本文我们讲述一下Nginx cycle运行上下文相关的实现。

1. 相关静态函数声明

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_event.h>


//销毁nginx cycle相关的内存池
static void ngx_destroy_cycle_pools(ngx_conf_t *conf);

//初始化共享内存
static ngx_int_t ngx_init_zone_pool(ngx_cycle_t *cycle,
    ngx_shm_zone_t *shm_zone);


//nginx使用锁机制来实现accept mutex,并且顺序的来访问共享内存。在大多数的系统上,锁都是通过原子操作来实现的,
//因此会忽略配置文件中的lock_file file指令;而对于其他的一些系统,lock file机制会被使用
//默认的lock文件存放位置为logs/nginx.lock
static ngx_int_t ngx_test_lockfile(u_char *file, ngx_log_t *log);

//清除老的nginx cycle上下文
static void ngx_clean_old_cycles(ngx_event_t *ev);

2. 相关变量定义

volatile ngx_cycle_t  *ngx_cycle;
ngx_array_t            ngx_old_cycles;

static ngx_pool_t     *ngx_temp_pool;
static ngx_event_t     ngx_cleaner_event;

ngx_uint_t             ngx_test_config;
ngx_uint_t             ngx_dump_config;
ngx_uint_t             ngx_quiet_mode;


/* STUB NAME */
static ngx_connection_t  dumb;
/* STUB */

下面对各个变量做一个简单的说明:

  • ngx_cycle: 这里ngx_cycle作为一个全局变量指向nginx当前运行的上下文环境。因为在运行过程中,上下文可能会经常发生变动,因此这里用volatile修饰。

  • ngx_old_cycles: 保存所有原来到的nginx上下文对象

  • ngx_temp_pool: nginx的一个临时内存池。这是因为在nginx升级过程中,有一些老的ngx_cycle_t *信息需要保存,这需要空间,因此这里开辟一个临时的内存池来存储这些信息。

  • ngx_cleaner_event: 这里对于ngx_old_cycles的清理会采用事件机制来完成,因此这里定义一个cleaner event。

  • ngx_test_config: 是否是对nginx配置文件进行测试

  • ngx_dump_config: 是否要dump出nginx配置文件

  • ngx_quiet_mode: 在测试nginx配置文件时,抑制非错误信息的输出

  • dumb: 这里之所以用一个桩dumb,是因为这里的ngx_event_t设计主要是针对nginx网络事件的,每个网络事件都关联着一个ngx_connection_t。这里虽然dumb是用于定时器事件,但是还是会把该定时器事件看成是一个网络事件来处理,因此要设立一个STUB来表明这只是一个桩,并不是一个网络事件。

3. 函数ngx_init_cycle()

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
    void                *rv;
    char               **senv, **env;
    ngx_uint_t           i, n;
    ngx_log_t           *log;
    ngx_time_t          *tp;
    ngx_conf_t           conf;
    ngx_pool_t          *pool;
    ngx_cycle_t         *cycle, **old;
    ngx_shm_zone_t      *shm_zone, *oshm_zone;
    ngx_list_part_t     *part, *opart;
    ngx_open_file_t     *file;
    ngx_listening_t     *ls, *nls;
    ngx_core_conf_t     *ccf, *old_ccf;
    ngx_core_module_t   *module;
    char                 hostname[NGX_MAXHOSTNAMELEN];

    ngx_timezone_update();

    /* force localtime update with a new timezone */

    tp = ngx_timeofday();
    tp->sec = 0;

    ngx_time_update();


    log = old_cycle->log;

    pool = ngx_create_pool(NGX_CYCLE_POOL_SIZE, log);
    if (pool == NULL) {
        return NULL;
    }
    pool->log = log;

    cycle = ngx_pcalloc(pool, sizeof(ngx_cycle_t));
    if (cycle == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    cycle->pool = pool;
    cycle->log = log;
    cycle->old_cycle = old_cycle;

    cycle->conf_prefix.len = old_cycle->conf_prefix.len;
    cycle->conf_prefix.data = ngx_pstrdup(pool, &old_cycle->conf_prefix);
    if (cycle->conf_prefix.data == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    cycle->prefix.len = old_cycle->prefix.len;
    cycle->prefix.data = ngx_pstrdup(pool, &old_cycle->prefix);
    if (cycle->prefix.data == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    cycle->conf_file.len = old_cycle->conf_file.len;
    cycle->conf_file.data = ngx_pnalloc(pool, old_cycle->conf_file.len + 1);
    if (cycle->conf_file.data == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }
    ngx_cpystrn(cycle->conf_file.data, old_cycle->conf_file.data,
                old_cycle->conf_file.len + 1);

    cycle->conf_param.len = old_cycle->conf_param.len;
    cycle->conf_param.data = ngx_pstrdup(pool, &old_cycle->conf_param);
    if (cycle->conf_param.data == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }


    n = old_cycle->paths.nelts ? old_cycle->paths.nelts : 10;

    cycle->paths.elts = ngx_pcalloc(pool, n * sizeof(ngx_path_t *));
    if (cycle->paths.elts == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    cycle->paths.nelts = 0;
    cycle->paths.size = sizeof(ngx_path_t *);
    cycle->paths.nalloc = n;
    cycle->paths.pool = pool;


    if (ngx_array_init(&cycle->config_dump, pool, 1, sizeof(ngx_conf_dump_t))
        != NGX_OK)
    {
        ngx_destroy_pool(pool);
        return NULL;
    }

    if (old_cycle->open_files.part.nelts) {
        n = old_cycle->open_files.part.nelts;
        for (part = old_cycle->open_files.part.next; part; part = part->next) {
            n += part->nelts;
        }

    } else {
        n = 20;
    }

    if (ngx_list_init(&cycle->open_files, pool, n, sizeof(ngx_open_file_t))
        != NGX_OK)
    {
        ngx_destroy_pool(pool);
        return NULL;
    }


    if (old_cycle->shared_memory.part.nelts) {
        n = old_cycle->shared_memory.part.nelts;
        for (part = old_cycle->shared_memory.part.next; part; part = part->next)
        {
            n += part->nelts;
        }

