eio_readahead
(PECL eio >= 0.0.1dev)
eio_readahead — Perform file readahead into page cache
说明
eio_readahead(
mixed
int
int
int
callable
mixed
): resource
mixed
$fd,int
$offset,int
$length,int
$pri = EIO_PRI_DEFAULT,callable
$callback = NULL,mixed
$data = NULL): resource
eio_readahead() populates the page cache with data from a file so that subsequent reads from
that file will not block on disk I/O. See READAHEAD(2) man page for details.
参数
-
fd -
Stream, Socket resource, or numeric file descriptor
-
offset -
Starting point from which data is to be read.
-
length -
Number of bytes to be read.
-
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_readahead() returns request resource on success, 或者在失败时返回 false.
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