Initial Commit

src/graph_memstore/llrb-iterator.go

@@ -0,0 +1,149 @@
+// Copyright 2014 The Cayley Authors. All rights reserved.
+//
+// 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 graph_memstore
+
+import (
+	"fmt"
+	"github.com/petar/GoLLRB/llrb"
+	"graph"
+	"math"
+	"strings"
+)
+
+type LlrbIterator struct {
+	graph.BaseIterator
+	tree      *llrb.LLRB
+	values    chan llrb.Item
+	another   chan bool
+	data      string
+	isRunning bool
+}
+
+type Int64 int64
+
+func (i Int64) Less(than llrb.Item) bool {
+	return i < than.(Int64)
+}
+
+func IterateAll(tree *llrb.LLRB, c chan llrb.Item, another chan bool) {
+	tree.AscendGreaterOrEqual(Int64(-1), func(i llrb.Item) bool {
+		want_more := <-another
+		if want_more {
+			c <- i
+			return true
+		}
+		return false
+	})
+}
+
+func NewLlrbIterator(tree *llrb.LLRB, data string) *LlrbIterator {
+	var it LlrbIterator
+	graph.BaseIteratorInit(&it.BaseIterator)
+	it.tree = tree
+	it.isRunning = false
+	it.values = make(chan llrb.Item)
+	it.another = make(chan bool, 1)
+	it.data = data
+	return &it
+}
+
+func (it *LlrbIterator) Reset() {
+	if it.another != nil {
+		it.another <- false
+		close(it.another)
+	}
+	it.another = nil
+	if it.values != nil {
+		close(it.values)
+	}
+	it.values = nil
+	it.isRunning = false
+	it.another = make(chan bool)
+	it.values = make(chan llrb.Item)
+}
+
+func (it *LlrbIterator) Clone() graph.Iterator {
+	var new_it = NewLlrbIterator(it.tree, it.data)
+	new_it.CopyTagsFrom(it)
+	return new_it
+}
+
+func (it *LlrbIterator) Close() {
+	if it.another != nil {
+		it.another <- false
+		close(it.another)
+	}
+	it.another = nil
+	if it.values != nil {
+		close(it.values)
+	}
+	it.values = nil
+}
+
+func (it *LlrbIterator) Next() (graph.TSVal, bool) {
+	graph.NextLogIn(it)
+	// Little hack here..
+	if !it.isRunning {
+		go IterateAll(it.tree, it.values, it.another)
+		it.isRunning = true
+	}
+	last := int64(0)
+	if it.Last != nil {
+		last = it.Last.(int64)
+	}
+	if it.tree.Max() == nil || last == int64(it.tree.Max().(Int64)) {
+		return graph.NextLogOut(it, nil, false)
+	}
+	it.another <- true
+	val := <-it.values
+	it.Last = int64(val.(Int64))
+	return graph.NextLogOut(it, it.Last, true)
+}
+
+func (it *LlrbIterator) Size() (int64, bool) {
+	return int64(it.tree.Len()), true
+}
+
+func (it *LlrbIterator) Check(v graph.TSVal) bool {
+	graph.CheckLogIn(it, v)
+	if it.tree.Has(Int64(v.(int64))) {
+		it.Last = v
+		return graph.CheckLogOut(it, v, true)
+	}
+	return graph.CheckLogOut(it, v, false)
+}
+
+func (it *LlrbIterator) DebugString(indent int) string {
+	size, _ := it.Size()
+	return fmt.Sprintf("%s(%s tags:%s size:%d %s)", strings.Repeat(" ", indent), it.Type(), it.Tags(), size, it.data)
+}
+
+func (it *LlrbIterator) Type() string {
+	return "llrb"
+}
+func (it *LlrbIterator) Sorted() bool {
+	return true
+}
+func (it *LlrbIterator) Optimize() (graph.Iterator, bool) {
+	return it, false
+}
+
+func (it *LlrbIterator) GetStats() *graph.IteratorStats {
+	return &graph.IteratorStats{
+		CheckCost: int64(math.Log(float64(it.tree.Len()))) + 1,
+		NextCost:  1,
+		Size:      int64(it.tree.Len()),
+	}
+}