ngx_epoll_module分析

本文深入解析了Nginx中epoll模块的工作原理,包括epoll模块的初始化、事件添加与删除、连接管理和事件处理等核心过程。通过源代码分析,详细介绍了epoll在Nginx中的具体实现方式。

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static ngx_int_t
ngx_epoll_init(ngx_cycle_t *cycle, ngx_msec_t timer)
{
    ngx_epoll_conf_t  *epcf;

    epcf = ngx_event_get_conf(cycle->conf_ctx, ngx_epoll_module);

    if (ep == -1) {
        ep = epoll_create(cycle->connection_n / 2); // 创建epoll fd

        if (ep == -1) {
            ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
                          "epoll_create() failed");
            return NGX_ERROR;
        }

#if (NGX_HAVE_FILE_AIO)

        ngx_epoll_aio_init(cycle, epcf);

#endif
    }

    if (nevents < epcf->events) {
        if (event_list) {
            ngx_free(event_list);
        }
        // 创建epoll_event数组
        event_list = ngx_alloc(sizeof(struct epoll_event) * epcf->events,
                               cycle->log);
        if (event_list == NULL) {
            return NGX_ERROR;
        }
    }

    nevents = epcf->events;

    ngx_io = ngx_os_io;  // 注册io回调函数

    ngx_event_actions = ngx_epoll_module_ctx.actions;  // 注册事件回调函数

#if (NGX_HAVE_CLEAR_EVENT)
    ngx_event_flags = NGX_USE_CLEAR_EVENT  // edge触发
#else
    ngx_event_flags = NGX_USE_LEVEL_EVENT  // level触发
#endif
                      |NGX_USE_GREEDY_EVENT  // 需要一直读到EAGAIN
                      |NGX_USE_EPOLL_EVENT;

    return NGX_OK;
}

static void
ngx_epoll_done(ngx_cycle_t *cycle)
{
    if (close(ep) == -1) {  // 关闭epoll fd
        ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                      "epoll close() failed");
    }

    ep = -1;

#if (NGX_HAVE_FILE_AIO)

    if (ngx_eventfd != -1) {

        if (io_destroy(ngx_aio_ctx) == -1) {
            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                          "io_destroy() failed");
        }

        if (close(ngx_eventfd) == -1) {
            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                          "eventfd close() failed");
        }

        ngx_eventfd = -1;
    }

    ngx_aio_ctx = 0;

#endif

    ngx_free(event_list); // 释放epoll_event数组

    event_list = NULL;
    nevents = 0;
}
static ngx_int_t
ngx_epoll_add_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags)
{
    int                  op;
    uint32_t             events, prev;
    ngx_event_t         *e;
    ngx_connection_t    *c;
    struct epoll_event   ee;

    c = ev->data;  // 获得connection指针

    events = (uint32_t) event;

    if (event == NGX_READ_EVENT) {
        e = c->write;
        prev = EPOLLOUT;
#if (NGX_READ_EVENT != EPOLLIN|EPOLLRDHUP)
        events = EPOLLIN|EPOLLRDHUP;
#endif

    } else {
        e = c->read;
        prev = EPOLLIN|EPOLLRDHUP;
#if (NGX_WRITE_EVENT != EPOLLOUT)
        events = EPOLLOUT;
#endif
    }

    if (e->active) {  // connection已经在epoll中注册
        op = EPOLL_CTL_MOD;
        events |= prev; // merge

    } else {  // 未注册,直接添加
        op = EPOLL_CTL_ADD;
    }

    ee.events = events | (uint32_t) flags;  // merge flags
    ee.data.ptr = (void *) ((uintptr_t) c | ev->instance);  // 利用最低位保存instance flag

    ngx_log_debug3(NGX_LOG_DEBUG_EVENT, ev->log, 0,
                   "epoll add event: fd:%d op:%d ev:%08XD",
                   c->fd, op, ee.events);

    if (epoll_ctl(ep, op, c->fd, &ee) == -1) {
        ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_errno,
                      "epoll_ctl(%d, %d) failed", op, c->fd);
        return NGX_ERROR;
    }

    ev->active = 1;  // 已注册flag
#if 0
    ev->oneshot = (flags & NGX_ONESHOT_EVENT) ? 1 : 0;
#endif

    return NGX_OK;
}
static ngx_int_t
ngx_epoll_del_event(ngx_event_t *ev, ngx_int_t event, ngx_uint_t flags)
{
    int                  op;
    uint32_t             prev;
    ngx_event_t         *e;
    ngx_connection_t    *c;
    struct epoll_event   ee;

