(PECL eio >= 0.0.1dev)
eio_fdatasync — Synchronize a file's in-core state with storage device.
eio_fdatasync() synchronizes a file's in-core state with storage device.
The file descriptor, e.g. returned by eio_open().
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 function is called when the request is done. It should match the following prototype:
void callback($data, $result);
Arbitrary variable passed to callback.
eio_fdatasync() returns request resource on success or FALSE on error.