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

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

+// 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
+}