(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
] ) : resource
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);
/* Is called when eio_read() is done */
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);
}
/* Is called when eio_open() is done */
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"