// NewDBConnection returns a new DBConnection based on the ConnectionParams
// and will use the provided stats to collect timing.
func NewDBConnection(info *mysql.ConnectionParams, mysqlStats *stats.Timings) (*DBConnection, error) {
params, err := dbconfigs.MysqlParams(info)
if err != nil {
return nil, err
}
c, err := mysql.Connect(params)
return &DBConnection{c, mysqlStats}, err
}
func (dc *DBClient) Connect() error {
params, err := dbconfigs.MysqlParams(dc.dbConfig)
if err != nil {
return err
}
dc.dbConn, err = mysql.Connect(params)
if err != nil {
return fmt.Errorf("error in connecting to mysql db, err %v", err)
}
return nil
}
// NewSlaveConnection creates a new slave connection to the mysqld instance.
// It uses a pools.IDPool to ensure that the server IDs used to connect are
// unique within this process. This is done with the assumptions that:
//
// 1) No other processes are making fake slave connections to our mysqld.
// 2) No real slave servers will have IDs in the range 1-N where N is the peak
// number of concurrent fake slave connections we will ever make.
func NewSlaveConnection(mysqld *Mysqld) (*SlaveConnection, error) {
params, err := dbconfigs.MysqlParams(mysqld.dba)
if err != nil {
return nil, err
}
conn, err := mysql.Connect(params)
if err != nil {
return nil, err
}
sc := &SlaveConnection{
Connection: conn,
mysqld: mysqld,
slaveID: slaveIDPool.Get(),
}
log.Infof("new slave connection: slaveID=%d", sc.slaveID)
return sc, nil
}
// setupPrimerConnections creates the channel and the consumers for
// the sql statements
func (pc *PrimeCache) setupPrimerConnections() error {
pc.workerChannel = make(chan string, 1000)
for i := 0; i < pc.WorkerCount; i++ {
// connect to the database using client for a replay connection
params, err := dbconfigs.MysqlParams(&pc.dbcfgs.App.ConnectionParams)
if err != nil {
return fmt.Errorf("cannot get parameters to connect to MySQL: %v", err)
}
dbConn, err := mysql.Connect(params)
if err != nil {
return fmt.Errorf("mysql.Connect failed: %v", err)
}
// and launch the go routine that applies the statements
go applyLoop(dbConn, pc.workerChannel)
}
return nil
}
// OneRun tries a single cycle connecting to MySQL, and if behind on
// replication, starts playing the logs ahead to prime the cache.
func (pc *PrimeCache) OneRun() {
// connect to the database using dba for a control connection
params, err := dbconfigs.MysqlParams(&pc.dbcfgs.Dba)
if err != nil {
log.Errorf("Cannot get parameters to connect to MySQL: %v", err)
return
}
pc.dbConn, err = mysql.Connect(params)
if err != nil {
log.Errorf("mysql.Connect failed: %v", err)
return
}
// get the slave status
slavestat, err := pc.getSlaveStatus()
if err != nil {
log.Warningf("getSlaveStatus failed: %v", err)
return
}
// if we're not replicating, we're done
if !slavestat.slaveSQLRunning {
log.Warningf("Slave is not replicating (SQL)")
return
}
if !slavestat.slaveIORunning {
log.Warningf("Slave is not replicating (IO)")
return
}
if slavestat.secondsBehindMaster < 2 {
return
}
log.Infof("Replication lag is high (%v seconds), activating", slavestat.secondsBehindMaster)
// setup the connections to the db to apply the statements
if err := pc.setupPrimerConnections(); err != nil {
log.Errorf("setupPrimerConnections failed: %v", err)
return
}
// open the binlogs from where we are on
reader, err := pc.openBinlog(slavestat)
if err != nil {
log.Errorf("openBinlog failed: %v", err)
return
}
maxLineCount := 10000
var maxLeadBytes int64 = 5000000
// and start the loop
lineCount := 0
deleteCount := 0
appliedDeleteCount := 0
updateCount := 0
appliedUpdateCount := 0
sleepCount := 0
var logPos uint64
scanner := bufio.NewScanner(reader)
for scanner.Scan() {
line := scanner.Text()
lowerLine := strings.ToLower(line)
lineCount++
if p, isComment := parseLogPos(line); isComment {
// handle the comments with a log pos
if p > logPos {
logPos = p
}
} else if s, isDelete := parseDeleteStatement(line, lowerLine); isDelete {
// handle delete statements
deleteCount++
if s != "" {
appliedDeleteCount++
pc.workerChannel <- s
}
} else if s, isUpdate := parseUpdateStatement(line, lowerLine); isUpdate {
// handle update statements
updateCount++
if s != "" {
appliedUpdateCount++
pc.workerChannel <- s
}
}
if lineCount%maxLineCount == 0 {
var leadBytes int64
for {
slavestat, err = pc.getSlaveStatus()
if err != nil {
log.Errorf("getSlaveStatus failed: %v", err)
return
}
// see how far ahead we are (it's signed because
// we can be behind too)
leadBytes = int64(logPos) - int64(slavestat.execMasterLogPos)
if leadBytes > maxLeadBytes {
sleepCount++
log.Infof("Sleeping for 1 second waiting for SQL thread to advance: %v > %v", leadBytes, maxLeadBytes)
time.Sleep(1 * time.Second)
continue
} else {
break
}
}
log.Infof("STATS: readahead: %10d lag: %7d sleeps: %4d deletes: %10d missed updates: %10d updates: %10d\n",
leadBytes, slavestat.secondsBehindMaster, sleepCount, deleteCount, updateCount-appliedUpdateCount, appliedUpdateCount)
}
}
reader.Close()
if err := scanner.Err(); err != nil {
log.Errorf("Scanner failed: %v", err)
}
}