    } else {
        n = 1;
    }

    if (ngx_list_init(&cycle->shared_memory, pool, n, sizeof(ngx_shm_zone_t))
        != NGX_OK)
    {
        ngx_destroy_pool(pool);
        return NULL;
    }

    n = old_cycle->listening.nelts ? old_cycle->listening.nelts : 10;

    cycle->listening.elts = ngx_pcalloc(pool, n * sizeof(ngx_listening_t));
    if (cycle->listening.elts == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    cycle->listening.nelts = 0;
    cycle->listening.size = sizeof(ngx_listening_t);
    cycle->listening.nalloc = n;
    cycle->listening.pool = pool;


    ngx_queue_init(&cycle->reusable_connections_queue);


    cycle->conf_ctx = ngx_pcalloc(pool, ngx_max_module * sizeof(void *));
    if (cycle->conf_ctx == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }


    if (gethostname(hostname, NGX_MAXHOSTNAMELEN) == -1) {
        ngx_log_error(NGX_LOG_EMERG, log, ngx_errno, "gethostname() failed");
        ngx_destroy_pool(pool);
        return NULL;
    }

    /* on Linux gethostname() silently truncates name that does not fit */

    hostname[NGX_MAXHOSTNAMELEN - 1] = '\0';
    cycle->hostname.len = ngx_strlen(hostname);

    cycle->hostname.data = ngx_pnalloc(pool, cycle->hostname.len);
    if (cycle->hostname.data == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    ngx_strlow(cycle->hostname.data, (u_char *) hostname, cycle->hostname.len);


    if (ngx_cycle_modules(cycle) != NGX_OK) {
        ngx_destroy_pool(pool);
        return NULL;
    }


    for (i = 0; cycle->modules[i]; i++) {
        if (cycle->modules[i]->type != NGX_CORE_MODULE) {
            continue;
        }

        module = cycle->modules[i]->ctx;

        if (module->create_conf) {
            rv = module->create_conf(cycle);
            if (rv == NULL) {
                ngx_destroy_pool(pool);
                return NULL;
            }
            cycle->conf_ctx[cycle->modules[i]->index] = rv;
        }
    }


    senv = environ;


    ngx_memzero(&conf, sizeof(ngx_conf_t));
    /* STUB: init array ? */
    conf.args = ngx_array_create(pool, 10, sizeof(ngx_str_t));
    if (conf.args == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    conf.temp_pool = ngx_create_pool(NGX_CYCLE_POOL_SIZE, log);
    if (conf.temp_pool == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }


    conf.ctx = cycle->conf_ctx;
    conf.cycle = cycle;
    conf.pool = pool;
    conf.log = log;
    conf.module_type = NGX_CORE_MODULE;
    conf.cmd_type = NGX_MAIN_CONF;

#if 0
    log->log_level = NGX_LOG_DEBUG_ALL;
#endif

    if (ngx_conf_param(&conf) != NGX_CONF_OK) {
        environ = senv;
        ngx_destroy_cycle_pools(&conf);
        return NULL;
    }

    if (ngx_conf_parse(&conf, &cycle->conf_file) != NGX_CONF_OK) {
        environ = senv;
        ngx_destroy_cycle_pools(&conf);
        return NULL;
    }

    if (ngx_test_config && !ngx_quiet_mode) {
        ngx_log_stderr(0, "the configuration file %s syntax is ok",
                       cycle->conf_file.data);
    }

    for (i = 0; cycle->modules[i]; i++) {
        if (cycle->modules[i]->type != NGX_CORE_MODULE) {
            continue;
        }

        module = cycle->modules[i]->ctx;

        if (module->init_conf) {
            if (module->init_conf(cycle,
                                  cycle->conf_ctx[cycle->modules[i]->index])
                == NGX_CONF_ERROR)
            {
                environ = senv;
                ngx_destroy_cycle_pools(&conf);
                return NULL;
            }
        }
    }

    if (ngx_process == NGX_PROCESS_SIGNALLER) {
        return cycle;
    }

    ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);

    if (ngx_test_config) {

        if (ngx_create_pidfile(&ccf->pid, log) != NGX_OK) {
            goto failed;
        }

    } else if (!ngx_is_init_cycle(old_cycle)) {

        /*
         * we do not create the pid file in the first ngx_init_cycle() call
         * because we need to write the demonized process pid
         */

        old_ccf = (ngx_core_conf_t *) ngx_get_conf(old_cycle->conf_ctx,
                                                   ngx_core_module);
        if (ccf->pid.len != old_ccf->pid.len
            || ngx_strcmp(ccf->pid.data, old_ccf->pid.data) != 0)
        {
            /* new pid file name */

            if (ngx_create_pidfile(&ccf->pid, log) != NGX_OK) {
                goto failed;
            }

            ngx_delete_pidfile(old_cycle);
        }
    }


    if (ngx_test_lockfile(cycle->lock_file.data, log) != NGX_OK) {
        goto failed;
    }


    if (ngx_create_paths(cycle, ccf->user) != NGX_OK) {
        goto failed;
    }


    if (ngx_log_open_default(cycle) != NGX_OK) {
        goto failed;
    }

    /* open the new files */

    part = &cycle->open_files.part;
    file = part->elts;

    for (i = 0; /* void */ ; i++) {

        if (i >= part->nelts) {
            if (part->next == NULL) {
                break;
            }
            part = part->next;
            file = part->elts;
            i = 0;
        }

        if (file[i].name.len == 0) {
            continue;
        }

        file[i].fd = ngx_open_file(file[i].name.data,
                                   NGX_FILE_APPEND,
                                   NGX_FILE_CREATE_OR_OPEN,
                                   NGX_FILE_DEFAULT_ACCESS);

        ngx_log_debug3(NGX_LOG_DEBUG_CORE, log, 0,
                       "log: %p %d \"%s\"",
                       &file[i], file[i].fd, file[i].name.data);

        if (file[i].fd == NGX_INVALID_FILE) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
                          ngx_open_file_n " \"%s\" failed",
                          file[i].name.data);
            goto failed;
        }

#if !(NGX_WIN32)
        if (fcntl(file[i].fd, F_SETFD, FD_CLOEXEC) == -1) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
                          "fcntl(FD_CLOEXEC) \"%s\" failed",
                          file[i].name.data);
            goto failed;
        }
#endif
    }

    cycle->log = &cycle->new_log;
    pool->log = &cycle->new_log;


