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Revert "REP-6766 Compare documents using a batch cursor" #159

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Merged
merged 1 commit into from
Nov 5, 2025
Merged

Revert "REP-6766 Compare documents using a batch cursor" #159

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163 changes: 52 additions & 111 deletions internal/verifier/compare.go
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,6 @@ import (
"bytes"
"context"
"fmt"
"iter"
"time"

"github.com/10gen/migration-verifier/chanutil"
Expand All @@ -13,7 +12,6 @@ import (
"github.com/10gen/migration-verifier/internal/retry"
"github.com/10gen/migration-verifier/internal/types"
"github.com/10gen/migration-verifier/internal/util"
"github.com/10gen/migration-verifier/mmongo/cursor"
"github.com/10gen/migration-verifier/option"
"github.com/pkg/errors"
"go.mongodb.org/mongo-driver/v2/bson"
Expand All @@ -32,11 +30,6 @@ const (
docKeyInHashedCompare = "k"
)

type seqWithTs struct {
seq iter.Seq2[bson.Raw, error]
ts bson.Timestamp
}

type docWithTs struct {
doc bson.Raw
ts bson.Timestamp
Expand All @@ -52,7 +45,7 @@ func (verifier *Verifier) FetchAndCompareDocuments(
types.ByteCount,
error,
) {
var srcChannel, dstChannel <-chan seqWithTs
var srcChannel, dstChannel <-chan docWithTs
var readSrcCallback, readDstCallback func(context.Context, *retry.FuncInfo) error

results := []VerificationResult{}
Expand Down Expand Up @@ -107,7 +100,7 @@ func (verifier *Verifier) compareDocsFromChannels(
workerNum int,
fi *retry.FuncInfo,
task *VerificationTask,
srcChannel, dstChannel <-chan seqWithTs,
srcChannel, dstChannel <-chan docWithTs,
) (
[]VerificationResult,
types.DocumentCount,
Expand Down Expand Up @@ -211,7 +204,7 @@ func (verifier *Verifier) compareDocsFromChannels(
for !srcClosed || !dstClosed {
simpleTimerReset(readTimer, readTimeout)

var srcDocsWithTs, dstDocsWithTs seqWithTs
var srcDocWithTs, dstDocWithTs docWithTs

eg, egCtx := contextplus.ErrGroup(ctx)

Expand All @@ -226,13 +219,21 @@ func (verifier *Verifier) compareDocsFromChannels(
"failed to read from source after %s",
readTimeout,
)
case srcDocsWithTs, alive = <-srcChannel:
case srcDocWithTs, alive = <-srcChannel:
if !alive {
srcClosed = true
break
}

fi.NoteSuccess("received document from source")

srcDocCount++
srcByteCount += types.ByteCount(len(srcDocWithTs.doc))
verifier.workerTracker.SetSrcCounts(
workerNum,
srcDocCount,
srcByteCount,
)
}

return nil
Expand All @@ -250,7 +251,7 @@ func (verifier *Verifier) compareDocsFromChannels(
"failed to read from destination after %s",
readTimeout,
)
case dstDocsWithTs, alive = <-dstChannel:
case dstDocWithTs, alive = <-dstChannel:
if !alive {
dstClosed = true
break
Expand All @@ -270,72 +271,32 @@ func (verifier *Verifier) compareDocsFromChannels(
)
}

if srcDocsWithTs.seq != nil {
for doc, err := range srcDocsWithTs.seq {
if err != nil {
return nil, 0, 0, errors.Wrapf(
err,
"reading batch of docs from source (task: %s)",
task.PrimaryKey,
)
}
if srcDocWithTs.doc != nil {
err := handleNewDoc(srcDocWithTs, true)

srcDocCount++
srcByteCount += types.ByteCount(len(doc))
verifier.workerTracker.SetSrcCounts(
workerNum,
srcDocCount,
srcByteCount,
)
if err != nil {

err := handleNewDoc(
docWithTs{
doc: doc,
ts: srcDocsWithTs.ts,
},
true,
return nil, 0, 0, errors.Wrapf(
err,
"comparer thread failed to handle %#q's source doc (task: %s) with ID %v",
namespace,
task.PrimaryKey,
srcDocWithTs.doc.Lookup("_id"),
)

if err != nil {
return nil, 0, 0, errors.Wrapf(
err,
"comparer thread failed to handle %#q's source doc (task: %s) with ID %v",
namespace,
task.PrimaryKey,
doc.Lookup("_id"),
)
}
}

