I'm extending an open-source AdvancedRobot in Robocode. That robot uses setFire to shoot, but never calls execute (doesn't appear in the code). I'm wondering how it's possible to still be able to shoot (it does). SetFire's doc says : This call returns immediately, and will not execute until you call execute() or take an action that executes.
I have no idea what "take an action that executes" mean.
Even better, what does "action" mean ?
My main goal was to do something every time a bullet is fired, so I have overridden the fire and fireBullet methods, but that doesn't work with the "set" methods (since it's possible to call it several times, ovveriding the previous order each time and shooting only when you "call execute() or take an action that executes"). So, maybe there is a way around.
Whatever, I'd be glad if anyone could help on any of those concerns.
Thank you very much.
This question sure is old, but for future reference:
Actions that execute are basically "stuff the robot can do that doesn't start with set", like fire or ahead, and so on. Calling any of these will also execute.
If you want to do something special every time a bullet is fired, you can use the following:
if (setFireBullet(someBulletPower) != null) {
// you only land here when a REAL bullet is fired,
// that is, when the gun heat was down.
}
Of course this only works if the open source bot you're extending is executing (it seems to be doing that, though I can't be sure if it is doing this every turn without knowing the code).
Related
I have a table in MSSQL database, and I have an ASPX page, I need to push all new rows to the page in a descending order. I found this awesome tutorial which is using SignalR and SqlDependency and it shows only the last row descarding the previous rows which have been added when I'm online, it does that because it has a span element to show data and every time it overwrites this span, so I modified the JavaScript code to append the new data and it works fine.
The problem now is when I refreshed the page for the first time, I'll get the new rows twice, and if I refreshed the page again I'll get the new rows triple .. and so on.
The only solution is to close the application and reopen it again, it looks like reset the IIS.
So, what can I do to avoid duplicating data in the online show?
It is not a SignalR issue, that happens because the mentioned tutorial has a series of mistakes, the most evident being the fact that it continuously creates SqlDependency instances but then it trashes them without never unsubscribing from the OnChange event. You should start by adding something like this:
SqlDependency dependency = sender as SqlDependency;
dependency.OnChange -= dependency_OnChange;
before calling SendNotifications inside your event handler. Check this for some inspiration.
UPDATE (previous answer not fully accurate but kept in place for context)
The main problem here is that this technique creates a sort of auto-regenerating infinite sequence of SqlDependencies from inside instances of Web Forms pages, which makes them unreachable as soon as you page has finished rendering. This means, once your page lifecycle is complete and the page is rendered, the chain of dependencies stays alive and keeps on working even if the page instance which created has finished its cycle. The event handler also keeps the page instance alive even if unreachable, causing a memory leak.
The only way you can control this is actually to generate these chains somewhere else, for example within a static type you can call passing some unique identifier (maybe a combination of page name and username? that depends on your logic). At the first call it will do what currently happens in your current code, but as soon as you do another call with the same parameters it will do nothing, hence the previously created chain will go on being the only one notifying, with no duplicate calls.
It's just a suggestion, there would be many possible solutions, but you need to understand the original problem and the fact that it is practically impossible to remove those chains of auto-regenerating dependencies if you don't find a way to keep track of them and create them only when necessary. I hope that part is clear.
PS: this behavior is very similar to what you get sometimes with event handlers getting leaked and keeping alive objects which should be killed, this is what fooled me with the previous answer. It is in a way a similar problem (leaked objects), but with a totally different cause. The tutorial you follow does not clarify that and brings you to this situation where phantom code keeps on executing and memory is lost.
I got it, although I don't like this way absolutely, I have declared a static member in the Global.asax file and in the Page_Load event I checked its value, if it was true don't run a new instance of SqlDependency, otherwise run it.
if (!Global.PageIsFired)
{
Global.PageIsFired = true;
SqlDependency.Stop(ConfigurationManager.ConnectionStrings["db"].ConnectionString);
SqlDependency.Start(ConfigurationManager.ConnectionStrings["db"].ConnectionString);
SendNotifications();
}
Dear #Wasp,
Your last update helped me a lot to understand the problem, so thank you so much for your time and prompt support.
Dear #dyatchenko,
Thanks a lot for your comments, it was very useful too.
I'm stepping through my code to figure out why a certain function takes more time to run the first time it gets called than on successive calls. The code flow for each function call is the same up to when a dispatchEvent gets called. I'm pretty sure it's different afterwards, as that call takes a lot more time the first time around. Unfortunately, I have no idea which other parts of the code chew on this specific event and thus cannot step through the handling of such event.
The question: is there a way to either figure out who handles such events or magically step through the handling code without explicitly setting breakpoints there?
thank you!
Not in an easy fashion, no. It's a pro and con of Flash (or any event based framework). You don't know when it's fired, where it's fired from (think bubbling), or who is listening for it. But at the same time, anyone could listen for any event, from anywhere (so long as it's within the display tree).
Normally what I do is just do a workspace search (ctrl+H in Flash Builder) and search for that specific event (you should be using static constants for dispatching/listening event types) and see who's doing what.
