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

go/src/infra/gae/libs/gae/helper/serialize.go

Index: go/src/infra/gae/libs/gae/helper/serialize.go
diff --git a/go/src/infra/gae/libs/gae/helper/serialize.go b/go/src/infra/gae/libs/gae/helper/serialize.go
new file mode 100644
index 0000000000000000000000000000000000000000..e47285aa32bf190c3d3d549b7bd8097fefe83557
--- /dev/null
+++ b/go/src/infra/gae/libs/gae/helper/serialize.go
@@ -0,0 +1,335 @@
+// 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 helper
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"sort"
+	"time"
+
+	"infra/gae/libs/gae"
+
+	"github.com/luci/luci-go/common/cmpbin"
+)
+
+// WriteDSPropertyMapDeterministic allows tests to make WriteDSPropertyMap
+// deterministic.
+var WriteDSPropertyMapDeterministic = false
+
+// ReadDSPropertyMapReasonableLimit sets a limit on the number of rows and
+// number of properties per row which can be read by ReadDSPropertyMap. The
+// total number of Property objects readable by this method is this number
+// squared (e.g. Limit rows * Limit properties)
+const ReadDSPropertyMapReasonableLimit uint64 = 30000
+
+// ReadKeyNumToksReasonableLimit is the maximum number of DSKey tokens that
+// ReadDSKey is willing to read for a single key.
+const ReadKeyNumToksReasonableLimit uint64 = 50
+
+// DSKeyContext controls whether the various Write and Read serializtion
+// routines should encode the context of DSKeys (read: the appid and namespace).
+// Frequently the appid and namespace of keys are known in advance and so there's
+// no reason to redundantly encode them.
+type DSKeyContext bool
+
+// With- and WithoutContext indicate if the serialization method should include
+// context for DSKeys. See DSKeyContext for more information.
+const (
+	WithContext    DSKeyContext = true
+	WithoutContext              = false
+)
+
+// WriteDSKey encodes a key to the buffer. If context is WithContext, then this
+// encoded value will include the appid and namespace of the key.
+func WriteDSKey(buf *bytes.Buffer, context DSKeyContext, k gae.DSKey) {
+	// [appid ++ namespace]? ++ #tokens ++ tokens*
+	appid, namespace, toks := DSKeySplit(k)
+	if context == WithContext {
+		buf.WriteByte(1)
+		cmpbin.WriteString(buf, appid)
+		cmpbin.WriteString(buf, namespace)
+	} else {
+		buf.WriteByte(0)
+	}
+	cmpbin.WriteUint(buf, uint64(len(toks)))
+	for _, tok := range toks {
+		WriteDSKeyTok(buf, tok)
+	}
+}
+
+// ReadDSKey deserializes a key from the buffer. The value of context must match
+// the value of context that was passed to WriteDSKey when the key was encoded.
+// If context == WithoutContext, then the appid and namespace parameters are
+// used in the decoded DSKey. Otherwise they're ignored.
+func ReadDSKey(buf *bytes.Buffer, context DSKeyContext, appid, namespace string) (ret gae.DSKey, err error) {
+	actualCtx, err := buf.ReadByte()
+	if err != nil {
+		return
+	}
+
+	actualAid, actualNS := "", ""
+	if actualCtx == 1 {
+		if actualAid, _, err = cmpbin.ReadString(buf); err != nil {
+			return
+		}
+		if actualNS, _, err = cmpbin.ReadString(buf); err != nil {
+			return
+		}
+	} else if actualCtx != 0 {
+		err = fmt.Errorf("helper: expected actualCtx to be 0 or 1, got %d", actualCtx)
+		return
+	}
+
+	if context == WithoutContext {
+		// overrwrite with the supplied ones
+		actualAid = appid
+		actualNS = namespace
+	}
+
+	numToks := uint64(0)
+	if numToks, _, err = cmpbin.ReadUint(buf); err != nil {
+		return
+	}
+	if numToks > ReadKeyNumToksReasonableLimit {
+		err = fmt.Errorf("helper: tried to decode huge key of length %d", numToks)
+		return
+	}
+
+	toks := make([]gae.DSKeyTok, numToks)
+	for i := uint64(0); i < numToks; i++ {
+		if toks[i], err = ReadDSKeyTok(buf); err != nil {
+			return
+		}
+	}
+
+	return NewDSKeyToks(actualAid, actualNS, toks), nil
+}
+
+// WriteDSKeyTok writes a DSKeyTok to the buffer. You usually want WriteDSKey
+// instead of this.
+func WriteDSKeyTok(buf *bytes.Buffer, tok gae.DSKeyTok) {
+	// tok.kind ++ tok.stringID ++ tok.intID?
