I have a situation in my application where based on the different notifications I have to put a semaphore. Thing is that if I get type 1 notification, the semaphore should get by different portion of code.
Example:
void funcNotify(int notify)
{
switch(notify)
{
case type1:
Rtos_SemaphorePut(nitificationSemaphore, 1)
break;
case type2:
Rtos_SemaphorePut(nitificationSemaphore, 1)
break;
case type3:
Rtos_SemaphorePut(nitificationSemaphore, 1)
break;
default:
break;
}
}
So my question is can we create a semaphore which can be used for multiple notifications? And based on what type of notification I get, I will execute the required code for that.
The freeRTOS event_groups gave me the solution for this issue. I could set individual bits for each notification. Thanks.
Related
So basically, I am trying to get the switch statement to only execute one time. And not execute all of them.
Assume the player has all of the keys in their inventory.
I want only one case to execute and not go through all the cases.
(I'd like to only see one execute)
public int[] allKeys = {1543, 1544, 1545, 1546, 1547, 1548};
if (player.getInventory().containsAny(allKeys)) {
for (int id : allKeys) {
switch(id) {
case 1543:
System.out.println("executed");
break;
case 1544:
System.out.println("executed");
break;
case 1545:
System.out.println("executed");
break;
case 1546:
System.out.println("executed");
break;
case 1547:
System.out.println("executed");
break;
case 1548:
System.out.println("executed");
break;
default:
System.out.println("error!");
}
}
}
Your switch does only do "one at a time" - it is the fact your switch is in a for loop that is causing you problems...
You could put a "break" after the switch switch(x) { ... } break;, but really why loop when you don't want to - just switch on say the first key.
You are currently running the switch case inside the for loop that goes through every id's inside the array allKeys. Because you assumed the user to have allKeys, I would just remove the for loop, and pick whatever key you want the user to execute, and let that key go through the switch statement.
Here's my problem : I'm doing a background work, where I parse some JSON and write some Objects into my Realm, and in the main thread I try to update the UI (reloading the TableView, it's linked to an array of Object). But when I reload the UI, my tableView doesn't update, like my Realm wasn't updated. I have the reload my View to see the updates. Here's my code :
if (Realm().objects(Objects).filter("...").count > 0)
{
var results = Realm().objects(Objects) // I get the existing objects but it's empty
tableView.reloadData()
}
request(.GET, url).responseJSON() {
(request, response, data, error) in
let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
dispatch_async(dispatch_get_global_queue(priority, 0)) {
// Parsing my JSON
Realm().write {
Realm().add(object)
}
dispatch_sync(dispatch_get_main_queue()) {
// Updating the UI
if (Realm().objects(Objects).filter("...").count > 0)
{
results = Realm().objects(Objects) // I get the existing objects but it's empty
tableView.reloadData()
}
}
}
}
I have to do something bad with my threads, but I couldn't find what. Can someone know what's wrong?
Thank you for your answer!
such workflow makes more sense to me for your case:
let priority = DISPATCH_QUEUE_PRIORITY_DEFAULT
dispatch_async(dispatch_get_global_queue(priority, 0)) {
// Parsing my JSON
Realm().write {
Realm().add(object)
dispatch_sync(dispatch_get_main_queue()) {
// Updating the UI
if (Realm().objects(Objects).filter("...").count > 0)
{
results = Realm().objects(Objects) // I get the existing objects but it's empty
tableView.reloadData()
}
}
}
}
NOTE: you have a problem with timing in your original workflow: the UI might be updated before the write's block executed, that is why your UI looks abandoned; this idea above would be a more synchronised way between tasks, according their performance's schedule.
You are getting some new objects and storing them into "results".
How is tableView.reloadData () supposed to access that variable? You must change something that your tableView delegate will access.
PS. Every dispatch_sync () is a potential deadlock. You are using one that is absolutely pointless. Avoid dispatch_sync unless you have a very, very good reason to use it.
I'm trying to make my MVC4-website check to see if people should be alerted with an email because they haven't done something.
I'm having a hard time figuring out how to approach this. I checked if the shared hosting platform would allow me to activate some sort of cronjob, but this is not available.
So now my idea is to perform this check on each page-request, which already seems suboptimal (because of the overhead). But I thought that with using an async it would not be in the way of people just visiting the site.
I first tried to do this in the Application_BeginRequest method in Global.asax, but then it gets called multiple times per page-request, so that didn't work.
Next I found that I can make a Global Filter which executes on OnResultExecuted, which would seemed promising, but still it's no go.
The problem I get there is that I'm using MVCMailer to send the mails, and when I execute it I get the error: {"Value cannot be null.\r\nParameter name: httpContext"}
This probably means that mailer needs the context.
The code I now have in my global filter is the following:
public override void OnResultExecuted(ResultExecutedContext filterContext)
{
base.OnResultExecuted(filterContext);
HandleEmptyProfileAlerts();
}
private void HandleEmptyProfileAlerts()
{
new Thread(() =>
{
bool active = false;
new UserMailer().AlertFirst("bla#bla.com").Send();
DB db = new DB();
DateTime CutoffDate = DateTime.Now.AddDays(-5);
var ProfilesToAlert = db.UserProfiles.Where(x => x.CreatedOn < CutoffDate && !x.ProfileActive && x.AlertsSent.Where(y => y.AlertType == "First").Count() == 0).ToList();
foreach (UserProfile up in ProfilesToAlert)
{
if (active)
{
new UserMailer().AlertFirst(up.UserName).Send();
up.AlertsSent.Add(new UserAlert { AlertType = "First", DateSent = DateTime.Now, UserProfileID = up.UserId });
}
else
System.Diagnostics.Debug.WriteLine(up.UserName);
}
db.SaveChanges();
}).Start();
}
So my question is, am I going about this the right way, and if so, how can I make sure that MVCMailer gets the right context?
