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Reconnect database when connection is invalid. #4

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Reconnect database when connection is invalid. #4

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92 changes: 82 additions & 10 deletions short/short.go
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ package short

import (
"database/sql"
"database/sql/driver"
"errors"
"fmt"
"log"
Expand All @@ -10,7 +11,7 @@ import (
"github.com/andyxning/shortme/conf"
"github.com/andyxning/shortme/sequence"
_ "github.com/andyxning/shortme/sequence/db"
_ "github.com/go-sql-driver/mysql"
"github.com/go-sql-driver/mysql"
)

type shorter struct {
Expand All @@ -21,6 +22,16 @@ type shorter struct {

// connect will panic when it can not connect to DB server.
func (shorter *shorter) mustConnect() {
shorter.reconnectReadDB()
shorter.reconnectWriteDB()
}

func (shorter *shorter) reconnectReadDB() {
if shorter.readDB != nil {
shorter.readDB.Close()
shorter.readDB = nil
}

db, err := sql.Open("mysql", conf.Conf.ShortDB.ReadDSN)
if err != nil {
log.Panicf("short read db open error. %v", err)
Expand All @@ -35,8 +46,15 @@ func (shorter *shorter) mustConnect() {
db.SetMaxOpenConns(conf.Conf.ShortDB.MaxOpenConns)

shorter.readDB = db
}

func (shorter *shorter) reconnectWriteDB() {
if shorter.writeDB != nil {
shorter.writeDB.Close()
shorter.writeDB = nil
}

db, err = sql.Open("mysql", conf.Conf.ShortDB.WriteDSN)
db, err := sql.Open("mysql", conf.Conf.ShortDB.WriteDSN)
if err != nil {
log.Panicf("short write db open error. %v", err)
}
Expand All @@ -54,6 +72,15 @@ func (shorter *shorter) mustConnect() {

// initSequence will panic when it can not open the sequence successfully.
func (shorter *shorter) mustInitSequence() {
shorter.reconnectSequence()
}

func (shorter *shorter) reconnectSequence() {
if shorter.sequence != nil {
shorter.sequence.Close()
shorter.sequence = nil
}

sequence, err := sequence.GetSequence("db")
if err != nil {
log.Panicf("get sequence instance error. %v", err)
Expand All @@ -79,14 +106,29 @@ func (shorter *shorter) close() {
}
}

func (shorter *shorter) connectionError(err *error) bool {
return *err == driver.ErrBadConn || *err == mysql.ErrInvalidConn
}

func (shorter *shorter) Expand(shortURL string) (longURL string, err error) {
selectSQL := fmt.Sprintf(`SELECT long_url FROM short WHERE short_url=?`)

var rows *sql.Rows
rows, err = shorter.readDB.Query(selectSQL, shortURL)

if err != nil {
log.Printf("short read db query error. %v", err)
return "", errors.New("short read db query error")
if shorter.connectionError(&err) {
shorter.reconnectReadDB()

rows, err = shorter.readDB.Query(selectSQL, shortURL)
if err != nil {
log.Printf("short read db query error. %v", err)
return "", errors.New("short read db query error")
}
} else {
log.Printf("short read db query error. %v", err)
return "", errors.New("short read db query error")
}
}

defer rows.Close()
Expand All @@ -113,8 +155,18 @@ func (shorter *shorter) Short(longURL string) (shortURL string, err error) {
var seq uint64
seq, err = shorter.sequence.NextSequence()
if err != nil {
log.Printf("get next sequence error. %v", err)
return "", errors.New("get next sequence error")
if shorter.connectionError(&err) {
shorter.reconnectSequence()

seq, err = shorter.sequence.NextSequence()
if err != nil {
log.Printf("get next sequence error. %v", err)
return "", errors.New("get next sequence error")
}
} else {
log.Printf("get next sequence error. %v", err)
return "", errors.New("get next sequence error")
}
}

shortURL = base.Int2String(seq)
Expand All @@ -130,15 +182,35 @@ func (shorter *shorter) Short(longURL string) (shortURL string, err error) {
var stmt *sql.Stmt
stmt, err = shorter.writeDB.Prepare(insertSQL)
if err != nil {
log.Printf("short write db prepares error. %v", err)
return "", errors.New("short write db prepares error")
if shorter.connectionError(&err) {
shorter.reconnectWriteDB()

stmt, err = shorter.writeDB.Prepare(insertSQL)
if err != nil {
log.Printf("short write db prepares error. %v", err)
return "", errors.New("short write db prepares error")
}
} else {
log.Printf("short write db prepares error. %v", err)
return "", errors.New("short write db prepares error")
}
}
defer stmt.Close()

_, err = stmt.Exec(longURL, shortURL)
if err != nil {
log.Printf("short write db insert error. %v", err)
return "", errors.New("short write db insert error")
if shorter.connectionError(&err) {
shorter.reconnectWriteDB()

_, err = stmt.Exec(longURL, shortURL)
if err != nil {
log.Printf("short write db insert error. %v", err)
return "", errors.New("short write db insert error")
}
} else {
log.Printf("short write db insert error. %v", err)
return "", errors.New("short write db insert error")
}
}

return shortURL, nil
Expand Down