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database/sql: simplify retry logic when the connection is bad

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Simplify retry logic when got bad connection

Change-Id: I92494c6c020576ec01bc4868334ee920ded7aa57
GitHub-Last-Rev: 7499b0c941
GitHub-Pull-Request: golang/go#54043
Reviewed-on: https://go-review.googlesource.com/c/go/+/419182
Reviewed-by: Daniel Theophanes <kardianos@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Run-TryBot: hopehook <hopehook@golangcn.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
Jinzhu 2022-09-05 09:02:11 +00:00 committed by Daniel Theophanes
parent 88149ed43e
commit 0752f4a12c
1 changed files with 64 additions and 96 deletions
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158
src/database/sql/sql.go
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@ -846,17 +846,12 @@ func (db *DB) pingDC(ctx context.Context, dc *driverConn, release func(error)) e
func (db *DB) PingContext(ctx context.Context) error {
var dc *driverConn
var err error
var isBadConn bool
for i := 0; i < maxBadConnRetries; i++ {
dc, err = db.conn(ctx, cachedOrNewConn)
isBadConn = errors.Is(err, driver.ErrBadConn)
if !isBadConn {
break
}
}
if isBadConn {
dc, err = db.conn(ctx, alwaysNewConn)
}
err = db.retry(func(strategy connReuseStrategy) error {
dc, err = db.conn(ctx, strategy)
return err
})
if err != nil {
return err
}
@ -1539,6 +1534,18 @@ func (db *DB) putConnDBLocked(dc *driverConn, err error) bool {
// connection to be opened.
const maxBadConnRetries = 2
func (db *DB) retry(fn func(strategy connReuseStrategy) error) error {
for i := int64(0); i < maxBadConnRetries; i++ {
err := fn(cachedOrNewConn)
// retry if err is driver.ErrBadConn
if err == nil || !errors.Is(err, driver.ErrBadConn) {
return err
}
}
return fn(alwaysNewConn)
}
// PrepareContext creates a prepared statement for later queries or executions.
// Multiple queries or executions may be run concurrently from the
// returned statement.
@ -1550,17 +1557,12 @@ const maxBadConnRetries = 2
func (db *DB) PrepareContext(ctx context.Context, query string) (*Stmt, error) {
var stmt *Stmt
var err error
var isBadConn bool
for i := 0; i < maxBadConnRetries; i++ {
stmt, err = db.prepare(ctx, query, cachedOrNewConn)
isBadConn = errors.Is(err, driver.ErrBadConn)
if !isBadConn {
break
}
}
if isBadConn {
return db.prepare(ctx, query, alwaysNewConn)
}
err = db.retry(func(strategy connReuseStrategy) error {
stmt, err = db.prepare(ctx, query, strategy)
return err
})
return stmt, err
}
@ -1628,17 +1630,12 @@ func (db *DB) prepareDC(ctx context.Context, dc *driverConn, release func(error)
func (db *DB) ExecContext(ctx context.Context, query string, args ...any) (Result, error) {
var res Result
var err error
var isBadConn bool
for i := 0; i < maxBadConnRetries; i++ {
res, err = db.exec(ctx, query, args, cachedOrNewConn)
isBadConn = errors.Is(err, driver.ErrBadConn)
if !isBadConn {
break
}
}
if isBadConn {
return db.exec(ctx, query, args, alwaysNewConn)
}
err = db.retry(func(strategy connReuseStrategy) error {
res, err = db.exec(ctx, query, args, strategy)
return err
})
return res, err
}
@ -1703,17 +1700,12 @@ func (db *DB) execDC(ctx context.Context, dc *driverConn, release func(error), q
func (db *DB) QueryContext(ctx context.Context, query string, args ...any) (*Rows, error) {
