Files
Tim Deeb-SwihartandGitHub be7b5514a5 Reconnect to SQL databases when connections fail (#5926)
## What changed?

Both our PostgreSQL and MySQL database backends will now automatically
reconnect to the database when certain errors occur: all errors chosen
have been experienced when testing this behavior through an AWS Aurora
RDS failover of either MySQL or PostgreSQL.

For both backends we will reconnect when we see:
- `ECONNRESET`
- `ECONNABORTED`
- `ECONNREFUSED`
- `io.EOF`
- `io.ErrUnexpectedEOF`
- `database/sql/driver.ErrBadConn`

for postgres we will also reconnect on the following SQLStates:
- `25006` read-only transaction
- `57P03` cannot connect now
- `0A000` feature not supported, but ONLY when the message is `cannot
set transaction read-write mode during recovery`

for mysql we will also reconnect when we see the following error codes:
- `1040` too many connections 
- `1792` read-only transaction (SQLstate `25006`)
- `1836` running in read-only mode

This logic is easily extensible should we discover more failure modes
over time

## Why?

We've had multiple community reports of Temporal problems during RDS
failover. One part of this is the fact that we wouldn't necessarily
reconnect; we were at the whims of our chosen SQL abstraction's
connection pooling logic.

## How did you test it?

I manually tested this functionality in the presence of repeated RDS
failovers: 

- [x] postgres12 plugin with pq driver
- [x] postgres12 plugin with pgx driver
- [x] mysql plugin

Automated testing will be added to our regular testing pipelines once
our infrastructure friends have added the support I need (it's in
progress)

## Potential risks

We're concerned there's a correctness issue in our PostgreSQL backend
that's related to our behavior during an RDS failover. If we merge this
before I figure out what's going on, we could hide the issue and make it
harder to reproduce.

