add vendor directory

vendor/github.com/vmihailenco/bufpool/buf_pool.go

@@ -0,0 +1,67 @@
+package bufpool
+
+import (
+	"log"
+	"sync"
+)
+
+var thePool bufPool
+
+// Get retrieves a buffer of the appropriate length from the buffer pool or
+// allocates a new one. Get may choose to ignore the pool and treat it as empty.
+// Callers should not assume any relation between values passed to Put and the
+// values returned by Get.
+//
+// If no suitable buffer exists in the pool, Get creates one.
+func Get(length int) *Buffer {
+	return thePool.Get(length)
+}
+
+// Put returns a buffer to the buffer pool.
+func Put(buf *Buffer) {
+	thePool.Put(buf)
+}
+
+type bufPool struct {
+	pools [steps]sync.Pool
+}
+
+func (p *bufPool) Get(length int) *Buffer {
+	if length > maxPoolSize {
+		return NewBuffer(make([]byte, length))
+	}
+
+	idx := index(length)
+	if bufIface := p.pools[idx].Get(); bufIface != nil {
+		buf := bufIface.(*Buffer)
+		unlock(buf)
+		if length > buf.Cap() {
+			log.Println(idx, buf.Len(), buf.Cap(), buf.String())
+		}
+		buf.buf = buf.buf[:length]
+		return buf
+	}
+
+	b := make([]byte, length, indexSize(idx))
+	return NewBuffer(b)
+}
+
+func (p *bufPool) Put(buf *Buffer) {
+	length := buf.Cap()
+	if length > maxPoolSize || length < minSize {
+		return // drop it
+	}
+
+	idx := prevIndex(length)
+	lock(buf)
+	p.pools[idx].Put(buf)
+}
+
+func lock(buf *Buffer) {
+	buf.buf = buf.buf[:cap(buf.buf)]
+	buf.off = cap(buf.buf) + 1
+}
+
+func unlock(buf *Buffer) {
+	buf.off = 0
+}