Php/docs/function.eio-read
eio_read
(PECL eio >= 0.0.1dev)
eio_read — Read from a file descriptor at given offset
Description
eio_read
( 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
.
Parameters
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 $req]);
data
is custom data passed to the request.
result
request-specific result value; basically, the value returned by corresponding system call.
req
is optional request resource which can be used with functions like eio_get_last_error()
data
Arbitrary variable passed to
callback
.
Return Values
eio_read() stores read bytes in
result
argument of callback
function.
Examples
Example #1 eio_read() example
<?php// Open a temporary file and write some bytes there$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 writingeio_open($temp_filename, EIO_O_RDWR, NULL, EIO_PRI_DEFAULT, "my_file_opened_callback", $temp_filename);eio_event_loop();?>
The above example will output something similar to:
string(5) "34567"
See Also
- eio_open() - Opens a file
- eio_write() - Write to file
- eio_close() - Close file
- eio_event_loop() - Polls libeio until all requests proceeded