(PECL eio >= 0.0.1dev)
eio_readahead — Perform file readahead into page cache
$fd
, int $offset
, int $length
[, int $pri = EIO_PRI_DEFAULT
[, callable $callback = NULL
[, mixed $data = NULL
]]] )eio_readahead() populates the page cache with data from a file so that subsequent reads from that file will not block on disk I/O. See READAHEAD(2) man page for details.
fd
Stream, Socket resource, or numeric file descriptor
offset
Starting point from which data is to be read.
length
Number of bytes to be read.
pri
请求的优先级: EIO_PRI_DEFAULT, EIO_PRI_MIN, EIO_PRI_MAX, or NULL.
如果是 NULL , pri 将设为
EIO_PRI_DEFAULT.
callback
callback 函数将在请求结束时被调用.
必须符合此原型:
void callback($data, $result);
$data 是传给该请求的特定数据.
$result 包含特定请求的结果值, 通常是相应的系统调用的返回值.
data
Arbitrary variable passed to callback.
eio_readahead() returns request resource on success or FALSE on error.