Adding upstream version 2.5.1.

Signed-off-by: Daniel Baumann <daniel@debian.org>

index/upsidedown/store/gtreap/iterator.go

@@ -0,0 +1,152 @@
+//  Copyright (c) 2015 Couchbase, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// 		http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package gtreap provides an in-memory implementation of the
+// KVStore interfaces using the gtreap balanced-binary treap,
+// copy-on-write data structure.
+package gtreap
+
+import (
+	"bytes"
+	"sync"
+
+	"github.com/blevesearch/gtreap"
+)
+
+type Iterator struct {
+	t *gtreap.Treap
+
+	m        sync.Mutex
+	cancelCh chan struct{}
+	nextCh   chan *Item
+	curr     *Item
+	currOk   bool
+
+	prefix []byte
+	start  []byte
+	end    []byte
+}
+
+func (w *Iterator) Seek(k []byte) {
+	if w.start != nil && bytes.Compare(k, w.start) < 0 {
+		k = w.start
+	}
+	if w.prefix != nil && !bytes.HasPrefix(k, w.prefix) {
+		if bytes.Compare(k, w.prefix) < 0 {
+			k = w.prefix
+		} else {
+			var end []byte
+			for i := len(w.prefix) - 1; i >= 0; i-- {
+				c := w.prefix[i]
+				if c < 0xff {
+					end = make([]byte, i+1)
+					copy(end, w.prefix)
+					end[i] = c + 1
+					break
+				}
+			}
+			k = end
+		}
+	}
+	w.restart(&Item{k: k})
+}
+
+func (w *Iterator) restart(start *Item) *Iterator {
+	cancelCh := make(chan struct{})
+	nextCh := make(chan *Item, 1)
+
+	w.m.Lock()
+	if w.cancelCh != nil {
+		close(w.cancelCh)
+	}
+	w.cancelCh = cancelCh
+	w.nextCh = nextCh
+	w.curr = nil
+	w.currOk = false
+	w.m.Unlock()
+
+	go func() {
+		if start != nil {
+			w.t.VisitAscend(start, func(itm gtreap.Item) bool {
+				select {
+				case <-cancelCh:
+					return false
+				case nextCh <- itm.(*Item):
+					return true
+				}
+			})
+		}
+		close(nextCh)
+	}()
+
+	w.Next()
+
+	return w
+}
+
+func (w *Iterator) Next() {
+	w.m.Lock()
+	nextCh := w.nextCh
+	w.m.Unlock()
+	w.curr, w.currOk = <-nextCh
+}
+
+func (w *Iterator) Current() ([]byte, []byte, bool) {
+	w.m.Lock()
+	defer w.m.Unlock()
+	if !w.currOk || w.curr == nil {
+		return nil, nil, false
+	}
+	if w.prefix != nil && !bytes.HasPrefix(w.curr.k, w.prefix) {
+		return nil, nil, false
+	} else if w.end != nil && bytes.Compare(w.curr.k, w.end) >= 0 {
+		return nil, nil, false
+	}
+	return w.curr.k, w.curr.v, w.currOk
+}
+
+func (w *Iterator) Key() []byte {
+	k, _, ok := w.Current()
+	if !ok {
+		return nil
+	}
+	return k
+}
+
+func (w *Iterator) Value() []byte {
+	_, v, ok := w.Current()
+	if !ok {
+		return nil
+	}
+	return v
+}
+
+func (w *Iterator) Valid() bool {
+	_, _, ok := w.Current()
+	return ok
+}
+
+func (w *Iterator) Close() error {
+	w.m.Lock()
+	if w.cancelCh != nil {
+		close(w.cancelCh)
+	}
+	w.cancelCh = nil
+	w.nextCh = nil
+	w.curr = nil
+	w.currOk = false
+	w.m.Unlock()
+
+	return nil
+}