perf(cloudflared): reuse memory from buffer pool to get better throughput (#161)

* perf(cloudflared): reuse memory from buffer pool to get better throughput

https://github.com/cloudflare/cloudflared/issues/160

buffer/pool.go

@@ -0,0 +1,29 @@
+package buffer
+
+import (
+	"sync"
+)
+
+type Pool struct {
+	// A Pool must not be copied after first use.
+	// https://golang.org/pkg/sync/#Pool
+	buffers sync.Pool
+}
+
+func NewPool(bufferSize int) *Pool {
+	return &Pool{
+		buffers: sync.Pool{
+			New: func() interface{} {
+				return make([]byte, bufferSize)
+			},
+		},
+	}
+}
+
+func (p *Pool) Get() []byte {
+	return p.buffers.Get().([]byte)
+}
+
+func (p *Pool) Put(buf []byte) {
+	p.buffers.Put(buf)
+}