exp/lighthorizon: Add initial support for XDR serialization (#4369)

exp/lighthorizon/index/Makefile

@@ -0,0 +1,24 @@
+XDRS = xdr/LightHorizon-types.x
+
+XDRGEN_COMMIT=3f6808cd161d72474ffbe9eedbd7013de7f92748
+
+.PHONY: xdr clean update
+
+xdr/xdr_generated.go: $(XDRS)
+	docker run -it --rm -v $$PWD:/wd -w /wd ruby /bin/bash -c '\
+		gem install specific_install -v 0.3.7 && \
+		gem specific_install https://github.com/stellar/xdrgen.git -b $(XDRGEN_COMMIT) && \
+		xdrgen \
+			--language go \
+			--namespace xdr \
+			--output xdr/ \
+			$(XDRS)'
+	ls -lAh
+	go fmt $@
+
+xdr: xdr/xdr_generated.go
+
+clean:
+	rm ./xdr/xdr_generated.go || true
+
+update: clean xdr

exp/lighthorizon/index/cmd/batch/main.go

@@ -4,5 +4,5 @@ import "github.com/stellar/go/support/log"
 
 func main() {
 	log.SetLevel(log.InfoLevel)
-	Map()
+	// Map()
 }

exp/lighthorizon/index/cmd/batch/reduce/main.go

@@ -137,7 +137,7 @@ func main() {
 					if err != nil {
 						// TODO: in final version this should be critical error, now just skip it
 						if err == os.ErrNotExist {
-							log.Errorf("Account %d is unavailable - TODO fix", account)
+							log.Errorf("Account %s is unavailable - TODO fix", account)
 							continue
 						}
 						panic(err)

exp/lighthorizon/index/cmd/single/main.go

@@ -119,7 +119,6 @@ func main() {
 						)
 					}
 
-
 					if strings.Contains(*modules, "accounts") {
 						allParticipants, err := participantsForOperations(tx, false)
 						if err != nil {

exp/lighthorizon/index/main.go

@@ -1,11 +1,11 @@
 package index
 
 import (
-	"bufio"
 	"bytes"
 	"io"
-	"strconv"
 	"sync"
+
+	"github.com/stellar/go/exp/lighthorizon/index/xdr"
 )
 
 const CheckpointIndexVersion = 1
@@ -18,44 +18,16 @@ type CheckpointIndex struct {
 }
 
 func NewCheckpointIndexFromBytes(b []byte) (*CheckpointIndex, error) {
-	buf := bytes.NewBuffer(b)
-	r := bufio.NewReader(buf)
-
-	firstCheckpointString, err := r.ReadString(0x00)
-	if err != nil {
-		return nil, err
-	}
-
-	// Remove trailing 0x00 byte
-	firstCheckpointString = firstCheckpointString[:len(firstCheckpointString)-1]
-
-	firstCheckpoint, err := strconv.ParseUint(firstCheckpointString, 10, 32)
-	if err != nil {
-		return nil, err
-	}
-
-	lastCheckpointString, err := r.ReadString(0x00)
-	if err != nil {
-		return nil, err
-	}
-
-	// Remove trailing 0x00 byte
-	lastCheckpointString = lastCheckpointString[:len(lastCheckpointString)-1]
-
-	lastCheckpoint, err := strconv.ParseUint(lastCheckpointString, 10, 32)
-	if err != nil {
-		return nil, err
-	}
-
-	bitmap, err := io.ReadAll(r)
+	xdrCheckpoint := xdr.CheckpointIndex{}
+	err := xdrCheckpoint.UnmarshalBinary(b)
 	if err != nil {
 		return nil, err
 	}
 
 	return &CheckpointIndex{
-		bitmap:          bitmap,
-		firstCheckpoint: uint32(firstCheckpoint),
-		lastCheckpoint:  uint32(lastCheckpoint),
+		bitmap:          xdrCheckpoint.Bitmap,
+		firstCheckpoint: uint32(xdrCheckpoint.FirstCheckpoint),
+		lastCheckpoint:  uint32(xdrCheckpoint.LastCheckpoint),
 	}, nil
 }
 
@@ -243,13 +215,17 @@ func (i *CheckpointIndex) Buffer() *bytes.Buffer {
 	i.mutex.RLock()
 	defer i.mutex.RUnlock()
 
-	var b bytes.Buffer
-	b.WriteString(strconv.FormatUint(uint64(i.firstCheckpoint), 10))
-	b.WriteByte(0)
-	b.WriteString(strconv.FormatUint(uint64(i.lastCheckpoint), 10))
-	b.WriteByte(0)
-	b.Write(i.bitmap)
-	return &b
+	xdrCheckpoint := xdr.CheckpointIndex{
+		FirstCheckpoint: xdr.Uint32(i.firstCheckpoint),
+		LastCheckpoint:  xdr.Uint32(i.lastCheckpoint),
+		Bitmap:          i.bitmap,
+	}
+
+	b, err := xdrCheckpoint.MarshalBinary()
+	if err != nil {
+		panic(err)
+	}
+	return bytes.NewBuffer(b)
 }
 
 // Flush flushes the index data to byte slice in index format.

exp/lighthorizon/index/xdr/LightHorizon-types.x

@@ -0,0 +1,17 @@
+// Copyright 2022 Stellar Development Foundation and contributors. Licensed
+// under the Apache License, Version 2.0. See the COPYING file at the root
+// of this distribution or at http://www.apache.org/licenses/LICENSE-2.0
+
+namespace stellar
+{
+
+typedef unsigned int uint32;
+typedef opaque Value<>;
+
+struct CheckpointIndex {
+    uint32 firstCheckpoint;
+    uint32 lastCheckpoint;
+    Value bitmap;
+};
+
+}