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sequence_number.go
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sequence_number.go
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package sequence_number
import (
"database/sql"
"errors"
"fmt"
"strconv"
"net/http"
"code.cloudfoundry.org/lager"
"github.com/cloudfoundry-incubator/galera-healthcheck/config"
"github.com/cloudfoundry-incubator/galera-healthcheck/mysqld_cmd"
)
type SequenceNumberChecker struct {
db *sql.DB
config config.Config
logger lager.Logger
mysqldCmd mysqld_cmd.MysqldCmd
}
func New(db *sql.DB,
mysqldCmd mysqld_cmd.MysqldCmd,
config config.Config,
logger lager.Logger,
) *SequenceNumberChecker {
return &SequenceNumberChecker{
db: db,
config: config,
logger: logger,
mysqldCmd: mysqldCmd,
}
}
func (s *SequenceNumberChecker) Check(req *http.Request) (string, error) {
s.logger.Info("Checking sequence number of database node...")
if s.config.Monit.ServiceName == "garbd" {
return "no sequence number - running on arbitrator node", nil
} else if s.dbReachable() {
return "", errors.New("can't determine sequence number when database is running")
} else {
returnedSeqNo, err := s.readSeqNoFromRecoverCmd()
if err != nil {
return "", err
}
returnedSeqNoInt, converr := strconv.Atoi(returnedSeqNo)
if converr != nil {
return "", converr
}
if returnedSeqNoInt < 0 {
return "", errors.New(fmt.Sprintf("Invalid sequence number %s", returnedSeqNo))
}
return returnedSeqNo, nil
}
}
func (s *SequenceNumberChecker) readSeqNoFromRecoverCmd() (string, error) {
s.logger.Info("Reading seqno from logs")
seqno, err := s.mysqldCmd.RecoverSeqno()
if err != nil {
s.logger.Error("Failed to retrieve seqno from logs", err)
return "", err
}
return seqno, nil
}
func (s *SequenceNumberChecker) dbReachable() bool {
_, err := s.db.Exec("SHOW VARIABLES")
if err != nil {
s.logger.Info(fmt.Sprintf("Database not reachable, continuing: %s", err.Error()))
}
return err == nil
}