eio_read
(PECL eio >= 0.0.1dev)
eio_read — Read from a file descriptor at given offset
说明
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.
参数
-
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.
返回值
eio_read() stores read bytes in result argument of callback function.
范例
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"
参见
- eio_open
- eio_write
- eio_close
- eio_event_loop
