Refactor current GAE abstraction library to be free of the SDK*

go/src/infra/gae/libs/gae/memory/plist.go

Index: go/src/infra/gae/libs/gae/memory/plist.go
diff --git a/go/src/infra/gae/libs/gae/memory/plist.go b/go/src/infra/gae/libs/gae/memory/plist.go
new file mode 100644
index 0000000000000000000000000000000000000000..09cfec514c826f817a271b01f121500a6147b22a
--- /dev/null
+++ b/go/src/infra/gae/libs/gae/memory/plist.go
@@ -0,0 +1,298 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package memory
+
+import (
+	"bytes"
+	"fmt"
+	"sort"
+
+	"infra/gae/libs/gae"
+	"infra/gae/libs/gae/helper"
+
+	"github.com/luci/gkvlite"
+)
+
+var indexCreationDeterministic = false
+
+type qIndexSlice []*qIndex
+
+func (s qIndexSlice) Len() int           { return len(s) }
+func (s qIndexSlice) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+func (s qIndexSlice) Less(i, j int) bool { return s[i].Less(s[j]) }
+
+func defaultIndicies(kind string, pmap gae.DSPropertyMap) []*qIndex {
+	ret := make(qIndexSlice, 0, 2*len(pmap)+1)
+	ret = append(ret, &qIndex{kind, false, nil})
+	for name, pvals := range pmap {
+		needsIndex := false
+		for _, v := range pvals {
+			if !v.NoIndex() {
+				needsIndex = true
+				break
+			}
+		}
+		if !needsIndex {
+			continue
+		}
+		ret = append(ret, &qIndex{kind, false, []qSortBy{{name, qASC}}})
+		ret = append(ret, &qIndex{kind, false, []qSortBy{{name, qDEC}}})
+	}
+	if indexCreationDeterministic {
+		sort.Sort(ret)
+	}
+	return ret
+}
+
+func indexEntriesWithBuiltins(k gae.DSKey, pm gae.DSPropertyMap, complexIdxs []*qIndex) *memStore {
+	sip := partiallySerialize(pm)
+	return sip.indexEntries(k, append(defaultIndicies(k.Kind(), pm), complexIdxs...))
+}
+
+// serializedPvals is all of the serialized DSProperty values in qASC order.
+type serializedPvals [][]byte
+
+func (s serializedPvals) Len() int           { return len(s) }
+func (s serializedPvals) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
+func (s serializedPvals) Less(i, j int) bool { return bytes.Compare(s[i], s[j]) < 0 }
+
+// prop name -> [<serialized DSProperty>, ...]
+type serializedIndexablePmap map[string]serializedPvals
+
+func partiallySerialize(pm gae.DSPropertyMap) (ret serializedIndexablePmap) {
+	if len(pm) == 0 {
+		return
+	}
+
+	buf := &bytes.Buffer{}
+	ret = make(serializedIndexablePmap, len(pm))
+	for k, vals := range pm {
+		newVals := make(serializedPvals, 0, len(vals))
+		for _, v := range vals {
+			if v.NoIndex() {
+				continue
+			}
+			buf.Reset()
+			helper.WriteDSProperty(buf, v, helper.WithoutContext)
+			newVal := make([]byte, buf.Len())
+			copy(newVal, buf.Bytes())
+			newVals = append(newVals, newVal)
+		}
+		if len(newVals) > 0 {
+			sort.Sort(newVals)
+			ret[k] = newVals
+		}
+	}
+	return
+}
+
+// indexRowGen contains enough information to generate all of the index rows which
+// correspond with a propertyList and a qIndex.
+type indexRowGen struct {
+	propVec []serializedPvals
+	orders  []qDirection
+}
+
+// permute calls cb for each index row, in the sorted order of the rows.
+func (s indexRowGen) permute(cb func([]byte)) {
+	iVec := make([]int, len(s.propVec))
+	iVecLim := make([]int, len(s.propVec))
+
+	incPos := func() bool {
+		for i := len(iVec) - 1; i >= 0; i-- {
+			var done bool
+			var newVal int
+			if s.orders[i] == qASC {
+				newVal = (iVec[i] + 1) % iVecLim[i]
+				done = newVal != 0
+			} else {
+				newVal = (iVec[i] - 1)
+				if newVal < 0 {
+					newVal = iVecLim[i] - 1
+				} else {
+					done = true
+				}
+			}
+			iVec[i] = newVal
+			if done {
+				return true
+			}
+		}
+		return false
+	}
+
+	for i, sps := range s.propVec {
+		iVecLim[i] = len(sps)
+	}
+
+	for i := range iVec {
+		if s.orders[i] == qDEC {
+			iVec[i] = iVecLim[i] - 1
+		}
+	}
+
+	for {
+		bufsiz := 0
+		for pvalSliceIdx, pvalIdx := range iVec {
+			bufsiz += len(s.propVec[pvalSliceIdx][pvalIdx])
+		}
+		buf := bytes.NewBuffer(make([]byte, 0, bufsiz))
+		for pvalSliceIdx, pvalIdx := range iVec {
+			data := s.propVec[pvalSliceIdx][pvalIdx]
+			if s.orders[pvalSliceIdx] == qASC {
+				buf.Write(data)
+			} else {
+				for _, b := range data {
+					buf.WriteByte(b ^ 0xFF)
+				}
+			}
+		}
+		cb(buf.Bytes())
+		if !incPos() {
+			break
+		}
+	}
+}
+
+type matcher struct {
+	buf indexRowGen
+}
+
+// matcher.match checks to see if the mapped, serialized property values
+// match the index. If they do, it returns a indexRowGen. Do not write or modify
+// the data in the indexRowGen.
