Nginx源码分析 - 主流程篇 - 全局变量cycle初始化

Nginx的大部分初始化工作主要围绕一个类型为ngx_cycle_t类型的全局变量(cycle)展开。本文主要讲解cycle的数据结构以及初始化过程中干了什么事情。

cycle的初始化过程在/src/core/cycle.c文件中。

数据结构

ngx_cycle_t的数据结构

cycle是Nginx贯穿全局的一个全局变量。阅读Nginx的源码必须得先搞清楚cycle全局变量的初始化过程。

/** * Nginx全局变量cycle */struct ngx_cycle_s {    void                  ****conf_ctx; /* 配置文件 上下文的数组，每个模块的配置信息*/    ngx_pool_t               *pool;/* 内存池地址 */    ngx_log_t                *log;/* 日志 */    ngx_log_t                 new_log;    ngx_uint_t                log_use_stderr;  /* unsigned  log_use_stderr:1; */    ngx_connection_t        **files;/* 连接文件句柄 */    ngx_connection_t         *free_connections;/* 空闲连接 */    ngx_uint_t                free_connection_n;/* 空闲连接个数 */    ngx_module_t            **modules;/* 模块数组 */    ngx_uint_t                modules_n;/* 模块个数 */    ngx_uint_t                modules_used;    /* unsigned  modules_used:1; */    ngx_queue_t               reusable_connections_queue;    ngx_array_t               listening;/* 监听数组 */    ngx_array_t               paths;/* 路径数组 */    ngx_array_t               config_dump;    ngx_list_t                open_files;/* 打开的文件 */    ngx_list_t                shared_memory;/* 共享内存链表*/    ngx_uint_t                connection_n;/* 连接的个数*/    ngx_uint_t                files_n;/* 打开文件的个数 */    ngx_connection_t         *connections;/* 连接事件*/    ngx_event_t              *read_events;/* 读取事件*/    ngx_event_t              *write_events; /* 写入事件*/    ngx_cycle_t              *old_cycle;    ngx_str_t                 conf_file;/* 配置文件 */    ngx_str_t                 conf_param;/* 配置参数 */    ngx_str_t                 conf_prefix;/* 配置文件前缀*/    ngx_str_t                 prefix;/* 前缀*/    ngx_str_t                 lock_file;/* 锁文件*/    ngx_str_t                 hostname;/* 主机名称*/};

ngx_core_conf_t的数据结构

ngx_code_conf_t的数据结构主要用于装在Nginx的nginx.conf的核心配置文件的参数。后面我们会具体讲解配置文件nginx.conf的解析过程以及和模块。

/** * 核心配置文件信息 * 对应nginx.conf的 * #user  nobody;worker_processes  1;#error_log  logs/error.log;#error_log  logs/error.log  notice;#error_log  logs/error.log  info;#pid        logs/nginx.pid; */typedef struct {    ngx_flag_t                daemon;    ngx_flag_t                master;    ngx_msec_t                timer_resolution;    ngx_int_t                 worker_processes;    ngx_int_t                 debug_points;    ngx_int_t                 rlimit_nofile;    off_t                     rlimit_core;    int                       priority;    ngx_uint_t                cpu_affinity_auto;    ngx_uint_t                cpu_affinity_n;    ngx_cpuset_t             *cpu_affinity;    char                     *username;    ngx_uid_t                 user;    ngx_gid_t                 group;    ngx_str_t                 working_directory;    ngx_str_t                 lock_file;    ngx_str_t                 pid;    ngx_str_t                 oldpid;    ngx_array_t               env;    char                    **environment;} ngx_core_conf_t;

初始化过程

1. 创建一个内存池。

后续所有的内存都会被分配到这个内存池上面。

    /* 创建一块内存 */    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;

2. 拷贝配置文件的路径前缀（/usr/local/nginx）。

主要拷贝到 cycle->conf_prefix

    /* 配置文件路径拷贝 /usr/local/nginx/ */    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;    }

