深入理解php原理之include include_once require require_once

先看下总结：

require include php引擎是直接调用compile_filename来实现的

在compile_filename实现里面会把把resolved_path变量加入included_files数组中

 

而include_once,require_once 则是先通过zend_resolve_path得到一个解析过的路径（resolved_path）

然后通过zend_hash_exists查找included_files变量，如果找到则说明已经加载过

否则通过zend_stream_open判断文件是否存在，如果存在：1，把resolved_path变量加入included_files数组中 2，通过zend_compile_file调用刚才打开的文件指针进行编译

不存在则通过zend_message_dispatcher派发一个消息，然后分别处理

 

每次调用include_once,require_once都会进行路径解析（zend_resolve_path）,而绝对路径都是直接返回，速度最快

 

历史：

在php5.2之前的源码，include_once,require_once都会执行zend_stream_open也就是每次都会打开文件，然后再和included_files比较

所以5.2之后的实现，相同文件加载调用include_once,require_once是没有io操作的

 

 

 

分析过程

1，查看php语法定义文件Zend/zend_language_scanner.l

找到

<ST_IN_SCRIPTING>"include" {

return T_INCLUDE;

}

 

<ST_IN_SCRIPTING>"include_once" {

return T_INCLUDE_ONCE;

}

 

<ST_IN_SCRIPTING>"require" {

return T_REQUIRE;

}

 

<ST_IN_SCRIPTING>"require_once" {

return T_REQUIRE_ONCE;

}

 

可以看到被定义成T_INCLUDE T_INCLUDE_ONCE T_REQUIRE T_REQUIRE_ONCE四个标记(token)

 

 

2，查看php语法分析文件Zend/zend_language_parser.y

找到

|T_INCLUDE expr { zend_do_include_or_eval(ZEND_INCLUDE, &$$, &$2 TSRMLS_CC); }

|T_INCLUDE_ONCE expr { zend_do_include_or_eval(ZEND_INCLUDE_ONCE, &$$, &$2 TSRMLS_CC); }

|T_REQUIRE expr{ zend_do_include_or_eval(ZEND_REQUIRE, &$$, &$2 TSRMLS_CC); }

|T_REQUIRE_ONCE expr{ zend_do_include_or_eval(ZEND_REQUIRE_ONCE, &$$, &$2 TSRMLS_CC); }

 

可以看见四个函数都是用zend_do_include_or_eval实现的，只是参数不一样

 

 

3，搜索下源码，在Zend/zend_compile.c 找到函数实现

void zend_do_include_or_eval(int type, znode *result, const znode *op1 TSRMLS_DC) /* {{{ */

{

zend_do_extended_fcall_begin(TSRMLS_C);

{

zend_op *opline = get_next_op(CG(active_op_array) TSRMLS_CC);

 

opline->opcode = ZEND_INCLUDE_OR_EVAL;

opline->result_type = IS_VAR;

opline->result.var = get_temporary_variable(CG(active_op_array));

SET_NODE(opline->op1, op1);

SET_UNUSED(opline->op2);

opline->extended_value = type;

GET_NODE(result, opline->result);

}

zend_do_extended_fcall_end(TSRMLS_C);

}

 

这里是把opcode设置为ZEND_INCLUDE_OR_EVAL

 

 

4，在zend_vm_def.h找到ZEND_INCLUDE_OR_EVAL的定义

ZEND_VM_HANDLER(73, ZEND_INCLUDE_OR_EVAL, CONST|TMP|VAR|CV, ANY)

{

USE_OPLINE

zend_op_array *new_op_array=NULL;

zend_free_op free_op1;

zval *inc_filename;

    zval *tmp_inc_filename = NULL;

zend_bool failure_retval=0;

 

SAVE_OPLINE();

inc_filename = GET_OP1_ZVAL_PTR(BP_VAR_R);

 

if (inc_filename->type!=IS_STRING) {

MAKE_STD_ZVAL(tmp_inc_filename);

ZVAL_COPY_VALUE(tmp_inc_filename, inc_filename);

zval_copy_ctor(tmp_inc_filename);

convert_to_string(tmp_inc_filename);

inc_filename = tmp_inc_filename;

