1 files changed, 58 insertions, 0 deletions
diff --git a/service/watcher/state_watch.go b/service/watcher/state_watch.go
new file mode 100644
index 00000000..3090d15d
--- /dev/null
+++ b/service/watcher/state_watch.go
@@ -0,0 +1,58 @@
+package watcher
+
+import (
+	"github.com/spiral/roadrunner"
+	"time"
+)
+
+type stateWatcher struct {
+	prev map[*roadrunner.Worker]state
+	next map[*roadrunner.Worker]state
+}
+
+type state struct {
+	state    int64
+	numExecs int64
+	since    time.Time
+}
+
+func newStateWatcher() *stateWatcher {
+	return &stateWatcher{
+		prev: make(map[*roadrunner.Worker]state),
+		next: make(map[*roadrunner.Worker]state),
+	}
+}
+
+// add new worker to be watched
+func (sw *stateWatcher) push(w *roadrunner.Worker) {
+	sw.next[w] = state{state: w.State().Value(), numExecs: w.State().NumExecs()}
+}
+
+// update worker states.
+func (sw *stateWatcher) sync(t time.Time) {
+	for w := range sw.prev {
+		if _, ok := sw.next[w]; !ok {
+			delete(sw.prev, w)
+		}
+	}
+
+	for w, s := range sw.next {
+		ps, ok := sw.prev[w]
+		if !ok || ps.state != s.state || ps.numExecs != s.numExecs {
+			sw.prev[w] = state{state: s.state, numExecs: s.numExecs, since: t}
+		}
+
+		delete(sw.next, w)
+	}
+}
+
+// find all workers which spend given amount of time in a specific state.
+func (sw *stateWatcher) find(state int64, since time.Time) (workers []*roadrunner.Worker) {
+	for w, s := range sw.prev {
+		if s.state == state && s.since.Before(since) {
+			workers = append(workers, w)
+		}
+	}
+
+	return
+}