通信用的channel
if (respawn != NGX_PROCESS_DETACHED) {
/* Solaris 9 still has no AF_LOCAL */
// 创建socketpair,进程间通信用
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 %d:%d",
ngx_processes[s].channel[0],
ngx_processes[s].channel[1]);
// 进程间通信非阻塞
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;
}
ngx_channel = ngx_processes[s].channel[1];
} else {
ngx_processes[s].channel[0] = -1;
ngx_processes[s].channel[1] = -1;
}
// 设置全局变量,当前进程在数组ngx_processes里的位置
ngx_process_slot = s;
// 调用fork产生子进程
pid = fork();
switch (pid) {
// -1产生子进程出错
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;
// 0是子进程,开始执行worker进程的核心函数
// ngx_worker_process_cycle,即无限循环处理事件
case 0:
// 1.14.0,获取父进程pid,即masterpid
ngx_parent = ngx_pid;
// worker进程重新获取进程id
ngx_pid = ngx_getpid();
// 这里是子进程的真正工作,无限循环
// proc = ngx_worker_process_cycle
// data = (void *) (intptr_t) i,即worker id
proc(cycle, data);
break;
// 父进程得到子进程的pid
default:
break;
}
ngx_log_error(NGX_LOG_NOTICE, cycle->log, 0, "start %s %P", name, pid);
// 把子进程的pid存入数组,记录状态
ngx_processes[s].pid = pid;
ngx_processes[s].exited = 0;
if (respawn >= 0) {
return pid;
}
// 填充worker进程的其他状态
// name = "worker process"
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;
}
// ngx_last_process增加,用于之后产生新进程用
if (s == ngx_last_process) {
ngx_last_process++;
}
return pid;
}
// 执行外部程序
ngx_pid_t
ngx_execute(ngx_cycle_t *cycle, ngx_exec_ctx_t *ctx)
{
// 产生进程执行ngx_execute_proc
// 不与worker发生关系,没有channel通信
return ngx_spawn_process(cycle, ngx_execute_proc, ctx, ctx->name,
NGX_PROCESS_DETACHED);
}
static void
ngx_execute_proc(ngx_cycle_t *cycle, void *data)
{
ngx_exec_ctx_t *ctx = data;
// 系统调用execve()
if (execve(ctx->path, ctx->argv, ctx->envp) == -1) {
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"execve() failed while executing %s \"%s\"",
ctx->name, ctx->path);
}
exit(1);
}
// 初始化signals数组
ngx_int_t
ngx_init_signals(ngx_log_t *log)
{
ngx_signal_t *sig;
struct sigaction sa;
for (sig = signals; sig->signo != 0; sig++) {
ngx_memzero(&sa, sizeof(struct sigaction));
// 设置信号处理函数
// 大多是ngx_signal_handler
if (sig->handler) {
sa.sa_sigaction = sig->handler;
sa.sa_flags = SA_SIGINFO;
} else {
sa.sa_handler = SIG_IGN;
}
sigemptyset(&sa.sa_mask);
// 安装信号处理函数
if (sigaction(sig->signo, &sa, NULL) == -1) {
#if (NGX_VALGRIND)
ngx_log_error(NGX_LOG_ALERT, log, ngx_errno,
"sigaction(%s) failed, ignored", sig->signame);
#else
ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
"sigaction(%s) failed", sig->signame);
return NGX_ERROR;
#endif
}
}
return NGX_OK;
}
// 1.13.0 变动了函数接口
// static void ngx_signal_handler(int signo, siginfo_t *siginfo, void *ucontext);
//
// 处理unix信号
// 收到信号后设置ngx_quit/ngx_sigalrm/ngx_reconfigue等全局变量
// 由进程里的无限循环检查这些变量再处理
// 检查子进程结束,设置进程数组ngx_processes里的状态
static void
ngx_signal_handler(int signo, siginfo_t *siginfo, void *ucontext)
{
char *action;
ngx_int_t ignore;
ngx_err_t err;
ngx_signal_t *sig;
ignore = 0;
err = ngx_errno;
// 遍历信号数组,因为数量少,所以不太影响效率
for (sig = signals; sig->signo != 0; sig++) {
if (sig->signo == signo) {
break;
}
}
ngx_time_sigsafe_update();
action = "";
switch (ngx_process) {
// master/single进程可以处理的信号
case NGX_PROCESS_MASTER:
case NGX_PROCESS_SINGLE:
switch (signo) {
// 优雅关闭, -s quit
case ngx_signal_value(NGX_SHUTDOWN_SIGNAL):
ngx_quit = 1;
action = ", shutting down";
break;
// 直接关闭, -s stop
case ngx_signal_value(NGX_TERMINATE_SIGNAL):
case SIGINT:
ngx_terminate = 1;
action = ", exiting";
break;
// 不再接受新请求,用于热升级、平滑升级
case ngx_signal_value(NGX_NOACCEPT_SIGNAL):
if (ngx_daemonized) {
ngx_noaccept = 1;
action = ", stop accepting connections";
}
break;
// 重新加载配置文件, -s reload
case ngx_signal_value(NGX_RECONFIGURE_SIGNAL):
ngx_reconfigure = 1;
action = ", reconfiguring";
break;
// 重新打开文件, -s reopen
case ngx_signal_value(NGX_REOPEN_SIGNAL):
ngx_reopen = 1;
action = ", reopening logs";
break;
// hot upgrade, kill -s SIGUSR2 masterpid
case ngx_signal_value(NGX_CHANGEBIN_SIGNAL):
if (ngx_getppid() == ngx_parent || ngx_new_binary > 0) {
/*
* Ignore the signal in the new binary if its parent is
* not changed, i.e. the old binary's process is still
* running. Or ignore the signal in the old binary's
* process if the new binary's process is already running.
