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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

234 lines
7.4 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"
"go.temporal.io/server/common/persistence/sql/sqlplugin"
)
const (
// below are templates for history_node table
addHistoryNodesQuery = `INSERT INTO history_node (` +
`shard_id, tree_id, branch_id, node_id, prev_txn_id, txn_id, data, data_encoding) ` +
`VALUES (:shard_id, :tree_id, :branch_id, :node_id, :prev_txn_id, :txn_id, :data, :data_encoding) ` +
`ON DUPLICATE KEY UPDATE prev_txn_id=:prev_txn_id, data=:data, data_encoding=:data_encoding `
getHistoryNodesQuery = `SELECT node_id, prev_txn_id, txn_id, data, data_encoding FROM history_node ` +
`WHERE shard_id = ? AND tree_id = ? AND branch_id = ? AND ((node_id = ? AND txn_id > ?) OR node_id > ?) AND node_id < ? ` +
`ORDER BY shard_id, tree_id, branch_id, node_id, txn_id LIMIT ? `
getHistoryNodesReverseQuery = `SELECT node_id, prev_txn_id, txn_id, data, data_encoding FROM history_node ` +
`WHERE shard_id = ? AND tree_id = ? AND branch_id = ? AND node_id >= ? AND ((node_id = ? AND txn_id < ?) OR node_id < ?) ` +
`ORDER BY shard_id, tree_id, branch_id DESC, node_id DESC, txn_id DESC LIMIT ? `
getHistoryNodeMetadataQuery = `SELECT node_id, prev_txn_id, txn_id FROM history_node ` +
`WHERE shard_id = ? AND tree_id = ? AND branch_id = ? AND ((node_id = ? AND txn_id > ?) OR node_id > ?) AND node_id < ? ` +
`ORDER BY shard_id, tree_id, branch_id, node_id, txn_id LIMIT ? `
deleteHistoryNodeQuery = `DELETE FROM history_node WHERE shard_id = ? AND tree_id = ? AND branch_id = ? AND node_id = ? AND txn_id = ? `
deleteHistoryNodesQuery = `DELETE FROM history_node WHERE shard_id = ? AND tree_id = ? AND branch_id = ? AND node_id >= ? `
// below are templates for history_tree table
addHistoryTreeQuery = `INSERT INTO history_tree (` +
`shard_id, tree_id, branch_id, data, data_encoding) ` +
`VALUES (:shard_id, :tree_id, :branch_id, :data, :data_encoding) ` +
`ON DUPLICATE KEY UPDATE data=VALUES(data), data_encoding=VALUES(data_encoding)`
getHistoryTreeQuery = `SELECT branch_id, data, data_encoding FROM history_tree WHERE shard_id = ? AND tree_id = ? `
// conceptually this query is WHERE (shard_id, tree_id, branch_id) > (?, ?, ?)
// but mysql doesn't execute it efficiently unless it's spelled out like this
paginateBranchesQuery = `SELECT shard_id, tree_id, branch_id, data, data_encoding
FROM history_tree
WHERE (shard_id = ? AND ((tree_id = ? AND branch_id > ?) OR tree_id > ?)) OR shard_id > ?
