type Context struct {
// The system context with cancel capability. SystemContext context.Context// Coordination signal WG *sync.WaitGroup// Report errors to bootstrap component// Once error is reported by lower components, the whole system should exit
ErrorChan chan error// The base job context reference// It will be the parent context of job execution context
JobContext job.Context
}
Context keep some sharable materials and system controlling channels.
The system context.Context interface is also included.