Destutter filenames

graph/leveldb/iterator.go

@@ -0,0 +1,212 @@
+// 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 leveldb
+
+import (
+	"bytes"
+	_ "encoding/binary"
+	"fmt"
+	"strings"
+
+	leveldb_it "github.com/syndtr/goleveldb/leveldb/iterator"
+	leveldb_opt "github.com/syndtr/goleveldb/leveldb/opt"
+
+	"github.com/google/cayley/graph"
+)
+
+type LevelDBIterator struct {
+	graph.BaseIterator
+	nextPrefix     []byte
+	checkId        []byte
+	dir            string
+	open           bool
+	it             leveldb_it.Iterator
+	ts             *LevelDBTripleStore
+	ro             *leveldb_opt.ReadOptions
+	originalPrefix string
+}
+
+func NewLevelDBIterator(prefix, dir string, value graph.TSVal, ts *LevelDBTripleStore) *LevelDBIterator {
+	var it LevelDBIterator
+	graph.BaseIteratorInit(&it.BaseIterator)
+	it.checkId = value.([]byte)
+	it.dir = dir
+	it.originalPrefix = prefix
+	it.nextPrefix = make([]byte, 0, 2+ts.hasher.Size())
+	it.nextPrefix = append(it.nextPrefix, []byte(prefix)...)
+	it.nextPrefix = append(it.nextPrefix, []byte(it.checkId[1:])...)
+	it.ro = &leveldb_opt.ReadOptions{}
+	it.ro.DontFillCache = true
+	it.it = ts.db.NewIterator(nil, it.ro)
+	it.open = true
+	it.ts = ts
+	ok := it.it.Seek(it.nextPrefix)
+	if !ok {
+		it.open = false
+		it.it.Release()
+	}
+	return &it
+}
+
+func (lit *LevelDBIterator) Reset() {
+	if !lit.open {
+		lit.it = lit.ts.db.NewIterator(nil, lit.ro)
+		lit.open = true
+	}
+	ok := lit.it.Seek(lit.nextPrefix)
+	if !ok {
+		lit.open = false
+		lit.it.Release()
+	}
+}
+
+func (lit *LevelDBIterator) Clone() graph.Iterator {
+	out := NewLevelDBIterator(lit.originalPrefix, lit.dir, lit.checkId, lit.ts)
+	out.CopyTagsFrom(lit)
+	return out
+}
+
+func (lit *LevelDBIterator) Close() {
+	if lit.open {
+		lit.it.Release()
+		lit.open = false
+	}
+}
+
+func (lit *LevelDBIterator) Next() (graph.TSVal, bool) {
+	if lit.it == nil {
+		lit.Last = nil
+		return nil, false
+	}
+	if !lit.open {
+		lit.Last = nil
+		return nil, false
+	}
+	if !lit.it.Valid() {
+		lit.Last = nil
+		lit.Close()
+		return nil, false
+	}
+	if bytes.HasPrefix(lit.it.Key(), lit.nextPrefix) {
+		out := make([]byte, len(lit.it.Key()))
+		copy(out, lit.it.Key())
+		lit.Last = out
+		ok := lit.it.Next()
+		if !ok {
+			lit.Close()
+		}
+		return out, true
+	}
+	lit.Close()
+	lit.Last = nil
+	return nil, false
+}
+
+func GetPositionFromPrefix(prefix []byte, dir string, ts *LevelDBTripleStore) int {
+	if bytes.Equal(prefix, []byte("sp")) {
+		switch dir {
+		case "s":
+			return 2
+		case "p":
+			return ts.hasher.Size() + 2
+		case "o":
+			return 2*ts.hasher.Size() + 2
+		case "c":
+			return -1
+		}
+	}
+	if bytes.Equal(prefix, []byte("po")) {
+		switch dir {
+		case "s":
+			return 2*ts.hasher.Size() + 2
+		case "p":
+			return 2
+		case "o":
+			return ts.hasher.Size() + 2
+		case "c":
+			return -1
+		}
+	}
+	if bytes.Equal(prefix, []byte("os")) {
+		switch dir {
+		case "s":
+			return ts.hasher.Size() + 2
+		case "p":
+			return 2*ts.hasher.Size() + 2
+		case "o":
+			return 2
+		case "c":
+			return -1
+		}
+	}
+	if bytes.Equal(prefix, []byte("cp")) {
+		switch dir {
+		case "s":
+			return 2*ts.hasher.Size() + 2
+		case "p":
+			return ts.hasher.Size() + 2
+		case "o":
+			return 3*ts.hasher.Size() + 2
+		case "c":
+			return 2
+		}
+	}
+	panic("Notreached")
+}
+
+func (lit *LevelDBIterator) Check(v graph.TSVal) bool {
+	val := v.([]byte)
+	if val[0] == 'z' {
+		return false
+	}
+	offset := GetPositionFromPrefix(val[0:2], lit.dir, lit.ts)
+	if offset != -1 {
+		if bytes.HasPrefix(val[offset:], lit.checkId[1:]) {
+			return true
+		}
+	} else {
+		nameForDir := lit.ts.GetTriple(v).Get(lit.dir)
+		hashForDir := lit.ts.GetIdFor(nameForDir).([]byte)
+		if bytes.Equal(hashForDir, lit.checkId) {
+			return true
+		}
+	}
+	return false
+}
+
+func (lit *LevelDBIterator) Size() (int64, bool) {
+	return lit.ts.GetSizeFor(lit.checkId), true
+}
+
+func (lit *LevelDBIterator) DebugString(indent int) string {
+	size, _ := lit.Size()
+	return fmt.Sprintf("%s(%s %d tags: %v dir: %s size:%d %s)", strings.Repeat(" ", indent), lit.Type(), lit.GetUid(), lit.Tags(), lit.dir, size, lit.ts.GetNameFor(lit.checkId))
+}
+
+func (lit *LevelDBIterator) Type() string { return "leveldb" }
+func (lit *LevelDBIterator) Sorted() bool { return false }
+
+func (lit *LevelDBIterator) Optimize() (graph.Iterator, bool) {
+	return lit, false
+}
+
+func (lit *LevelDBIterator) GetStats() *graph.IteratorStats {
+	s, _ := lit.Size()
+	return &graph.IteratorStats{
+		CheckCost: 1,
+		NextCost:  2,
+		Size:      s,
+	}
+}