* Events subsystem merged from `server/events.go` and
`utils/jsonmessagepublisher.go` and moved to `events/events.go`
* Only public interface for this subsystem is engine jobs
* There is two new engine jobs - `log_event` and `subscribers_count`
* There is auxiliary function `container.LogEvent` for logging events for
containers
Docker-DCO-1.1-Signed-off-by: Alexandr Morozov <lk4d4math@gmail.com> (github: LK4D4)
[solomon@docker.com: resolve merge conflicts]
Signed-off-by: Solomon Hykes <solomon@docker.com>
Events subscription (/events API endpoint) attributes pseudo-unique identifiers to incoming subscribers: originally its host, then its subscription time. This is unecessary and leads to code complexity.
Introduce a JSONMessagePublisher to provide simple pub/sub mechanism for JSONMessage, and rely on this new type to publish events to all subscribed listeners. The original logic is kept for the 'since' and 'until' parameters, and for client disconnection handling.
Docker-DCO-1.1-Signed-off-by: Arnaud Porterie <icecrime@gmail.com> (github: icecrime)
