Show warnings in GUI (fixes #66)

suppressor.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"sync"
+	"time"
+)
+
+const (
+	MAX_CHANGE_HISTORY = 4
+)
+
+type change struct {
+	size int64
+	when time.Time
+}
+
+type changeHistory struct {
+	changes []change
+	next    int64
+	prevSup bool
+}
+
+type suppressor struct {
+	sync.Mutex
+	changes   map[string]changeHistory
+	threshold int64 // bytes/s
+}
+
+func (h changeHistory) bandwidth(t time.Time) int64 {
+	if len(h.changes) == 0 {
+		return 0
+	}
+
+	var t0 = h.changes[0].when
+	if t == t0 {
+		return 0
+	}
+
+	var bw float64
+	for _, c := range h.changes {
+		bw += float64(c.size)
+	}
+	return int64(bw / t.Sub(t0).Seconds())
+}
+
+func (h *changeHistory) append(size int64, t time.Time) {
+	c := change{size, t}
+	if len(h.changes) == MAX_CHANGE_HISTORY {
+		h.changes = h.changes[1:MAX_CHANGE_HISTORY]
+	}
+	h.changes = append(h.changes, c)
+}
+
+func (s *suppressor) suppress(name string, size int64, t time.Time) (bool, bool) {
+	s.Lock()
+
+	if s.changes == nil {
+		s.changes = make(map[string]changeHistory)
+	}
+	h := s.changes[name]
+	sup := h.bandwidth(t) > s.threshold
+	prevSup := h.prevSup
+	h.prevSup = sup
+	if !sup {
+		h.append(size, t)
+	}
+	s.changes[name] = h
+
+	s.Unlock()
+
+	return sup, prevSup
+}