nginx系列第五篇：nginx中相关通信总结

news/2024/11/28 22:49:31/

目录

1.master进程监听socket

2.master和worker进程通信机制

2.1通信渠道

2.2通信方法

2.3通信内容

2.4子进程事件处理

3.epoll封装

4.linux系统下信号查看

1.master进程监听socket

nginx在master进程socket bind listen，accept在通过epoll在子进程中控制，代码如下：

ngx_int_t
ngx_open_listening_sockets(ngx_cycle_t *cycle)
{
...
    s = ngx_socket(ls[i].sockaddr->sa_family, ls[i].type, 0);
...
    if (setsockopt(s, SOL_SOCKET, SO_REUSEADDR,
                               (const void *) &reuseaddr, sizeof(int))
                    == -1)
...
    if (bind(s, ls[i].sockaddr, ls[i].socklen) == -1) {
...
    if (listen(s, ls[i].backlog) == -1) {
...
    
}

调用堆栈如下：
ngx_open_listening_sockets(ngx_cycle_t * cycle) (nginx-1.22.1/src/core/ngx_connection.c:604)
ngx_init_cycle(ngx_cycle_t * old_cycle) (nginx-1.22.1/src/core/ngx_cycle.c:618)
main(int argc, char * const * argv) (nginx-1.22.1/src/core/nginx.c:292)

2.master和worker进程通信机制

2.1通信渠道

创建套接字组用于读和写，master用fd[0]写，worker用fd[1]进行读
socketpair

2.2通信方法

master用sendmsg发送，work用recvmsg接收
#include <sys/types.h>
#include <sys/socket.h>

ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags);
ssize_t recvmsg(int sockfd, struct msghdr *msg, int flags);

2.3通信内容

struct msghdr

2.4子进程事件处理

子进程注册fd[1] -> ngx_channel读事件到epoll上

static void
ngx_worker_process_init(ngx_cycle_t *cycle, ngx_int_t worker)
{
    ...
    if (ngx_add_channel_event(cycle, ngx_channel, NGX_READ_EVENT,
                              ngx_channel_handler)
        == NGX_ERROR)
    {
        /* fatal */
        exit(2);
    }
}

ngx_channel在如下函数进行赋值，为fd[1]
ngx_pid_t
ngx_spawn_process(ngx_cycle_t *cycle, ngx_spawn_proc_pt proc, void *data,
    char *name, ngx_int_t respawn)
{
    ...
    ngx_channel = ngx_processes[s].channel[1];
    ...
}

3.epoll封装

文件：
nginx-1.22.1/src/event/modules/ngx_epoll_module.c
结构：
static ngx_event_module_t  ngx_epoll_module_ctx = {
    &epoll_name,
    ngx_epoll_create_conf,               /* create configuration */
    ngx_epoll_init_conf,                 /* init configuration */

    {
        ngx_epoll_add_event,             /* add an event */
        ngx_epoll_del_event,             /* delete an event */
        ngx_epoll_add_event,             /* enable an event */
        ngx_epoll_del_event,             /* disable an event */
        ngx_epoll_add_connection,        /* add an connection */
        ngx_epoll_del_connection,        /* delete an connection */
#if (NGX_HAVE_EVENTFD)
        ngx_epoll_notify,                /* trigger a notify */
#else
        NULL,                            /* trigger a notify */
#endif
        ngx_epoll_process_events,        /* process the events */
        ngx_epoll_init,                  /* init the events */
        ngx_epoll_done,                  /* done the events */
    }
};