## Documentation
N/A

## Is hotfix candidate?
Yes?
2024-05-17 16:59:15 -07:00

336 lines
10 KiB
Go

// The MIT License
//
// Copyright (c) 2020 Temporal Technologies Inc. All rights reserved.
//
// Copyright (c) 2020 Uber Technologies, Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
package mysql
import (
"context"
"database/sql"
"errors"
"fmt"
"strings"
"go.temporal.io/server/common/persistence/sql/sqlplugin"
)
var (
templateInsertWorkflowExecution = fmt.Sprintf(
`INSERT INTO executions_visibility (%s)
VALUES (%s)
ON DUPLICATE KEY UPDATE run_id = VALUES(run_id)`,
strings.Join(sqlplugin.DbFields, ", "),
sqlplugin.BuildNamedPlaceholder(sqlplugin.DbFields...),
)
templateInsertCustomSearchAttributes = `
INSERT INTO custom_search_attributes (
namespace_id, run_id, search_attributes
) VALUES (:namespace_id, :run_id, :search_attributes)
ON DUPLICATE KEY UPDATE run_id = VALUES(run_id)`
templateUpsertWorkflowExecution = fmt.Sprintf(
`INSERT INTO executions_visibility (%s)
VALUES (%s)
%s`,
strings.Join(sqlplugin.DbFields, ", "),
sqlplugin.BuildNamedPlaceholder(sqlplugin.DbFields...),
buildOnDuplicateKeyUpdate(sqlplugin.DbFields...),
)
templateUpsertCustomSearchAttributes = `
INSERT INTO custom_search_attributes (
namespace_id, run_id, search_attributes
) VALUES (:namespace_id, :run_id, :search_attributes)
ON DUPLICATE KEY UPDATE search_attributes = VALUES(search_attributes)`
templateDeleteWorkflowExecution_v8 = `
DELETE FROM executions_visibility
WHERE namespace_id = :namespace_id AND run_id = :run_id`
templateDeleteCustomSearchAttributes = `
DELETE FROM custom_search_attributes
WHERE namespace_id = :namespace_id AND run_id = :run_id`
templateGetWorkflowExecution_v8 = fmt.Sprintf(
`SELECT %s FROM executions_visibility
WHERE namespace_id = :namespace_id AND run_id = :run_id`,
strings.Join(sqlplugin.DbFields, ", "),
)
)
func buildOnDuplicateKeyUpdate(fields ...string) string {
items := make([]string, len(fields))
for i, field := range fields {
items[i] = fmt.Sprintf("%s = VALUES(%s)", field, field)
}
return fmt.Sprintf("ON DUPLICATE KEY UPDATE %s", strings.Join(items, ", "))
}
// InsertIntoVisibility inserts a row into visibility table. If an row already exist,
// its left as such and no update will be made
func (mdb *db) InsertIntoVisibility(
ctx context.Context,
row *sqlplugin.VisibilityRow,
) (result sql.Result, retError error) {
finalRow := mdb.prepareRowForDB(row)
defer func() {
retError = mdb.handle.ConvertError(retError)
}()
db, err := mdb.handle.DB()
if err != nil {
return nil, err
}
tx, err := db.BeginTxx(ctx, nil)
if err != nil {
return nil, err
}
defer func() {
err := tx.Rollback()
// If the error is sql.ErrTxDone, it means the transaction already closed, so ignore error.
if err != nil && !errors.Is(err, sql.ErrTxDone) {
// Transaction rollback error should never happen, unless db connection was lost.
retError = fmt.Errorf("transaction rollback failed: %w", retError)
}
}()
result, err = tx.NamedExecContext(ctx, templateInsertWorkflowExecution, finalRow)
if err != nil {
return nil, fmt.Errorf("unable to insert workflow execution: %w", err)
}
_, err = tx.NamedExecContext(ctx, templateInsertCustomSearchAttributes, finalRow)
if err != nil {
return nil, fmt.Errorf("unable to insert custom search attributes: %w", err)
}
err = tx.Commit()
if err != nil {
return nil, err
}
return result, nil
}
// ReplaceIntoVisibility replaces an existing row if it exist or creates a new row in visibility table
func (mdb *db) ReplaceIntoVisibility(
ctx context.Context,
row *sqlplugin.VisibilityRow,
) (result sql.Result, retError error) {
defer func() {
retError = mdb.handle.ConvertError(retError)
}()
finalRow := mdb.prepareRowForDB(row)
db, err := mdb.handle.DB()
if err != nil {
return nil, err
}
tx, err := db.BeginTxx(ctx, nil)
if err != nil {
return nil, err
}
defer func() {
err := tx.Rollback()
// If the error is sql.ErrTxDone, it means the transaction already closed, so ignore error.
if err != nil && !errors.Is(err, sql.ErrTxDone) {
// Transaction rollback error should never happen, unless db connection was lost.
retError = fmt.Errorf("transaction rollback failed: %w", retError)
}
}()
result, err = tx.NamedExecContext(ctx, templateUpsertWorkflowExecution, finalRow)
if err != nil {
return nil, fmt.Errorf("unable to upsert workflow execution: %w", err)
}
_, err = tx.NamedExecContext(ctx, templateUpsertCustomSearchAttributes, finalRow)
if err != nil {
