Files
tasks/common/persistence/sql/sqlplugin/postgresql/db.go
T
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

198 lines
5.6 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 postgresql
import (
"context"
"database/sql"
"fmt"
"github.com/jmoiron/sqlx"
"go.temporal.io/server/common/config"
"go.temporal.io/server/common/persistence/schema"
"go.temporal.io/server/common/persistence/sql/sqlplugin"
"go.temporal.io/server/common/persistence/sql/sqlplugin/postgresql/driver"
"go.temporal.io/server/common/resolver"
postgresqlschemaV12 "go.temporal.io/server/schema/postgresql/v12"
)
func (pdb *db) IsDupEntryError(err error) bool {
return pdb.dbDriver.IsDupEntryError(err)
}
func (pdb *db) IsDupDatabaseError(err error) bool {
return pdb.dbDriver.IsDupDatabaseError(err)
}
// db represents a logical connection to postgresql database
type db struct {
dbKind sqlplugin.DbKind
dbName string
dbDriver driver.Driver
plugin *plugin
cfg *config.SQL
resolver resolver.ServiceResolver
converter DataConverter
handle *sqlplugin.DatabaseHandle
tx *sqlx.Tx
}
var _ sqlplugin.DB = (*db)(nil)
// newDB returns an instance of DB, which is a logical
// connection to the underlying postgresql database
func newDB(
dbKind sqlplugin.DbKind,
dbName string,
dbDriver driver.Driver,
handle *sqlplugin.DatabaseHandle,
tx *sqlx.Tx,
) *db {
mdb := &db{
dbKind: dbKind,
dbName: dbName,
dbDriver: dbDriver,
handle: handle,
tx: tx,
}
mdb.converter = &converter{}
return mdb
}
func (pdb *db) conn() sqlplugin.Conn {
if pdb.tx != nil {
return pdb.tx
}
return pdb.handle.Conn()
}
// BeginTx starts a new transaction and returns a reference to the Tx object
func (pdb *db) BeginTx(ctx context.Context) (sqlplugin.Tx, error) {
db, err := pdb.handle.DB()
if err != nil {
// This error needs no conversion
return nil, err
}
tx, err := db.BeginTxx(ctx, nil)
if err != nil {
return nil, pdb.handle.ConvertError(err)
}
return newDB(pdb.dbKind, pdb.dbName, pdb.dbDriver, pdb.handle, tx), nil
}
// Close closes the connection to the mysql db
func (pdb *db) Close() error {
pdb.handle.Close()
return nil
}
// PluginName returns the name of the mysql plugin
func (pdb *db) PluginName() string {
return PluginName
}
// DbName returns the name of the database
func (pdb *db) DbName() string {
return pdb.dbName
}
// ExpectedVersion returns expected version.
func (pdb *db) ExpectedVersion() string {
switch pdb.dbKind {
case sqlplugin.DbKindMain:
return postgresqlschemaV12.Version
case sqlplugin.DbKindVisibility:
return postgresqlschemaV12.VisibilityVersion
default:
panic(fmt.Sprintf("unknown db kind %v", pdb.dbKind))
}
}
// VerifyVersion verify schema version is up to date
func (pdb *db) VerifyVersion() error {
expectedVersion := pdb.ExpectedVersion()
return schema.VerifyCompatibleVersion(pdb, pdb.dbName, expectedVersion)
}
// Commit commits a previously started transaction
func (pdb *db) Commit() error {
return pdb.tx.Commit()
}
// Rollback triggers rollback of a previously started transaction
func (pdb *db) Rollback() error {
return pdb.tx.Rollback()
}
// Helper methods to hide common error handling
func (pdb *db) ExecContext(ctx context.Context, stmt string, args ...any) (sql.Result, error) {
res, err := pdb.conn().ExecContext(ctx, stmt, args...)
return res, pdb.handle.ConvertError(err)
}
func (pdb *db) GetContext(ctx context.Context, dest any, query string, args ...any) error {
err := pdb.conn().GetContext(ctx, dest, query, args...)
return pdb.handle.ConvertError(err)
}
func (pdb *db) Select(dest any, query string, args ...any) error {
db, err := pdb.handle.DB()
if err != nil {
return err
}
err = db.Select(dest, query, args...)
return pdb.handle.ConvertError(err)
}
func (pdb *db) SelectContext(ctx context.Context, dest any, query string, args ...any) error {
err := pdb.conn().SelectContext(ctx, dest, query, args...)
return pdb.handle.ConvertError(err)
}
func (pdb *db) NamedExecContext(ctx context.Context, query string, arg any) (sql.Result, error) {
res, err := pdb.conn().NamedExecContext(ctx, query, arg)
return res, pdb.handle.ConvertError(err)
}
func (pdb *db) PrepareNamedContext(ctx context.Context, query string) (*sqlx.NamedStmt, error) {
stmt, err := pdb.conn().PrepareNamedContext(ctx, query)
return stmt, pdb.handle.ConvertError(err)
}
func (pdb *db) QueryContext(ctx context.Context, query string, args ...any) (*sql.Rows, error) {
db, err := pdb.handle.DB()
if err != nil {
return nil, err
}
rows, err := db.QueryContext(ctx, query, args...)
return rows, pdb.handle.ConvertError(err)
}
func (pdb *db) Rebind(query string) string {
return pdb.conn().Rebind(query)
}