If I start transition on element by adding a class, can I somehow figure out if it finished or do I need to measure time separately?
Or even better, can I get current intermediate values?
Related
After noticing that my problem is not a database specific problem, but an UI problem I'm creating this new question here.
I have a SearchBar (source) that is used to filter a dataset from a realm database. This works so far well and fast. But when I want to display the result in a list it's pretty slow.
I've tried different approaches to display the elements. I thought the LazyVGrid could be a good solution for this use case since it doesn't create the view for each element but only when I scroll down and need to display them.
ScrollView {
LazyVGrid{
ForEach(...)
}
}
But this approach was veeeery slow and sometimes my app crashed.
So I switched to the classic approach with List{ ForEach(...){ } }.id(UUID()) that is my current solution. The performance is okay. ~2-3 second for 15.000 elements. Additionally my CPU and memory is increasing extremely for the 2-3 seconds. I'm not using any animations or other stuff. For testing I just used a single line text to represent each element.
I'm looking more for a solution like: Display the first n results immediately. And when I scroll down and really need the other results the view for each element should be created only then.
We are implementing support for tracking of Mailgun events in our application. We reviewed the proposed event polling algorithm but find ourselves not quite comfortable with it. First, we would prefer not to discard the data that we have already fetched and then retry from scratch after a pause. It is not very efficient and leaves a door open for a long loop of retries, as it is not clear when the loop is supposed to end. Second, the "threshold age" seems to be the key to determine "trustworthiness", but its value is not defined, only a very large "half an hour" is suggested.
It is our understanding that the events become "trustworthy" after some threshold delay, let us call it D_max, when the events are guaranteed to reside in the event storage. If so, we can implement this algorithm in a different way, so that we do not fetch the data that we know are not "trustworthy" and make use of all data which have been fetched.
We would be fetching data periodically, and on each iteration we would:
Make a request to the events API specifying an ascending time range from T_1 to T_2 = now() - D_max. For the first iteration, T_1 can be set to some time in the past, "e.g., half an hour ago". For the subsequent iterations, T_1 is set to the value of T_2 from the previous iteration.
Fetch all pages one by one while the next page URL is returned.
Use all fetched events, as they are all "trustworthy".
My questions are:
Q1: Are there any problems with this approach?
Q2: What is the minimum realistic value of D_max? Obviously, we can use "half an hour" for it, but we would like to be more agile in tracking events, so it would be great to know what is the minimum value we can set it to and still reliably fetch all events.
Thanks!
1: I see no problems with this solution (in fact I'm doing something very similar). I'm also storing ID's of the events to validate I'm not inserting duplicate entries.
2: I've been working through this similar process. Right now I am testing with D_max at 10 minutes.
Additionally, While going through a testing process I'm running an additional task nightly that goes back over the entire day to validate a few things:
Am I missing existing metrics?
Diagnose if there is a problem with the assumptions I've made about D_max.
How do I run a second batch on a HIT but ensure I have a new set of workers? I want to make a small change to the HIT and start a new batch, but I don't want any of the workers who participated in the first batch to participate in the second.
Your best bet is to add assignments to your existing HITs (you can do this easily through the RUI), which will exclude workers who have already done those HITs.
But, before you do that, you'll need to change the HITs, which is more difficult (but relatively easy through the API using a ChangeHITTypeOfHIT operation for title/description/duration/qualification changes). If you need to change the Question parameter of a HIT (the actual displayed content of the HIT) or the amount it pays (reward), then you need to create new HITs and send them out as a new batch.
To prevent workers from redoing the HITs you can either put a qualification on the HIT and assign all of your current workers to a score below that level.
Or, you can put a note on the HIT saying that duplicate work will be unpaid. If you do this, you should include a link on the HIT that takes workers to a list of past workerids so that they can check whether they've already done the task.
Update 2018:
You don't need to modify the content of the HIT anymore.
Instead, you assign a qualification to the previous participants in a csv sheet.
Then, in the new HIT, you set as requirement that this qualification "has not been granted".
Detailed explanation at the bottom here and step-by-step procedure describe in this pdf.
I was implemnting some functionaliy in which i get a set of queries on database One shouldnt loose the query for a certain time lets say some 5min unless and untill the query is executed fine (this is incase the DB is down, we dont loose the query). so, what i was thinking to do is to set a sort of timer for each query through a different thread and wait on it for that time frame, and at the end if it still exists, remove it from the queue, but, i am not happy with this solution as i have to create as many threads as the number of queries. is there a better way to design this (environment is vc++), If the question is unclear, please let me know, i will try to frame it better.
One thread is enough to check lets say every 10 seconds that you do not have queries in that queue of yours whose due time has been reached and so should be aborted / rolled back.
Queues are usually grown from one end and erased from other end so you have to check only if the query on the end where the oldest items are has not reached its due time.
What is the choise better than QListWidget to display a lot of log lines in GUI that are coming from backend at average speed 40 lines per second?
QListWidget gives a flickering and even white box instead of a widget for a long time when a lot of strings are already placed into ListWidget.
Is there any better solution to dynamically display log lines to a user?
update:
Changed architecture. Adding new QStrings to std::deque< QString* >. Using QTimer i add that strings every 1/10 of second to QPlainTextEdit, deleting from deque. boost::mutex is used to protect std::deque (log lines are coming from different threads).
Would be nice to have a time to implement my own QListView and keep strings in big chunks of pre-allocated memory.
Are you sure you need the functionalities of a QListWidget? If you just want to display log lines, I think a simple read-only QPlainTextEdit would be more appropriate.
You might try to use QListView and you own implementation of QAbstractItemModel. Then you can store your lines as you wish and append new lines in big groups (about every second should be ok). Then view is not refreshed at adding every line but only in groups, which should highly improve performace.
I would suggest setting a refresh rate and append all gathered items at once. You will avoid repaint of widget every line you append.
Long story short:
QTimer with refresh rate (~1-3 seconds would be enough), QListWidget::addItems instead of QListWidget::addItem