I want to paste a background loop into my Python-Kivy script. The problem is, that I've got only a App().run() under my script. So, if I put a loop, somewhere in the the App-Class, the whole App stopps updating and checking for events. Is there a function name like build(self), that's recognized by Kivy, and represents a main/background-loop?
If you don't know, what I'm talking about, feel free to ask.
In case you need to schedule a repeated activity in a loop, you can use Clock.schedule_interval() to call a function on a regular schedule:
def my_repeated_function(data):
print ("My function called.")
Clock.schedule_interval(my_repeated_function, 1.0 / 30) # no brackets on function reference
# call it 30 times per second
There is a lot more information on how to schedule events on a regular, conditional or one-time basis with Kivy's event loop here.
Related
I'd like to use traceview to measure performance for several asynchronous events. The asynchronous events are passed to me in a callback that looks similar to the below code.
interface EventCallback {
void onStartEvent(String name);
void onStopEvent(String name);
}
where every asynchronous event will start with a "onStartEvent" call and end with an "onStopEvent" call.
I'd like to create trace files for every event. From my reading here (http://developer.android.com/tools/debugging/debugging-tracing.html#creatingtracefiles), it's not possible to trace asynchronous events since the ordering of the calls must be "structured" in a "stack" like ordering. So, the call to "Debug.stopMethodTracing()" always applies to the most recent call to "Debug.startMethodTracing("calc");"
So, if I receive callbacks in the following order.
onStartEvent(A)
onStartEvent(B)
onStopEvent(A)
onStopEvent(B)
which will get interpreted to
Debug.startMethodTracing("A");
Debug.startMethodTracing("B");
Debug.stopMethodTracing(); // will apply to "B" instead of "A"
Debug.stopMethodTracing(); // will apply to "A" instead of "B"
Using traceview, is there anyway to do what I want? i.e. trace "non-structured" asynchronous events?
traceview might be the wrong tool. If you really want to go this route you can keep an "active event count", and keep the tracefile open so long as there is an event being handled. This can result in multiple events being present in the same trace file, but you're tracing method calls in the VM, so there's no simple way around that.
If your events happen on different threads, you could separate them out with a post-processing step. This would require some effort to parse the data and strip out the undesirable records. (See e.g. this or this.)
You don't really say what you're trying to measure. For example, if you just want start/end times, you could just write those to a log file of your own and skip all the traceview fun.
Depending on what you're after, systrace may be easier to work with. Unfortunately the custom event class (Trace) only makes the synchronous event APIs public -- if you don't mind using reflection to access non-public interfaces you can also generate async events.
I’m writing the error/failures of my steps to a file with this function:
def addToErrorFile(errorName)
open('error.txt', 'a') { |f| f.puts"#{errorName}"}
end
This function is located in a lot of places in my test flow.
To make it easier to read it in the end, I would like to add the step name (Then /I go to…) and also the scenario (Scenario: login to..).
Is there a way to copy those into the function?
You could put some code in your before and after scenario hooks that writes to the error log. That should break it up a bit and make it easier to read. Something like this.
Before do |scenario|
your_logging_method(scenario.name)
end
After do |scenario|
your_logging_method(scenario.name)
end
And there is an AfterStep hook too, though I haven't used it.
AfterStep do |step|
another_logging_method(step)
end
You may have to call some methods on the step variable to get it in a useful format.
Here's a link to the cucumber hooks documentatioon - https://github.com/cucumber/cucumber/wiki/Hooks
it wouldn't be better to use ruby (begin rescue ensure ) and put the code in there. You save your test session and you can progress your test to next steps, where you can put line of code to save name of next step to file
I have problem, as you can see I want to delete all objects in corona. I'm looking for one function that will remove all of them.
I can't find it, I'm not sure if it's even possible.
I'd like it to work like this:
Display all objects
Wait for event
When you touch, then remove all objects from 1 and go back to it.
Possible or not?
I'm not aware of one function that does that. But what you can do is every time you create an object you put it in a table. Then when you want to remove them all you iterate over the table and call removeSelf on each. After the loop, you reset the table. See my answer to remove all spawned coins.
I will start this by saying that on iOS this algorithm takes, on average, <2 seconds to complete and given a simpler, more specific input that is the same between how I test it on iOS vs. Android it takes 0.09 seconds and 2.5 seconds respectively, and the Android version simply quits on me, no idea if that would be significantly longer. (The test data gives the sorting algorithm a relatively simple task)
More specifically, I have a HashMap (Using an NSMutableDictionary on iOS) that maps a unique key(Its a string of only integers called its course. For example: "12345") used to get specific sections under a course title. The hash map knows what course a specific section falls under because each section has a value "Course". Once they are retrieved these section objects are compared, to see if they can fit into a schedule together based on user input and their "timeBegin", "timeEnd", and "days" values.