    /*
     * when the file descriptor is closed, the epoll automatically deletes
     * it from its queue, so we do not need to delete explicitly the event
     * before the closing the file descriptor
     */

    if (flags & NGX_CLOSE_EVENT) {  // close fd时,内核自动将其从epoll中剔除
        ev->active = 0;  // 更新为未注册
        return NGX_OK;
    }

    c = ev->data;  // 获取connection指针

    if (event == NGX_READ_EVENT) {
        e = c->write;
        prev = EPOLLOUT;

    } else {
        e = c->read;
        prev = EPOLLIN|EPOLLRDHUP;
    }

    if (e->active) {  // 还不能删除
        op = EPOLL_CTL_MOD;
        ee.events = prev | (uint32_t) flags;
        ee.data.ptr = (void *) ((uintptr_t) c | ev->instance);

    } else {  // 可以删除
        op = EPOLL_CTL_DEL;
        ee.events = 0;
        ee.data.ptr = NULL;
    }

    ngx_log_debug3(NGX_LOG_DEBUG_EVENT, ev->log, 0,
                   "epoll del event: fd:%d op:%d ev:%08XD",
                   c->fd, op, ee.events);

    if (epoll_ctl(ep, op, c->fd, &ee) == -1) {
        ngx_log_error(NGX_LOG_ALERT, ev->log, ngx_errno,
                      "epoll_ctl(%d, %d) failed", op, c->fd);
        return NGX_ERROR;
    }

    ev->active = 0;  // 更新为未注册

    return NGX_OK;
}
static ngx_int_t
ngx_epoll_add_connection(ngx_connection_t *c)
{
    struct epoll_event  ee;

    ee.events = EPOLLIN|EPOLLOUT|EPOLLET|EPOLLRDHUP;  // 监听事件,边触发模式
    ee.data.ptr = (void *) ((uintptr_t) c | c->read->instance);

    ngx_log_debug2(NGX_LOG_DEBUG_EVENT, c->log, 0,
                   "epoll add connection: fd:%d ev:%08XD", c->fd, ee.events);

    if (epoll_ctl(ep, EPOLL_CTL_ADD, c->fd, &ee) == -1) {
        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno,
                      "epoll_ctl(EPOLL_CTL_ADD, %d) failed", c->fd);
        return NGX_ERROR;
    }

    c->read->active = 1;  // 已注册标记
    c->write->active = 1;  // 已注册标记

    return NGX_OK;
}
static ngx_int_t
ngx_epoll_del_connection(ngx_connection_t *c, ngx_uint_t flags)
{
    int                 op;
    struct epoll_event  ee;

    /*
     * when the file descriptor is closed the epoll automatically deletes
     * it from its queue so we do not need to delete explicitly the event
     * before the closing the file descriptor
     */

    if (flags & NGX_CLOSE_EVENT) {
        c->read->active = 0;
        c->write->active = 0;
        return NGX_OK;
    }

    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, c->log, 0,
                   "epoll del connection: fd:%d", c->fd);

    op = EPOLL_CTL_DEL;
    ee.events = 0;
    ee.data.ptr = NULL;

    if (epoll_ctl(ep, op, c->fd, &ee) == -1) {
        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_errno,
                      "epoll_ctl(%d, %d) failed", op, c->fd);
        return NGX_ERROR;
    }

    c->read->active = 0;
    c->write->active = 0;

    return NGX_OK;
}
static ngx_int_t
ngx_epoll_process_events(ngx_cycle_t *cycle, ngx_msec_t timer, ngx_uint_t flags)
{
    int                events;
    uint32_t           revents;
    ngx_int_t          instance, i;
    ngx_uint_t         level;
    ngx_err_t          err;
    ngx_event_t       *rev, *wev, **queue;
    ngx_connection_t  *c;