}

if dstDocsWithTs.seq != nil {
for doc, err := range dstDocsWithTs.seq {
if err != nil {
return nil, 0, 0, errors.Wrapf(
err,
"reading batch of docs from destination (task: %s)",
task.PrimaryKey,
)
}
if dstDocWithTs.doc != nil {
err := handleNewDoc(dstDocWithTs, false)

err := handleNewDoc(
docWithTs{
doc: doc,
ts: dstDocsWithTs.ts,
},
false,
if err != nil {
return nil, 0, 0, errors.Wrapf(
err,
"comparer thread failed to handle %#q's destination doc (task: %s) with ID %v",
namespace,
task.PrimaryKey,
dstDocWithTs.doc.Lookup("_id"),
)

if err != nil {
return nil, 0, 0, errors.Wrapf(
err,
"comparer thread failed to handle %#q's destination doc (task: %s) with ID %v",
namespace,
task.PrimaryKey,
doc.Lookup("_id"),
)
}
}
}
}
Expand Down Expand Up @@ -466,13 +427,13 @@ func simpleTimerReset(t *time.Timer, dur time.Duration) {
func (verifier *Verifier) getFetcherChannelsAndCallbacks(
task *VerificationTask,
) (
<-chan seqWithTs,
<-chan seqWithTs,
<-chan docWithTs,
<-chan docWithTs,
func(context.Context, *retry.FuncInfo) error,
func(context.Context, *retry.FuncInfo) error,
) {
srcChannel := make(chan seqWithTs)
dstChannel := make(chan seqWithTs)
srcChannel := make(chan docWithTs)
dstChannel := make(chan docWithTs)

readSrcCallback := func(ctx context.Context, state *retry.FuncInfo) error {
// We open a session here so that we can read the session’s cluster
Expand Down Expand Up @@ -549,44 +510,38 @@ func (verifier *Verifier) getFetcherChannelsAndCallbacks(
}

func iterateCursorToChannel(
ctx context.Context,
sctx context.Context,
state *retry.FuncInfo,
myCursor *cursor.BatchCursor,
writer chan<- seqWithTs,
cursor *mongo.Cursor,
writer chan<- docWithTs,
) error {
defer close(writer)

for {
seq := myCursor.GetCurrentBatchIterator()
sess := mongo.SessionFromContext(sctx)

for cursor.Next(sctx) {
state.NoteSuccess("received a document")

ct, err := myCursor.GetClusterTime()
clusterTime, err := util.GetClusterTimeFromSession(sess)
if err != nil {
return errors.Wrap(err, "reading cluster time from batch")
return errors.Wrap(err, "reading cluster time from session")
}

err = chanutil.WriteWithDoneCheck(
ctx,
sctx,
writer,
seqWithTs{
seq: seq,
ts: ct,
docWithTs{
doc: slices.Clone(cursor.Current),
ts: clusterTime,
},
)

if err != nil {
return errors.Wrapf(err, "sending iterator to compare thread")
}

if myCursor.IsFinished() {
return nil
}

if err := myCursor.GetNext(ctx); err != nil {
return errors.Wrap(err, "failed to iterate cursor")
return errors.Wrapf(err, "sending document to compare thread")
}
}

return errors.Wrap(cursor.Err(), "failed to iterate cursor")
}

func getMapKey(docKeyValues []bson.RawValue) string {
Expand All @@ -600,13 +555,8 @@ func getMapKey(docKeyValues []bson.RawValue) string {
return keyBuffer.String()
}

func (verifier *Verifier) getDocumentsCursor(
ctx context.Context,
collection *mongo.Collection,
clusterInfo *util.ClusterInfo,
startAtTs *bson.Timestamp,
task *VerificationTask,
) (*cursor.BatchCursor, error) {
func (verifier *Verifier) getDocumentsCursor(ctx context.Context, collection *mongo.Collection, clusterInfo *util.ClusterInfo,
startAtTs *bson.Timestamp, task *VerificationTask) (*mongo.Cursor, error) {
var findOptions bson.D
runCommandOptions := options.RunCmd()
var andPredicates bson.A
Expand Down Expand Up @@ -723,16 +673,7 @@ func (verifier *Verifier) getDocumentsCursor(
}
}

c, err := cursor.New(
collection.Database(),
collection.Database().RunCommand(ctx, cmd, runCommandOptions),
)

if err == nil {
c.SetSession(mongo.SessionFromContext(ctx))
}

return c, err
return collection.Database().RunCommandCursor(ctx, cmd, runCommandOptions)
}

func transformPipelineForToHashedIndexKey(
Expand Down
13 changes: 5 additions & 8 deletions internal/verifier/migration_verifier_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -26,7 +26,6 @@ import (
"github.com/10gen/migration-verifier/internal/types"
"github.com/10gen/migration-verifier/internal/util"
"github.com/10gen/migration-verifier/mbson"
"github.com/10gen/migration-verifier/mseq"
"github.com/10gen/migration-verifier/mslices"
"github.com/cespare/permute/v2"
"github.com/rs/zerolog"
Expand Down Expand Up @@ -1151,15 +1150,13 @@ func TestVerifierCompareDocs(t *testing.T) {

namespace := "testdb.testns"

makeDocChannel := func(docs []bson.D) <-chan seqWithTs {
theChan := make(chan seqWithTs, len(docs))
makeDocChannel := func(docs []bson.D) <-chan docWithTs {
theChan := make(chan docWithTs, len(docs))

for d, doc := range docs {
theChan <- seqWithTs{
seq: mseq.FromSliceWithNilErr(
mslices.Of(testutil.MustMarshal(doc)),
),
ts: bson.Timestamp{1, uint32(d)},
theChan <- docWithTs{
doc: testutil.MustMarshal(doc),
ts: bson.Timestamp{1, uint32(d)},
}
}

Expand Down
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