Utils/API: Replaced semaphore-mutex API

api/rate/rate.go

@@ -38,7 +38,7 @@ type CustomRateLimit struct {
 }
 
 type bucket struct {
-	lock   moreatomic.BusyMutex
+	lock   moreatomic.CtxMutex
 	custom *CustomRateLimit
 
 	remaining uint64
@@ -48,6 +48,13 @@ type bucket struct {
 	lastReset time.Time // only for custom
 }
 
+func newBucket() *bucket {
+	return &bucket{
+		lock:      *moreatomic.NewCtxMutex(),
+		remaining: 1,
+	}
+}
+
 func NewLimiter(prefix string) *Limiter {
 	return &Limiter{
 		Prefix:       prefix,
@@ -66,9 +73,7 @@ func (l *Limiter) getBucket(path string, store bool) *bucket {
 	}
 
 	if !ok {
-		bc := &bucket{
+		bc := newBucket()
-			remaining: 1,
-		}
 
 		for _, limit := range l.CustomLimits {
 			if strings.Contains(path, limit.Contains) {
@@ -131,11 +136,7 @@ func (l *Limiter) Release(path string, headers http.Header) error {
 		return nil
 	}
 
-	defer func() {
+	defer b.lock.Unlock()
-		// Try and lock the bucket, to prevent unlocking an unlocked lock:
-		b.lock.TryLock()
-		b.lock.Unlock()
-	}()
 
 	// Check custom limiter
 	if b.custom != nil {

go.mod

@@ -7,6 +7,5 @@ require (
 	github.com/gorilla/websocket v1.4.2
 	github.com/pkg/errors v0.9.1
 	golang.org/x/crypto v0.0.0-20200423211502-4bdfaf469ed5
-	golang.org/x/sync v0.0.0-20200317015054-43a5402ce75a
 	golang.org/x/time v0.0.0-20200416051211-89c76fbcd5d1
 )

go.sum

@@ -10,8 +10,6 @@ golang.org/x/crypto v0.0.0-20200423211502-4bdfaf469ed5 h1:Q7tZBpemrlsc2I7IyODzht
 golang.org/x/crypto v0.0.0-20200423211502-4bdfaf469ed5/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3 h1:0GoQqolDA55aaLxZyTzK/Y2ePZzZTUrRacwib7cNsYQ=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/sync v0.0.0-20200317015054-43a5402ce75a h1:WXEvlFVvvGxCJLG6REjsT03iWnKLEWinaScsxF2Vm2o=
-golang.org/x/sync v0.0.0-20200317015054-43a5402ce75a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d h1:+R4KGOnez64A81RvjARKc4UT5/tI9ujCIVX+P5KiHuI=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=

utils/moreatomic/mutex.go

@@ -2,36 +2,51 @@ package moreatomic
 
 import (
 	"context"
-
-	"golang.org/x/sync/semaphore"
 )
 
-type BusyMutex struct {
+type CtxMutex struct {
-	sema semaphore.Weighted
+	mut chan struct{}
 }
 
-func NewBusyMutex() *BusyMutex {
+func NewCtxMutex() *CtxMutex {
-	return &BusyMutex{
+	return &CtxMutex{
-		sema: *semaphore.NewWeighted(1),
+		mut: make(chan struct{}, 1),
 	}
 }
 
-func (m *BusyMutex) TryLock() bool {
+// func (m *CtxMutex) TryLock() bool {
-	return m.sema.TryAcquire(1)
+// 	select {
+// 	case m.mut <- struct{}{}:
+// 		return true
+// 	default:
+// 		return false
+// 	}
+// }
+
+// func (m *CtxMutex) IsBusy() bool {
+// 	select {
+// 	case m.mut <- struct{}{}:
+// 		<-m.mut
+// 		return false
+// 	default:
+// 		return true
+// 	}
+// }
+
+func (m *CtxMutex) Lock(ctx context.Context) error {
+	select {
+	case m.mut <- struct{}{}:
+		return nil
+	case <-ctx.Done():
+		return ctx.Err()
+	}
 }
 
-func (m *BusyMutex) IsBusy() bool {
+func (m *CtxMutex) Unlock() {
-	if !m.sema.TryAcquire(1) {
+	select {
-		return false
+	case <-m.mut:
+		// return
+	default:
+		panic("Unlock of already unlocked mutex.")
 	}
-	m.sema.Release(1)
-	return true
-}
-
-func (m *BusyMutex) Lock(ctx context.Context) error {
-	return m.sema.Acquire(ctx, 1)
-}
-
-func (m *BusyMutex) Unlock() {
-	m.sema.Release(1)
 }