本文整理匯總了Golang中github.com/lib/pq.Listener.Listen方法的典型用法代碼示例。如果您正苦於以下問題：Golang Listener.Listen方法的具體用法？Golang Listener.Listen怎麽用？Golang Listener.Listen使用的例子？那麽, 這裏精選的方法代碼示例或許可以為您提供幫助。您也可以進一步了解該方法所在類github.com/lib/pq.Listener的用法示例。
在下文中一共展示了Listener.Listen方法的1個代碼示例，這些例子默認根據受歡迎程度排序。您可以為喜歡或者感覺有用的代碼點讚，您的評價將有助於係統推薦出更棒的Golang代碼示例。
示例1: setupDatabaseListener
func setupDatabaseListener() {
if !checkDatabaseHandleValid(db) {
return
}
//create/replace function for notifyPhoneNumber()
if _, err := db.Exec(`CREATE or REPLACE FUNCTION notifyPhoneNumber() RETURNS trigger AS $$
BEGIN
IF TG_OP='DELETE' THEN
EXECUTE FORMAT('NOTIFY notifyphonenumber, ''%s''', OLD.PhoneNumber);
ELSE
EXECUTE FORMAT('NOTIFY notifyphonenumber, ''%s''', NEW.PhoneNumber);
END IF;
RETURN NULL;
END;
$$ LANGUAGE plpgsql;`); err != nil {
log.Println(err)
} else {
log.Println("Successfully create/replace function notifyPhoneNumber()")
}
//check for trigger existence
var triggerExist bool
if err := db.QueryRow(`SELECT EXISTS(
SELECT 1
FROM pg_trigger
WHERE tgname='inprogresschange')`).Scan(&triggerExist); err != nil {
log.Println(err)
}
if !triggerExist {
if _, err := db.Exec(`CREATE TRIGGER inprogresschange AFTER INSERT OR UPDATE OR DELETE
ON inprogress
FOR EACH ROW
EXECUTE PROCEDURE notifyPhoneNumber();`); err != nil {
log.Println(err)
} else {
log.Println("Successfully create trigger inprogresschange")
}
} else {
log.Println("Trigger inprogresschange exists.")
}
//Create handler for logging listener errors
reportProblem := func(ev pq.ListenerEventType, err error) {
if err != nil {
fmt.Println(err.Error())
}
}
//Listen for table updates
var listenerObj *pq.Listener
listenerObj = pq.NewListener(os.Getenv("DATABASE_URL"), 10*time.Second, time.Minute, reportProblem)
err := listenerObj.Listen("notifyphonenumber")
if err != nil {
log.Println(err)
}
//Find our session PID so we can ignore notifications from ourselves
var pid int
fmt.Println("Getting session PID...")
if rows, err := db.Query(`SELECT *
FROM pg_stat_activity
WHERE pid = pg_backend_pid();`); err != nil {
log.Println(err)
} else {
var i interface{} //empty interface to read unneeded columns into
for rows.Next() {
if err := rows.Scan(&i, &i, &pid, &i, &i, &i, &i, &i, &i, &i, &i, &i, &i, &i, &i, &i, &i, &i); err != nil {
log.Println(err)
} else {
fmt.Println("Session PID:", pid)
}
}
}
//Monitor for noitification in background
go func() {
for {
var notificationObj *pq.Notification
notificationObj = <-listenerObj.Notify
fmt.Printf("Backend PID %v\nChannel %v\nPayload %v\n", notificationObj.BePid, notificationObj.Channel, notificationObj.Extra)
//Get updated row from database if the notifying PID is not this instance's PID
if pid != notificationObj.BePid {
if updatedRows := selectRowsFromTableByPhoneNumber("inprogress", notificationObj.Extra); updatedRows == nil {
log.Println(err)
} else {
//We handle the possibility of deleted rows in laod pickups rows into memory since we can only enumerate over rows object once
loadPickupRowsIntoMemory(&pickups, updatedRows, notificationObj)
}
}
}
}()
}