4.linux系统下信号查看

kill -l

5.信号处理模拟

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <signal.h>
#include <errno.h>
#include <stdint.h>int parentProcess(int* fds, int num) {if (num < 2) {return -1;}close(fds[0]); // 关闭fds[0] 使用fds[1]读写，子进程中关闭fds[1] 使用fds[0]读写char buf[128] {0};char *pStr = (char*)"hello child, I am parent";int inum = 0;while (inum++ < 3) {memset(buf, 0x00, sizeof(buf));//写write(fds[1], pStr, strlen(pStr));//读read(fds[1], buf, 128);printf("parent [%d] %d :: %s\n", getpid(), inum, buf);sleep(1);}close(fds[1]);return 0;
}int childProcess(int* fds, int num) {if (num < 2) {return -1;}close(fds[1]);char buf[128] {0};char *pStr = (char*)"hello parent, I am child";char sendBuf[128] = {0};sprintf(sendBuf, "hello parent, I am child %d", getpid());int inum = 0;while (inum++ < 3) {memset(buf, 0x00, sizeof(buf));//读read(fds[0], buf, 128);printf("child [%d] %d :: %s\n", getpid(), inum, buf);//写write(fds[0], sendBuf, strlen(sendBuf));sleep(1);}close(fds[0]);return 0;
}//设置文件描述符非阻塞
int fd_nonblocking(int s)
{int  nb;nb = 1;//方法一/*int flag = fcntl(s, F_GETFL);flag |= O_NONBLOCK;return fcntl(s, F_SETFL, flag);*///方法二return ioctl(s, FIONBIO, &nb);
}int close_channel(int* fds) {if (close(fds[0]) == -1) {printf("close() channel fds[0] failed\n");}if (close(fds[1]) == -1) {printf("close() channel fds[1] failed\n");}return 0;
}void testNonblockingSocketFd(int* fds) {if (-1 == fd_nonblocking(fds[0])) {printf("fd_nonblocking fds[0] failed\n");close_channel(fds);}if (-1 == fd_nonblocking(fds[1])) {printf("fd_nonblocking fds[1] failed\n");close_channel(fds);}
}struct TDataExchangeChannel {int fds[2];
};#define GROUP_NUM 2typedef struct {int     signo;char   *signame;char   *name;void  (*handler)(int signo, siginfo_t *siginfo, void *ucontext);
} ngx_signal_t;#define ngx_signal_helper(n)     SIG##n
#define ngx_signal_value(n)      ngx_signal_helper(n)#define ngx_value_helper(n)   #n
#define ngx_value(n)          ngx_value_helper(n)#define NGX_SHUTDOWN_SIGNAL      QUIT
#define NGX_TERMINATE_SIGNAL     TERM
#define NGX_NOACCEPT_SIGNAL      WINCH
#define NGX_RECONFIGURE_SIGNAL   HUP#if (NGX_LINUXTHREADS)
#define NGX_REOPEN_SIGNAL        INFO
#define NGX_CHANGEBIN_SIGNAL     XCPU
#else
#define NGX_REOPEN_SIGNAL        USR1
#define NGX_CHANGEBIN_SIGNAL     USR2
#endif#define ngx_errno                  errnotypedef intptr_t        ngx_int_t;
typedef int             ngx_err_t;
typedef uintptr_t       ngx_uint_t;#define NGX_PROCESS_SINGLE     0
#define NGX_PROCESS_MASTER     1
#define NGX_PROCESS_SIGNALLER  2
#define NGX_PROCESS_WORKER     3
#define NGX_PROCESS_HELPER     4#define  NGX_OK          0
#define  NGX_ERROR      -1
#define  NGX_AGAIN      -2
#define  NGX_BUSY       -3
#define  NGX_DONE       -4
#define  NGX_DECLINED   -5
#define  NGX_ABORT      -6ngx_uint_t    ngx_process;void
ngx_signal_handler(int signo, siginfo_t *siginfo, void *ucontext);ngx_signal_t  signals[] = {{ ngx_signal_value(NGX_RECONFIGURE_SIGNAL),"SIG" ngx_value(NGX_RECONFIGURE_SIGNAL),"reload",ngx_signal_handler },{ 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 },{ ngx_signal_value(NGX_TERMINATE_SIGNAL),"SIG" ngx_value(NGX_TERMINATE_SIGNAL),"stop",ngx_signal_handler },{ ngx_signal_value(NGX_SHUTDOWN_SIGNAL),"SIG" ngx_value(NGX_SHUTDOWN_SIGNAL),"quit",ngx_signal_handler },{ 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 }