For Example: If I asked for schedules with only the Course ABC1234(There are 50 different time slots or "sections" under that course title) and DEF5678(50 sections) it will iterate through the Hashmap to find every section that falls under those two courses. Then it will sort them into schedules of two classes each(one ABC1234 and one DEF5678) If no two courses have a conflict then a total of 2500(50*50) schedules are possible.
These "schedules" (Stored in ArrayLists since the number of user inputs varies from 1-8 and possible number of results varies from 1-100,000. The group of all schedules is a double ArrayList that looks like this ArrayList>. On iOS I use NSMutableArray) are then fed into the intent that is the next Activity. This Activity (Fragment techincally?) will be a pager that allows the user to scroll through the different combinations.
I copied the method of search and sort exactly as it is in iOS(This may not be the right thing to do since the languages and data structures may be fundamentally different) and it works correctly with small output but when it gets too large it can't handle it.
So is multithreading the answer? Should I use something other than a HashMap? Something other than ArrayLists? I only assume multithreading because the errors indicate that too much is being done on the main thread. I've also read that there is a limit to the size of data passed using Intents but I have no idea.
If I was unclear on anything feel free to ask for clarification. Also, I've been doing Android for ~2 weeks so I may completely off track but hopefully not, this is a fully functional and complete app in the iTunes Store already so I don't think I'm that far off. Thanks!
1) I think you should go with AsynTask of Android .The way it handle the View into `UI
threadandBackground threadfor operations (Like Sorting` ) is sufficient enough to help
you to get the Data Processed into Background thread And on Processing you can get the
Content on UI Thread.
Follow This ShorHand Example for This:
Example to Use Asyntask
2) Example(How to Proceed):
a) define your view into onPreExecute()
b) Do your Background Operation into doInBackground()
c) Get the Result into onPostExceute() and call the content for New Activty
Hope this could help...
I think it's better for you to use TreeMap instead of HashMap, which sorts data automatically everytime you mutate it. Therefore you won't have to sort your data before start another activity, you just pass it and that's all.
Also for using it you have to implement Comparable interface in your class which represents value of Map.
You can also read about TreeMap class there:
http://docs.oracle.com/javase/7/docs/api/java/util/TreeMap.html
I am not fully understanding what the synchronization block is doing nor why it is necessary.
Can someone explain in a "synchronizing for dummies" kind of way?
In a book I am reading, the author tells me "The synchronization is necessary, since the members we manipulate within the
synchronized block could be manipulated in the onPause() method on the UI thread."
He creates an Object named stateChanged and instantiates it as a new object.
Then, in the synchronization block he uses the stateChanged object as the argument.
This whole thing is throwing me off and I do not like to move on until I have a pretty good understanding of what is going on.
The classic example is: Imagine you have two threads of operation, and both of them reference the same method:
public void addToGlobalVar(int y) {
int x = globalVar; //what if a thread stops right after this line?
x += y;
globalVar = y;
}
where globalVar is some other predefined number that this method can interact with and set. Lets say globalVar is 50.
Threads get computing time on a somewhat arbitrary basis, so you never fully know the precise nanosecond one stops and the other gets CPU time.
In this example, if you launched an AsyncTask in addition to the UI thread, and both at some point use addToGlobalVar(10), what can happen is that one thread might be interrupted at line 2 of that code block. If the other thread goes through while that one is sleeping, it will successfully set globalVar to 60. But when the other one wakes up, it still thinks x = 50, and its going to then set it to 60. So in essence you just made 50+10+10 = 60. Hopefully you can see how this becomes a problem.
You can fix this simple example by making the calculation atomic (skip declaring x, 1 line, all calcs done) or if the logic wasn't able to be condensed to 1 line, you make a block of code atomic by using synchronized.
The book to read is Java Concurrency in Practice.
You should really just segregate this idea from Android, although your code is going to be running on Dalvik this is a Java concept. Not an Android one.
The synchronized block takes an object as a parameter, any object, and when flow enters the body of the synchronized block, any other thread that runs in to a synchronized block with the same instance (object) as the parameter has to wait for the previous one to complete. That's a very basic description.
This is an entire sub-field of computer science and without serious study you will probably not understand it.
You have to fully understand it before you use it. It is standard android synchronization using object-oriented monitors. You have to understand it to write multi-threaded programs, however it is somehow dated (better use java.util.concurrent for anything thread/synchronisation related instead).
Anyhow - you need to know what it is about - read the related java tutorial part:
http://download.oracle.com/javase/tutorial/essential/concurrency/sync.html