Do not use defer in performance-sensitive contexts

src/chunklist.go

@@ -55,7 +55,6 @@ func CountItems(cs []*Chunk) int {
 // Push adds the item to the list
 func (cl *ChunkList) Push(data []byte) bool {
 	cl.mutex.Lock()
-	defer cl.mutex.Unlock()
 
 	if len(cl.chunks) == 0 || cl.lastChunk().IsFull() {
 		newChunk := Chunk(make([]Item, 0, chunkSize))
@@ -64,15 +63,16 @@ func (cl *ChunkList) Push(data []byte) bool {
 
 	if cl.lastChunk().push(cl.trans, data, cl.count) {
 		cl.count++
+		cl.mutex.Unlock()
 		return true
 	}
+	cl.mutex.Unlock()
 	return false
 }
 
 // Snapshot returns immutable snapshot of the ChunkList
 func (cl *ChunkList) Snapshot() ([]*Chunk, int) {
 	cl.mutex.Lock()
-	defer cl.mutex.Unlock()
 
 	ret := make([]*Chunk, len(cl.chunks))
 	copy(ret, cl.chunks)
@@ -82,5 +82,7 @@ func (cl *ChunkList) Snapshot() ([]*Chunk, int) {
 		newChunk := *ret[cnt-1]
 		ret[cnt-1] = &newChunk
 	}
+
+	cl.mutex.Unlock()
 	return ret, cl.count
 }

src/core.go

@@ -205,7 +205,6 @@ func Run(opts *Options, revision string) {
 		delay := true
 		ticks++
 		eventBox.Wait(func(events *util.Events) {
-			defer events.Clear()
 			for evt, value := range *events {
 				switch evt {
 
@@ -265,6 +264,7 @@ func Run(opts *Options, revision string) {
 					}
 				}
 			}
+			events.Clear()
 		})
 		if delay && reading {
 			dur := util.DurWithin(

src/util/eventbox.go

@@ -26,23 +26,23 @@ func NewEventBox() *EventBox {
 // Wait blocks the goroutine until signaled
 func (b *EventBox) Wait(callback func(*Events)) {
 	b.cond.L.Lock()
-	defer b.cond.L.Unlock()
 
 	if len(b.events) == 0 {
 		b.cond.Wait()
 	}
 
 	callback(&b.events)
+	b.cond.L.Unlock()
 }
 
 // Set turns on the event type on the box
 func (b *EventBox) Set(event EventType, value interface{}) {
 	b.cond.L.Lock()
-	defer b.cond.L.Unlock()
 	b.events[event] = value
 	if _, found := b.ignore[event]; !found {
 		b.cond.Broadcast()
 	}
+	b.cond.L.Unlock()
 }
 
 // Clear clears the events
@@ -56,27 +56,27 @@ func (events *Events) Clear() {
 // Peek peeks at the event box if the given event is set
 func (b *EventBox) Peek(event EventType) bool {
 	b.cond.L.Lock()
-	defer b.cond.L.Unlock()
 	_, ok := b.events[event]
+	b.cond.L.Unlock()
 	return ok
 }
 
 // Watch deletes the events from the ignore list
 func (b *EventBox) Watch(events ...EventType) {
 	b.cond.L.Lock()
-	defer b.cond.L.Unlock()
 	for _, event := range events {
 		delete(b.ignore, event)
 	}
+	b.cond.L.Unlock()
 }
 
 // Unwatch adds the events to the ignore list
 func (b *EventBox) Unwatch(events ...EventType) {
 	b.cond.L.Lock()
-	defer b.cond.L.Unlock()
 	for _, event := range events {
 		b.ignore[event] = true
 	}
+	b.cond.L.Unlock()
 }
 
 // WaitFor blocks the execution until the event is received