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(PECL eio >= 0.0.1dev)
eio_read — Read from a file descriptor at given offset.
$fd
, int $length
, int $offset
, int $pri
, callable $callback
[, mixed $data
= NULL
] ) eio_read() reads up to length
bytes from fd
file descriptor at
offset
. The read bytes are stored in
result
argument of callback
.
fd
Stream, Socket resource, or numeric file descriptor
length
Maximum number of bytes to read.
offset
Offset within the file.
pri
请求的优先级: EIO_PRI_DEFAULT
, EIO_PRI_MIN
, EIO_PRI_MAX
或 NULL
。如果是
NULL
,pri
将设为
EIO_PRI_DEFAULT
。
callback
callback
函数在请求完成时被调用。其应匹配一下原型:
void callback(mixed $data, int $result[, resource $req]);
data
传递给请求的用户数据。
result
针对请求的结果的值。通常是相应的系统调用返回的值。
req
可选的请求资源,可被 eio_get_last_error() 之类的函数使用。
data
Arbitrary variable passed to callback
.
eio_read() stores read bytes in
result
argument of callback
function.
Example #1 eio_read() example
<?php
// Open a temporary file and write some bytes there
$temp_filename = "eio-temp-file.tmp" ;
$fp = fopen ( $temp_filename , "w" );
fwrite ( $fp , "1234567890" );
fclose ( $fp );
function my_read_cb ( $data , $result ) {
global $temp_filename ;
// Output read bytes
var_dump ( $result );
// Close file
eio_close ( $data );
eio_event_loop ();
// Remove temporary file
@ unlink ( $temp_filename );
}
function my_file_opened_callback ( $data , $result ) {
// $result should contain the file descriptor
if ( $result > 0 ) {
// Read 5 bytes starting from third
eio_read ( $result , 5 , 2 , EIO_PRI_DEFAULT , "my_read_cb" , $result );
eio_event_loop ();
} else {
// eio_open() failed
unlink ( $data );
}
}
// Open the file for reading and writing
eio_open ( $temp_filename , EIO_O_RDWR , NULL ,
EIO_PRI_DEFAULT , "my_file_opened_callback" , $temp_filename );
eio_event_loop ();
?>
以上例程的输出类似于:
string(5) "34567"