    /* create shared memory */

    part = &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;
        }

        if (shm_zone[i].shm.size == 0) {
            ngx_log_error(NGX_LOG_EMERG, log, 0,
                          "zero size shared memory zone \"%V\"",
                          &shm_zone[i].shm.name);
            goto failed;
        }

        shm_zone[i].shm.log = cycle->log;

        opart = &old_cycle->shared_memory.part;
        oshm_zone = opart->elts;

        for (n = 0; /* void */ ; n++) {

            if (n >= opart->nelts) {
                if (opart->next == NULL) {
                    break;
                }
                opart = opart->next;
                oshm_zone = opart->elts;
                n = 0;
            }

            if (shm_zone[i].shm.name.len != oshm_zone[n].shm.name.len) {
                continue;
            }

            if (ngx_strncmp(shm_zone[i].shm.name.data,
                            oshm_zone[n].shm.name.data,
                            shm_zone[i].shm.name.len)
                != 0)
            {
                continue;
            }

            if (shm_zone[i].tag == oshm_zone[n].tag
                && shm_zone[i].shm.size == oshm_zone[n].shm.size
                && !shm_zone[i].noreuse)
            {
                shm_zone[i].shm.addr = oshm_zone[n].shm.addr;
#if (NGX_WIN32)
                shm_zone[i].shm.handle = oshm_zone[n].shm.handle;
#endif

                if (shm_zone[i].init(&shm_zone[i], oshm_zone[n].data)
                    != NGX_OK)
                {
                    goto failed;
                }

                goto shm_zone_found;
            }

            ngx_shm_free(&oshm_zone[n].shm);

            break;
        }

        if (ngx_shm_alloc(&shm_zone[i].shm) != NGX_OK) {
            goto failed;
        }

        if (ngx_init_zone_pool(cycle, &shm_zone[i]) != NGX_OK) {
            goto failed;
        }

        if (shm_zone[i].init(&shm_zone[i], NULL) != NGX_OK) {
            goto failed;
        }

    shm_zone_found:

        continue;
    }


    /* handle the listening sockets */

    if (old_cycle->listening.nelts) {
        ls = old_cycle->listening.elts;
        for (i = 0; i < old_cycle->listening.nelts; i++) {
            ls[i].remain = 0;
        }

        nls = cycle->listening.elts;
        for (n = 0; n < cycle->listening.nelts; n++) {

            for (i = 0; i < old_cycle->listening.nelts; i++) {
                if (ls[i].ignore) {
                    continue;
                }

                if (ls[i].remain) {
                    continue;
                }

                if (ls[i].type != nls[n].type) {
                    continue;
                }

                if (ngx_cmp_sockaddr(nls[n].sockaddr, nls[n].socklen,
                                     ls[i].sockaddr, ls[i].socklen, 1)
                    == NGX_OK)
                {
                    nls[n].fd = ls[i].fd;
                    nls[n].previous = &ls[i];
                    ls[i].remain = 1;

                    if (ls[i].backlog != nls[n].backlog) {
                        nls[n].listen = 1;
                    }

#if (NGX_HAVE_DEFERRED_ACCEPT && defined SO_ACCEPTFILTER)

                    /*
                     * FreeBSD, except the most recent versions,
                     * could not remove accept filter
                     */
                    nls[n].deferred_accept = ls[i].deferred_accept;

                    if (ls[i].accept_filter && nls[n].accept_filter) {
                        if (ngx_strcmp(ls[i].accept_filter,
                                       nls[n].accept_filter)
                            != 0)
                        {
                            nls[n].delete_deferred = 1;
                            nls[n].add_deferred = 1;
                        }

                    } else if (ls[i].accept_filter) {
                        nls[n].delete_deferred = 1;

                    } else if (nls[n].accept_filter) {
                        nls[n].add_deferred = 1;
                    }
#endif

#if (NGX_HAVE_DEFERRED_ACCEPT && defined TCP_DEFER_ACCEPT)

                    if (ls[i].deferred_accept && !nls[n].deferred_accept) {
                        nls[n].delete_deferred = 1;

                    } else if (ls[i].deferred_accept != nls[n].deferred_accept)
                    {
                        nls[n].add_deferred = 1;
                    }
#endif

#if (NGX_HAVE_REUSEPORT)
                    if (nls[n].reuseport && !ls[i].reuseport) {
                        nls[n].add_reuseport = 1;
                    }
#endif

                    break;
                }
            }

            if (nls[n].fd == (ngx_socket_t) -1) {
                nls[n].open = 1;
#if (NGX_HAVE_DEFERRED_ACCEPT && defined SO_ACCEPTFILTER)
                if (nls[n].accept_filter) {
                    nls[n].add_deferred = 1;
                }
#endif
#if (NGX_HAVE_DEFERRED_ACCEPT && defined TCP_DEFER_ACCEPT)
                if (nls[n].deferred_accept) {
                    nls[n].add_deferred = 1;
                }
#endif
            }
        }

    } else {
        ls = cycle->listening.elts;
        for (i = 0; i < cycle->listening.nelts; i++) {
            ls[i].open = 1;
#if (NGX_HAVE_DEFERRED_ACCEPT && defined SO_ACCEPTFILTER)
            if (ls[i].accept_filter) {
                ls[i].add_deferred = 1;
            }
#endif
#if (NGX_HAVE_DEFERRED_ACCEPT && defined TCP_DEFER_ACCEPT)
            if (ls[i].deferred_accept) {
                ls[i].add_deferred = 1;
            }
#endif
        }
    }

    if (ngx_open_listening_sockets(cycle) != NGX_OK) {
        goto failed;
    }

    if (!ngx_test_config) {
        ngx_configure_listening_sockets(cycle);
    }


    /* commit the new cycle configuration */

    if (!ngx_use_stderr) {
        (void) ngx_log_redirect_stderr(cycle);
    }

    pool->log = cycle->log;

    if (ngx_init_modules(cycle) != NGX_OK) {
        /* fatal */
        exit(1);
    }


    /* close and delete stuff that lefts from an old cycle */

    /* free the unnecessary shared memory */

    opart = &old_cycle->shared_memory.part;
    oshm_zone = opart->elts;

    for (i = 0; /* void */ ; i++) {

        if (i >= opart->nelts) {
            if (opart->next == NULL) {
                goto old_shm_zone_done;
            }
            opart = opart->next;
            oshm_zone = opart->elts;
            i = 0;
        }

        part = &cycle->shared_memory.part;
        shm_zone = part->elts;

        for (n = 0; /* void */ ; n++) {

            if (n >= part->nelts) {
                if (part->next == NULL) {
                    break;
                }
                part = part->next;
                shm_zone = part->elts;
                n = 0;
            }

            if (oshm_zone[i].shm.name.len == shm_zone[n].shm.name.len
                && ngx_strncmp(oshm_zone[i].shm.name.data,
                               shm_zone[n].shm.name.data,
                               oshm_zone[i].shm.name.len)
                == 0)
            {
                goto live_shm_zone;
            }
        }

        ngx_shm_free(&oshm_zone[i].shm);

    live_shm_zone:

        continue;
    }

old_shm_zone_done:


    /* close the unnecessary listening sockets */

    ls = old_cycle->listening.elts;
    for (i = 0; i < old_cycle->listening.nelts; i++) {

        if (ls[i].remain || ls[i].fd == (ngx_socket_t) -1) {
            continue;
        }

        if (ngx_close_socket(ls[i].fd) == -1) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_socket_errno,
                          ngx_close_socket_n " listening socket on %V failed",
                          &ls[i].addr_text);
        }

