PHP Manual: Sync a file segment with disk

Description

resource eio_sync_file_range(
    mixed $fd,
    int $offset,
    int $nbytes,
    int $flags,
    int $pri = EIO_PRI_DEFAULT,
    callable $callback = NULL,
    mixed $data = NULL
)

eio_sync_file_range permits fine control when synchronizing the open file referred to by the file descriptor fd with disk.

Parameters

fd

File descriptor

offset

The starting byte of the file range to be synchronized

nbytes

Specifies the length of the range to be synchronized, in bytes. If nbytes is zero, then all bytes from offset through to the end of file are synchronized.

flags

A bit-mask. Can include any of the following values: EIO_SYNC_FILE_RANGE_WAIT_BEFORE, EIO_SYNC_FILE_RANGE_WRITE, EIO_SYNC_FILE_RANGE_WAIT_AFTER. These flags have the same meaning as their SYNC_FILE_RANGE_* counterparts(see SYNC_FILE_RANGE(2) man page).

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_sync_file_range returns request resource on success, or false on failure.