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Fix snapshot selection during restore-by-index

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This commit fixes a bug where restoring to a specific index will
incorrectly choose the latest snapshot instead of choosing the
latest snapshot that occurred before the given index.
This commit is contained in:
Ben Johnson
2021-04-21 12:09:05 -06:00
parent bbd0f3b33c
commit 1c01af4e69
3 changed files with 57 additions and 12 deletions
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31
db.go
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@@ -1434,7 +1434,7 @@ func (db *DB) monitor() {
// replica or generation or it will automatically choose the best one. Finally,
// a timestamp can be specified to restore the database to a specific
// point-in-time.
func RestoreReplica(ctx context.Context, r Replica, opt RestoreOptions) error {
func RestoreReplica(ctx context.Context, r Replica, opt RestoreOptions) (err error) {
// Validate options.
if opt.OutputPath == "" {
return fmt.Errorf("output path required")
@@ -1462,10 +1462,16 @@ func RestoreReplica(ctx context.Context, r Replica, opt RestoreOptions) error {
return err
}
// Find lastest snapshot that occurs before timestamp.
minWALIndex, err := SnapshotIndexAt(ctx, r, opt.Generation, opt.Timestamp)
if err != nil {
return fmt.Errorf("cannot find snapshot index for restore: %w", err)
// Find lastest snapshot that occurs before timestamp or index.
var minWALIndex int
if opt.Index < math.MaxInt32 {
if minWALIndex, err = SnapshotIndexByIndex(ctx, r, opt.Generation, opt.Index); err != nil {
return fmt.Errorf("cannot find snapshot index: %w", err)
}
} else {
if minWALIndex, err = SnapshotIndexAt(ctx, r, opt.Generation, opt.Timestamp); err != nil {
return fmt.Errorf("cannot find snapshot index by timestamp: %w", err)
}
}
// Find the maximum WAL index that occurs before timestamp.
@@ -1487,7 +1493,7 @@ func RestoreReplica(ctx context.Context, r Replica, opt RestoreOptions) error {
// Restore each WAL file until we reach our maximum index.
for index := minWALIndex; index <= maxWALIndex; index++ {
logger.Printf("%s: restoring wal %s/%08x", logPrefix, opt.Generation, index)
restoreStartTime := time.Now()
if err = restoreWAL(ctx, r, opt.Generation, index, tmpPath); os.IsNotExist(err) && index == minWALIndex && index == maxWALIndex {
logger.Printf("%s: no wal available, snapshot only", logPrefix)
break // snapshot file only, ignore error
@@ -1495,10 +1501,21 @@ func RestoreReplica(ctx context.Context, r Replica, opt RestoreOptions) error {
return fmt.Errorf("cannot restore wal: %w", err)
}
logger.Printf("%s: applying wal %s/%08x", logPrefix, opt.Generation, index)
fi, err := os.Stat(tmpPath + "-wal")
if err != nil {
return fmt.Errorf("cannot stat restored wal: %w", err)
}
applyStartTime := time.Now()
if err = applyWAL(ctx, tmpPath); err != nil {
return fmt.Errorf("cannot apply wal: %w", err)
}
logger.Printf("%s: restored wal %s/%08x (sz=%d restore=%s apply=%s)",
logPrefix, opt.Generation, index,
fi.Size(),
applyStartTime.Sub(restoreStartTime).String(),
time.Since(applyStartTime).String(),
)
}
// Copy file to final location.