Request processing of two major processes in PHP kernel_PHP tutorial

static int php_handler(request_rec *r)
{
	/* Initiliaze the context */
        php_struct * volatile ctx;
        void *conf;
        apr_bucket_brigade * volatile brigade;
        apr_bucket *bucket;
        apr_status_t rv;
        request_rec * volatile parent_req = NULL;
        TSRMLS_FETCH();

	......

        zend_file_handle zfd;

        zfd.type = ZEND_HANDLE_FILENAME;
        zfd.filename = (char *) r->filename;
        zfd.free_filename = 0;
        zfd.opened_path = NULL;

	zend_execute_scripts(ZEND_INCLUDE TSRMLS_CC, NULL, 1, &zfd);

	......
}

ZEND_API int zend_execute_scripts(int type TSRMLS_DC, zval **retval, int file_count, ...) /* {{{ */
{
	......

	EG(active_op_array) = \
	zend_compile_file(file_handle, type TSRMLS_CC);

	......

	zend_execute(EG(active_op_array) TSRMLS_CC);

	......
}

ZEND_API void execute(zend_op_array *op_array TSRMLS_DC)  
{  
    // 初始化执行上下文  
    zend_execute_data execute_data;  
  
    // 如果有异常就退出执行  
    if (EG(exception)) {  
        return;  
    }  
  
    /* Initialize execute_data */  
    EX(fbc) = NULL; // 初始化正在调用的函数  
    EX(object) = NULL; // 初始化正在调用的对象  
    EX(old_error_reporting) = NULL; // 初始化错误报告变量  
      
    // 为执行栈分配空间  
&#160; &#160; if (op_array->T < TEMP_VAR_STACK_LIMIT) { &#160;
&#160; &#160; &#160; &#160; EX(Ts) = (temp_variable *) do_alloca(sizeof(temp_variable) * op_array->T); &#160;
&#160; &#160; } else { &#160;
&#160; &#160; &#160; &#160; EX(Ts) = (temp_variable *) safe_emalloc(sizeof(temp_variable), op_array->T, 0); &#160;
&#160; &#160; } &#160;
&#160; &#160; // 为临时变量分配空间并初始化这些空间 &#160;
&#160; &#160; EX(CVs) = (zval***)do_alloca(sizeof(zval**) * op_array->last_var); &#160;
&#160; &#160; memset(EX(CVs), 0, sizeof(zval**) * op_array->last_var); &#160;
&#160; &#160; &#160;&#160;
&#160; &#160; EX(op_array) = op_array; &#160;
&#160; &#160; &#160;&#160;
&#160; &#160; // 切换执行上下文 &#160;
&#160; &#160; EX(original_in_execution) = EG(in_execution); &#160;
&#160; &#160; EX(symbol_table) = EG(active_symbol_table); &#160;
&#160; &#160; EX(prev_execute_data) = EG(current_execute_data); // 将当前全局变量中的执行数据压栈 &#160;
&#160; &#160; EG(current_execute_data) = &execute_data; // 将当前执行上下文压栈 &#160;
&#160;&#160;
&#160; &#160; EG(in_execution) = 1; &#160;
&#160; &#160; // 初始化第一个指令(opcode) &#160;
&#160; &#160; /*&#160;
&#160; &#160; #define ZEND_VM_SET_OPCODE(new_op) \&#160;
&#160; &#160; CHECK_SYMBOL_TABLES() \&#160;
&#160; &#160; EX(opline) = new_op&#160;
&#160; &#160; &#160;
&#160; &#160; execute_data.opline 为当前执行的 opcode&#160;
&#160; &#160; */ &#160;
&#160; &#160; if (op_array->start_op) { &#160;
&#160; &#160; &#160; &#160; ZEND_VM_SET_OPCODE(op_array->start_op); &#160;
&#160; &#160; } else { &#160;
&#160; &#160; &#160; &#160; ZEND_VM_SET_OPCODE(op_array->opcodes); &#160;
&#160; &#160; } &#160;
&#160;&#160;
&#160; &#160; if (op_array->uses_this && EG(This)) { &#160;
&#160; &#160; &#160; &#160; EG(This)->refcount++; /* For $this pointer */ &#160;
&#160; &#160; &#160; &#160; if (zend_hash_add(EG(active_symbol_table), "this", sizeof("this"), &EG(This), sizeof(zval *), NULL)==FAILURE) { &#160;
&#160; &#160; &#160; &#160; &#160; &#160; EG(This)->refcount--; &#160;
&#160; &#160; &#160; &#160; } &#160;
&#160; &#160; } &#160;
&#160;&#160;
&#160; &#160; // 将存储opline的内存地址赋给 executor_globals.online_ptr ，可以实时跟踪opcode的执行 &#160;
&#160; &#160; EG(opline_ptr) = &EX(opline); &#160;
&#160;&#160;
&#160; &#160; EX(function_state).function = (zend_function *) op_array; &#160;
&#160; &#160; EG(function_state_ptr) = &EX(function_state); &#160;
#if ZEND_DEBUG &#160;
&#160; &#160; /* function_state.function_symbol_table is saved as-is to a stack,&#160;
&#160; &#160; &#160;* which is an intentional UMR. &#160;Shut it up if we&#39;re in DEBUG.&#160;
&#160; &#160; &#160;*/ &#160;
&#160; &#160; EX(function_state).function_symbol_table = NULL; &#160;
#endif &#160;
&#160; &#160; &#160;&#160;
&#160; &#160; while (1) { &#160;
#ifdef ZEND_WIN32 &#160;
&#160; &#160; &#160; &#160; if (EG(timed_out)) { &#160;
&#160; &#160; &#160; &#160; &#160; &#160; zend_timeout(0); &#160;
&#160; &#160; &#160; &#160; } &#160;
#endif &#160;
&#160; &#160; &#160; &#160; &#160;&#160;
&#160; &#160; &#160; &#160; // 循环调用每个opline的 handler 函数，如果是推出函数的话，返回值大于0，就退出 &#160;
&#160; &#160; &#160; &#160; if (EX(opline)->handler(&execute_data TSRMLS_CC) > 0) { &#160;
&#160; &#160; &#160; return; &#160;
&#160; &#160; &#160; &#160; } &#160;
&#160;&#160;
&#160; &#160; } &#160;
&#160; &#160; zend_error_noreturn(E_ERROR, "Arrived at end of main loop which shouldn&#39;t happen"); &#160;
} &#160;