#if (NGX_HAVE_UNIX_DOMAIN)

        if (ls[i].sockaddr->sa_family == AF_UNIX) {
            u_char  *name;

            name = ls[i].addr_text.data + sizeof("unix:") - 1;

            ngx_log_error(NGX_LOG_WARN, cycle->log, 0,
                          "deleting socket %s", name);

            if (ngx_delete_file(name) == NGX_FILE_ERROR) {
                ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_socket_errno,
                              ngx_delete_file_n " %s failed", name);
            }
        }

#endif
    }


    /* close the unnecessary open files */

    part = &old_cycle->open_files.part;
    file = part->elts;

    for (i = 0; /* void */ ; i++) {

        if (i >= part->nelts) {
            if (part->next == NULL) {
                break;
            }
            part = part->next;
            file = part->elts;
            i = 0;
        }

        if (file[i].fd == NGX_INVALID_FILE || file[i].fd == ngx_stderr) {
            continue;
        }

        if (ngx_close_file(file[i].fd) == NGX_FILE_ERROR) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
                          ngx_close_file_n " \"%s\" failed",
                          file[i].name.data);
        }
    }

    ngx_destroy_pool(conf.temp_pool);

    if (ngx_process == NGX_PROCESS_MASTER || ngx_is_init_cycle(old_cycle)) {

        /*
         * perl_destruct() frees environ, if it is not the same as it was at
         * perl_construct() time, therefore we save the previous cycle
         * environment before ngx_conf_parse() where it will be changed.
         */

        env = environ;
        environ = senv;

        ngx_destroy_pool(old_cycle->pool);
        cycle->old_cycle = NULL;

        environ = env;

        return cycle;
    }


    if (ngx_temp_pool == NULL) {
        ngx_temp_pool = ngx_create_pool(128, cycle->log);
        if (ngx_temp_pool == NULL) {
            ngx_log_error(NGX_LOG_EMERG, cycle->log, 0,
                          "could not create ngx_temp_pool");
            exit(1);
        }

        n = 10;
        ngx_old_cycles.elts = ngx_pcalloc(ngx_temp_pool,
                                          n * sizeof(ngx_cycle_t *));
        if (ngx_old_cycles.elts == NULL) {
            exit(1);
        }
        ngx_old_cycles.nelts = 0;
        ngx_old_cycles.size = sizeof(ngx_cycle_t *);
        ngx_old_cycles.nalloc = n;
        ngx_old_cycles.pool = ngx_temp_pool;

        ngx_cleaner_event.handler = ngx_clean_old_cycles;
        ngx_cleaner_event.log = cycle->log;
        ngx_cleaner_event.data = &dumb;
        dumb.fd = (ngx_socket_t) -1;
    }

    ngx_temp_pool->log = cycle->log;

    old = ngx_array_push(&ngx_old_cycles);
    if (old == NULL) {
        exit(1);
    }
    *old = old_cycle;

    if (!ngx_cleaner_event.timer_set) {
        ngx_add_timer(&ngx_cleaner_event, 30000);
        ngx_cleaner_event.timer_set = 1;
    }

    return cycle;


failed:

    if (!ngx_is_init_cycle(old_cycle)) {
        old_ccf = (ngx_core_conf_t *) ngx_get_conf(old_cycle->conf_ctx,
                                                   ngx_core_module);
        if (old_ccf->environment) {
            environ = old_ccf->environment;
        }
    }

    /* rollback the new cycle configuration */

    part = &cycle->open_files.part;
    file = part->elts;

    for (i = 0; /* void */ ; i++) {

        if (i >= part->nelts) {
            if (part->next == NULL) {
                break;
            }
            part = part->next;
            file = part->elts;
            i = 0;
        }

        if (file[i].fd == NGX_INVALID_FILE || file[i].fd == ngx_stderr) {
            continue;
        }

        if (ngx_close_file(file[i].fd) == NGX_FILE_ERROR) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
                          ngx_close_file_n " \"%s\" failed",
                          file[i].name.data);
        }
    }

    if (ngx_test_config) {
        ngx_destroy_cycle_pools(&conf);
        return NULL;
    }

    ls = cycle->listening.elts;
    for (i = 0; i < cycle->listening.nelts; i++) {
        if (ls[i].fd == (ngx_socket_t) -1 || !ls[i].open) {
            continue;
        }

        if (ngx_close_socket(ls[i].fd) == -1) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_socket_errno,
                          ngx_close_socket_n " %V failed",
                          &ls[i].addr_text);
        }
    }

    ngx_destroy_cycle_pools(&conf);

    return NULL;
}

函数ngx_init_cycle()很长,下面我们分成几个部分来进行讲解:

3.1 更新当前时间

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
    ngx_time_t          *tp;


    ngx_timezone_update();

    /* force localtime update with a new timezone */

    tp = ngx_timeofday();
    tp->sec = 0;

    ngx_time_update();
}

这里首先更新时区(timezone),然后更新时间。这里tp是nginx缓存的最新时间,只所有有tp->sec=0,主要是跟nginx时间更新的实现策略有关:

void
ngx_time_update(void)
{
    ...
   
    tp = &cached_time[slot];

    if (tp->sec == sec) {
        tp->msec = msec;
        ngx_unlock(&ngx_time_lock);
        return;
    }
    ...
}

可以看到,在sec相同的情况下,ngx_time_update()并不会对所有缓存的内容进行更新,这是为了效率方面的考虑。而tp->sec=0,能够确保实现对所有缓存时间的更新。

