eio_read
(PECL eio >= 0.0.1dev)
eio_read — Read from a file descriptor at given offset
Beschreibung
mixed
$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
.
Parameter-Liste
-
fd
-
Stream, Socket resource, or numeric file descriptor
-
length
-
Maximum number of bytes to read.
-
offset
-
Offset within the file.
-
pri
-
The request priority:
EIO_PRI_DEFAULT
,EIO_PRI_MIN
,EIO_PRI_MAX
, ornull
. Ifnull
passed,pri
internally is set toEIO_PRI_DEFAULT
. -
callback
-
callback
function is called when the request is done. It should match the following prototype:void callback(mixed $data, int $result[, resource $req]);
-
data
-
is custom data passed to the request.
-
result
-
request-specific result value; basically, the value returned by corresponding system call.
-
req
-
is optional request resource which can be used with functions like eio_get_last_error()
-
-
data
-
Arbitrary variable passed to
callback
.
Rückgabewerte
eio_read() stores read bytes in
result
argument of callback
function.
Beispiele
Beispiel #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();
?>
Das oben gezeigte Beispiel erzeugt eine ähnliche Ausgabe wie:
string(5) "34567"
Siehe auch
- eio_open() - Opens a file
- eio_write() - Write to file
- eio_close() - Close file
- eio_event_loop() - Polls libeio until all requests proceeded