nginx0.1.0之event模块初始化源码分析(3)

theanarkh

发布于 2019-03-06 10:58:49

5170

发布于 2019-03-06 10:58:49

前面已经分析了event初始化的整体流程和第一步create_conf，接下来看一下第二步ngx_conf_parse。这里不分析该函数的代码，该函数主要是遍历配置文件的内容，然后读取命令和参数。最后匹配nginx所有模块的配置，找到处理该指令的函数。我们首先看一下event模块中ngx_event_core_module模块的指令配置。

static ngx_command_t  ngx_event_core_commands[] = {

    { ngx_string("connections"),
      NGX_EVENT_CONF|NGX_CONF_TAKE1,
      ngx_event_connections,
      0,
      0,
      NULL },

    { ngx_string("use"),
      NGX_EVENT_CONF|NGX_CONF_TAKE1,
      ngx_event_use,
      0,
      0,
      NULL },

    { ngx_string("multi_accept"),
      NGX_EVENT_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_flag_slot,
      0,
      offsetof(ngx_event_conf_t, multi_accept),
      NULL },

    { ngx_string("accept_mutex"),
      NGX_EVENT_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_flag_slot,
      0,
      offsetof(ngx_event_conf_t, accept_mutex),
      &ngx_accept_mutex_post },

    { ngx_string("accept_mutex_delay"),
      NGX_EVENT_CONF|NGX_CONF_TAKE1,
      ngx_conf_set_msec_slot,
      0,
      offsetof(ngx_event_conf_t, accept_mutex_delay),
      NULL },

    { ngx_string("debug_connection"),
      NGX_EVENT_CONF|NGX_CONF_TAKE1,
      ngx_event_debug_connection,
      0,
      0,
      NULL },

      ngx_null_command
}

然后在看一下每个指令处理函数的代码。

connections指令

//把连接数记录在结构体中
static char *ngx_event_connections(ngx_conf_t *cf, ngx_command_t *cmd,
                                   void *conf)
{
    ngx_event_conf_t  *ecf = conf;

    ngx_str_t  *value;
    // 已经初始化过了
    if (ecf->connections != NGX_CONF_UNSET_UINT) {
        return "is duplicate" ;
    }
    // 从配置文件中解析出来的配置
    value = cf->args->elts;
    // 字符串转成整形
    ecf->connections = ngx_atoi(value[1].data, value[1].len);
    if (ecf->connections == (ngx_uint_t) NGX_ERROR) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "invalid number \"%s\"", value[1].data);

        return NGX_CONF_ERROR;
    }

    cf->cycle->connection_n = ecf->connections;

    return NGX_CONF_OK;
}

use指令

// 记录use和name的值
static char *ngx_event_use(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_event_conf_t  *ecf = conf;

    ngx_int_t             m;
    ngx_str_t            *value;
    ngx_event_conf_t     *old_ecf;
    ngx_event_module_t   *module;

    if (ecf->use != NGX_CONF_UNSET_UINT) {
        return "is duplicate" ;
    }

    value = cf->args->elts;

    if (cf->cycle->old_cycle->conf_ctx) {
        old_ecf = ngx_event_get_conf(cf->cycle->old_cycle->conf_ctx,
                                     ngx_event_core_module);
    } else {
        old_ecf = NULL;
    }

    // 判断使用哪个事件驱动模块，比如use epoll，则使用epoll
    for (m = 0; ngx_modules[m]; m++) {
        if (ngx_modules[m]->type != NGX_EVENT_MODULE) {
            continue;
        }

        module = ngx_modules[m]->ctx;
        if (module->name->len == value[1].len) {
            if (ngx_strcmp(module->name->data, value[1].data) == 0) {
                // 存储事件模块的下标,而不是字符串
                ecf->use = ngx_modules[m]->ctx_index;
                ecf->name = module->name->data;

                if (ngx_process == NGX_PROCESS_SINGLE
                    && old_ecf
                    && old_ecf->use != ecf->use)
                {
                    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                        "when the server runs without a master process "
                        "the \"%s\" event type must be the same as "
                        "in previous configuration - \"%s\" "
                        "and it can not be changed on the fly, "
                        "to change it you need to stop server "
                        "and start it again",
                        value[1].data, old_ecf->name);

                    return NGX_CONF_ERROR;
                }

                return NGX_CONF_OK;
            }
        }
    }

    ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                       "invalid event type \"%s\"", value[1].data);

    return NGX_CONF_ERROR;
}

multi_accept指令

char *ngx_conf_set_flag_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    char  *p = conf;

    ngx_str_t        *value;
    ngx_flag_t       *fp;
    ngx_conf_post_t  *post;

    fp = (ngx_flag_t *) (p + cmd->offset);

    if (*fp != NGX_CONF_UNSET) {
        return "is duplicate";
    }

    value = cf->args->elts;
    // on代表开启
    if (ngx_strcasecmp(value[1].data, "on") == 0) {
        *fp = 1;

    } else if (ngx_strcasecmp(value[1].data, "off") == 0) {
        *fp = 0;

    } else {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                     "invalid value \"%s\" in \"%s\" directive, "
                     "it must be \"on\" or \"off\"",
                     value[1].data, cmd->name.data);
        return NGX_CONF_ERROR;
    }
    // 设置完值后执行后置函数，一般是参数检查
    if (cmd->post) {
        post = cmd->post;
        return post->post_handler(cf, post, fp);
    }

    return NGX_CONF_OK;
}

accept_mutex指令（见上面的ngx_conf_set_flag_slot函数）

该指令配置了handle函数
ngx_conf_post_t  ngx_accept_mutex_post = { ngx_accept_mutex_check } 
static char *ngx_accept_mutex_check(ngx_conf_t *cf, void *post, void *data)
{
// 不支持该功能，重置字段
#if !(NGX_HAVE_ATOMIC_OPS)

    ngx_flag_t *fp = data;

