Initial commit

vendor/github.com/cockroachdb/pebble/internal/cache/value.go

@@ -0,0 +1,46 @@
+// Copyright 2020 The LevelDB-Go and Pebble Authors. All rights reserved. Use
+// of this source code is governed by a BSD-style license that can be found in
+// the LICENSE file.
+
+package cache
+
+// Value holds a reference counted immutable value.
+type Value struct {
+	buf []byte
+	// Reference count for the value. The value is freed when the reference count
+	// drops to zero.
+	ref refcnt
+}
+
+// Buf returns the buffer associated with the value. The contents of the buffer
+// should not be changed once the value has been added to the cache. Instead, a
+// new Value should be created and added to the cache to replace the existing
+// value.
+func (v *Value) Buf() []byte {
+	if v == nil {
+		return nil
+	}
+	return v.buf
+}
+
+// Truncate the buffer to the specified length. The buffer length should not be
+// changed once the value has been added to the cache as there may be
+// concurrent readers of the Value. Instead, a new Value should be created and
+// added to the cache to replace the existing value.
+func (v *Value) Truncate(n int) {
+	v.buf = v.buf[:n]
+}
+
+func (v *Value) refs() int32 {
+	return v.ref.refs()
+}
+
+func (v *Value) acquire() {
+	v.ref.acquire()
+}
+
+func (v *Value) release() {
+	if v != nil && v.ref.release() {
+		v.free()
+	}
+}