* Consistent license message for all the go files
* Fixing the last set of unconsistencies with the license headers
* Addressing PR review comments
* Fixing busy.go and busy_test.go license header
* MM-18540 - Demo plugin crashes on server shutdown
* MM-18540 - Removed unncessary lock statements
* Added comments, logging a warning if PluginsEnv is updated while shutting down plugins
* Don't clean up PluginsEnv if another Env is detected
* Changing warn to debug
* Revert "Changing warn to debug"
This reverts commit 46f20ab21e.
* Rerouted the unit test logs through t.Log
* resolving merge confilvts
* Update testing.go
* Update helper_test.go
* Added godocs for NewTestingLogger
* Added go docs for NewTestingLogger
* Resolving conflicts
* ensure plugin is always shutdown
Once we call `.client.Client()` the plugin has started, and must be shut
down. `newSupervisor` sometimes returned with an error (and without a
reference to the supervisor), leaving the client running indefinitely.
* Clarify the documentation to explain that plugin hooks will not trigger until `OnActivate` returns successfully, and will stop triggering just before `OnDeactivate` is called.
* test for plugin deadlock
* plugin/environment.go: switch to sync.Map
From: https://golang.org/pkg/sync/#Map
> If a goroutine holds a RWMutex for reading and another goroutine might call Lock, no goroutine should expect to be able to acquire a read lock until the initial read lock is released. In particular, this prohibits recursive read locking. This is to ensure that the lock eventually becomes available; a blocked Lock call excludes new readers from acquiring the lock.
The previous `RWMutex` was not safe given that we effectively acquired read locks recursively (hook -> api -> hook). This worked up until we activated or deactivated plugins, tried to acquire a write lock, and the plugin used the API to effectively trigger another hook.
Switching to sync.Map avoids this by divesting the need to lock at all, avoiding the potential for a recursive lock in the first place.
