Barak Michener
d639aa3205
A linkage is a direction/value pair, and that's all. A set of these can have helper functions and the like. Cleans up some assumptions of functionality that isn't useful (yet).
120 lines
2.9 KiB
Go
120 lines
2.9 KiB
Go
// Copyright 2014 The Cayley Authors. All rights reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package mongo
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import (
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"github.com/barakmich/glog"
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"github.com/google/cayley/graph"
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"github.com/google/cayley/graph/iterator"
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)
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func (qs *QuadStore) OptimizeIterator(it graph.Iterator) (graph.Iterator, bool) {
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switch it.Type() {
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case graph.LinksTo:
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return qs.optimizeLinksTo(it.(*iterator.LinksTo))
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case graph.And:
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return qs.optimizeAndIterator(it.(*iterator.And))
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}
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return it, false
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}
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func (qs *QuadStore) optimizeAndIterator(it *iterator.And) (graph.Iterator, bool) {
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// Fail fast if nothing can happen
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glog.V(4).Infoln("Entering optimizeAndIterator", it.UID())
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found := false
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for _, it := range it.SubIterators() {
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glog.V(4).Infoln(it.Type())
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if it.Type() == mongoType {
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found = true
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}
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}
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if !found {
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glog.V(4).Infoln("Aborting optimizeAndIterator")
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return it, false
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}
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newAnd := iterator.NewAnd(qs)
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var mongoIt *Iterator
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for _, it := range it.SubIterators() {
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switch it.Type() {
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case mongoType:
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if mongoIt == nil {
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mongoIt = it.(*Iterator)
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} else {
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newAnd.AddSubIterator(it)
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}
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case graph.LinksTo:
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continue
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default:
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newAnd.AddSubIterator(it)
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}
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}
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stats := mongoIt.Stats()
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lset := []graph.Linkage{
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{
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Dir: mongoIt.dir,
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Value: qs.ValueOf(mongoIt.name),
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},
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}
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n := 0
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for _, it := range it.SubIterators() {
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if it.Type() == graph.LinksTo {
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lto := it.(*iterator.LinksTo)
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// Is it more effective to do the replacement, or let the mongo check the linksto?
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ltostats := lto.Stats()
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if (ltostats.ContainsCost+stats.NextCost)*stats.Size > (ltostats.NextCost+stats.ContainsCost)*ltostats.Size {
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continue
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}
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newLto := NewLinksTo(qs, lto.SubIterators()[0], "quads", lto.Direction(), lset)
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newAnd.AddSubIterator(newLto)
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n++
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}
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}
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if n == 0 {
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return it, false
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}
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return newAnd.Optimize()
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}
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func (qs *QuadStore) optimizeLinksTo(it *iterator.LinksTo) (graph.Iterator, bool) {
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subs := it.SubIterators()
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if len(subs) != 1 {
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return it, false
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}
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primary := subs[0]
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if primary.Type() == graph.Fixed {
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size, _ := primary.Size()
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if size == 1 {
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if !graph.Next(primary) {
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panic("unexpected size during optimize")
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}
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val := primary.Result()
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newIt := qs.QuadIterator(it.Direction(), val)
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nt := newIt.Tagger()
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nt.CopyFrom(it)
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for _, tag := range primary.Tagger().Tags() {
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nt.AddFixed(tag, val)
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}
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it.Close()
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return newIt, true
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}
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}
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return it, false
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}
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