+	cmpbin.WriteString(buf, tok.Kind)
+	cmpbin.WriteString(buf, tok.StringID)
+	if tok.StringID == "" {
+		cmpbin.WriteInt(buf, tok.IntID)
+	}
+}
+
+// ReadDSKeyTok reads a DSKeyTok from the buffer. You usually want ReadDSKey
+// instead of this.
+func ReadDSKeyTok(buf *bytes.Buffer) (ret gae.DSKeyTok, err error) {
+	if ret.Kind, _, err = cmpbin.ReadString(buf); err != nil {
+		return
+	}
+	if ret.StringID, _, err = cmpbin.ReadString(buf); err != nil {
+		return
+	}
+	if ret.StringID == "" {
+		if ret.IntID, _, err = cmpbin.ReadInt(buf); err != nil {
+			return
+		}
+		if ret.IntID <= 0 {
+			err = errors.New("helper: decoded key with empty stringID and zero/negative intID")
+			return
+		}
+	}
+	return
+}
+
+// WriteDSGeoPoint writes a DSGeoPoint to the buffer.
+func WriteDSGeoPoint(buf *bytes.Buffer, gp gae.DSGeoPoint) {
+	cmpbin.WriteFloat64(buf, gp.Lat)
+	cmpbin.WriteFloat64(buf, gp.Lng)
+}
+
+// ReadDSGeoPoint reads a DSGeoPoint from the buffer.
+func ReadDSGeoPoint(buf *bytes.Buffer) (gp gae.DSGeoPoint, err error) {
+	if gp.Lat, _, err = cmpbin.ReadFloat64(buf); err != nil {
+		return
+	}
+	gp.Lng, _, err = cmpbin.ReadFloat64(buf)
+	if err == nil && !gp.Valid() {
+		err = fmt.Errorf("helper: decoded invalid DSGeoPoint: %v", gp)
+	}
+	return
+}
+
+// WriteTime writes a time.Time in a byte-sortable way.
+//
+// This method truncates the time to microseconds and drops the timezone,
+// because that's the (undocumented) way that the appengine SDK does it.
+func WriteTime(buf *bytes.Buffer, t time.Time) {
+	name, off := t.Zone()
+	if name != "UTC" || off != 0 {
+		panic(fmt.Errorf("helper: UTC OR DEATH: %s", t))
+	}
+	cmpbin.WriteUint(buf, uint64(t.Unix())*1e6+uint64(t.Nanosecond()/1e3))
+}
+
+// ReadTime reads a time.Time from the buffer.
+func ReadTime(buf *bytes.Buffer) (time.Time, error) {
+	v, _, err := cmpbin.ReadUint(buf)
+	if err != nil {
+		return time.Time{}, err
+	}
+	return time.Unix(int64(v/1e6), int64((v%1e6)*1e3)).UTC(), nil
+}
+
+// WriteDSProperty writes a DSProperty to the buffer. `context` behaves the same
+// way that it does for WriteDSKey, but only has an effect if `p` contains a
+// DSKey as its Value.
+func WriteDSProperty(buf *bytes.Buffer, p gae.DSProperty, context DSKeyContext) {
+	typb := byte(p.Type())
+	if p.NoIndex() {
+		typb |= 0x80
+	}
+	buf.WriteByte(typb)
+	switch p.Type() {
+	case gae.DSPTNull, gae.DSPTBoolTrue, gae.DSPTBoolFalse:
+	case gae.DSPTInt:
+		cmpbin.WriteInt(buf, p.Value().(int64))
+	case gae.DSPTFloat:
+		cmpbin.WriteFloat64(buf, p.Value().(float64))
+	case gae.DSPTString:
+		cmpbin.WriteString(buf, p.Value().(string))
+	case gae.DSPTBytes:
+		if p.NoIndex() {
+			cmpbin.WriteBytes(buf, p.Value().([]byte))
+		} else {
+			cmpbin.WriteBytes(buf, p.Value().(gae.DSByteString))
+		}
+	case gae.DSPTTime:
+		WriteTime(buf, p.Value().(time.Time))
+	case gae.DSPTGeoPoint:
+		WriteDSGeoPoint(buf, p.Value().(gae.DSGeoPoint))
+	case gae.DSPTKey:
+		WriteDSKey(buf, context, p.Value().(gae.DSKey))
+	case gae.DSPTBlobKey:
+		cmpbin.WriteString(buf, string(p.Value().(gae.BSKey)))
+	}
+}
+
+// ReadDSProperty reads a DSProperty from the buffer. `context`, `appid`, and
+// `namespace` behave the same way they do for ReadDSKey, but only have an
+// effect if the decoded property has a DSKey value.
