Fixes for re-running migration script on same destination db (#246)

* add reset flag

* add --checksum to rsync options

op-chain-ops/cmd/celo-migrate/db.go

@@ -113,3 +113,21 @@ func getHeadHeader(dbpath string) (*types.Header, error) {
 	}
 	return headHeader, nil
 }
+
+func cleanupNonAncientDb(dir string) error {
+	log.Info("Cleaning up non-ancient data in new db")
+
+	files, err := os.ReadDir(dir)
+	if err != nil {
+		return fmt.Errorf("failed to read directory: %w", err)
+	}
+	for _, file := range files {
+		if file.Name() != "ancient" {
+			err := os.RemoveAll(filepath.Join(dir, file.Name()))
+			if err != nil {
+				return fmt.Errorf("failed to remove file: %w", err)
+			}
+		}
+	}
+	return nil
+}

op-chain-ops/cmd/celo-migrate/main.go

@@ -94,13 +94,19 @@ var (
 		Usage: "Memory limit in MiB, should be set lower than the available amount of memory in your system to prevent out of memory errors",
 		Value: 7500,
 	}
+	reset = &cli.BoolFlag{
+		Name:  "reset",
+		Usage: "Delete everything in the destination directory aside from /ancients. This is useful if you need to re-run the full migration but do not want to repeat the lengthy ancients migration. If you'd like to reset the entire destination directory, you can delete it manually.",
+		Value: false,
+	}
 
 	preMigrationFlags = []cli.Flag{
 		oldDBPathFlag,
 		newDBPathFlag,
 		batchSizeFlag,
 		bufferSizeFlag,
 		memoryLimitFlag,
+		reset,
 	}
 	fullMigrationFlags = append(
 		preMigrationFlags,
@@ -116,11 +122,12 @@ var (
 )
 
 type preMigrationOptions struct {
-	oldDBPath   string
-	newDBPath   string
-	batchSize   uint64
-	bufferSize  uint64
-	memoryLimit int64
+	oldDBPath        string
+	newDBPath        string
+	batchSize        uint64
+	bufferSize       uint64
+	memoryLimit      int64
+	resetNonAncients bool
 }
 
 type stateMigrationOptions struct {
@@ -141,11 +148,12 @@ type fullMigrationOptions struct {
 
 func parsePreMigrationOptions(ctx *cli.Context) preMigrationOptions {
 	return preMigrationOptions{
-		oldDBPath:   ctx.String(oldDBPathFlag.Name),
-		newDBPath:   ctx.String(newDBPathFlag.Name),
-		batchSize:   ctx.Uint64(batchSizeFlag.Name),
-		bufferSize:  ctx.Uint64(bufferSizeFlag.Name),
-		memoryLimit: ctx.Int64(memoryLimitFlag.Name),
+		oldDBPath:        ctx.String(oldDBPathFlag.Name),
+		newDBPath:        ctx.String(newDBPathFlag.Name),
+		batchSize:        ctx.Uint64(batchSizeFlag.Name),
+		bufferSize:       ctx.Uint64(bufferSizeFlag.Name),
+		memoryLimit:      ctx.Int64(memoryLimitFlag.Name),
+		resetNonAncients: ctx.Bool(reset.Name),
 	}
 }
 
@@ -270,6 +278,12 @@ func runPreMigration(opts preMigrationOptions) ([]*rawdb.NumberHash, uint64, err
 		return nil, 0, fmt.Errorf("failed to create new db path: %w", err)
 	}
 
+	if opts.resetNonAncients {
+		if err = cleanupNonAncientDb(opts.newDBPath); err != nil {
+			return nil, 0, fmt.Errorf("failed to cleanup non-ancient db: %w", err)
+		}
+	}
+
 	var numAncientsNewBefore uint64
 	var numAncientsNewAfter uint64
 	var strayAncientBlocks []*rawdb.NumberHash

op-chain-ops/cmd/celo-migrate/non-ancients.go

@@ -24,17 +24,18 @@ func copyDbExceptAncients(oldDbPath, newDbPath string) error {
 	// Convert output to string
 	outputStr := string(output)
 
+	opts := []string{"-v", "-a", "--exclude=ancient", "--checksum", "--delete"}
+
 	// Check for supported options
-	var cmd *exec.Cmd
 	// Prefer --info=progress2 over --progress
 	if strings.Contains(outputStr, "--info") {
-		cmd = exec.Command("rsync", "-v", "-a", "--info=progress2", "--exclude=ancient", "--delete", oldDbPath+"/", newDbPath)
+		opts = append(opts, "--info=progress2")
 	} else if strings.Contains(outputStr, "--progress") {
-		cmd = exec.Command("rsync", "-v", "-a", "--progress", "--exclude=ancient", "--delete", oldDbPath+"/", newDbPath)
-	} else {
-		cmd = exec.Command("rsync", "-v", "-a", "--exclude=ancient", "--delete", oldDbPath+"/", newDbPath)
+		opts = append(opts, "--progress")
 	}
 
+	cmd := exec.Command("rsync", append(opts, oldDbPath+"/", newDbPath)...)
+
 	// rsync copies any file with a different timestamp or size.
 	//
 	// '--exclude=ancient' excludes the ancient directory from the copy
@@ -46,6 +47,8 @@ func copyDbExceptAncients(oldDbPath, newDbPath string) error {
 	//
 	// '--whole-file' This is the default when both the source and destination are specified as local paths, which they are here (oldDbPath and newDbPath).
 	// This option disables rsync’s delta-transfer algorithm, which causes all transferred files to be sent whole. The delta-transfer algorithm is normally used when the destination is a remote system.
+	//
+	// '--checksum' This forces rsync to compare the checksums of all files to determine if they are the same. This is slows down the transfer but ensures that source and destination directories end up with the same contents (excluding /ancients).
 
 	log.Info("Running rsync command", "command", cmd.String())
 	cmd.Stdout = os.Stdout