    /* NGX_TIMER_INFINITE == INFTIM */

    ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                   "epoll timer: %M", timer);

    events = epoll_wait(ep, event_list, (int) nevents, timer);

    err = (events == -1) ? ngx_errno : 0;

    if (flags & NGX_UPDATE_TIME || ngx_event_timer_alarm) {  // 调用方指定强制更新时间 || 时间定时器发送了SIGALRM信号
        ngx_time_update();  // 更新时间
    }

    if (err) {
        if (err == NGX_EINTR) {  // 信号中断

            if (ngx_event_timer_alarm) {  // timer定时器中断ok
                ngx_event_timer_alarm = 0;  // 清除标记
                return NGX_OK;
            }

            level = NGX_LOG_INFO;

        } else {
            level = NGX_LOG_ALERT;
        }

        ngx_log_error(level, cycle->log, err, "epoll_wait() failed");
        return NGX_ERROR;
    }

    if (events == 0) {
        if (timer != NGX_TIMER_INFINITE) {  // just超时
            return NGX_OK;
        }

        ngx_log_error(NGX_LOG_ALERT, cycle->log, 0,
                      "epoll_wait() returned no events without timeout");
        return NGX_ERROR;
    }

    ngx_mutex_lock(ngx_posted_events_mutex);  // start to post event

    for (i = 0; i < events; i++) {
        c = event_list[i].data.ptr;  // 获得该socket绑定的connection

        instance = (uintptr_t) c & 1;  // 获取instance标记
        c = (ngx_connection_t *) ((uintptr_t) c & (uintptr_t) ~1);  // 纠正connection指针

        rev = c->read;  // 获得read event

        if (c->fd == -1 || rev->instance != instance) {

            /*
             * the stale event from a file descriptor
             * that was just closed in this iteration
             */

            ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                           "epoll: stale event %p", c);
            continue;
        }

        revents = event_list[i].events;

        ngx_log_debug3(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                       "epoll: fd:%d ev:%04XD d:%p",
                       c->fd, revents, event_list[i].data.ptr);

        if (revents & (EPOLLERR|EPOLLHUP)) {
            ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                           "epoll_wait() error on fd:%d ev:%04XD",
                           c->fd, revents);
        }

#if 0
        if (revents & ~(EPOLLIN|EPOLLOUT|EPOLLERR|EPOLLHUP)) {
            ngx_log_error(NGX_LOG_ALERT, cycle->log, 0,
                          "strange epoll_wait() events fd:%d ev:%04XD",
                          c->fd, revents);
        }
#endif

        if ((revents & (EPOLLERR|EPOLLHUP))
             && (revents & (EPOLLIN|EPOLLOUT)) == 0)
        {
            /*
             * if the error events were returned without EPOLLIN or EPOLLOUT,
             * then add these flags to handle the events at least in one
             * active handler
             */

            revents |= EPOLLIN|EPOLLOUT;  // 保证出错时,能调用read or write handler
        }

        if ((revents & EPOLLIN) && rev->active) {  // 读事件

#if (NGX_HAVE_EPOLLRDHUP)
            if (revents & EPOLLRDHUP) {
                rev->pending_eof = 1;  // 对端连接关闭
            }
#endif

            if ((flags & NGX_POST_THREAD_EVENTS) && !rev->accept) {
                rev->posted_ready = 1;

            } else {
                rev->ready = 1;
            }

            if (flags & NGX_POST_EVENTS) {  // post event
                queue = (ngx_event_t **) (rev->accept ?
                               &ngx_posted_accept_events : &ngx_posted_events);

                ngx_locked_post_event(rev, queue);

            } else {  // 直接调用handler处理事件
                rev->handler(rev);
            }
        }

        wev = c->write;  // 获得write event

        if ((revents & EPOLLOUT) && wev->active) {  // 写事件

            if (c->fd == -1 || wev->instance != instance) {

                /*
                 * the stale event from a file descriptor
                 * that was just closed in this iteration
                 */

                ngx_log_debug1(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                               "epoll: stale event %p", c);
                continue;
            }

            if (flags & NGX_POST_THREAD_EVENTS) {
                wev->posted_ready = 1;

            } else {
                wev->ready = 1;
            }

            if (flags & NGX_POST_EVENTS) {  // post event
                ngx_locked_post_event(wev, &ngx_posted_events);