+func ReadDSProperty(buf *bytes.Buffer, context DSKeyContext, appid, namespace string) (p gae.DSProperty, err error) {
+	val := interface{}(nil)
+	typb, err := buf.ReadByte()
+	if err != nil {
+		return
+	}
+	noIndex := (typb & 0x80) != 0 // highbit means noindex
+	switch gae.DSPropertyType(typb & 0x7f) {
+	case gae.DSPTNull:
+	case gae.DSPTBoolTrue:
+		val = true
+	case gae.DSPTBoolFalse:
+		val = false
+	case gae.DSPTInt:
+		val, _, err = cmpbin.ReadInt(buf)
+	case gae.DSPTFloat:
+		val, _, err = cmpbin.ReadFloat64(buf)
+	case gae.DSPTString:
+		val, _, err = cmpbin.ReadString(buf)
+	case gae.DSPTBytes:
+		b := []byte(nil)
+		if b, _, err = cmpbin.ReadBytes(buf); err != nil {
+			break
+		}
+		if noIndex {
+			val = b
+		} else {
+			val = gae.DSByteString(b)
+		}
+	case gae.DSPTTime:
+		val, err = ReadTime(buf)
+	case gae.DSPTGeoPoint:
+		val, err = ReadDSGeoPoint(buf)
+	case gae.DSPTKey:
+		val, err = ReadDSKey(buf, context, appid, namespace)
+	case gae.DSPTBlobKey:
+		s := ""
+		if s, _, err = cmpbin.ReadString(buf); err != nil {
+			break
+		}
+		val = gae.BSKey(s)
+	default:
+		err = fmt.Errorf("read: unknown type! %v", typb)
+	}
+	if err == nil {
+		err = p.SetValue(val, noIndex)
+	}
+	return
+}
+
+// WriteDSPropertyMap writes an entire DSPropertyMap to the buffer. `context`
+// behaves the same way that it does for WriteDSKey. If
+// WriteDSPropertyMapDeterministic is true, then the rows will be sorted by
+// property name before they're serialized to buf (mostly useful for testing,
+// but also potentially useful if you need to make a hash of the property data).
+func WriteDSPropertyMap(buf *bytes.Buffer, propMap gae.DSPropertyMap, context DSKeyContext) {
+	rows := make(sort.StringSlice, 0, len(propMap))
+	tmpBuf := &bytes.Buffer{}
+	for name, vals := range propMap {
+		tmpBuf.Reset()
+		cmpbin.WriteString(tmpBuf, name)
+		cmpbin.WriteUint(tmpBuf, uint64(len(vals)))
+		for _, p := range vals {
+			WriteDSProperty(tmpBuf, p, context)
+		}
+		rows = append(rows, tmpBuf.String())
+	}
+
+	if WriteDSPropertyMapDeterministic {
+		rows.Sort()
+	}
+
+	cmpbin.WriteUint(buf, uint64(len(propMap)))
+	for _, r := range rows {
+		buf.WriteString(r)
+	}
+}
+
+// ReadDSPropertyMap reads a DSPropertyMap from the buffer. `context` and
+// friends behave the same way that they do for ReadDSKey.
+func ReadDSPropertyMap(buf *bytes.Buffer, context DSKeyContext, appid, namespace string) (propMap gae.DSPropertyMap, err error) {
+	numRows := uint64(0)
+	if numRows, _, err = cmpbin.ReadUint(buf); err != nil {
+		return
+	}
+	if numRows > ReadDSPropertyMapReasonableLimit {
+		err = fmt.Errorf("helper: tried to decode map with huge number of rows %d", numRows)
+		return
+	}
+
+	name, prop := "", gae.DSProperty{}
+	propMap = make(gae.DSPropertyMap, numRows)
+	for i := uint64(0); i < numRows; i++ {
+		if name, _, err = cmpbin.ReadString(buf); err != nil {
+			return
+		}
+
+		numProps := uint64(0)
+		if numProps, _, err = cmpbin.ReadUint(buf); err != nil {
+			return
+		}
+		if numProps > ReadDSPropertyMapReasonableLimit {
+			err = fmt.Errorf("helper: tried to decode map with huge number of properties %d", numProps)
+			return
+		}
+		props := make([]gae.DSProperty, 0, numProps)
+		for j := uint64(0); j < numProps; j++ {
+			if prop, err = ReadDSProperty(buf, context, appid, namespace); err != nil {
+				return
+			}
+			props = append(props, prop)
+		}
+		propMap[name] = props
+	}
+	return
+}