The usual way to do this kind of thing is to have a single background thread that periodically does the checks you're interested in.
You would start the thread from Application_Start(). It's common to use a database to queue and store work items, although it can also be done in memory if it's better for your app.
Ok, I'm working on my final dilemna for my project. The project is an IPv4 endpoint updater for TunnelBroker's IPv6 tunnel. I have everything working, except for the timer. It works, however if the user disables the "automatic update" and reenables it, the application crashes. I need the timer to be on an thread outside of the EDT (in such a way that it can be destroyed and recreated when the user unchecks/checks the automatic update feature or changes the amount of time between updates).
What I'm pasting here is the code for the checkbox that handles automatic updates, and the timer class. Hopefully this will be enough to get an answer on how to do this (I'm thinking either it needs to be a worker, or use multi-threading--even though only one timer will be active).
private void jCheckBox1ItemStateChanged(java.awt.event.ItemEvent evt) {
// TODO add your handling code here:
// if selected, then run timer for auto update
// set time textbox to setEditable(true) and get the time from it.
// else cancel timer. Try doing this on different
// class to prevent errors from happening on reselect.
int updateAutoTime = 0;
if (jCheckBox1.isSelected())
{
updateAutoTime = Integer.parseInt(jTextField4.getText())*60*1000;
if (updateAutoTime < 3600000)
{
updateAutoTime = 3600000;
jTextField4.setText(new Integer(updateAutoTime/60/1000).toString());
}
updateTimer.scheduleAtFixedRate(new TimerTask() {
public void run()
{
// Task here ...
if (jRadioButton1.isSelected())
{
newIPAddress = GetIP.getIPAddress();
}
else
{
newIPAddress = jTextField3.getText();
}
strUsername = jTextField1.getText();
jPasswordField1.selectAll();
strPassword = jPasswordField1.getSelectedText().toString();
strTunnelID = jTextField2.getText();
strIPAddress = newIPAddress;
if (!newIPAddress.equals(oldIPAddress))
{
//fire the tunnelbroker updater class
updateIP.setIPAddress(strUsername, strPassword, strTunnelID, strIPAddress);
oldIPAddress = newIPAddress;
jLabel8.setText(newIPAddress);
serverStatus = updateIP.getStatus().toString();
jLabel6.setText(serverStatus);
}
else
{
serverStatus = "No IP Update was needed.";
jLabel6.setText(serverStatus);
}
}
}, 0, updateAutoTime);
}
else
{
updateTimer.cancel();
System.out.println("Timer cancelled");
System.out.println("Purged {updateTimer.purge()} tasks.");
}
}
As I mentioned, this works once. But if the user deselects the checkbox, it won't work again. And the user can't change the value in jTextField4 after they select the checkbox.
So, what I'm looking for is this:
How to make this so that user can select and deselect the checkbox as they want (even if it's multiple times in a row).
How to make this so the user can change the value in jTextField4, and have it automatically cancel the current timer, and start a new one with the new value (I haven't done anything with the jTextField4 at all, so I'll have to create an event to cover it later).
Thanks, and have a great day:)
Patrick.
Perhaps this task would be better suited to a javax.swing.Timer. See Timer.restart() for details.
Note that Timer is relatively inaccurate over long time periods. One way to account for that is to have it repeat frequently but perform it's assigned task only one a certain time has been reached or passed.
Would I be able to wrap everything in the "task" portion of the call to Swing Timer, or do I have to create another class that handles the task?
You might want to wrap the grunt work in a SwingWorker to ensure the EDT is not blocked.
..I'm assuming that I would have to create the timer as a class-level declaration .. correct?
Yes, that is what I was thinking.
I have already added 5 cammands in a form and I want to add a sixth but It does not display the sixth?
I am posting my codes below.
public Command getOk_Lastjourney() {
if (Ok_Lastjourney == null) {
// write pre-init user code here
Ok_Lastjourney = new Command("Last Journey", Command.OK, 0);
// write post-init user code here
}
return Ok_Lastjourney;
}
public Form getFrm_planjourney() {
if (frm_planjourney == null) {
// write pre-init user code here
frm_planjourney = new Form("Plan journey", new Item[] { getTxt_From(), getTxt_To(), getCg_usertype(), getCg_userpref(), getCg_searchalgo() });
frm_planjourney.addCommand(getExt_planjourney());
frm_planjourney.addCommand(getOk_planjourney());
frm_planjourney.addCommand(getOk_planFare());
frm_planjourney.addCommand(getOk_planDistance());
frm_planjourney.addCommand(getOk_planTime());
frm_planjourney.addCommand(getOk_planRoute());
frm_planjourney.setCommandListener(this);
// write post-init user code here
System.out.println("Appending.....");
System.out.println("Append completed...");
System.out.println(frm_planjourney.size());
frm_planjourney.setItemStateListener(this);
}
return frm_planjourney;
}
Given System.out.println I assume you were debugging with emulator, right? in that case it would be really helpful to provide a screen shot showing how exactly does not display the sixth looks like.
Most likely you just got too many commands to fit to area allocated so that some of them are not shown until scrolled. There is also a chance that sixth command was reassigned to some other soft-button and you didn't notice that. Or there's something else - hard to tell with details you provided.
A general note - handling six actions with commands might be not the best choice in MIDP UI. For stuff like that, consider using lcdui List API instead. IMPLICIT kind of lists allow for more reliable and user friendly design than commands.