Support override of symlink to config file
Include tests for WatchConfig of regular files, as well
as config file which links to a folder which is itself a
link to another folder in the same "watch dir" (the way
Kubernetes exposes config files from ConfigMaps mounted
on a volume in a Pod)
Also:
- Add synchronization with WaitGroup to ensure that the WatchConfig
is properly started before returning
- Remove the watcher when the Config file is removed.
Fixes#284
Signed-off-by: Xavier Coulon <xcoulon@redhat.com>
Also avoid doing a strings.Split in the Get common case.
Any TRACE statements in these hot paths must be totally turned off when not testing.
```
benchmark old ns/op new ns/op delta
BenchmarkGetBool-4 4090 409 -90.00%
BenchmarkGetBoolFromMap-4 6.33 6.28 -0.79%
benchmark old allocs new allocs delta
BenchmarkGetBool-4 6 3 -50.00%
BenchmarkGetBoolFromMap-4 0 0 +0.00%
benchmark old bytes new bytes delta
BenchmarkGetBool-4 129 33 -74.42%
BenchmarkGetBoolFromMap-4 0 0 +0.00%
```
Fixes#242