*/
action = ", ignoring";
ignore = 1;
break;
}
// 标志位,热更新二进制文件
ngx_change_binary = 1;
action = ", changing binary";
break;
// SIGALRM,更新时间
case SIGALRM:
ngx_sigalrm = 1;
break;
case SIGIO:
ngx_sigio = 1;
break;
// 子进程结束,可能发生了意外
case SIGCHLD:
// 将导致master进程ngx_master_process_cycle()调用ngx_reap_children()
// 重新产生子进程
ngx_reap = 1;
break;
}
break;
// worker能够处理的信号较少
case NGX_PROCESS_WORKER:
case NGX_PROCESS_HELPER:
switch (signo) {
// 不再接受新请求,用于热升级、平滑升级
// 进入 -s quit
case ngx_signal_value(NGX_NOACCEPT_SIGNAL):
if (!ngx_daemonized) {
break;
}
ngx_debug_quit = 1;
/* fall through */
// 优雅关闭, -s quit
case ngx_signal_value(NGX_SHUTDOWN_SIGNAL):
ngx_quit = 1;
action = ", shutting down";
break;
// 直接关闭, -s stop
case ngx_signal_value(NGX_TERMINATE_SIGNAL):
case SIGINT:
ngx_terminate = 1;
action = ", exiting";
break;
// 重新打开文件, -s reopen
case ngx_signal_value(NGX_REOPEN_SIGNAL):
ngx_reopen = 1;
action = ", reopening logs";
break;
// 重新加载配置文件, -s reload
case ngx_signal_value(NGX_RECONFIGURE_SIGNAL):
case ngx_signal_value(NGX_CHANGEBIN_SIGNAL):
case SIGIO:
action = ", ignoring";
break;
}
break;
}
if (siginfo && siginfo->si_pid) {
ngx_log_error(NGX_LOG_NOTICE, ngx_cycle->log, 0,
"signal %d (%s) received from %P%s",
signo, sig->signame, siginfo->si_pid, action);
} else {
ngx_log_error(NGX_LOG_NOTICE, ngx_cycle->log, 0,
"signal %d (%s) received%s",
signo, sig->signame, action);
}
if (ignore) {
ngx_log_error(NGX_LOG_CRIT, ngx_cycle->log, 0,
"the changing binary signal is ignored: "
"you should shutdown or terminate "
"before either old or new binary's process");
}
// 父进程收到了子进程结束的信号
if (signo == SIGCHLD) {
ngx_process_get_status();
}
ngx_set_errno(err);
}
// 检查子进程结束,设置进程数组ngx_processes里的状态
static void
ngx_process_get_status(void)
{
int status;
char *process;
ngx_pid_t pid;
ngx_err_t err;
ngx_int_t i;
ngx_uint_t one;
one = 0;
for ( ;; ) {
// 系统调用,获得结束的子进程
// WNOHANG 若pid指定的子进程没有结束,则waitpid()函数返回0,不予以等待。
// 若结束,则返回该子进程的ID。
pid = waitpid(-1, &status, WNOHANG);
if (pid == 0) {
return;
}
if (pid == -1) {
err = ngx_errno;
if (err == NGX_EINTR) {
continue;
}
if (err == NGX_ECHILD && one) {
return;
}
/*
* Solaris always calls the signal handler for each exited process
* despite waitpid() may be already called for this process.
