Merge pull request #480 from Arceliar/speedup

Speedup

src/util/util.go

@@ -26,27 +26,25 @@ func UnlockThread() {
 }
 
 // This is used to buffer recently used slices of bytes, to prevent allocations in the hot loops.
-var byteStoreMutex sync.Mutex
-var byteStore [][]byte
+var byteStore = sync.Pool{New: func() interface{} { return []byte(nil) }}
 
 // Gets an empty slice from the byte store.
 func GetBytes() []byte {
-	byteStoreMutex.Lock()
-	defer byteStoreMutex.Unlock()
-	if len(byteStore) > 0 {
-		var bs []byte
-		bs, byteStore = byteStore[len(byteStore)-1][:0], byteStore[:len(byteStore)-1]
-		return bs
-	} else {
-		return nil
-	}
+	return byteStore.Get().([]byte)[:0]
 }
 
 // Puts a slice in the store.
 func PutBytes(bs []byte) {
-	byteStoreMutex.Lock()
-	defer byteStoreMutex.Unlock()
-	byteStore = append(byteStore, bs)
+	byteStore.Put(bs)
+}
+
+// Gets a slice of the appropriate length, reusing existing slice capacity when possible
+func ResizeBytes(bs []byte, length int) []byte {
+	if cap(bs) >= length {
+		return bs[:length]
+	} else {
+		return make([]byte, length)
+	}
 }
 
 // This is a workaround to go's broken timer implementation

src/util/workerpool.go

@@ -0,0 +1,29 @@
+package util
+
+import "runtime"
+
+var workerPool chan func()
+
+func init() {
+	maxProcs := runtime.GOMAXPROCS(0)
+	if maxProcs < 1 {
+		maxProcs = 1
+	}
+	workerPool = make(chan func(), maxProcs)
+	for idx := 0; idx < maxProcs; idx++ {
+		go func() {
+			for f := range workerPool {
+				f()
+			}
+		}()
+	}
+}
+
+// WorkerGo submits a job to a pool of GOMAXPROCS worker goroutines.
+// This is meant for short non-blocking functions f() where you could just go f(),
+// but you want some kind of backpressure to prevent spawning endless goroutines.
+// WorkerGo returns as soon as the function is queued to run, not when it finishes.
+// In Yggdrasil, these workers are used for certain cryptographic operations.
+func WorkerGo(f func()) {
+	workerPool <- f
+}