3.2 配置文件路径相关初始化

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
    log = old_cycle->log;

    pool = ngx_create_pool(NGX_CYCLE_POOL_SIZE, log);
    if (pool == NULL) {
        return NULL;
    }
    pool->log = log;

    cycle = ngx_pcalloc(pool, sizeof(ngx_cycle_t));
    if (cycle == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    cycle->pool = pool;
    cycle->log = log;
    cycle->old_cycle = old_cycle;

    cycle->conf_prefix.len = old_cycle->conf_prefix.len;
    cycle->conf_prefix.data = ngx_pstrdup(pool, &old_cycle->conf_prefix);
    if (cycle->conf_prefix.data == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    cycle->prefix.len = old_cycle->prefix.len;
    cycle->prefix.data = ngx_pstrdup(pool, &old_cycle->prefix);
    if (cycle->prefix.data == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    cycle->conf_file.len = old_cycle->conf_file.len;
    cycle->conf_file.data = ngx_pnalloc(pool, old_cycle->conf_file.len + 1);
    if (cycle->conf_file.data == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }
    ngx_cpystrn(cycle->conf_file.data, old_cycle->conf_file.data,
                old_cycle->conf_file.len + 1);

    cycle->conf_param.len = old_cycle->conf_param.len;
    cycle->conf_param.data = ngx_pstrdup(pool, &old_cycle->conf_param);
    if (cycle->conf_param.data == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }


    n = old_cycle->paths.nelts ? old_cycle->paths.nelts : 10;

    cycle->paths.elts = ngx_pcalloc(pool, n * sizeof(ngx_path_t *));
    if (cycle->paths.elts == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    cycle->paths.nelts = 0;
    cycle->paths.size = sizeof(ngx_path_t *);
    cycle->paths.nalloc = n;
    cycle->paths.pool = pool;


    if (ngx_array_init(&cycle->config_dump, pool, 1, sizeof(ngx_conf_dump_t))
        != NGX_OK)
    {
        ngx_destroy_pool(pool);
        return NULL;
    }

    if (old_cycle->open_files.part.nelts) {
        n = old_cycle->open_files.part.nelts;
        for (part = old_cycle->open_files.part.next; part; part = part->next) {
            n += part->nelts;
        }

    } else {
        n = 20;
    }

    if (ngx_list_init(&cycle->open_files, pool, n, sizeof(ngx_open_file_t))
        != NGX_OK)
    {
        ngx_destroy_pool(pool);
        return NULL;
    }
}

这里首先为新创建的nginx cycle创建一个NGX_CYCLE_POOL_SIZE(默认16KB)大小的内存池,然后完成配置路径等数据的相关初始化:

  • conf_prefix: 存放nginx配置文件路径前缀(一般是通过-p选项来指定nginx的工作路径,然后使用该路径下的配置文件),这里从old_cycle中进行复制。

  • prefix: nginx路径前缀(后续如日志,pid等都会参考该前缀),这里从old_cycle中进行复制

  • conf_file: nginx配置文件路径。注意到这里并不是用ngx_pstrdup()函数来进行复制,这里conf_file符合标准的C语言字符串形式,以\0方式结尾。从old_cycle中进行复制

  • conf_param: 存放nginx启动时,通过-g选项传递进来的参数。这里从old_cycle中进行复制

  • paths: 这里主要是分配一个ngx_path_t *类型的数组空间,在后续主要是解析配置文件时遇到要打开的文件路径,则把该路径加入到paths中。

  • config_dump: 初始化config_dump数组。config_dump主要是为了在检查nginx配置文件时,将相应的配置dump出来.

  • open_files: 这里为所有以后要打开的文件(用ngx_open_file_t来抽象)分配链表空间

3.3 共享内存抽象数据结构初始化

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{

    if (old_cycle->shared_memory.part.nelts) {
        n = old_cycle->shared_memory.part.nelts;
        for (part = old_cycle->shared_memory.part.next; part; part = part->next)
        {
            n += part->nelts;
        }

    } else {
        n = 1;
    }

    if (ngx_list_init(&cycle->shared_memory, pool, n, sizeof(ngx_shm_zone_t))
        != NGX_OK)
    {
        ngx_destroy_pool(pool);
        return NULL;
    }
}

这里为存放ngx_shm_zone_t数据结构,开辟一个链表空间。

3.4 监听结构数组空间初始化

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
   n = old_cycle->listening.nelts ? old_cycle->listening.nelts : 10;

    cycle->listening.elts = ngx_pcalloc(pool, n * sizeof(ngx_listening_t));
    if (cycle->listening.elts == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    cycle->listening.nelts = 0;
    cycle->listening.size = sizeof(ngx_listening_t);
    cycle->listening.nalloc = n;
    cycle->listening.pool = pool;


    ngx_queue_init(&cycle->reusable_connections_queue);

}

这里为存放ngx_listening_t数据结构,开辟一个数组空间。另外初始化可复用连接(一般为http长连接)队列。

3.5 nginx模块相关数据结构初始化

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
    cycle->conf_ctx = ngx_pcalloc(pool, ngx_max_module * sizeof(void *));
    if (cycle->conf_ctx == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }


    if (gethostname(hostname, NGX_MAXHOSTNAMELEN) == -1) {
        ngx_log_error(NGX_LOG_EMERG, log, ngx_errno, "gethostname() failed");
        ngx_destroy_pool(pool);
        return NULL;
    }

    /* on Linux gethostname() silently truncates name that does not fit */

    hostname[NGX_MAXHOSTNAMELEN - 1] = '\0';
    cycle->hostname.len = ngx_strlen(hostname);

    cycle->hostname.data = ngx_pnalloc(pool, cycle->hostname.len);
    if (cycle->hostname.data == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    ngx_strlow(cycle->hostname.data, (u_char *) hostname, cycle->hostname.len);


    if (ngx_cycle_modules(cycle) != NGX_OK) {
        ngx_destroy_pool(pool);
        return NULL;
    }


    for (i = 0; cycle->modules[i]; i++) {
        if (cycle->modules[i]->type != NGX_CORE_MODULE) {
            continue;
        }

        module = cycle->modules[i]->ctx;

        if (module->create_conf) {
            rv = module->create_conf(cycle);
            if (rv == NULL) {
                ngx_destroy_pool(pool);
                return NULL;
            }
            cycle->conf_ctx[cycle->modules[i]->index] = rv;
        }
    }
}

这里首先为cycle->conf_ctx四级指针分配足够大的空间,来存储各个模块对应的上下文指针; 然后获得当前nginx运行的主机名;再接着为当前cycle拷贝一份modules指针:

ngx-cycle-modules

对于核心模块,调用module->create_conf来创建上下文对象。例如对于上图所示的ngx_core_module,则会创建出ngx_core_conf_t上下文。然后将上下文保存到cycle->conf_ctx的对应索引处。

3.7 配置文件初始化

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
senv = environ;


    ngx_memzero(&conf, sizeof(ngx_conf_t));
    /* STUB: init array ? */
    conf.args = ngx_array_create(pool, 10, sizeof(ngx_str_t));
    if (conf.args == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }

    conf.temp_pool = ngx_create_pool(NGX_CYCLE_POOL_SIZE, log);
    if (conf.temp_pool == NULL) {
        ngx_destroy_pool(pool);
        return NULL;
    }


    conf.ctx = cycle->conf_ctx;
    conf.cycle = cycle;
    conf.pool = pool;
    conf.log = log;
    conf.module_type = NGX_CORE_MODULE;
    conf.cmd_type = NGX_MAIN_CONF;