3. Nginx的路径前缀拷贝。

拷贝到cycle->prefix

    /* Nginx路径拷贝 */    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;    }

4. 拷贝配置文件信息。

/nginx/conf/nginx.conf 文件路径

    /* 配置文件 信息拷贝*/    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);

5. 拷贝配置参数信息。

    /* 配置参数 信息拷贝 */    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;    }

6. 路径信息初始化。

    /* 路径信息 */    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;    }

7. 初始化打开的文件句柄。

    /* 初始化打开的文件句柄 */    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;    }

8. 初始化shared_memory链表

    /* 初始化shared_memory链表 */    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;    }

9. 初始化listening数组

    /* 初始化listening */    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;

10. 模块创建和核心配置结构初始化ngx_core_conf_t

1. 主要初始化cycle->modules

2. 创建核心配置结构，Nginx的核心配置会放到ngx_core_conf_t  *ccf数据结构上

3. 初始化核心配置结构ngx_core_conf_t  *

 /* 创建模块以及创建模块的配置信息 */    if (ngx_cycle_modules(cycle) != NGX_OK) {        ngx_destroy_pool(pool);        return NULL;    }    /*     * 核心模块的配置文件创建     * 配置创建调用nginx.c 中的 ngx_core_module_create_conf     * */    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); //模块回调函数，创建模块的配置信息            if (rv == NULL) {                ngx_destroy_pool(pool);                return NULL;            }            cycle->conf_ctx[cycle->modules[i]->index] = rv; //配置文件复制        }    }

    /* 获取核心配置文件的数据结构 ngx_core_conf_t */    ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);

11. 配置文件nginx.conf解析

配置文件解析会在下章中详细解读。

  /* 解析配置文件 */    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;    }    /* 创建一个临时的内存池，后面会清空掉;conf也主要用于解析配置文件的临时变量 */    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    /* 解析命令行中的配置参数；例如：nginx -t -c /usr/local/nginx/conf/nginx.conf */    if (ngx_conf_param(&conf) != NGX_CONF_OK) {        environ = senv;        ngx_destroy_cycle_pools(&conf);        return NULL;    }    /* 解析配置文件/usr/local/nginx/conf/nginx.conf 信息 */    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);    }

12. 创建PID文件

Nginx将PID写入文件内，/usr/local/nginx-1.4.7/nginx.pid，后续对Nginx进行重启、停止、信号操作就可以使用这个PID了。

 /* 创建pid文件，/usr/local/nginx-1.4.7/nginx.pid*/    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);        }    }

13. 遍历cycle->open_files链表中的文件，并且打开

cycle->open_file主要是在ngx_conf_open_file这个方法里面放入文件路径，然后下面去打开文件。

主要是日志文件和配置文件。

    /* 打开日志，并调用ngx_conf_open_file方法，会将打开的文件放到cycle->open_files链表中 主要是日志文件和配置文件*/    if (ngx_log_open_default(cycle) != NGX_OK) {        goto failed;    }

    /* 遍历cycle->open_files链表中的文件，并打开 */    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    }

14. 创建共享内存并初始化

新旧shared_memory链表的比较，相同的共享内存保留，旧的不同的共享内存被释放，新的被创建

   /* 创建共享内存并初始化 */    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;        }

15. 处理listening数组，并开始监听socket

  /* handle the listening sockets */    /* 处理listening数组，并开始监听socket */    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);    }

16. 关闭或删除残留在old_cycle中的资源

1. 释放多余的共享内存;

2. 关闭多余的侦听sockets;

3. 关闭多余的打开文件

 /* close and delete stuff that lefts from an old cycle */    /* free the unnecessary shared memory */    /* 关闭或删除残留在old_cycle中的资源 释放多余的共享内存;关闭多余的侦听sockets;关闭多余的打开文件*/    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);