+func (m *matcher) match(idx *qIndex, sip serializedIndexablePmap) (indexRowGen, bool) {
+	m.buf.propVec = m.buf.propVec[:0]
+	m.buf.orders = m.buf.orders[:0]
+	for _, sb := range idx.sortby {
+		if pv, ok := sip[sb.prop]; ok {
+			m.buf.propVec = append(m.buf.propVec, pv)
+			m.buf.orders = append(m.buf.orders, sb.dir)
+		} else {
+			return indexRowGen{}, false
+		}
+	}
+	return m.buf, true
+}
+
+func (sip serializedIndexablePmap) indexEntries(k gae.DSKey, idxs []*qIndex) *memStore {
+	ret := newMemStore()
+	idxColl := ret.SetCollection("idx", nil)
+	// getIdxEnts retrieves an index collection or adds it if it's not there.
+	getIdxEnts := func(qi *qIndex) *memCollection {
+		buf := &bytes.Buffer{}
+		qi.WriteBinary(buf)
+		b := buf.Bytes()
+		idxColl.Set(b, []byte{})
+		return ret.SetCollection(fmt.Sprintf("idx:%s:%s", k.Namespace(), b), nil)
+	}
+
+	buf := &bytes.Buffer{}
+	helper.WriteDSKey(buf, helper.WithoutContext, k)
+	keyData := buf.Bytes()
+
+	walkPermutations := func(prefix []byte, irg indexRowGen, ents *memCollection) {
+		prev := []byte{} // intentionally make a non-nil slice, gkvlite hates nil.
+		irg.permute(func(data []byte) {
+			buf := bytes.NewBuffer(make([]byte, 0, len(prefix)+len(data)+len(keyData)))
+			buf.Write(prefix)
+			buf.Write(data)
+			buf.Write(keyData)
+			ents.Set(buf.Bytes(), prev)
+			prev = data
+		})
+	}
+
+	mtch := matcher{}
+	for _, idx := range idxs {
+		if irg, ok := mtch.match(idx, sip); ok {
+			idxEnts := getIdxEnts(idx)
+			if len(irg.propVec) == 0 {
+				idxEnts.Set(keyData, []byte{}) // propless index, e.g. kind -> key = nil
+			} else if idx.ancestor {
+				for ancKey := k; ancKey != nil; ancKey = ancKey.Parent() {
+					buf := &bytes.Buffer{}
+					helper.WriteDSKey(buf, helper.WithoutContext, ancKey)
+					walkPermutations(buf.Bytes(), irg, idxEnts)
+				}
+			} else {
+				walkPermutations(nil, irg, idxEnts)
+			}
+		}
+	}
+
+	return ret
+}
+
+func updateIndicies(store *memStore, key gae.DSKey, oldEnt, newEnt gae.DSPropertyMap) error {
+	var err error
+
+	idxColl := store.GetCollection("idx")
+	if idxColl == nil {
+		idxColl = store.SetCollection("idx", nil)
+	}
+
+	// load all current complex query index definitions.
+	compIdx := []*qIndex{}
+	idxColl.VisitItemsAscend(complexQueryPrefix, false, func(i *gkvlite.Item) bool {
+		if !bytes.HasPrefix(i.Key, complexQueryPrefix) {
+			return false
+		}
+		qi := &qIndex{}
+		if err = qi.ReadBinary(bytes.NewBuffer(i.Key)); err != nil {
+			return false
+		}
+		compIdx = append(compIdx, qi)
+		return true
+	})
+	if err != nil {
+		return err
+	}
+
+	oldIdx := indexEntriesWithBuiltins(key, oldEnt, compIdx)
+
+	newIdx := indexEntriesWithBuiltins(key, newEnt, compIdx)
+
+	prefix := "idx:" + key.Namespace() + ":"
+
+	gkvCollide(oldIdx.GetCollection("idx"), newIdx.GetCollection("idx"), func(k, ov, nv []byte) {
+		ks := prefix + string(k)
+		idxColl.Set(k, []byte{})
+
+		coll := store.GetCollection(ks)
+		if coll == nil {
+			coll = store.SetCollection(ks, nil)
+		}
+		oldColl := oldIdx.GetCollection(ks)
+		newColl := newIdx.GetCollection(ks)
+
+		switch {
+		case ov == nil && nv != nil: // all additions
+			newColl.VisitItemsAscend(nil, false, func(i *gkvlite.Item) bool {
+				coll.Set(i.Key, i.Val)
+				return true
+			})
+		case ov != nil && nv == nil: // all deletions
+			oldColl.VisitItemsAscend(nil, false, func(i *gkvlite.Item) bool {
+				coll.Delete(i.Key)
+				return true
+			})
+		case ov != nil && nv != nil: // merge
+			gkvCollide(oldColl, newColl, func(k, ov, nv []byte) {
+				if nv == nil {
+					coll.Delete(k)
+				} else {
+					coll.Set(k, nv)
+				}
+			})
+		default:
+			panic("impossible")
+		}
+		// TODO(riannucci): remove entries from idxColl and remove index collections
+		// when there are no index entries for that index any more.
+	})
+
+	return nil
+}