func updateHandler(ctx *fasthttp.RequestCtx) {
n := common.GetQueriesCount(ctx)
worlds := make([]common.World, n)
for i := 0; i < n; i++ {
w := &worlds[i]
fetchRandomWorld(w)
w.RandomNumber = int32(common.RandomWorldNum())
}
// sorting is required for insert deadlock prevention.
sort.Sort(common.WorldsByID(worlds))
txn, err := db.Begin()
if err != nil {
log.Fatalf("Error starting transaction: %s", err)
}
for i := 0; i < n; i++ {
w := &worlds[i]
if _, err = txn.Exec("worldUpdateStmt", w.RandomNumber, w.Id); err != nil {
log.Fatalf("Error updating world row %d: %s", i, err)
}
}
if err = txn.Commit(); err != nil {
log.Fatalf("Error when commiting world rows: %s", err)
}
common.JSONMarshal(ctx, worlds)
}
func initDatabase(dbHost string, dbUser string, dbPass string, dbName string, dbPort uint16, maxConnectionsInPool int) (*pgx.ConnPool, error) {
var successOrFailure string = "OK"
var config pgx.ConnPoolConfig
config.Host = dbHost
config.User = dbUser
config.Password = dbPass
config.Database = dbName
config.Port = dbPort
config.MaxConnections = maxConnectionsInPool
config.AfterConnect = func(conn *pgx.Conn) error {
worldSelectStmt = mustPrepare(conn, "worldSelectStmt", "SELECT id, randomNumber FROM World WHERE id = $1")
worldUpdateStmt = mustPrepare(conn, "worldUpdateStmt", "UPDATE World SET randomNumber = $1 WHERE id = $2")
fortuneSelectStmt = mustPrepare(conn, "fortuneSelectStmt", "SELECT id, message FROM Fortune")
return nil
}
fmt.Println("--------------------------------------------------------------------------------------------")
connPool, err := pgx.NewConnPool(config)
if err != nil {
successOrFailure = "FAILED"
log.Println("Connecting to database ", dbName, " as user ", dbUser, " ", successOrFailure, ": \n ", err)
} else {
log.Println("Connecting to database ", dbName, " as user ", dbUser, ": ", successOrFailure)
log.Println("Fetching one record to test if db connection is valid...")
var w common.World
n := common.RandomWorldNum()
if errPing := connPool.QueryRow("worldSelectStmt", n).Scan(&w.Id, &w.RandomNumber); errPing != nil {
log.Fatalf("Error scanning world row: %s", errPing)
}
log.Println("OK")
}
fmt.Println("--------------------------------------------------------------------------------------------")
return connPool, err
}
func fetchRandomWorld(w *common.World) {
n := common.RandomWorldNum()
if err := db.QueryRow("worldSelectStmt", n).Scan(&w.Id, &w.RandomNumber); err != nil {
log.Fatalf("Error scanning world row: %s", err)
}
}