1 main 函数

sapi\fpm\fpm\fpm_main.c 的大约 1570 行

2 调用startup 初始化扩展和其他内容
这个函数会启动所有的扩展的初始化函数 也就是PHP_MINIT

    /* startup after we get the above ini override se we get things right */
    if (cgi_sapi_module.startup(&cgi_sapi_module) == FAILURE) {    // 初始化

3 初始化完成之后调用 fpm_init

    if (0 > fpm_init(argc, argv, fpm_config ? fpm_config : CGIG(fpm_config), fpm_prefix, fpm_pid, test_conf, php_allow_to_run_as_root, force_daemon, force_stderr)) {   

        if (fpm_globals.send_config_pipe[1]) {
            int writeval = 0;
            zlog(ZLOG_DEBUG, "Sending \"0\" (error) to parent via fd=%d", fpm_globals.send_config_pipe[1]);
            zend_quiet_write(fpm_globals.send_config_pipe[1], &writeval, sizeof(writeval));
            close(fpm_globals.send_config_pipe[1]);
        }
        return FPM_EXIT_CONFIG;
    }

• 然后我们看看fpm_init 具体定义,fpm_init 会初始化非常多的东西 ,我有空会重新看一下这些初始化函数的具体内容

//  sapi\fpm\fpm\fpm.c
int fpm_init(int argc, char **argv, char *config, char *prefix, char *pid, int test_conf, int run_as_root, int force_daemon, int force_stderr) /* {{{ */
{
    ...

    if (0 > fpm_php_init_main()           ||
        0 > fpm_stdio_init_main()         ||
        0 > fpm_conf_init_main(test_conf, force_daemon) ||
        0 > fpm_unix_init_main()          ||
        0 > fpm_scoreboard_init_main()    ||
        0 > fpm_pctl_init_main()          ||
        0 > fpm_env_init_main()           ||
        0 > fpm_signals_init_main()       ||
        0 > fpm_children_init_main()      ||
        0 > fpm_sockets_init_main()       ||
        0 > fpm_worker_pool_init_main()   ||
        0 > fpm_event_init_main()) {

           ...
}

4 调用fpm_run

• 这里估计会调用fork (linux有fork 函数但是Windows我就不知道了) 函数
• 具体定义

//  sapi\fpm\fpm\fpm.c

/*  children: return listening socket
    parent: never return */
int fpm_run(int *max_requests) /* {{{ */
{
    struct fpm_worker_pool_s *wp;

    /* create initial children in all pools */
    for (wp = fpm_worker_all_pools; wp; wp = wp->next) {
        int is_parent;

        is_parent = fpm_children_create_initial(wp);

        if (!is_parent) {
            goto run_child;
        }

        /* handle error */
        if (is_parent == 2) {
            fpm_pctl(FPM_PCTL_STATE_TERMINATING, FPM_PCTL_ACTION_SET);
            fpm_event_loop(1);
        }
    }

    /* run event loop forever */
    fpm_event_loop(0);

run_child: /* only workers reach this point */

    fpm_cleanups_run(FPM_CLEANUP_CHILD);

    *max_requests = fpm_globals.max_requests;
    return fpm_globals.listening_socket;
}

5 调用请求相关的初始化函数fpm_init_request

·   /* library is already initialized, now init our request */
    request = fpm_init_request(fcgi_fd);

6 调用完 fpm_init_reques 后，我们继续往main函数下走，走到我今天要讨论的 核心循环

        while (EXPECTED(fcgi_accept_request(request) >= 0)) {  // (1)  内部主要是accept 函数 
            char *primary_script = NULL;
            request_body_fd = -1;
            SG(server_context) = (void *) request;  // （2） 设置上下文
            init_request_info();

            fpm_request_info();

            /* request startup only after we've done all we can to
             *            get path_translated */
            if (UNEXPECTED(php_request_startup() == FAILURE)) {
                fcgi_finish_request(request, 1);
                SG(server_context) = NULL;
                php_module_shutdown();
                return FPM_EXIT_SOFTWARE;
            }

            /* check if request_method has been sent.
             * if not, it's certainly not an HTTP over fcgi request */
            if (UNEXPECTED(!SG(request_info).request_method)) {
                goto fastcgi_request_done;
            }

            if (UNEXPECTED(fpm_status_handle_request())) {
                goto fastcgi_request_done;
            }