}

 

if (opline->extended_value != ZEND_EVAL && strlen(Z_STRVAL_P(inc_filename)) != Z_STRLEN_P(inc_filename)) {

if (opline->extended_value == ZEND_INCLUDE_ONCE || opline->extended_value == ZEND_INCLUDE) {

zend_message_dispatcher(ZMSG_FAILED_INCLUDE_FOPEN, Z_STRVAL_P(inc_filename) TSRMLS_CC);

} else {

zend_message_dispatcher(ZMSG_FAILED_REQUIRE_FOPEN, Z_STRVAL_P(inc_filename) TSRMLS_CC);

}

} else {

switch (opline->extended_value) {

case ZEND_INCLUDE_ONCE:

case ZEND_REQUIRE_ONCE: {

zend_file_handle file_handle;

char *resolved_path;

 

resolved_path = zend_resolve_path(Z_STRVAL_P(inc_filename), Z_STRLEN_P(inc_filename) TSRMLS_CC);

if (resolved_path) {

failure_retval = zend_hash_exists(&EG(included_files), resolved_path, strlen(resolved_path)+1);

} else {

resolved_path = Z_STRVAL_P(inc_filename);

}

 

if (failure_retval) {

/* do nothing, file already included */

} else if (SUCCESS == zend_stream_open(resolved_path, &file_handle TSRMLS_CC)) {

 

if (!file_handle.opened_path) {

file_handle.opened_path = estrdup(resolved_path);

}

 

if (zend_hash_add_empty_element(&EG(included_files), file_handle.opened_path, strlen(file_handle.opened_path)+1)==SUCCESS) {

new_op_array = zend_compile_file(&file_handle, (opline->extended_value==ZEND_INCLUDE_ONCE?ZEND_INCLUDE:ZEND_REQUIRE) TSRMLS_CC);

zend_destroy_file_handle(&file_handle TSRMLS_CC);

} else {

zend_file_handle_dtor(&file_handle TSRMLS_CC);

failure_retval=1;

}

} else {

if (opline->extended_value == ZEND_INCLUDE_ONCE) {

zend_message_dispatcher(ZMSG_FAILED_INCLUDE_FOPEN, Z_STRVAL_P(inc_filename) TSRMLS_CC);

} else {

zend_message_dispatcher(ZMSG_FAILED_REQUIRE_FOPEN, Z_STRVAL_P(inc_filename) TSRMLS_CC);

}

}

if (resolved_path != Z_STRVAL_P(inc_filename)) {

efree(resolved_path);

}

}

break;

case ZEND_INCLUDE:

case ZEND_REQUIRE:

new_op_array = compile_filename(opline->extended_value, inc_filename TSRMLS_CC);

break;

case ZEND_EVAL: {

char *eval_desc = zend_make_compiled_string_description("eval()'d code" TSRMLS_CC);

 

new_op_array = zend_compile_string(inc_filename, eval_desc TSRMLS_CC);

efree(eval_desc);

}

break;

EMPTY_SWITCH_DEFAULT_CASE()

}

}

if (tmp_inc_filename) {

zval_ptr_dtor(&tmp_inc_filename);

}

FREE_OP1();

if (UNEXPECTED(EG(exception) != NULL)) {

HANDLE_EXCEPTION();

} else if (EXPECTED(new_op_array != NULL)) {

EX(original_return_value) = EG(return_value_ptr_ptr);

EG(active_op_array) = new_op_array;

if (RETURN_VALUE_USED(opline)) {

EX_T(opline->result.var).var.ptr = NULL;

EX_T(opline->result.var).var.ptr_ptr = &EX_T(opline->result.var).var.ptr;

EG(return_value_ptr_ptr) = EX_T(opline->result.var).var.ptr_ptr;

} else {

EG(return_value_ptr_ptr) = NULL;

}

 

EX(current_object) = EX(object);

 

EX(function_state).function = (zend_function *) new_op_array;

EX(object) = NULL;