    *fp = 0;

    ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
                       "\"accept_mutex\" is not supported, ignored");

#endif

    return NGX_CONF_OK;
}

accept_mutex_delay指令

char *ngx_conf_set_msec_slot(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    char  *p = conf;

    ngx_msec_t       *msp;
    ngx_str_t        *value;
    ngx_conf_post_t  *post;


    msp = (ngx_msec_t *) (p + cmd->offset);
    if (*msp != NGX_CONF_UNSET_MSEC) {
        return "is duplicate";
    }

    value = cf->args->elts;
    // 把字符串解析成时间
    *msp = ngx_parse_time(&value[1], 0);
    if (*msp == (ngx_msec_t) NGX_ERROR) {
        return "invalid value";
    }

    if (*msp == (ngx_msec_t) NGX_PARSE_LARGE_TIME) {
        return "value must be less than 597 hours";
    }

    if (cmd->post) {
        post = cmd->post;
        return post->post_handler(cf, post, msp);
    }

    return NGX_CONF_OK;
}

debug_connection指令

static char *ngx_event_debug_connection(ngx_conf_t *cf, ngx_command_t *cmd,
                                        void *conf)
{
// 配置后需要开启debug参数
#if (NGX_DEBUG)
    ngx_event_conf_t  *ecf = conf;

    in_addr_t       *addr;
    ngx_str_t       *value;
    struct hostent  *h;

    value = cf->args->elts;

    /* AF_INET only */

    if (!(addr = ngx_push_array(&ecf->debug_connection))) {
        return NGX_CONF_ERROR;
    }
    // 将ip转成长整型
    *addr = inet_addr((char *) value[1].data);
    // 转成功则返回
    if (*addr != INADDR_NONE) {
        return NGX_OK;
    }
    // 没转成功可能是一个主机字符串，获取该主机对应的ip信息
    h = gethostbyname((char *) value[1].data);

    if (h == NULL || h->h_addr_list[0] == NULL) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "host %s not found", value[1].data);
        return NGX_CONF_ERROR;
}

    *addr = *(in_addr_t *)(h->h_addr_list[0]);

#else

    ngx_conf_log_error(NGX_LOG_WARN, cf, 0,
                       "\"debug_connection\" is ignored, you need to rebuild "
                       "nginx using --with-debug option to enable it");

#endif

    return NGX_OK;
}

还有事件驱动模块的一些配置，比如epoll模块的epoll_events指令，几乎都是简单地对相应模块的配置结构体的某个字段进行赋值。

到这里，event模块关于配置文件解析的部分就结束了。主要就是对下图中最右边的那个数组里的结构体进行赋值。event各子模块的init_conf函数的功能就是，如果解析配置文件的时候，没有对下图右侧的结构体相应的字段进行赋值，那init_conf函数就初始化一个默认的值。

如epoll的init_conf函数如下。

static char *ngx_epoll_init_conf(ngx_cycle_t *cycle, void *conf)
{
    ngx_epoll_conf_t *epcf = conf;

    ngx_conf_init_unsigned_value(epcf->events, 512);

    return NGX_CONF_OK;
}

初始化完配置后，nginx执行各模块的init_module函数，event模块中只有ngx_core_module子模块实现了该函数。代码如下。

static ngx_int_t ngx_event_module_init(ngx_cycle_t *cycle)
{
#if !(WIN32)

    size_t             size;
    char              *shared;
    ngx_core_conf_t   *ccf;
    ngx_event_conf_t  *ecf;

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

    if (ccf->master == 0 || ngx_accept_mutex_ptr) {
        return NGX_OK;
    }
    // 获取ngx_event_core_module模块的配置，即ngx_event_conf_t结构体
    ecf = ngx_event_get_conf(cycle->conf_ctx, ngx_event_core_module);


    /* TODO: 128 is cache line size */

    size = 128            /* ngx_accept_mutex */
           + 128;         /* ngx_connection_counter */

#if (NGX_STAT_STUB)

    size += 128           /* ngx_stat_accepted */
           + 128          /* ngx_stat_requests */
           + 128          /* ngx_stat_active */
           + 128          /* ngx_stat_reading */
           + 128;         /* ngx_stat_writing */

#endif
    // 创建进程间共享的内存
    if (!(shared = ngx_create_shared_memory(size, cycle->log))) {
        return NGX_ERROR;
    }

    ngx_accept_mutex_ptr = (ngx_atomic_t *) shared;
    ngx_connection_counter = (ngx_atomic_t *) (shared + 128);

#if (NGX_STAT_STUB)

    ngx_stat_accepted = (ngx_atomic_t *) (shared + 2 * 128);
    ngx_stat_requests = (ngx_atomic_t *) (shared + 3 * 128);
    ngx_stat_active = (ngx_atomic_t *) (shared + 4 * 128);
    ngx_stat_reading = (ngx_atomic_t *) (shared + 5 * 128);
    ngx_stat_writing = (ngx_atomic_t *) (shared + 6 * 128);

#endif

    ngx_log_debug2(NGX_LOG_DEBUG_EVENT, cycle->log, 0,
                   "counter: " PTR_FMT ", %d",
                   ngx_connection_counter, *ngx_connection_counter);

#endif

    return NGX_OK;
}

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原始发表：2019-03-01，如有侵权请联系 cloudcommunity@tencent.com 删除

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