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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"