            } else {  // 直接调用handler处理事件
                wev->handler(wev);
            }
        }
    }

    ngx_mutex_unlock(ngx_posted_events_mutex);  // end of posting events

    return NGX_OK;
}
[root@VM-24-11-opencloudos nginx-1.24.0]# pcre-config --version 8.35 [root@VM-24-11-opencloudos nginx-1.24.0]# ./configure --prefix=/www/server/nginx --add-module=/www/server/nginx/src/ngx_devel_kit --add-module=/www/server/nginx/src/lua_nginx_module --add-module=/www/server/nginx/src/ngx_cache_purge --with-openssl=/www/server/nginx/src/openssl --with-pcre=pcre-8.43 --with-http_v2_module --with-stream --with-stream_ssl_module --with-stream_ssl_preread_module --with-http_stub_status_module --with-http_ssl_module --with-http_image_filter_module --with-http_gzip_static_module --with-http_gunzip_module --with-ipv6 --with-http_sub_module --with-http_flv_module --with-http_addition_module --with-http_realip_module --with-http_mp4_module --add-module=/www/server/nginx/src/ngx_http_substitutions_filter_module-master --with-ld-opt=-Wl,-E --with-cc-opt=-Wno-error --with-http_dav_module --add-module=/www/server/nginx/src/nginx-dav-ext-module --add-module=/usr/local/fastdfs-nginx-module/src checking for OS + Linux 6.6.47-12.oc9.x86_64 x86_64 checking for C compiler ... found + using GNU C compiler + gcc version: 12.3.1 20230912 (OpenCloudOS 12.3.1.3-1) (Tencent Compiler 12.3.1.3) checking for gcc -pipe switch ... found checking for --with-ld-opt="-Wl,-E" ... found checking for -Wl,-E switch ... found checking for gcc builtin atomic operations ... found checking for C99 variadic macros ... found checking for gcc variadic macros ... found checking for gcc builtin 64 bit byteswap ... found checking for unistd.h ... found checking for inttypes.h ... found checking for limits.h ... found checking for sys/filio.h ... not found checking for sys/param.h ... found checking for sys/mount.h ... found checking for sys/statvfs.h ... found checking for crypt.h ... found checking for Linux specific features checking for epoll ... found checking for EPOLLRDHUP ... found checking for EPOLLEXCLUSIVE ... found checking for eventfd() ... found checking for O_PATH ... found checking for sendfile() ... found checking for sendfile64() ... found checking for sys/prctl.h ... found checking for prctl(PR_SET_DUMPABLE) ... found checking for prctl(PR_SET_KEEPCAPS) ... found checking for capabilities ... found checking for crypt_r() ... found checking for sys/vfs.h ... found checking for UDP_SEGMENT ... found checking for nobody group ... found checking for poll() ... found checking for /dev/poll ... not found checking for kqueue ... not found checking for crypt() ... not found checking for crypt() in libcrypt ... found checking for F_READAHEAD ... not found checking for posix_fadvise() ... found checking for O_DIRECT ... found checking for F_NOCACHE ... not found checking for directio() ... not found checking for statfs() ... found checking for statvfs() ... found checking for dlopen() ... found checking for sched_yield() ... found checking for sched_setaffinity() ... found checking for SO_SETFIB ... not found checking for SO_REUSEPORT ... found checking for SO_ACCEPTFILTER ... not found checking for SO_BINDANY ... not found checking for IP_TRANSPARENT ... found checking for IP_BINDANY ... not found checking for IP_BIND_ADDRESS_NO_PORT ... found checking for IP_RECVDSTADDR ... not found checking for IP_SENDSRCADDR ... not found checking for IP_PKTINFO ... found checking for IPV6_RECVPKTINFO ... found checking for TCP_DEFER_ACCEPT ... found checking for TCP_KEEPIDLE ... found checking for TCP_FASTOPEN ... found checking for TCP_INFO ... found checking for accept4() ... found checking for int size ... 4 bytes checking for long size ... 8 bytes checking for long long size ... 8 bytes checking for void * size ... 8 bytes checking for uint32_t ... found checking for uint64_t ... found checking for sig_atomic_t ... found checking for sig_atomic_t size ... 