PHP extension - C extension to implement rolling logging

Foreword

Everything is difficult at the beginning, that’s right! !

Before I really developed PHP extensions, I always felt that PHP extension development was a very distant thing for me. Although I have some CC++ foundation, it was still very difficult to look at the PHP source code. Now it seems that I still haven’t made up my mind. To do this, this time I finally decided to build a PHP extension class library. After working on it for a weekend, I finally encapsulated a previous logging class library into a PHP extension form. This can be regarded as an introduction to developing PHP extensions. Here I will share with you Share, this is the source code: a PHP extension for logging in singleton mode

Development

What I developed is a PHP extension for logging. The function is basically the same as the PHP rolling log a few days ago, and it is also a singleton. Run in example mode.

Record some points to pay attention to during development:

Here are only a few parts. For details, you can look at my source code. I think the best way to learn is to look at the source code. If you encounter something you don’t know how to do on your own, Check, the memory will be deeper.

Understand the zval structure, zval is a data structure defined in the PHP kernel

<code>//定义在Zend/zend_types.h:55 和 Zend/zend.h:322行
typedef struct _zval_struct zval;
struct _zval_struct {
    /* Variable information */
    zvalue_value value;     /* value */
    zend_uint refcount;
    zend_uchar type;    /* active type */
    zend_uchar is_ref;
};
typedef union _zvalue_value {
    long lval;                  /* long value */
    double dval;                /* double value */
    struct {
        char *val;
        int len;
    } str;
    HashTable *ht;              /* hash table value */
    zend_object_value obj;
} zvalue_value;

//其中的zval.type表示变量的类型，基本类型有下面几种，定义在Zend/zend.h:583中
#define IS_NULL		0
#define IS_LONG		1
#define IS_DOUBLE	2
#define IS_BOOL		3
#define IS_ARRAY	4
#define IS_OBJECT	5
#define IS_STRING	6

//部分常用的zval相关函数或者宏，定义在Zend/zend_operators.h:441行
Z_LVAL_P(zval_p)	//获取zval_p指针所指向的zval结构的值，值得类型为LONG
Z_STRVAL_P(zval_p)</code>

How to pass parameters to functions

<code>PHP扩展中接受参数的时候通过函数zend_parse_parameters，类似下面的形式进行传参：
zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s", &msg, &msg_len);
第二个参数是要传入参数类型的列表，有下面规范</code>

<code>从PHP5.3开始, zend_parse_paramters_函数新增了如下几个新的类型描述符:
f - function or array containing php method call info (returned as zend_fcall_info and zend_fcall_info_cache)
H - array or HASH_OF(object) (returned as HashTable)
L - long, limits out-of-range numbers to LONG_MAX/LONG_MIN (long)
Z - the actual zval (zval**)</code>

Some functions commonly used when developing surface class libraries

<code>zend_declare_property_null(mylogs_ce, ZEND_STRL("level"), ZEND_ACC_PRIVATE TSRMLS_CC);	
//类似上面的函数是类进行初始化的时候设置变量
zend_declare_class_constant_long(mylogs_ce, ZEND_STRL("LOG_DEBUG"), 0 TSRMLS_CC);
//类似上面的函数是类型进行初始化的时候设置常量
zend_read_property(mylogs_ce, instance, ZEND_STRL("level"), 0 TSRMLS_CC);
//上面的是从实例instance中读取变量的值
zend_hash_find(&ce->constants_table, ZEND_STRS("LOG_DEBUG"), (void **)&_level);
//上面的是从mylogs_ce这个类中读取常量
zend_update_property_long(mylogs_ce, instance, ZEND_STRL("level"), level TSRMLS_CC);
//上面的是从instance中读取变量level</code>

Note

1. Pay attention to the release of memory to prevent memory leaks. After the development was completed, I found that there was a memory leak. You can use valgrind to check the memory leaks and release the memory that is no longer needed. Otherwise, it may be processed in a large number of loops. Sometimes too much memory is used, resulting in an error.
   
2. Also, look at more examples. You can refer to Brother Niao's YAF source code. This helped me a lot. In the early days of learning, I just "imitated the cat and painted the tiger".

Let’s see the effect

After the development was completed, I wrote a script and tried it, cyclically outputting the log 100,000 times (300,000 times to be precise, debug, msg, and err 100,000 times each). The following is the environment and results
Environment:

<code>centos虚拟机，64位
内存 1G
CPU i5-2410M @ 2.30GHz #这个获取到的是我电脑的</code>

times	PHP code	PHP extension
First time	8.83s	6.13s
Second time	8.60s	6.14s
Average	8.72s	6.14s

You can see that using PHP extension can increase the speed by about 1/4 of the original, haha, not bad, my code may still have a lot of room for optimization, Keep up the hard work~~

I put all the code on github:

A singleton mode logging PHP extension

Reference article

Extend your PHP with C/C++ - Laruence

In-depth PHP Variable storage structure - Wen Daxia

5/24/2015 3:10:45 PM

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The above introduces the PHP extension-C extension to implement rolling logging, including aspects of the content. I hope it will be helpful to friends who are interested in PHP tutorials.