4 files changed, 152 insertions, 0 deletions
diff --git a/pkg/events/general.go b/pkg/events/general.go
new file mode 100755
index 00000000..a09a8759
--- /dev/null
+++ b/pkg/events/general.go
@@ -0,0 +1,39 @@
+package events
+
+import (
+	"sync"
+)
+
+// HandlerImpl helps to broadcast events to multiple listeners.
+type HandlerImpl struct {
+	listeners    []Listener
+	sync.RWMutex // all receivers should be pointers
+}
+
+func NewEventsHandler() Handler {
+	return &HandlerImpl{listeners: make([]Listener, 0, 2)}
+}
+
+// NumListeners returns number of event listeners.
+func (eb *HandlerImpl) NumListeners() int {
+	eb.Lock()
+	defer eb.Unlock()
+	return len(eb.listeners)
+}
+
+// AddListener registers new event listener.
+func (eb *HandlerImpl) AddListener(listener Listener) {
+	eb.Lock()
+	defer eb.Unlock()
+	eb.listeners = append(eb.listeners, listener)
+}
+
+// Push broadcast events across all event listeners.
+func (eb *HandlerImpl) Push(e interface{}) {
+	// ReadLock here because we are not changing listeners
+	eb.RLock()
+	defer eb.RUnlock()
+	for k := range eb.listeners {
+		eb.listeners[k](e)
+	}
+}
diff --git a/pkg/events/interface.go b/pkg/events/interface.go
new file mode 100644
index 00000000..ac6c15a4
--- /dev/null
+++ b/pkg/events/interface.go
@@ -0,0 +1,14 @@
+package events
+
+// Handler interface
+type Handler interface {
+	// Return number of active listeners
+	NumListeners() int
+	// AddListener adds lister to the publisher
+	AddListener(listener Listener)
+	// Push pushes event to the listeners
+	Push(e interface{})
+}
+
+// Event listener listens for the events produced by worker, worker pool or other service.
+type Listener func(event interface{})
diff --git a/pkg/events/pool_events.go b/pkg/events/pool_events.go
new file mode 100644
index 00000000..3925df56
--- /dev/null
+++ b/pkg/events/pool_events.go
@@ -0,0 +1,66 @@
+package events
+
+// TODO event numbers
+const (
+	// EventWorkerConstruct thrown when new worker is spawned.
+	EventWorkerConstruct P = iota + 10000
+
+	// EventWorkerDestruct thrown after worker destruction.
+	EventWorkerDestruct
+
+	// EventPoolError caused on pool wide errors.
+	EventPoolError
+
+	// EventSupervisorError triggered when supervisor can not complete work.
+	EventSupervisorError
+
+	// EventNoFreeWorkers triggered when there are no free workers in the stack and timeout for worker allocate elapsed
+	EventNoFreeWorkers
+
+	// EventMaxMemory caused when worker consumes more memory than allowed.
+	EventMaxMemory
+
+	// EventTTL thrown when worker is removed due TTL being reached. TTL defines maximum time worker is allowed to live (seconds)
+	EventTTL
+
+	// EventIdleTTL triggered when worker spends too much time at rest.
+	EventIdleTTL
+
+	// EventExecTTL triggered when worker spends too much time doing the task (max_execution_time).
+	EventExecTTL
+)
+
+type P int64
+
+func (ev P) String() string {
+	switch ev {
+	case EventWorkerConstruct:
+		return "EventWorkerConstruct"
+	case EventWorkerDestruct:
+		return "EventWorkerDestruct"
+	case EventPoolError:
+		return "EventPoolError"
+	case EventSupervisorError:
+		return "EventSupervisorError"
+	case EventNoFreeWorkers:
+		return "EventNoFreeWorkers"
+	case EventMaxMemory:
+		return "EventMaxMemory"
+	case EventTTL:
+		return "EventTTL"
+	case EventIdleTTL:
+		return "EventIdleTTL"
+	case EventExecTTL:
+		return "EventExecTTL"
+	}
+	return "Unknown event type"
+}
+
+// PoolEvent triggered by pool on different events. Pool as also trigger WorkerEvent in case of log.
+type PoolEvent struct {
+	// Event type, see below.
+	Event P
+
+	// Payload depends on event type, typically it's worker or error.
+	Payload interface{}
+}
diff --git a/pkg/events/worker_events.go b/pkg/events/worker_events.go
new file mode 100644
index 00000000..9d428f7d
--- /dev/null
+++ b/pkg/events/worker_events.go
@@ -0,0 +1,33 @@
+package events
+
+const (
+	// EventWorkerError triggered after WorkerProcess. Except payload to be error.
+	EventWorkerError W = iota + 11000
+
+	// EventWorkerLog triggered on every write to WorkerProcess StdErr pipe (batched). Except payload to be []byte string.
+	EventWorkerLog
+)
+
+type W int64
+
+func (ev W) String() string {
+	switch ev {
+	case EventWorkerError:
+		return "EventWorkerError"
+	case EventWorkerLog:
+		return "EventWorkerLog"
+	}
+	return "Unknown event type"
+}
+
+// WorkerEvent wraps worker events.
+type WorkerEvent struct {
+	// Event id, see below.
+	Event W
+
+	// Worker triggered the event.
+	Worker interface{}
+
+	// Event specific payload.
+	Payload interface{}
+}