[edit] Last updated: Fri, 23 Mar 2012

eio_read

(PECL eio >= 0.0.1dev)

eio_read — Read from a file descriptor at given offset.

Opis

resource eio_read ( int $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.

Parametry

fd

The 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, or NULL. If NULL passed, pri internally is set to EIO_PRI_DEFAULT.

callback

callback function is called when the request is done. It should match the following prototype:


void callback($data, $result);

$data is custom data passed to the request. $result contains request-specific result value; basically, the value returned by corresponding system call.

data

Arbitrary variable passed to callback.

Zwracane wartości

eio_read() stores read bytes in result argument of callback function.

Przykłady

Przykład #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();
?>

Powyższy przykład wyświetli coś podobnego do:

string(5) "34567"

Zobacz też:

eio_open
eio_write
eio_close
eio_event_loop

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