PHP Manual: Perform file readahead into page cache

Description

resource eio_readahead(
    mixed $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.

Parameters

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

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(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_readahead returns request resource on success, or false on failure.