forked from cayleygraph/cayley
/
quadstore_iterator_optimize.go
120 lines (109 loc) · 2.95 KB
/
quadstore_iterator_optimize.go
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// 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 mongo
import (
"github.com/barakmich/glog"
"github.com/google/cayley/graph"
"github.com/google/cayley/graph/iterator"
)
func (qs *QuadStore) OptimizeIterator(it graph.Iterator) (graph.Iterator, bool) {
switch it.Type() {
case graph.LinksTo:
return qs.optimizeLinksTo(it.(*iterator.LinksTo))
case graph.And:
return qs.optimizeAndIterator(it.(*iterator.And))
}
return it, false
}
func (qs *QuadStore) optimizeAndIterator(it *iterator.And) (graph.Iterator, bool) {
// Fail fast if nothing can happen
glog.V(4).Infoln("Entering optimizeAndIterator", it.UID())
found := false
for _, it := range it.SubIterators() {
glog.V(4).Infoln(it.Type())
if it.Type() == mongoType {
found = true
}
}
if !found {
glog.V(4).Infoln("Aborting optimizeAndIterator")
return it, false
}
newAnd := iterator.NewAnd(qs)
var mongoIt *Iterator
for _, it := range it.SubIterators() {
switch it.Type() {
case mongoType:
if mongoIt == nil {
mongoIt = it.(*Iterator)
} else {
newAnd.AddSubIterator(it)
}
case graph.LinksTo:
continue
default:
newAnd.AddSubIterator(it)
}
}
stats := mongoIt.Stats()
lset := []graph.Linkage{
{
Dir: mongoIt.dir,
Value: qs.ValueOf(mongoIt.name),
},
}
n := 0
for _, it := range it.SubIterators() {
if it.Type() == graph.LinksTo {
lto := it.(*iterator.LinksTo)
// Is it more effective to do the replacement, or let the mongo check the linksto?
ltostats := lto.Stats()
if (ltostats.ContainsCost+stats.NextCost)*stats.Size > (ltostats.NextCost+stats.ContainsCost)*ltostats.Size {
continue
}
newLto := NewLinksTo(qs, lto.SubIterators()[0], "quads", lto.Direction(), lset)
newAnd.AddSubIterator(newLto)
n++
}
}
if n == 0 {
return it, false
}
return newAnd.Optimize()
}
func (qs *QuadStore) optimizeLinksTo(it *iterator.LinksTo) (graph.Iterator, bool) {
subs := it.SubIterators()
if len(subs) != 1 {
return it, false
}
primary := subs[0]
if primary.Type() == graph.Fixed {
size, _ := primary.Size()
if size == 1 {
if !graph.Next(primary) {
panic("unexpected size during optimize")
}
val := primary.Result()
newIt := qs.QuadIterator(it.Direction(), val)
nt := newIt.Tagger()
nt.CopyFrom(it)
for _, tag := range primary.Tagger().Tags() {
nt.AddFixed(tag, val)
}
it.Close()
return newIt, true
}
}
return it, false
}