precondition_before_starting_an_upgrade.go

// Copyright 2022 The Cockroach Authors.
//
// Use of this software is governed by the Business Source License
// included in the file licenses/BSL.txt.
//
// As of the Change Date specified in that file, in accordance with
// the Business Source License, use of this software will be governed
// by the Apache License, Version 2.0, included in the file
// licenses/APL.txt.

package upgrades

import (
	"context"

	"github.com/cockroachdb/cockroach/pkg/clusterversion"
	"github.com/cockroachdb/cockroach/pkg/kv"
	"github.com/cockroachdb/cockroach/pkg/sql/catalog/descpb"
	"github.com/cockroachdb/cockroach/pkg/sql/catalog/descs"
	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgcode"
	"github.com/cockroachdb/cockroach/pkg/sql/pgwire/pgerror"
	"github.com/cockroachdb/cockroach/pkg/sql/sem/tree"
	"github.com/cockroachdb/cockroach/pkg/sql/sqlutil"
	"github.com/cockroachdb/cockroach/pkg/upgrade"
	"github.com/cockroachdb/cockroach/pkg/util/log"
	"github.com/cockroachdb/redact"
)

func preconditionBeforeStartingAnUpgrade(
	ctx context.Context, cs clusterversion.ClusterVersion, d upgrade.TenantDeps,
) error {
	// precondition: make sure no invalid descriptors exist before starting an upgrade
	err := preconditionNoInvalidDescriptorsBeforeUpgrading(ctx, cs, d)
	if err != nil {
		return err
	}

	// Add other preconditions before starting an upgrade here.

	return nil
}

// preconditionNoInvalidDescriptorsBeforeUpgrading is a function
// that returns a non-nill error if there are any invalid descriptors.
// It is done by querying `crdb_internal.invalid_objects` and see if
// it is empty.
func preconditionNoInvalidDescriptorsBeforeUpgrading(
	ctx context.Context, cs clusterversion.ClusterVersion, d upgrade.TenantDeps,
) error {
	var errMsg redact.StringBuilder
	err := d.InternalExecutorFactory.DescsTxnWithExecutor(ctx, d.DB, d.SessionData,
		func(ctx context.Context, txn *kv.Txn, descriptors *descs.Collection, ie sqlutil.InternalExecutor) error {
			query := `SELECT id, database_name, schema_name, obj_name, error_redactable FROM crdb_internal.invalid_objects`
			rows, err := ie.QueryIterator(
				ctx, "check-if-there-are-any-invalid-descriptors", txn /* txn */, query)
			if err != nil {
				return err
			}
			var hasNext bool
			for hasNext, err = rows.Next(ctx); hasNext && err == nil; hasNext, err = rows.Next(ctx) {
				// There exists invalid objects; Accumulate their information into `errMsg`.
				// `crdb_internal.invalid_objects` has five columns: id, database name, schema name, table name, error.
				row := rows.Cur()
				descName := tree.MakeTableNameWithSchema(
					tree.Name(tree.MustBeDString(row[1])),
					tree.Name(tree.MustBeDString(row[2])),
					tree.Name(tree.MustBeDString(row[3])),
				)
				tableID := descpb.ID(tree.MustBeDInt(row[0]))
				// Note: the cast from the `error` column to RedactableString here is only valid because
				// the `error` column is populated via a RedactableString too. Conversion from string
				// to RedactableString is not safe in general.
				errString := redact.RedactableString(tree.MustBeDString(row[4]))
				// TODO(ssd): Remove in 23.1 once we are sure that the migration which fixes this corruption has run.
				if veryLikelyKnownUserfileBreakage(ctx, txn, descriptors, tableID, errString.StripMarkers()) {
					log.Infof(ctx, "ignoring invalid descriptor %v (%v) with error because it looks like known userfile-related corruption: %v",
						&descName, tableID, errString)
				} else {
					errMsg.Printf("invalid descriptor: %v (%d) because %v\n", &descName, tableID, errString)
				}
			}
			return err
		})
	if err != nil {
		return err
	}
	if errMsg.Len() == 0 {
		return nil
	}
	return pgerror.Newf(pgcode.ObjectNotInPrerequisiteState,
		"there exists invalid descriptors as listed below; fix these descriptors "+
			"before attempting to upgrade again:\n%v", errMsg)
}