};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;printf("signo = [%d]\n", signo);for (sig = signals; sig->signo != 0; sig++) {if (sig->signo == signo) {break;}}action = "";switch (ngx_process) {case NGX_PROCESS_MASTER:case NGX_PROCESS_SINGLE:switch (signo) {case ngx_signal_value(NGX_SHUTDOWN_SIGNAL)://ngx_quit = 1;action = ", shutting down";break;case ngx_signal_value(NGX_TERMINATE_SIGNAL):case SIGINT://ngx_terminate = 1;action = ", exiting";break;case ngx_signal_value(NGX_NOACCEPT_SIGNAL):/*if (ngx_daemonized) {ngx_noaccept = 1;action = ", stop accepting connections";}*/break;case ngx_signal_value(NGX_RECONFIGURE_SIGNAL)://ngx_reconfigure = 1;action = ", reconfiguring";break;case ngx_signal_value(NGX_REOPEN_SIGNAL)://ngx_reopen = 1;action = ", reopening logs";break;case ngx_signal_value(NGX_CHANGEBIN_SIGNAL):/*if (ngx_getppid() == ngx_parent || ngx_new_binary > 0) {action = ", ignoring";ignore = 1;break;}ngx_change_binary = 1;*/action = ", changing binary";break;case SIGALRM://ngx_sigalrm = 1;break;case SIGIO://ngx_sigio = 1;break;case SIGCHLD://ngx_reap = 1;break;}break;case NGX_PROCESS_WORKER:case NGX_PROCESS_HELPER:switch (signo) {case ngx_signal_value(NGX_NOACCEPT_SIGNAL):/*if (!ngx_daemonized) {break;}ngx_debug_quit = 1;*//* fall through */case ngx_signal_value(NGX_SHUTDOWN_SIGNAL)://ngx_quit = 1;action = ", shutting down";break;case ngx_signal_value(NGX_TERMINATE_SIGNAL):case SIGINT://ngx_terminate = 1;action = ", exiting";break;case ngx_signal_value(NGX_REOPEN_SIGNAL)://ngx_reopen = 1;action = ", reopening logs";break;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) {printf("signal %d (%s) received from %P%s",signo, sig->signame, siginfo->si_pid, action);} else {printf("signal %d (%s) received%s",signo, sig->signame, action);}*/if (ignore) {printf("the changing binary signal is ignored: ""you should shutdown or terminate ""before either old or new binary's process");}printf("action = [%s]\n", action);
}ngx_int_t
ngx_init_signals()
{ngx_signal_t      *sig;struct sigaction   sa;for (sig = signals; sig->signo != 0; sig++) {memset(&sa, 0x00, sizeof(struct sigaction));if (sig->handler) {sa.sa_sigaction = sig->handler;sa.sa_flags = SA_SIGINFO;} else {sa.sa_handler = SIG_IGN;}sigemptyset(&sa.sa_mask);if (sigaction(sig->signo, &sa, NULL) == -1) {
#if (NGX_VALGRIND)printf("sigaction(%s) failed, ignored", sig->signame);
#elseprintf("sigaction(%s) failed", sig->signame);return NGX_ERROR;
#endif}}return NGX_OK;
}int main()
{//信号初始化ngx_init_signals();#ifdef NOBLOCKFDtestNonblockingSocketFd(fds);
#endifTDataExchangeChannel channels[GROUP_NUM];for (int i = 0; i < GROUP_NUM; i++) {socketpair(PF_UNIX, SOCK_STREAM, 0, channels[i].fds);int pid = fork();switch (pid) {case -1: // errorreturn -1;case 0: // childchildProcess(channels[i].fds, 2);printf("child exit \n");exit(0);default: // parentbreak;}}//父进程给子进程发送消息，并接收子进程发来的消息for (int i = 0; i < GROUP_NUM; i++) {parentProcess(channels[i].fds, 2);}while(1) {sleep(20);}return 0;
}

运行结果：

Linux下信号处理可以参考如下博客：

https://www.cnblogs.com/Alliswell-WP/p/CPlusPlus_Linux_07.html


http://www.ppmy.cn/news/245358.html

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