If one program opens file(in our case log file) and this file is moved
or removed by other program, the first program still works with opened
file descriptor.
If we use WatchedFileHandler it allows to recreate file only after
first emitting of WatchedFileHandler. It means that deleted files still
consumes disk space.
Class FastWatchedFileHandler is designed to observe file system. If log
file is moved or removed FastWatchedFileHandler instantaneously closes
old file descriptor and creates new file with specified name.
Config option watch-log-file was added. If this option is set
FastWatchedFileHandler handler will be used.
Option watch-log-file brings effect for Linux platform only.
DocImpact
Closes-Bug: #1437444
Change-Id: Ie70c70ad2d8cf198a8fd72488a43fb1bd71c57be
a834e6a10c