This is mostly mechanical and changes how loggers are instantiated.
Logger is now associated with a context, passed around all methods,
(most methods had ctx, but had to add it in a few missing places).
By default Kopia does not produce any logs, but it can be overridden,
either locally for a nested context, by calling
ctx = logging.WithLogger(ctx, newLoggerFunc)
To override logs globally, call logging.SetDefaultLogger(newLoggerFunc)
This refactoring allowed removing dependency from Kopia repo
and go-logging library (the CLI still uses it, though).
It is now also possible to have all test methods emit logs using
t.Logf() so that they show up in failure reports, which should make
debugging of test failures suck less.
Motivation:
- Consistent locking/unlocking `c.mu` in `Cache.getEntries`
- Fix CI failure
`Cache.getEntriesFromCache()` was releasing `c.mu` when returning an
entry and not releasing it when returning nil. Previously, the caller
(`Cache.getEntries`) was accordingly not releasing `c.mu` when
`getEntriesFromCache()` was returning an entry, and unlocking `c.mu`
otherwise.
`Cache.getEntries` is the only caller for `getEntriesFromCache`.
After this change c.mu is consistently locked and unlocked in
`getEntries`