I'm trying to write a rule that delays firing until, at least, 15 minutes have passed since the last firing. However, the temporal operators in Drools Fusion only allow reasoning about two events in relation to each other and not one event in relation to the current time.
I would like something like this:
rule "some rule"
when
not LastFiredEvent(this before[0m, 15m] NOW)
…
I have resorted to writing a rule that fires every second and inserts a heartbeat event (also retracting the previous heartbeat), which I can use in other rules to serve as the current time.
I find this rather inelegant; am I missing something or does Drools Fusion really not have something for this?
NB. I am not looking for delayed firing of rules or rules that can only fire on multiples of 15 minutes; if nothing has happened in the last 17 minutes, the rule must fire immediately in response to a new event.
Although the concept of "NOW" might seem simple at first, it is not, as it is ambiguous and depends on the different semantics it can take based on the running environment. Drools Fusion does have a concept of "NOW" when you run it in STREAM mode, but it is different from what you are asking above. The explanation is a bit long to be done here, so lets focus on your problem.
First, you say: "I'm trying to write a rule that delays firing..." and then your say: "I am not looking for delayed firing of rules...", so I am confused about what you need.
If you want to delay the rule you can use the timer attribute:
rule X
timer( int: 15m )
...
If you want to fire a rule in case an event did or did not happen within an interval, you can use sliding windows. E.g.:
rule "Event did not happen in the last 15m"
when
not( SomeEvent() over time:window(15m) )
...
Hope that helps. And BTW, try posting your questions to the Drools mailing list as it will be easier for you to get an answer. I only saw your post because a friend pinged me about it.
Cheers,
Edson
On occasion, I have wanted to push a closure onto ActionScript's event stack so that it will be executed after the current event handler. Right now I use setTimeout(closure, 0). Is there a more direct way of doing this?
setTimeout(closure, 0) is creating a new event stack. I don't understand your objective if this solution isn't working for you. What is the goal you're trying to accomplish?
Flex has ENTER_FRAME events, Timer, callLater, setTimeout, setInterval, all which delay calls and create new execution stacks.
Are you trying to inject code into the current stack? If so, you might need to look at something like this: http://en.wikipedia.org/wiki/Active_object. The idea being that you push functions (closures) into an array, and the active object controller pulls the next one off the list when the previous one has run to completion. That's the simplest case. You can write a more complicated one that will have priority stacks like high, medium, low, with your own schedule management system. (e.g., low get promoted after waiting too long).
But hey! The devil is in the details. What's the goal?
Take a look at capture and bubbling phases of the as3 events.
I found this nice chapter that explains clearly the proccess: http://books.google.com/books?id=yFNZGjqJe9IC&lpg=PA250&ots=oPB9HXIby7&dq=flash%20event%20bubbling%20phase&pg=PA250#v=onepage&q=&f=false
And also check the EventDispatcher class documentation that explain the use of this different phases.
I guess it's quite a common problem in databinding scenarios.
What do you usually do, if you are running a batch update and want to avoid that a propertychanged-dependend calculations/actions/whatever are executed for every single update?
The first thing which usually comes to my mind, is to either introduces a new boolean or unhook/hook the eventhandler, ...
What I don't like about this approaches is:
they introduce new complexity (has to be maintained, ...)
they are error prone, because you have to make sure that a suppressed notifications are sent afterwards
I'm wondering if somebody addressed this problem already in a more convenient way that is more easy to handle?
tia
Martin
Edit: not to missunderstand me. I know about the things .NET provides like RaiseListChangedEvents from BindingList, ... They are all addressing the problem in more/less the same way as I described, but I'm searching for a different way which doesn't have to listed drawbacks.
Maybe I'm on the wrong track, but I though I give it a try here...
There isn't a single one-size-fits-all solution, unfortunately. I've applied or seen the following solutions:
There are two singals. One signal is emitted when the change comes from a user action, the other always fires. This allows to distinguish between changes in the UI and updates by code.
A boolean to protect code
The property event framework stops propagating events automatically when a value didn't really change.
A freeze/thaw method on the signal or the signal manager (i.e. the whole framework)
A way to merge signals into a single one. You can do N updates and they get collected into M signals where M <= N. If you change the same property 100 times, you still only get 1 signal.
Queuing of signals (instead of synchronous execution). The queuing code can then merge signals, too. I've used this with great success in an application that doesn't have a "Save" button. All changes are saved to the database as you make them. When you change a text, the changes are merged over a certain time (namely until the previous DB update returns) and then, they are committed as a single change.
An API to set several values at once; only a single signal is emitted.
The signal framework can send signals at different levels of granularity. Say you have a person with a name. When you change the name, you get two signals: One for the name change and one "instance field changed". So if you only care "has something changed", then you can hook into the instance instead of all the fields.
What platform? The post makes me think .NET.
What is the underlying objects? For example, BindingList<T> as a source allows you to disable notifications by setting RaiseListChangedEvents to false while doing the update.
Other than that (or similar); yes, disconnect the binding during big updates
The easiest route to take is to use the BindingSource component for your data binding. Instead of binding your controls to a particular object (or IList), use that object as the DataSource for the BindingSource, then bind the controls to the BindingSource.
The BindingSource class has SuspendBinding() and ResumeBinding() functions.