Add Traceroute Module

parallel_limiter/parallel_limiter.go

@@ -0,0 +1,52 @@
+package parallel_limiter
+
+import (
+	"sync"
+)
+
+type ParallelLimiter struct {
+	maxCount int
+
+	mu             sync.Mutex
+	currentRunning int
+
+	waiting []chan struct{}
+}
+
+func New(count int) *ParallelLimiter {
+	return &ParallelLimiter{
+		maxCount: count,
+
+		currentRunning: 0,
+		waiting:        []chan struct{}{},
+	}
+}
+
+func (p *ParallelLimiter) Start() chan struct{} {
+	p.mu.Lock()
+	if p.currentRunning+1 > p.maxCount {
+		waitChan := make(chan struct{})
+		p.waiting = append(p.waiting, waitChan)
+		p.mu.Unlock()
+		return waitChan
+	}
+	p.currentRunning++
+	p.mu.Unlock()
+	instantResolveChan := make(chan struct{})
+	go func() {
+		instantResolveChan <- struct{}{}
+	}()
+	return instantResolveChan
+}
+
+func (p *ParallelLimiter) Finished() {
+	p.mu.Lock()
+	if len(p.waiting) > 0 {
+		first := p.waiting[0]
+		p.waiting = p.waiting[1:]
+		first <- struct{}{}
+		p.currentRunning++
+	}
+	p.currentRunning--
+	p.mu.Unlock()
+}