            /* If path_translated is NULL, terminate here with a 404 */
            if (UNEXPECTED(!SG(request_info).path_translated)) {
                zend_try {
                    zlog(ZLOG_DEBUG, "Primary script unknown");
                    SG(sapi_headers).http_response_code = 404;
                    PUTS("File not found.\n");
                } zend_catch {
                } zend_end_try();
                goto fastcgi_request_done;
            }

            if (UNEXPECTED(fpm_php_limit_extensions(SG(request_info).path_translated))) {
                SG(sapi_headers).http_response_code = 403;
                PUTS("Access denied.\n");
                goto fastcgi_request_done;
            }

            /*
             * have to duplicate SG(request_info).path_translated to be able to log errrors
             * php_fopen_primary_script seems to delete SG(request_info).path_translated on failure
             */
            primary_script = estrdup(SG(request_info).path_translated);

            /* path_translated exists, we can continue ! */
            if (UNEXPECTED(php_fopen_primary_script(&file_handle) == FAILURE)) {  //（3） 转换路径
                zend_try {
                    zlog(ZLOG_ERROR, "Unable to open primary script: %s (%s)", primary_script, strerror(errno));
                    if (errno == EACCES) {
                        SG(sapi_headers).http_response_code = 403;
                        PUTS("Access denied.\n");
                    } else {
                        SG(sapi_headers).http_response_code = 404;
                        PUTS("No input file specified.\n");
                    }
                } zend_catch {
                } zend_end_try();
                /* we want to serve more requests if this is fastcgi
                 * so cleanup and continue, request shutdown is
                 * handled later */

                goto fastcgi_request_done;
            }

            fpm_request_executing();

            php_execute_script(&file_handle);  // （4）核心函数 执行脚本

fastcgi_request_done:
            if (EXPECTED(primary_script)) {
                efree(primary_script);
            }

            if (UNEXPECTED(request_body_fd != -1)) {
                close(request_body_fd);
            }
            request_body_fd = -2;

            if (UNEXPECTED(EG(exit_status) == 255)) {
                if (CGIG(error_header) && *CGIG(error_header)) {
                    sapi_header_line ctr = {0};

                    ctr.line = CGIG(error_header);
                    ctr.line_len = strlen(CGIG(error_header));
                    sapi_header_op(SAPI_HEADER_REPLACE, &ctr);
                }
            }

            fpm_request_end();
            fpm_log_write(NULL);

            efree(SG(request_info).path_translated);
            SG(request_info).path_translated = NULL;

            php_request_shutdown((void *) 0);

            requests++;
            if (UNEXPECTED(max_requests && (requests == max_requests))) {
                fcgi_request_set_keep(request, 0);
                fcgi_finish_request(request, 0);
                break;
            }
            /* end of fastcgi loop */
        }

• (1) 首先我们看到 while 循环里面有宏 EXPECTED 以及函数fcgi_accept_request
while (EXPECTED(fcgi_accept_request(request) >= 0)) { // (1) 内部主要是accept 函数

// 这里去掉了win32 相关的代码
int fcgi_accept_request(fcgi_request *req)
{
    ...
        int listen_socket = req->listen_socket;
    ...
        req->hook.on_accept();

        FCGI_LOCK(req->listen_socket);
        req->fd = accept(listen_socket, (struct sockaddr *)&sa, &len);
        FCGI_UNLOCK(req->listen_socket);

    ...
        if (fcgi_read_request(req)) {
            return req->fd;
    ...
}

不考虑网络模型的话（epoll kpoll 等等），其实就是一个accept 函数 然后返回一个文件描述符return req->fd;

• （2） 调用完fcgi_accept_request 后就对全局变量赋值fcgi_accept_request
• （3） 路径转换 php_fopen_primary_script

            /* path_translated exists, we can continue ! */
            if (UNEXPECTED(php_fopen_primary_script(&file_handle) == FAILURE)) {

• （4） 核心函数 ，执行脚本

分割线会详细讲述

zend_file_handle 结构 ，我们很容易可以看出是一个描述文件的结构其实和文件描述符是类似的

typedef struct _zend_file_handle {
    union {
        int           fd;
        FILE          *fp;
        zend_stream   stream;
    } handle;
    const char        *filename;
    zend_string       *opened_path;
    zend_stream_type  type;
    zend_bool free_filename;
} zend_file_handle;

执行函数php_execute_script，会调用 zend_execute_scripts

PHPAPI int php_execute_script(zend_file_handle *primary_file){
    ...
    retval = (zend_execute_scripts(ZEND_REQUIRE, NULL, 3, prepend_file_p, primary_file, append_file_p) == SUCCESS);
    ...