ORDER BY shard_id, tree_id, branch_id
LIMIT ?`
deleteHistoryTreeQuery = `DELETE FROM history_tree WHERE shard_id = ? AND tree_id = ? AND branch_id = ? `
)
// For history_node table:
// InsertIntoHistoryNode inserts a row into history_node table
func (mdb *db) InsertIntoHistoryNode(
ctx context.Context,
row *sqlplugin.HistoryNodeRow,
) (sql.Result, error) {
// NOTE: txn_id is *= -1 within DB
row.TxnID = -row.TxnID
return mdb.NamedExecContext(ctx,
addHistoryNodesQuery,
row,
)
}
// DeleteFromHistoryNode delete a row from history_node table
func (mdb *db) DeleteFromHistoryNode(
ctx context.Context,
row *sqlplugin.HistoryNodeRow,
) (sql.Result, error) {
// NOTE: txn_id is *= -1 within DB
row.TxnID = -row.TxnID
return mdb.ExecContext(ctx,
deleteHistoryNodeQuery,
row.ShardID,
row.TreeID,
row.BranchID,
row.NodeID,
row.TxnID,
)
}
// SelectFromHistoryNode reads one or more rows from history_node table
func (mdb *db) RangeSelectFromHistoryNode(
ctx context.Context,
filter sqlplugin.HistoryNodeSelectFilter,
) ([]sqlplugin.HistoryNodeRow, error) {
var query string
if filter.MetadataOnly {
query = getHistoryNodeMetadataQuery
} else if filter.ReverseOrder {
query = getHistoryNodesReverseQuery
} else {
query = getHistoryNodesQuery
}
var args []interface{}
if filter.ReverseOrder {
args = []interface{}{
filter.ShardID,
filter.TreeID,
filter.BranchID,
filter.MinNodeID,
filter.MaxTxnID,
-filter.MaxTxnID,
filter.MaxNodeID,
filter.PageSize,
}
} else {
args = []interface{}{
filter.ShardID,
filter.TreeID,
filter.BranchID,
filter.MinNodeID,
-filter.MinTxnID, // NOTE: transaction ID is *= -1 when stored
filter.MinNodeID,
filter.MaxNodeID,
filter.PageSize,
}
}
var rows []sqlplugin.HistoryNodeRow
if err := mdb.SelectContext(ctx, &rows, query, args...); err != nil {
return nil, err
}
// NOTE: since we let txn_id multiple by -1 when inserting, we have to revert it back here
for index := range rows {
rows[index].TxnID = -rows[index].TxnID
}
return rows, nil
}
// DeleteFromHistoryNode deletes one or more rows from history_node table
func (mdb *db) RangeDeleteFromHistoryNode(
ctx context.Context,
filter sqlplugin.HistoryNodeDeleteFilter,
) (sql.Result, error) {
return mdb.ExecContext(ctx,
deleteHistoryNodesQuery,
filter.ShardID,
filter.TreeID,
filter.BranchID,
filter.MinNodeID,
)
}
// For history_tree table:
// InsertIntoHistoryTree inserts a row into history_tree table
func (mdb *db) InsertIntoHistoryTree(
ctx context.Context,
row *sqlplugin.HistoryTreeRow,
) (sql.Result, error) {
return mdb.NamedExecContext(ctx,
addHistoryTreeQuery,
row,
)
}
// SelectFromHistoryTree reads one or more rows from history_tree table
func (mdb *db) SelectFromHistoryTree(
ctx context.Context,
filter sqlplugin.HistoryTreeSelectFilter,
) ([]sqlplugin.HistoryTreeRow, error) {
var rows []sqlplugin.HistoryTreeRow
err := mdb.SelectContext(ctx,
&rows,
getHistoryTreeQuery,
filter.ShardID,
filter.TreeID,
)
return rows, err
}
// PaginateBranchesFromHistoryTree reads up to page.Limit rows from the history_tree table sorted by their primary key,
// while skipping the first page.Offset rows.
func (mdb *db) PaginateBranchesFromHistoryTree(
ctx context.Context,
page sqlplugin.HistoryTreeBranchPage,
) ([]sqlplugin.HistoryTreeRow, error) {
var rows []sqlplugin.HistoryTreeRow
err := mdb.SelectContext(
ctx,
&rows,
paginateBranchesQuery,
page.ShardID,
page.TreeID,
page.BranchID,
page.TreeID,
page.ShardID,
page.Limit,
)
return rows, err
}
// DeleteFromHistoryTree deletes one or more rows from history_tree table
func (mdb *db) DeleteFromHistoryTree(
ctx context.Context,
filter sqlplugin.HistoryTreeDeleteFilter,
) (sql.Result, error) {
return mdb.ExecContext(ctx,
deleteHistoryTreeQuery,
filter.ShardID,
filter.TreeID,
filter.BranchID,
)
}