 

if (!EG(active_symbol_table)) {

zend_rebuild_symbol_table(TSRMLS_C);

}

 

if (EXPECTED(zend_execute == execute)) {

ZEND_VM_ENTER();

} else {

zend_execute(new_op_array TSRMLS_CC);

}

 

EX(function_state).function = (zend_function *) EX(op_array);

EX(object) = EX(current_object);

 

EG(opline_ptr) = &EX(opline);

EG(active_op_array) = EX(op_array);

EG(return_value_ptr_ptr) = EX(original_return_value);

destroy_op_array(new_op_array TSRMLS_CC);

efree(new_op_array);

if (UNEXPECTED(EG(exception) != NULL)) {

zend_throw_exception_internal(NULL TSRMLS_CC);

HANDLE_EXCEPTION();

} else if (RETURN_VALUE_USED(opline)) {

if (!EX_T(opline->result.var).var.ptr) { /* there was no return statement */

zval *retval;

 

ALLOC_ZVAL(retval);

ZVAL_BOOL(retval, 1);

INIT_PZVAL(retval);

EX_T(opline->result.var).var.ptr = retval;

}

}

 

} else if (RETURN_VALUE_USED(opline)) {

zval *retval;

 

ALLOC_ZVAL(retval);

ZVAL_BOOL(retval, failure_retval);

INIT_PZVAL(retval);

AI_SET_PTR(&EX_T(opline->result.var), retval);

}

ZEND_VM_NEXT_OPCODE();

}

 

5，在Zend/zend.c的zend_startup函数中找到对zend_resolve_path的赋值

zend_resolve_path = utility_functions->resolve_path_function;

也就是调用utility_functions的成员,而这个utility_functions是在php初始化(php_module_startup)的时候赋值的

 

 

总结：

require include php引擎是直接调用compile_filename来实现的

在compile_filename实现里面会把把resolved_path变量加入included_files数组中

 

而include_once,require_once 则是先通过zend_resolve_path得到一个解析过的路径（resolved_path）

然后通过zend_hash_exists查找included_files变量，如果找到则说明已经加载过

否则通过zend_stream_open判断文件是否存在，如果存在：1，把resolved_path变量加入included_files数组中 2，通过zend_compile_file调用刚才打开的文件指针进行编译

不存在则通过zend_message_dispatcher派发一个消息，然后分别处理

 

每次调用include_once,require_once都会进行路径解析（zend_resolve_path）,而绝对路径都是直接返回，速度最快

 

历史：

在php5.2之前的源码，include_once,require_once都会执行zend_stream_open也就是每次都会打开文件，然后再和included_files比较

所以5.2之后的实现，相同文件加载调用include_once,require_once是没有io操作的

 

附：

路径查询原则（手册上的）

寻找包含文件的顺序先是在当前工作目录的相对的 include_path 下寻找，然后是当前运行脚本所在目录相对的 include_path 下寻找。

例如 include_path 是 .，当前工作目录是 /www/，脚本中要 include 一个 include/a.php 并且在该文件中有一句 include "b.php"，则寻找 b.php 的顺序先是 /www/，然后是 /www/include/。如果文件名以 ./ 或者 ../ 开始，则只在当前工作目录相对的 include_path 下寻找

 

 

5.1.6的实现

if (SUCCESS == zend_stream_open(inc_filename->value.str.val, &file_handle TSRMLS_CC)) {

 

if (!file_handle.opened_path) {

file_handle.opened_path = estrndup(inc_filename->value.str.val, inc_filename->value.str.len);

}

 

if (zend_hash_add(&EG(included_files), file_handle.opened_path, strlen(file_handle.opened_path)+1, (void *)&dummy, sizeof(int), NULL)==SUCCESS) {

new_op_array = zend_compile_file(&file_handle, (opline->op2.u.constant.value.lval==ZEND_INCLUDE_ONCE?ZEND_INCLUDE:ZEND_REQUIRE) TSRMLS_CC);

zend_destroy_file_handle(&file_handle TSRMLS_CC);

} else {

zend_file_handle_dtor(&file_handle);

failure_retval=1;

}

}