}

然后我们看一下zend_execute_scripts定义

zend_execute_scripts 定义

ZEND_API int zend_execute_scripts(int type, zval *retval, int file_count, ...) /* {{{ */
{
    ...
        op_array = zend_compile_file(file_handle, type); // 编译获得opcode
    ...
        if (op_array) {
            zend_execute(op_array, retval);    // 执行opcode 的函数
            zend_exception_restore();
            zend_try_exception_handler();
            if (EG(exception)) {
                zend_exception_error(EG(exception), E_ERROR);
            }
            ...
        }   
    ...
}

zend_compile_file 是一个函数指针，指向 他等于 compile_file

然后我们看一下函数compile_file 的定义，其中compile_file 会调用函数zend_compile

ZEND_API zend_op_array *compile_file(zend_file_handle *file_handle, int type)
{
    zend_lex_state original_lex_state;
    zend_op_array *op_array = NULL;
    zend_save_lexical_state(&original_lex_state);

    if (open_file_for_scanning(file_handle)==FAILURE) {
        if (type==ZEND_REQUIRE) {
            zend_message_dispatcher(ZMSG_FAILED_REQUIRE_FOPEN, file_handle->filename);
            zend_bailout();
        } else {
            zend_message_dispatcher(ZMSG_FAILED_INCLUDE_FOPEN, file_handle->filename);
        }
    } else {
        op_array = zend_compile(ZEND_USER_FUNCTION);
    }

    zend_restore_lexical_state(&original_lex_state);
    return op_array;
}

核心函数 zend_compile 是由 lex/yacc 或者bison 这类工具去生成相应的c 源文件，所以你会在 zend_language_scanner.c 也会看到zend_compile ，但是其实是在php-7.1.8-src\Zend\zend_language_scanner.l 文件下生成的

// php-7.1.8-src\Zend\zend_language_scanner.l 下的`zend_compile` 函数
static zend_op_array *zend_compile(int type)   // 核心函数 貌似没有注释
{
    zend_op_array *op_array = NULL;
    zend_bool original_in_compilation = CG(in_compilation);

    CG(in_compilation) = 1;
    CG(ast) = NULL;
    CG(ast_arena) = zend_arena_create(1024 * 32);

    if (!zendparse()) {         //////////////////// 重点函数
        int last_lineno = CG(zend_lineno);
        zend_file_context original_file_context;
        zend_oparray_context original_oparray_context;
        zend_op_array *original_active_op_array = CG(active_op_array);

        op_array = emalloc(sizeof(zend_op_array));
        init_op_array(op_array, type, INITIAL_OP_ARRAY_SIZE);
        CG(active_op_array) = op_array;

        if (zend_ast_process) {
            zend_ast_process(CG(ast));
        }

        zend_file_context_begin(&original_file_context);
        zend_oparray_context_begin(&original_oparray_context);
        zend_compile_top_stmt(CG(ast));
        CG(zend_lineno) = last_lineno;
        zend_emit_final_return(type == ZEND_USER_FUNCTION);
        op_array->line_start = 1;
        op_array->line_end = last_lineno;
        pass_two(op_array);
        zend_oparray_context_end(&original_oparray_context);
        zend_file_context_end(&original_file_context);

        CG(active_op_array) = original_active_op_array;
    }

    zend_ast_destroy(CG(ast));
    zend_arena_destroy(CG(ast_arena));

    CG(in_compilation) = original_in_compilation;

    return op_array;
}

快到了最后的几步了

我们看到

static zend_op_array *zend_compile(int type)   // 核心函数 貌似没有注释
{

}