*
* When several processes exit at the same time FreeBSD may
* erroneously call the signal handler for exited process
* despite waitpid() may be already called for this process.
*/
if (err == NGX_ECHILD) {
ngx_log_error(NGX_LOG_INFO, ngx_cycle->log, err,
"waitpid() failed");
return;
}
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, err,
"waitpid() failed");
return;
}
one = 1;
process = "unknown process";
// 在进程数组里找到结束的进程
for (i = 0; i < ngx_last_process; i++) {
if (ngx_processes[i].pid == pid) {
// 设置结束进程的结束状态
ngx_processes[i].status = status;
ngx_processes[i].exited = 1;
process = ngx_processes[i].name;
break;
}
}
// WTERMSIG宏测试被执行后,若成功返回被终止的子进程的信号值。
// 只记录log,无其他动作
if (WTERMSIG(status)) {
#ifdef WCOREDUMP
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"%s %P exited on signal %d%s",
process, pid, WTERMSIG(status),
WCOREDUMP(status) ? " (core dumped)" : "");
#else
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"%s %P exited on signal %d",
process, pid, WTERMSIG(status));
#endif
} else {
ngx_log_error(NGX_LOG_NOTICE, ngx_cycle->log, 0,
"%s %P exited with code %d",
process, pid, WEXITSTATUS(status));
}
// 获取子进程的非正常返回值
// 如果worker进程使用exit(2),那么不重启子进程
// 在master cycle里的ngx_reap里判断
if (WEXITSTATUS(status) == 2 && ngx_processes[i].respawn) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"%s %P exited with fatal code %d "
"and cannot be respawned",
process, pid, WEXITSTATUS(status));
ngx_processes[i].respawn = 0;
}
// 解除子进程相关的共享内存锁
ngx_unlock_mutexes(pid);
}
}
// 解除子进程相关的共享内存锁
static void
ngx_unlock_mutexes(ngx_pid_t pid)
{
ngx_uint_t i;
ngx_shm_zone_t *shm_zone;
ngx_list_part_t *part;
ngx_slab_pool_t *sp;
/*
* unlock the accept mutex if the abnormally exited process
* held it
*/
// accept锁
if (ngx_accept_mutex_ptr) {
(void) ngx_shmtx_force_unlock(&ngx_accept_mutex, pid);
}
/*
* unlock shared memory mutexes if held by the abnormally exited
* process
*/
// 共享内存里的锁
part = (ngx_list_part_t *) &ngx_cycle->shared_memory.part;
shm_zone = part->elts;
for (i = 0; /* void */ ; i++) {
if (i >= part->nelts) {
if (part->next == NULL) {
break;
}
part = part->next;
shm_zone = part->elts;
i = 0;
}
sp = (ngx_slab_pool_t *) shm_zone[i].shm.addr;
if (ngx_shmtx_force_unlock(&sp->mutex, pid)) {
ngx_log_error(NGX_LOG_ALERT, ngx_cycle->log, 0,
"shared memory zone \"%V\" was locked by %P",
&shm_zone[i].shm.name, pid);
}
}
}
// debug断点时的动作,停止或是直接core
void
ngx_debug_point(void)
{
ngx_core_conf_t *ccf;
// 取核心配置
ccf = (ngx_core_conf_t *) ngx_get_conf(ngx_cycle->conf_ctx,
ngx_core_module);
switch (ccf->debug_points) {
// stop,使用stop信号停止运行
// 之后可以用gdb调试
case NGX_DEBUG_POINTS_STOP:
raise(SIGSTOP);
break;
// 直接abort
// 产生coredump,再用gdb调试
case NGX_DEBUG_POINTS_ABORT:
// ngx_config.h:#define ngx_abort abort
ngx_abort();
}
// 其他则无动作,不会有任何影响
}
// 被ngx_cycle.c里的ngx_signal_process()调用
// 发送reload/stop等信号
ngx_int_t
ngx_os_signal_process(ngx_cycle_t *cycle, char *name, ngx_pid_t pid)
{
ngx_signal_t *sig;
// 字符串比较,找到对应的信号,调用kill发送
// signals是本文件前面定义的一个数组
for (sig = signals; sig->signo != 0; sig++) {
if (ngx_strcmp(name, sig->name) == 0) {
if (kill(pid, sig->signo) != -1) {
return 0;
}
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"kill(%P, %d) failed", pid, sig->signo);
}
}
return 1;
}