前几天用PHP写一个socket网络服务,在文档里看到socket_read和socket_recv这两个方法时有点晕,乍一看这不是一样的嘛,干吗还要给两个不同的用法呢。看文档没看太明白,看了下源码才搞清楚,在这里记录一下。
先看一下这两个函数的声明:
代码如下:
string socket_read ( resource $socket , int $length [, int $type = PHP_BINARY_READ ] )
int socket_recv ( resource $socket , string &$buf , int $len , int $flags )
可以看到,从声明可以看到,一个是把收到的数据通过执行结果返回,另一个是把收到的数据通过引用的形式返回。另一个区别就是,socket_read多了一个type,socket_recv多了一个flags(够混乱的)。我们先来看看socket_recv的源码吧!
代码如下:
PHP_FUNCTION(socket_recv)
{
zval *php_sock_res, *buf;
char *recv_buf;
php_socket *php_sock;
int retval;
long len, flags;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "rzll", &php_sock_res, &buf, &len, &flags) == FAILURE) {
return;
}
ZEND_FETCH_RESOURCE(php_sock, php_socket *, &php_sock_res, -1, le_socket_name, le_socket);
/* overflow check */
if ((len + 1)
RETURN_FALSE;
}
recv_buf = emalloc(len + 1);
memset(recv_buf, 0, len + 1);
if ((retval = recv(php_sock->bsd_socket, recv_buf, len, flags)) efree(recv_buf);
zval_dtor(buf);
Z_TYPE_P(buf) = IS_NULL;
} else {
recv_buf[retval] = '\0';
/* Rebuild buffer zval */
zval_dtor(buf);
Z_STRVAL_P(buf) = recv_buf;
Z_STRLEN_P(buf) = retval;
Z_TYPE_P(buf) = IS_STRING;
}
if (retval == -1) {
PHP_SOCKET_ERROR(php_sock, "unable to read from socket", errno);
RETURN_FALSE;
}
RETURN_LONG(retval);
}
啰里啰嗦一大堆,其实有一行最关键:
代码如下:
if ((retval = recv(php_sock->bsd_socket, recv_buf, len, flags))
可以看到,实际上这个函数就是调用了系统的recv而已,只是把输入参数和得到的结果都处理了一下,比较好理解。那我们再来看下socket_read,socket_read比系统的recv函数多了一个$type参数,这也是我认为这个函数存在的意义,从文档里可以看到,type有两个值,分别是PHP_BINARY_READ和PHP_NORMAL_READ,文档里有写,PHP_BINARY_READ表示直接用系统的recv方法,PHP_NORMAL_READ表示会一读,直到遇到\n 或者 \r,我们来看下源码:
代码如下:
//省略一大堆
if (type == PHP_NORMAL_READ) {
retval = php_read(php_sock, tmpbuf, length, 0);
} else {
retval = recv(php_sock->bsd_socket, tmpbuf, length, 0);
}
可以看到,如果是PHP_NORMAL_READ模式,其实行为和socket_recv是一样的,都是用的系统的recv函数,但是如果是PHP_NORMAL_READ,则有很大区别,用了自己实现的php_read函数,那这个php_read是干啥的呢?我们继续看源码:
代码如下:
*t = '\0';
while (*t != '\n' && *t != '\r' && n
if (m > 0) {
t++;
n++;
} else if (m == 0) {
no_read++;
if (nonblock && no_read >= 2) {
return n;
/* The first pass, m always is 0, so no_read becomes 1
* in the first pass. no_read becomes 2 in the second pass,
* and if this is nonblocking, we should return.. */
}
if (no_read > 200) {
set_errno(ECONNRESET);
return -1;
}
}
if (n
m = recv(sock->bsd_socket, (void *) t, 1, flags);
}
if (errno != 0 && errno != ESPIPE && errno != EAGAIN) {
return -1;
}
set_errno(0);
}
还是指copy了关键部分,可以看到,这里的实现是一直循环调用recv,直到遇到\r或者\n或者读的数据长度到了指定的maxlen。
虽然这两个函数比较混乱,但是看到这里应该明白了吧!好了睡觉去啦!

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