1// Copyright (c) 2019 FOSS contributors of https://github.com/nxadm/tail
 2// Copyright (c) 2015 HPE Software Inc. All rights reserved.
 3// Copyright (c) 2013 ActiveState Software Inc. All rights reserved.
 4
 5package watch
 6
 7import "gopkg.in/tomb.v1"
 8
 9// FileWatcher monitors file-level events.
10type FileWatcher interface {
11	// BlockUntilExists blocks until the file comes into existence.
12	BlockUntilExists(*tomb.Tomb) error
13
14	// ChangeEvents reports on changes to a file, be it modification,
15	// deletion, renames or truncations. Returned FileChanges group of
16	// channels will be closed, thus become unusable, after a deletion
17	// or truncation event.
18	// In order to properly report truncations, ChangeEvents requires
19	// the caller to pass their current offset in the file.
20	ChangeEvents(*tomb.Tomb, int64) (*FileChanges, error)
21}