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在PHP的生命周期中，分为 词法分析-》语法分析-》编译PHP脚本为opcode-》Zend Engine
在上述执行过程中，经常被人提起的解释型语言性能问题也就是因为每次执行脚本，上述过程都会重复执行。因此，也就出现了APC， xcache， eAccelerator等缓存，不过现在官方主推的是opcache
一、安装VLD扩展
1、下载
地址：http://pecl.php.net/package/vld
wget http://pecl.php.net/get/vld-0.13.0.tgz
2、编译安装
cd /usr/local/src/ wget http://pecl.php.net/get/vld-0.13.0.tgz tar -zxf vld-0.13.0.tgz cd vld-0.13.0 phpize && ./configure --with-php-config=php-config --enable-vld make && make install echo extension=vld.so >> /etc/php.d/vld.ini service php-fpm reload php-config、phpize要加入环境变量
3、opcode的结构
vim Zend/zend_compile.h
typedef struct _zend_op_array zend_op_array; typedef struct _zend_op zend_op;
struct _zend_op {
opcode_handler_t handler;
znode_op op1;
znode_op op2;
znode_op result;
ulong extended_value;
uint lineno;
zend_uchar opcode;
zend_uchar op1_type;
zend_uchar op2_type;
zend_uchar result_type;
};
struct _zend_op_array {
/* Common elements */
zend_uchar type;
const char *function_name;
zend_class_entry *scope;
zend_uint fn_flags;
union _zend_function *prototype;
zend_uint num_args;
zend_uint required_num_args;
zend_arg_info *arg_info;
/* END of common elements */
zend_uint *refcount;
zend_op *opcodes;
zend_uint last;
zend_compiled_variable *vars;
int last_var;
zend_uint T;
zend_brk_cont_element *brk_cont_array;
int last_brk_cont;
zend_try_catch_element *try_catch_array;
int last_try_catch;
/* static variables support */
HashTable *static_variables;
zend_uint this_var;
const char *filename;
zend_uint line_start;
zend_uint line_end;
const char *doc_comment;
zend_uint doc_comment_len;
zend_uint early_binding; /* the linked list of delayed declarations */
zend_literal *literals;
int last_literal;
void **run_time_cache;
int last_cache_slot;
void *reserved[ZEND_MAX_RESERVED_RESOURCES];
};
4、opcode的使用
STD_PHP_INI_ENTRY("vld.active", "0", PHP_INI_SYSTEM, OnUpdateBool, active, zend_vld_globals, vld_globals)
STD_PHP_INI_ENTRY("vld.skip_prepend", "0", PHP_INI_SYSTEM, OnUpdateBool, skip_prepend, zend_vld_globals, vld_globals)
STD_PHP_INI_ENTRY("vld.skip_append", "0", PHP_INI_SYSTEM, OnUpdateBool, skip_append, zend_vld_globals, vld_globals)
STD_PHP_INI_ENTRY("vld.execute", "1", PHP_INI_SYSTEM, OnUpdateBool, execute, zend_vld_globals, vld_globals)
STD_PHP_INI_ENTRY("vld.verbosity", "1", PHP_INI_SYSTEM, OnUpdateBool, verbosity, zend_vld_globals, vld_globals)
STD_PHP_INI_ENTRY("vld.format", "0", PHP_INI_SYSTEM, OnUpdateBool, format, zend_vld_globals, vld_globals)
STD_PHP_INI_ENTRY("vld.col_sep", "\t", PHP_INI_SYSTEM, OnUpdateString, col_sep, zend_vld_globals, vld_globals)
STD_PHP_INI_ENTRY("vld.save_dir", "/tmp", PHP_INI_SYSTEM, OnUpdateString, save_dir, zend_vld_globals, vld_globals)
STD_PHP_INI_ENTRY("vld.save_paths", "0", PHP_INI_SYSTEM, OnUpdateBool, save_paths, zend_vld_globals, vld_globals)
STD_PHP_INI_ENTRY("vld.dump_paths", "1", PHP_INI_SYSTEM, OnUpdateBool, dump_paths, zend_vld_globals, vld_globals)
这些是vld的系统配置
默认值
static void vld_init_globals(zend_vld_globals *vld_globals)
{
vld_globals->active = 0;
vld_globals->skip_prepend = 0;
vld_globals->skip_append = 0;
vld_globals->execute = 1;
vld_globals->format = 0;
vld_globals->col_sep = "\t";
vld_globals->path_dump_file = NULL;
vld_globals->dump_paths = 1;
vld_globals->save_paths = 0;
vld_globals->verbosity = 1;
}
[root@localhost code]# php -dvld.active test.php
Finding entry points
Branch analysis from position: 0
Jump found. Position 1 = -2
filename: /data/code/test.php
function name: (null)
number of ops: 5
compiled vars: none
line #* E I O op fetch ext return operands
-------------------------------------------------------------------------------------
2 0 E > SEND_VAL ‘dbname‘
1 DO_FCALL 1 $0 ‘config‘
2 SEND_VAR_NO_REF 6 $0
3 DO_FCALL 1 ‘var_dump‘
3 4 > RETURN 1
branch: # 0; line: 2- 3; sop: 0; eop: 4; out1: -2
path #1: 0,
更多指令参见：http://php.net/manual/en/internals2.opcodes.list.php，同时列出了每条指令的案例
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原文地址：http://www.cnblogs.com/chenpingzhao/p/4648059.html