4 bytes checking for socklen_t ... found checking for in_addr_t ... found checking for in_port_t ... found checking for rlim_t ... found checking for uintptr_t ... uintptr_t found checking for system byte ordering ... little endian checking for size_t size ... 8 bytes checking for off_t size ... 8 bytes checking for time_t size ... 8 bytes checking for AF_INET6 ... found checking for setproctitle() ... not found checking for pread() ... found checking for pwrite() ... found checking for pwritev() ... found checking for strerrordesc_np() ... found checking for localtime_r() ... found checking for clock_gettime(CLOCK_MONOTONIC) ... found checking for posix_memalign() ... found checking for memalign() ... found checking for mmap(MAP_ANON|MAP_SHARED) ... found checking for mmap("/dev/zero", MAP_SHARED) ... found checking for System V shared memory ... found checking for POSIX semaphores ... found checking for struct msghdr.msg_control ... found checking for ioctl(FIONBIO) ... found checking for ioctl(FIONREAD) ... found checking for struct tm.tm_gmtoff ... found checking for struct dirent.d_namlen ... not found checking for struct dirent.d_type ... found checking for sysconf(_SC_NPROCESSORS_ONLN) ... found checking for sysconf(_SC_LEVEL1_DCACHE_LINESIZE) ... found checking for openat(), fstatat() ... found checking for getaddrinfo() ... found configuring additional modules adding module in /www/server/nginx/src/ngx_devel_kit + ngx_devel_kit was configured adding module in /www/server/nginx/src/lua_nginx_module checking for LuaJIT library in /usr/local/lib and /usr/local/include/luajit-2.1 (specified by the LUAJIT_LIB and LUAJIT_INC env, with -ldl) ... found checking for LuaJIT 2.x ... found checking for Lua language 5.1 ... found checking for LuaJIT has FFI ... found checking for export symbols by default (-E) ... found checking for export symbols by default (--export-all-symbols) ... not found checking for SO_PASSCRED ... found checking for SA_RESTART ... found checking for malloc_trim ... found checking for pipe2 ... found checking for signalfd ... found checking for execvpe ... found + ngx_http_lua_module was configured adding module in /www/server/nginx/src/ngx_cache_purge + ngx_http_cache_purge_module was configured adding module in /www/server/nginx/src/ngx_http_substitutions_filter_module-master + ngx_http_subs_filter_module was configured adding module in /www/server/nginx/src/nginx-dav-ext-module + ngx_http_dav_ext_module was configured adding module in /usr/local/fastdfs-nginx-module/src + ngx_http_fastdfs_module was configured checking for zlib library ... found checking for libxslt ... found checking for libexslt ... found checking for GD library ... found checking for GD WebP support ... found creating objs/Makefile Configuration summary + using PCRE library: pcre-8.43 + using OpenSSL library: /www/server/nginx/src/openssl + using system zlib library nginx path prefix: "/www/server/nginx" nginx binary file: "/www/server/nginx/sbin/nginx" nginx modules path: "/www/server/nginx/modules" nginx configuration prefix: "/www/server/nginx/conf" nginx configuration file: "/www/server/nginx/conf/nginx.conf" nginx pid file: "/www/server/nginx/logs/nginx.pid" nginx error log file: "/www/server/nginx/logs/error.log" nginx http access log file: "/www/server/nginx/logs/access.log" nginx http client request body temporary files: "client_body_temp" nginx http proxy temporary files: "proxy_temp" nginx http fastcgi temporary files: "fastcgi_temp" nginx http uwsgi temporary files: "uwsgi_temp" nginx http scgi temporary files: "scgi_temp" ./configure: warning: the "--with-ipv6" option is deprecated [root@VM-24-11-opencloudos nginx-1.24.0]# make make -f objs/Makefile make[1]: Entering directory '/www/server/nginx/src/nginx-1.24.0' cd pcre-8.43 \ && if [ -f Makefile ]; then make distclean; fi \ && CC="cc" CFLAGS="-O2 -fomit-frame-pointer -pipe " \ ./configure --disable-shared /bin/sh: line 1: cd: pcre-8.43: No such file or directory make[1]: *** [objs/Makefile:2256: pcre-8.43/Makefile] Error 1 make[1]: Leaving directory '/www/server/nginx/src/nginx-1.24.0' make: *** [Makefile:10: build] Error 2
最新发布
06-19
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