return nil, fmt.Errorf("unable to upsert custom search attributes: %w", err)
}
err = tx.Commit()
if err != nil {
return nil, err
}
return result, nil
}
// DeleteFromVisibility deletes a row from visibility table if it exist
func (mdb *db) DeleteFromVisibility(
ctx context.Context,
filter sqlplugin.VisibilityDeleteFilter,
) (result sql.Result, retError error) {
defer func() {
retError = mdb.handle.ConvertError(retError)
}()
db, err := mdb.handle.DB()
if err != nil {
return nil, err
}
tx, err := db.BeginTxx(ctx, nil)
if err != nil {
return nil, err
}
defer func() {
err := tx.Rollback()
// If the error is sql.ErrTxDone, it means the transaction already closed, so ignore error.
if err != nil && !errors.Is(err, sql.ErrTxDone) {
// Transaction rollback error should never happen, unless db connection was lost.
retError = fmt.Errorf("transaction rollback failed: %w", retError)
}
}()
_, err = mdb.NamedExecContext(ctx, templateDeleteCustomSearchAttributes, filter)
if err != nil {
return nil, fmt.Errorf("unable to delete custom search attributes: %w", err)
}
result, err = mdb.NamedExecContext(ctx, templateDeleteWorkflowExecution_v8, filter)
if err != nil {
return nil, fmt.Errorf("unable to delete workflow execution: %w", err)
}
err = tx.Commit()
if err != nil {
return nil, err
}
return result, nil
}
// SelectFromVisibility reads one or more rows from visibility table
func (mdb *db) SelectFromVisibility(
ctx context.Context,
filter sqlplugin.VisibilitySelectFilter,
) ([]sqlplugin.VisibilityRow, error) {
if len(filter.Query) == 0 {
// backward compatibility for existing tests
err := sqlplugin.GenerateSelectQuery(&filter, mdb.converter.ToMySQLDateTime)
if err != nil {
return nil, err
}
}
var rows []sqlplugin.VisibilityRow
err := mdb.SelectContext(ctx, &rows, filter.Query, filter.QueryArgs...)
if err != nil {
return nil, err
}
for i := range rows {
err = mdb.processRowFromDB(&rows[i])
if err != nil {
return nil, err
}
}
return rows, nil
}
// GetFromVisibility reads one row from visibility table
func (mdb *db) GetFromVisibility(
ctx context.Context,
filter sqlplugin.VisibilityGetFilter,
) (*sqlplugin.VisibilityRow, error) {
var row sqlplugin.VisibilityRow
stmt, err := mdb.PrepareNamedContext(ctx, templateGetWorkflowExecution_v8)
if err != nil {
return nil, err
}
err = stmt.GetContext(ctx, &row, filter)
if err != nil {
return nil, err
}
err = mdb.processRowFromDB(&row)
if err != nil {
return nil, err
}
return &row, nil
}
func (mdb *db) CountFromVisibility(
ctx context.Context,
filter sqlplugin.VisibilitySelectFilter,
) (int64, error) {
var count int64
err := mdb.GetContext(ctx, &count, filter.Query, filter.QueryArgs...)
if err != nil {
return 0, err
}
return count, nil
}
func (mdb *db) CountGroupByFromVisibility(
ctx context.Context,
filter sqlplugin.VisibilitySelectFilter,
) (_ []sqlplugin.VisibilityCountRow, retError error) {
defer func() {
retError = mdb.handle.ConvertError(retError)
}()
db, err := mdb.handle.DB()
if err != nil {
return nil, err
}
rows, err := db.QueryContext(ctx, filter.Query, filter.QueryArgs...)
if err != nil {
return nil, err
}
defer rows.Close()
return sqlplugin.ParseCountGroupByRows(rows, filter.GroupBy)
}
func (mdb *db) prepareRowForDB(row *sqlplugin.VisibilityRow) *sqlplugin.VisibilityRow {
if row == nil {
return nil
}
finalRow := *row
finalRow.StartTime = mdb.converter.ToMySQLDateTime(finalRow.StartTime)
finalRow.ExecutionTime = mdb.converter.ToMySQLDateTime(finalRow.ExecutionTime)
if finalRow.CloseTime != nil {
*finalRow.CloseTime = mdb.converter.ToMySQLDateTime(*finalRow.CloseTime)
}
return &finalRow
}
func (mdb *db) processRowFromDB(row *sqlplugin.VisibilityRow) error {
if row == nil {
return nil
}
row.StartTime = mdb.converter.FromMySQLDateTime(row.StartTime)
row.ExecutionTime = mdb.converter.FromMySQLDateTime(row.ExecutionTime)
if row.CloseTime != nil {
closeTime := mdb.converter.FromMySQLDateTime(*row.CloseTime)
row.CloseTime = &closeTime
}
if row.SearchAttributes != nil {
for saName, saValue := range *row.SearchAttributes {
switch typedSaValue := saValue.(type) {
case []interface{}:
// the only valid type is slice of strings
strSlice := make([]string, len(typedSaValue))
for i, item := range typedSaValue {
switch v := item.(type) {
case string:
strSlice[i] = v
default:
return fmt.Errorf("%w: %T (expected string)", sqlplugin.ErrInvalidKeywordListDataType, v)
}
}
(*row.SearchAttributes)[saName] = strSlice
default:
// no-op
}
}
}
return nil
}