Hulk did something

[bytom/vapor.git] / vendor / github.com / syndtr / goleveldb / leveldb / util / util.go

diff --git a/vendor/github.com/syndtr/goleveldb/leveldb/util/util.go b/vendor/github.com/syndtr/goleveldb/leveldb/util/util.go
new file mode 100644 (file)
index 0000000..f359768
--- /dev/null
+++ b/vendor/github.com/syndtr/goleveldb/leveldb/util/util.go
@@ -0,0 +1,73 @@
+// Copyright (c) 2013, Suryandaru Triandana <syndtr@gmail.com>
+// All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Package util provides utilities used throughout leveldb.
+package util
+
+import (
+       "errors"
+)
+
+var (
+       ErrReleased    = errors.New("leveldb: resource already relesed")
+       ErrHasReleaser = errors.New("leveldb: releaser already defined")
+)
+
+// Releaser is the interface that wraps the basic Release method.
+type Releaser interface {
+       // Release releases associated resources. Release should always success
+       // and can be called multipe times without causing error.
+       Release()
+}
+
+// ReleaseSetter is the interface that wraps the basic SetReleaser method.
+type ReleaseSetter interface {
+       // SetReleaser associates the given releaser to the resources. The
+       // releaser will be called once coresponding resources released.
+       // Calling SetReleaser with nil will clear the releaser.
+       //
+       // This will panic if a releaser already present or coresponding
+       // resource is already released. Releaser should be cleared first
+       // before assigned a new one.
+       SetReleaser(releaser Releaser)
+}
+
+// BasicReleaser provides basic implementation of Releaser and ReleaseSetter.
+type BasicReleaser struct {
+       releaser Releaser
+       released bool
+}
+
+// Released returns whether Release method already called.
+func (r *BasicReleaser) Released() bool {
+       return r.released
+}
+
+// Release implements Releaser.Release.
+func (r *BasicReleaser) Release() {
+       if !r.released {
+               if r.releaser != nil {
+                       r.releaser.Release()
+                       r.releaser = nil
+               }
+               r.released = true
+       }
+}
+
+// SetReleaser implements ReleaseSetter.SetReleaser.
+func (r *BasicReleaser) SetReleaser(releaser Releaser) {
+       if r.released {
+               panic(ErrReleased)
+       }
+       if r.releaser != nil && releaser != nil {
+               panic(ErrHasReleaser)
+       }
+       r.releaser = releaser
+}
+
+type NoopReleaser struct{}
+
+func (NoopReleaser) Release() {}