#if 0
    log->log_level = NGX_LOG_DEBUG_ALL;
#endif

    if (ngx_conf_param(&conf) != NGX_CONF_OK) {
        environ = senv;
        ngx_destroy_cycle_pools(&conf);
        return NULL;
    }

    if (ngx_conf_parse(&conf, &cycle->conf_file) != NGX_CONF_OK) {
        environ = senv;
        ngx_destroy_cycle_pools(&conf);
        return NULL;
    }

    if (ngx_test_config && !ngx_quiet_mode) {
        ngx_log_stderr(0, "the configuration file %s syntax is ok",
                       cycle->conf_file.data);
    }

    for (i = 0; cycle->modules[i]; i++) {
        if (cycle->modules[i]->type != NGX_CORE_MODULE) {
            continue;
        }

        module = cycle->modules[i]->ctx;

        if (module->init_conf) {
            if (module->init_conf(cycle,
                                  cycle->conf_ctx[cycle->modules[i]->index])
                == NGX_CONF_ERROR)
            {
                environ = senv;
                ngx_destroy_cycle_pools(&conf);
                return NULL;
            }
        }
    }

    if (ngx_process == NGX_PROCESS_SIGNALLER) {
        return cycle;
    }
}

这里首先创建出一个 ngx_conf_t对象,用于后面解析配置时使用。具体执行步骤如下:

  • 调用ngx_conf_param()解析从nginx命令行通过-g选项传递进来的参数(-g传递进来的参数保存在cycle->conf_param中)

  • 调用ngx_conf_parse()解析配置文件,配置文件名称保存在cycle->conf_file中

在通过上面的方法解析完相关配置之后,如果是以nginx -t/-T形式执行,且并未添加-q参数抑制相关错误输出,则这里调用ngx_conf_parse()函数打印出相关配置文件信息

再接着针对cycle->modules中的所有核心模块,会调用该核心模块所绑定上下文的init_conf函数指针完成相关的初始化(注意核心模块上下文所用到的数据结构会通过前面讲到的create_conf来完成)。

最后如果ngx_process值为NGX_PROCESS_SIGNALLER,则到此为止完成了整个nginx cycle的初始化。

3.8 完成相关文件及路径的创建

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
	   ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);

    if (ngx_test_config) {

        if (ngx_create_pidfile(&ccf->pid, log) != NGX_OK) {
            goto failed;
        }

    } else if (!ngx_is_init_cycle(old_cycle)) {

        /*
         * we do not create the pid file in the first ngx_init_cycle() call
         * because we need to write the demonized process pid
         */

        old_ccf = (ngx_core_conf_t *) ngx_get_conf(old_cycle->conf_ctx,
                                                   ngx_core_module);
        if (ccf->pid.len != old_ccf->pid.len
            || ngx_strcmp(ccf->pid.data, old_ccf->pid.data) != 0)
        {
            /* new pid file name */

            if (ngx_create_pidfile(&ccf->pid, log) != NGX_OK) {
                goto failed;
            }

            ngx_delete_pidfile(old_cycle);
        }
    }


    if (ngx_test_lockfile(cycle->lock_file.data, log) != NGX_OK) {
        goto failed;
    }


    if (ngx_create_paths(cycle, ccf->user) != NGX_OK) {
        goto failed;
    }


    if (ngx_log_open_default(cycle) != NGX_OK) {
        goto failed;
    }

    /* open the new files */

    part = &cycle->open_files.part;
    file = part->elts;

    for (i = 0; /* void */ ; i++) {

        if (i >= part->nelts) {
            if (part->next == NULL) {
                break;
            }
            part = part->next;
            file = part->elts;
            i = 0;
        }

        if (file[i].name.len == 0) {
            continue;
        }

        file[i].fd = ngx_open_file(file[i].name.data,
                                   NGX_FILE_APPEND,
                                   NGX_FILE_CREATE_OR_OPEN,
                                   NGX_FILE_DEFAULT_ACCESS);

        ngx_log_debug3(NGX_LOG_DEBUG_CORE, log, 0,
                       "log: %p %d \"%s\"",
                       &file[i], file[i].fd, file[i].name.data);

        if (file[i].fd == NGX_INVALID_FILE) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
                          ngx_open_file_n " \"%s\" failed",
                          file[i].name.data);
            goto failed;
        }

#if !(NGX_WIN32)
        if (fcntl(file[i].fd, F_SETFD, FD_CLOEXEC) == -1) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
                          "fcntl(FD_CLOEXEC) \"%s\" failed",
                          file[i].name.data);
            goto failed;
        }
#endif
    }

    cycle->log = &cycle->new_log;
    pool->log = &cycle->new_log;
}

主要是完成如下事情:

  • pid文件: 如果只是测试配置文件(ngx_test_config),则直接检测能否在指定的位置打开或创建pid文件;如果old_cycle没有初始化,则当前cycle会创建pid文件,并向该文件中写入当前nginx master进程的进程ID。

  • 测试锁文件: nginx使用锁机制来实现accept mutex,并且顺序的来访问共享内存。在大多数的系统上,锁都是通过原子操作来实现的,因此会忽略配置文件中的lock_file file指令;而对于其他的一些系统,lock file机制会被使用 默认的lock文件存放位置为logs/nginx.lock

  • 创建相应的路径: 这里调用ngx_create_paths()函数来创建相应的路径。在Nginx配置文件中,会配置一些临时路径,在解析配置文件时会将这些路径保存起来,然后在这里统一创建。

  • 打开默认的日志文件

  • 打开所有配置文件中指定的相关文件,例如http log文件等,并设置FD_CLOEXEC属性,这使得通过exec调用之后,文件描述符会被关闭

  • 设置cycle->log与pool->log

cycle->log = &cycle->new_log;
pool->log = &cycle->new_log;