var rows *Rows
var err error
var isBadConn bool
for i := 0; i < maxBadConnRetries; i++ {
rows, err = db.query(ctx, query, args, cachedOrNewConn)
isBadConn = errors.Is(err, driver.ErrBadConn)
if !isBadConn {
break
}
}
if isBadConn {
return db.query(ctx, query, args, alwaysNewConn)
}
err = db.retry(func(strategy connReuseStrategy) error {
rows, err = db.query(ctx, query, args, strategy)
return err
})
return rows, err
}
@ -1840,17 +1832,12 @@ func (db *DB) QueryRow(query string, args ...any) *Row {
func (db *DB) BeginTx(ctx context.Context, opts *TxOptions) (*Tx, error) {
var tx *Tx
var err error
var isBadConn bool
for i := 0; i < maxBadConnRetries; i++ {
tx, err = db.begin(ctx, opts, cachedOrNewConn)
isBadConn = errors.Is(err, driver.ErrBadConn)
if !isBadConn {
break
}
}
if isBadConn {
return db.begin(ctx, opts, alwaysNewConn)
}
err = db.retry(func(strategy connReuseStrategy) error {
tx, err = db.begin(ctx, opts, strategy)
return err
})
return tx, err
}
@ -1921,17 +1908,12 @@ var ErrConnDone = errors.New("sql: connection is already closed")
func (db *DB) Conn(ctx context.Context) (*Conn, error) {
var dc *driverConn
var err error
var isBadConn bool
for i := 0; i < maxBadConnRetries; i++ {
dc, err = db.conn(ctx, cachedOrNewConn)
isBadConn = errors.Is(err, driver.ErrBadConn)
if !isBadConn {
break
}
}
if isBadConn {
dc, err = db.conn(ctx, alwaysNewConn)
}
err = db.retry(func(strategy connReuseStrategy) error {
dc, err = db.conn(ctx, strategy)
return err
})
if err != nil {
return nil, err
}
@ -2620,26 +2602,18 @@ func (s *Stmt) ExecContext(ctx context.Context, args ...any) (Result, error) {
defer s.closemu.RUnlock()
var res Result
strategy := cachedOrNewConn
for i := 0; i < maxBadConnRetries+1; i++ {
if i == maxBadConnRetries {
strategy = alwaysNewConn
}
err := s.db.retry(func(strategy connReuseStrategy) error {
dc, releaseConn, ds, err := s.connStmt(ctx, strategy)
if err != nil {
if errors.Is(err, driver.ErrBadConn) {
continue
}
return nil, err
return err
}
res, err = resultFromStatement(ctx, dc.ci, ds, args...)
releaseConn(err)
if !errors.Is(err, driver.ErrBadConn) {
return err
})
return res, err
}
}
return nil, driver.ErrBadConn
}
// Exec executes a prepared statement with the given arguments and
@ -2768,24 +2742,19 @@ func (s *Stmt) QueryContext(ctx context.Context, args ...any) (*Rows, error) {
defer s.closemu.RUnlock()
var rowsi driver.Rows
strategy := cachedOrNewConn
for i := 0; i < maxBadConnRetries+1; i++ {
if i == maxBadConnRetries {
strategy = alwaysNewConn
}
var rows *Rows
err := s.db.retry(func(strategy connReuseStrategy) error {
dc, releaseConn, ds, err := s.connStmt(ctx, strategy)
if err != nil {
if errors.Is(err, driver.ErrBadConn) {
continue
}
return nil, err
return err
}
rowsi, err = rowsiFromStatement(ctx, dc.ci, ds, args...)
if err == nil {
// Note: ownership of ci passes to the *Rows, to be freed
// with releaseConn.
rows := &Rows{
rows = &Rows{
dc: dc,
rowsi: rowsi,
// releaseConn set below
@ -2805,15 +2774,14 @@ func (s *Stmt) QueryContext(ctx context.Context, args ...any) (*Rows, error) {
txctx = s.cg.txCtx()
}
rows.initContextClose(ctx, txctx)
return rows, nil
return nil
}
releaseConn(err)
if !errors.Is(err, driver.ErrBadConn) {
return nil, err
}
}
return nil, driver.ErrBadConn
return err
})
return rows, err
}
// Query executes a prepared query statement with the given arguments