3.9 创建共享内存

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
/* create shared memory */

    part = &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;
        }

        if (shm_zone[i].shm.size == 0) {
            ngx_log_error(NGX_LOG_EMERG, log, 0,
                          "zero size shared memory zone \"%V\"",
                          &shm_zone[i].shm.name);
            goto failed;
        }

        shm_zone[i].shm.log = cycle->log;

        opart = &old_cycle->shared_memory.part;
        oshm_zone = opart->elts;

        for (n = 0; /* void */ ; n++) {

            if (n >= opart->nelts) {
                if (opart->next == NULL) {
                    break;
                }
                opart = opart->next;
                oshm_zone = opart->elts;
                n = 0;
            }

            if (shm_zone[i].shm.name.len != oshm_zone[n].shm.name.len) {
                continue;
            }

            if (ngx_strncmp(shm_zone[i].shm.name.data,
                            oshm_zone[n].shm.name.data,
                            shm_zone[i].shm.name.len)
                != 0)
            {
                continue;
            }

            if (shm_zone[i].tag == oshm_zone[n].tag
                && shm_zone[i].shm.size == oshm_zone[n].shm.size
                && !shm_zone[i].noreuse)
            {
                shm_zone[i].shm.addr = oshm_zone[n].shm.addr;
#if (NGX_WIN32)
                shm_zone[i].shm.handle = oshm_zone[n].shm.handle;
#endif

                if (shm_zone[i].init(&shm_zone[i], oshm_zone[n].data)
                    != NGX_OK)
                {
                    goto failed;
                }

                goto shm_zone_found;
            }

            ngx_shm_free(&oshm_zone[n].shm);

            break;
        }

        if (ngx_shm_alloc(&shm_zone[i].shm) != NGX_OK) {
            goto failed;
        }

        if (ngx_init_zone_pool(cycle, &shm_zone[i]) != NGX_OK) {
            goto failed;
        }

        if (shm_zone[i].init(&shm_zone[i], NULL) != NGX_OK) {
            goto failed;
        }

    shm_zone_found:

        continue;
    }

}

这里首先在解析配置文件时,遇到要开设相关的公共缓冲区,就会调用ngx_shared_memory_add()方法将添加到cycle->shared_memory链表中。在这里会根据共享内存namesize,tag以及noreuse等标志决定是否复用原来老的共享内存还是创建新的共享内存。

3.10 处理listening sockets

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
	/* handle the listening sockets */

    if (old_cycle->listening.nelts) {
        ls = old_cycle->listening.elts;
        for (i = 0; i < old_cycle->listening.nelts; i++) {
            ls[i].remain = 0;
        }

        nls = cycle->listening.elts;
        for (n = 0; n < cycle->listening.nelts; n++) {

            for (i = 0; i < old_cycle->listening.nelts; i++) {
                if (ls[i].ignore) {
                    continue;
                }

                if (ls[i].remain) {
                    continue;
                }

                if (ls[i].type != nls[n].type) {
                    continue;
                }

                if (ngx_cmp_sockaddr(nls[n].sockaddr, nls[n].socklen,
                                     ls[i].sockaddr, ls[i].socklen, 1)
                    == NGX_OK)
                {
                    nls[n].fd = ls[i].fd;
                    nls[n].previous = &ls[i];
                    ls[i].remain = 1;

                    if (ls[i].backlog != nls[n].backlog) {
                        nls[n].listen = 1;
                    }

#if (NGX_HAVE_DEFERRED_ACCEPT && defined SO_ACCEPTFILTER)

                    /*
                     * FreeBSD, except the most recent versions,
                     * could not remove accept filter
                     */
                    nls[n].deferred_accept = ls[i].deferred_accept;

                    if (ls[i].accept_filter && nls[n].accept_filter) {
                        if (ngx_strcmp(ls[i].accept_filter,
                                       nls[n].accept_filter)
                            != 0)
                        {
                            nls[n].delete_deferred = 1;
                            nls[n].add_deferred = 1;
                        }

                    } else if (ls[i].accept_filter) {
                        nls[n].delete_deferred = 1;

                    } else if (nls[n].accept_filter) {
                        nls[n].add_deferred = 1;
                    }
#endif

#if (NGX_HAVE_DEFERRED_ACCEPT && defined TCP_DEFER_ACCEPT)

                    if (ls[i].deferred_accept && !nls[n].deferred_accept) {
                        nls[n].delete_deferred = 1;

                    } else if (ls[i].deferred_accept != nls[n].deferred_accept)
                    {
                        nls[n].add_deferred = 1;
                    }
#endif

#if (NGX_HAVE_REUSEPORT)
                    if (nls[n].reuseport && !ls[i].reuseport) {
                        nls[n].add_reuseport = 1;
                    }
#endif

                    break;
                }
            }

            if (nls[n].fd == (ngx_socket_t) -1) {
                nls[n].open = 1;
#if (NGX_HAVE_DEFERRED_ACCEPT && defined SO_ACCEPTFILTER)
                if (nls[n].accept_filter) {
                    nls[n].add_deferred = 1;
                }
#endif
#if (NGX_HAVE_DEFERRED_ACCEPT && defined TCP_DEFER_ACCEPT)
                if (nls[n].deferred_accept) {
                    nls[n].add_deferred = 1;
                }
#endif
            }
        }

    } else {
        ls = cycle->listening.elts;
        for (i = 0; i < cycle->listening.nelts; i++) {
            ls[i].open = 1;
#if (NGX_HAVE_DEFERRED_ACCEPT && defined SO_ACCEPTFILTER)
            if (ls[i].accept_filter) {
                ls[i].add_deferred = 1;
            }
#endif
#if (NGX_HAVE_DEFERRED_ACCEPT && defined TCP_DEFER_ACCEPT)
            if (ls[i].deferred_accept) {
                ls[i].add_deferred = 1;
            }
#endif
        }
    }

    if (ngx_open_listening_sockets(cycle) != NGX_OK) {
        goto failed;
    }

    if (!ngx_test_config) {
        ngx_configure_listening_sockets(cycle);
    }

}

这里分两种情况进行处理:

  • 如果old_cycle->listening.nelts不为0,则表明有遗留的监听socket。此种情况下分别遍历old_cyle->listening与ngx_cycle->listening,看old_cycle中是否有socket可以复用

  • 否则,直接遍历ngx_cycle->listening,设置相关属性

再接着打开cycle->listening中符合条件的socket,然后再对cycle->listening的socket进行配置。

3.11 提交cycle设置

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
    /* commit the new cycle configuration */

    if (!ngx_use_stderr) {
        (void) ngx_log_redirect_stderr(cycle);
    }

    pool->log = cycle->log;

    if (ngx_init_modules(cycle) != NGX_OK) {
        /* fatal */
        exit(1);
    }
}

在重新加载配置文件时,调用ngx_init_cycle(),此时ngx_use_stderr变量为0,调用:

ngx_log_redirect_stderr(cycle);

重定向标准错误。再接着调用ngx_init_modules()完成各个模块的初始化。

3.12 移除old cycle中的共享内存

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
	/* close and delete stuff that lefts from an old cycle */

    /* free the unnecessary shared memory */

    opart = &old_cycle->shared_memory.part;
    oshm_zone = opart->elts;

    for (i = 0; /* void */ ; i++) {

        if (i >= opart->nelts) {
            if (opart->next == NULL) {
                goto old_shm_zone_done;
            }
            opart = opart->next;
            oshm_zone = opart->elts;
            i = 0;
        }

        part = &cycle->shared_memory.part;
        shm_zone = part->elts;

        for (n = 0; /* void */ ; n++) {

            if (n >= part->nelts) {
                if (part->next == NULL) {
                    break;
                }
                part = part->next;
                shm_zone = part->elts;
                n = 0;
            }

            if (oshm_zone[i].shm.name.len == shm_zone[n].shm.name.len
                && ngx_strncmp(oshm_zone[i].shm.name.data,
                               shm_zone[n].shm.name.data,
                               oshm_zone[i].shm.name.len)
                == 0)
            {
                goto live_shm_zone;
            }
        }

        ngx_shm_free(&oshm_zone[i].shm);

    live_shm_zone:

        continue;
    }

old_shm_zone_done:
}

这里遍历old_cycle->shared_memory与cycle->shared_memory,找出可以删除掉的共享内存。

3.13 关闭不必要的监听socket

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
	
    /* close the unnecessary listening sockets */

    ls = old_cycle->listening.elts;
    for (i = 0; i < old_cycle->listening.nelts; i++) {

        if (ls[i].remain || ls[i].fd == (ngx_socket_t) -1) {
            continue;
        }

        if (ngx_close_socket(ls[i].fd) == -1) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_socket_errno,
                          ngx_close_socket_n " listening socket on %V failed",
                          &ls[i].addr_text);
        }

#if (NGX_HAVE_UNIX_DOMAIN)

        if (ls[i].sockaddr->sa_family == AF_UNIX) {
            u_char  *name;

            name = ls[i].addr_text.data + sizeof("unix:") - 1;

            ngx_log_error(NGX_LOG_WARN, cycle->log, 0,
                          "deleting socket %s", name);

            if (ngx_delete_file(name) == NGX_FILE_ERROR) {
                ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_socket_errno,
                              ngx_delete_file_n " %s failed", name);
            }
        }

#endif
    }

}

这里关闭不能复用的监听socket.

3.14 关闭不必要的打开文件

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
	
    /* close the unnecessary open files */

    part = &old_cycle->open_files.part;
    file = part->elts;

    for (i = 0; /* void */ ; i++) {

        if (i >= part->nelts) {
            if (part->next == NULL) {
                break;
            }
            part = part->next;
            file = part->elts;
            i = 0;
        }

        if (file[i].fd == NGX_INVALID_FILE || file[i].fd == ngx_stderr) {
            continue;
        }

        if (ngx_close_file(file[i].fd) == NGX_FILE_ERROR) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
                          ngx_close_file_n " \"%s\" failed",
                          file[i].name.data);
        }
    }
}

这里关闭掉old_cycle中的打开文件。

3.15 其他相关收尾操作

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
	ngx_destroy_pool(conf.temp_pool);

    if (ngx_process == NGX_PROCESS_MASTER || ngx_is_init_cycle(old_cycle)) {

        /*
         * perl_destruct() frees environ, if it is not the same as it was at
         * perl_construct() time, therefore we save the previous cycle
         * environment before ngx_conf_parse() where it will be changed.
         */

        env = environ;
        environ = senv;

        ngx_destroy_pool(old_cycle->pool);
        cycle->old_cycle = NULL;

        environ = env;

        return cycle;
    }


    if (ngx_temp_pool == NULL) {
        ngx_temp_pool = ngx_create_pool(128, cycle->log);
        if (ngx_temp_pool == NULL) {
            ngx_log_error(NGX_LOG_EMERG, cycle->log, 0,
                          "could not create ngx_temp_pool");
            exit(1);
        }

        n = 10;
        ngx_old_cycles.elts = ngx_pcalloc(ngx_temp_pool,
                                          n * sizeof(ngx_cycle_t *));
        if (ngx_old_cycles.elts == NULL) {
            exit(1);
        }
        ngx_old_cycles.nelts = 0;
        ngx_old_cycles.size = sizeof(ngx_cycle_t *);
        ngx_old_cycles.nalloc = n;
        ngx_old_cycles.pool = ngx_temp_pool;

        ngx_cleaner_event.handler = ngx_clean_old_cycles;
        ngx_cleaner_event.log = cycle->log;
        ngx_cleaner_event.data = &dumb;
        dumb.fd = (ngx_socket_t) -1;
    }

    ngx_temp_pool->log = cycle->log;

    old = ngx_array_push(&ngx_old_cycles);
    if (old == NULL) {
        exit(1);
    }
    *old = old_cycle;

    if (!ngx_cleaner_event.timer_set) {
        ngx_add_timer(&ngx_cleaner_event, 30000);
        ngx_cleaner_event.timer_set = 1;
    }

    return cycle;
}

在成功创建cycle上下文后,进行一些后续的收尾工作。这里在处理NGX_PROCESS_SINGLE类型进程时,我们开启定时器来清除old_cycle,这是为了尽快使进程进入工作状态。

3.16 失败情况下现场还原操作

ngx_cycle_t *
ngx_init_cycle(ngx_cycle_t *old_cycle)
{
	
failed:

    if (!ngx_is_init_cycle(old_cycle)) {
        old_ccf = (ngx_core_conf_t *) ngx_get_conf(old_cycle->conf_ctx,
                                                   ngx_core_module);
        if (old_ccf->environment) {
            environ = old_ccf->environment;
        }
    }

    /* rollback the new cycle configuration */

    part = &cycle->open_files.part;
    file = part->elts;

    for (i = 0; /* void */ ; i++) {

        if (i >= part->nelts) {
            if (part->next == NULL) {
                break;
            }
            part = part->next;
            file = part->elts;
            i = 0;
        }

        if (file[i].fd == NGX_INVALID_FILE || file[i].fd == ngx_stderr) {
            continue;
        }

        if (ngx_close_file(file[i].fd) == NGX_FILE_ERROR) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_errno,
                          ngx_close_file_n " \"%s\" failed",
                          file[i].name.data);
        }
    }

    if (ngx_test_config) {
        ngx_destroy_cycle_pools(&conf);
        return NULL;
    }

    ls = cycle->listening.elts;
    for (i = 0; i < cycle->listening.nelts; i++) {
        if (ls[i].fd == (ngx_socket_t) -1 || !ls[i].open) {
            continue;
        }

        if (ngx_close_socket(ls[i].fd) == -1) {
            ngx_log_error(NGX_LOG_EMERG, log, ngx_socket_errno,
                          ngx_close_socket_n " %V failed",
                          &ls[i].addr_text);
        }
    }

    ngx_destroy_cycle_pools(&conf);

    return NULL;
}

这里在创建新的nginx cycle失败之后,进行相应的现场还原。



[参看]

  1. nginx源码学习(二)ngx_init_cycle(&init_cycle)函数解析