While my app is working - I need to check, that GPS-location is on.
I DO NOT need any complex things with statusChanged and other - just check a value of setting.
If that setting is off - I must stop execute current operation. I got one method, which called every time, when user execute operation. And I wanna place check rule there. So - it must be fast and cheap.
Is there any human way? Without keeping GPSWatcher ON all the time, and check his last status. I must care about battery.
Thanks.
You can use this:
Geolocator geolocator = new Geolocator();
if (geolocator.LocationStatus == PositionStatus.Disabled)
{
...
}
According to the documentation
var accessStatus = await Geolocator.RequestAccessAsync();
switch (accessStatus)
{
case GeolocationAccessStatus.Allowed:
break;
case GeolocationAccessStatus.Denied:
_
break;
case GeolocationAccessStatus.Unspecified:
break;
}
Related
I am using GJS, how do I get Clutter.Actor via its name. For example, if I wanted to get GNOME Shell's top panel, how do I get its Clutter.Actor via its name "panel"?
My research ended up somewhere along Clutter.Stage which is where Actor(s) can go be appended to, however by the way I see things, there can be multiple Stages setup so I might also have to find which Stage it is the Actor I am trying to find is at. For now I want to know how I can get an Actor via its name.
I have seen from a code; Main.layoutManager.panelBox to get the GNOME Shell's top panel, however that doesn't seem applicable to my case since it's a third party Actor I am trying to get, and the way I wish to get Actor(s) is via the name since I may be working with different third party Actor(s).
There is one way that I can get this that I know of; Main.layoutManager.panelBox.get_parent().get_children() and I can just get the specific Actor via its index, but I don't think this is the best way to approach this, considering how dynamic things are, secondly, I find this way kinda sloppy so..
I was able to get the name via Looking Glass (Alt + F2 -> lg -> picker). For now, the specific Actor I am trying to get is the DashtoDock's, just for info.
Thank you~ Hope someone can help.
Unfortunately, it seems like what you're looking for is a searchByName() function, but you'll have to implement that yourself I think. Something like (untested):
function searchByName(topActor, name) {
let children = topActor.get_children();
for (let i = 0; i < children.length; i++) {
if (child.name === name) {
return child;
} else if (child.get_n_children()) {
let result = searchByName(child, name);
if (result) {
return result;
}
}
}
return false;
};
Then call it on Main.layoutManager.uiGroup where Dash to Dock is
const Main = imports.ui.main;
let dashToDock = searchByName(Main.layoutManager.uiGroup, "dashtodockContainer");
In my frontend I have an input-field that sends an ajax request on every character typed in (using vue.js) to get realtime-filtering (can't use vue filter because of pagination).
Everything works smooth in my test environment, but could this lead to performance issues on (a bigger amount of) real data and if so, what can I do to prevent this?
Is it problematic?
Yes.
The client will send a lot of requests. Depending on the network connection and browser, this could lead to a perceptible feeling of lag by the client.
The server will receive a lot of requests, potentially leading to degraded performance for all clients, and extra usage of resources on the server side.
Responses to requests have a higher chance of arriving out of order. If you send requests very fast, it has increased chances of being apparent (e.g. displaying autocomplete for "ab" when the user has already typed "abc")
Overall, it's bad practice mostly because it's not necessary to do that many requests.
How to fix it?
As J. B. mentioned in his answer, debouncing is the way to go.
The debounce function (copied below) ensures that a certain function doesn't get called more than once every X milliseconds. Concretely, it allows you to send a request as soon as the user hasn't typed anything for, say, 200ms.
Here's a complete example (try typing text very fast in the input):
function debounce(func, wait, immediate) {
var timeout;
return function() {
var context = this, args = arguments;
var later = function() {
timeout = null;
if (!immediate) func.apply(context, args);
};
var callNow = immediate && !timeout;
clearTimeout(timeout);
timeout = setTimeout(later, wait);
if (callNow) func.apply(context, args);
};
}
var sendAjaxRequest = function(inputText) {
// do your ajax request here
console.log("sent via ajax: " + inputText);
};
var sendAjaxRequestDebounced = debounce(sendAjaxRequest, 200, false); // 200ms
var el = document.getElementById("my-input");
el.onkeyup = function(evt) {
// user pressed a key
console.log("typed: " + this.value)
sendAjaxRequestDebounced(this.value);
}
<input type="text" id="my-input">
For more details on how the debounce function works, see this question
I actually discuss this exact scenario in my Vue.js training course. In short, you may want to wait until a user clicks a button or something of that nature to trigger sending the request. Another approach to consider is to use the lazy modifier, which will delay the event until the change event is fired.
It's hard to know the correct approach without knowing more about the goals of the app. Still, the options listed above are two options to consider.
I hope this helps.
The mechanism I was searching for is called debouncing.
I used this approach in the application.
I am trying to execute "scan" command with RedisConnection. I don't understand why the following code is throwing NoSuchElementException
RedisConnection redisConnection = redisTemplate.getConnectionFactory().getConnection();
Cursor c = redisConnection.scan(scanOptions);
while (c.hasNext()) {
c.next();
}
Exception:
java.util.NoSuchElementException at
java.util.Collections$EmptyIterator.next(Collections.java:4189) at
org.springframework.data.redis.core.ScanCursor.moveNext(ScanCursor.java:215)
at
org.springframework.data.redis.core.ScanCursor.next(ScanCursor.java:202)
Yes, I have tried this, in 1.6.6.RELEASE spring-data-redis.version. No issues, the below simple while loop code is enough. And i have set count value to 100 (more the value) to save round trip time.
RedisConnection redisConnection = null;
try {
redisConnection = redisTemplate.getConnectionFactory().getConnection();
ScanOptions options = ScanOptions.scanOptions().match(workQKey).count(100).build();
Cursor c = redisConnection.scan(options);
while (c.hasNext()) {
logger.info(new String((byte[]) c.next()));
}
} finally {
redisConnection.close(); //Ensure closing this connection.
}
I'm using spring-data-redis 1.6.0-RELEASE and Jedis 2.7.2; I do think that the ScanCursor implementation is slightly flawed w/rgds to handling this case on this version - I've not checked previous versions though.
So: rather complicated to explain, but in the ScanOptions object there is a "count" field that needs to be set (default is 10). This field, contains an "intent" or "expected" results for this search. As explained (not really clearly, IMHO) here, you may change the value of count at each invocation, especially if no result has been returned. I understand this as "a work intent" so if you do not get anything back, maybe your "key space" is vast and the SCAN command has not worked "hard enough". Obviously, as long as you're getting results back, you do not need to increase this.
A "simple-but-dangerous" approach would be to have a very large count (e.g 1 million or more). This will make REDIS go away trying to search your vast key space to find "at least or near as much" as your large count. Don't forget - REDIS is single-threaded so you just killed your performance. Try this with a REDIS of 12M keys and you'll see that although SCAN may happily return results with a very high count value, it will absolutely do nothing more during the time of that search.
To the solution to your problem:
ScanOptions options = ScanOptions.scanOptions().match(pattern).count(countValue).build();
boolean done = false;
// the while-loop below makes sure that we'll get a valid cursor -
// by looking harder if we don't get a result initially
while (!done) {
try(Cursor c = redisConnection.scan(scanOptions)) {
while (c.hasNext()) {
c.next();
}
done = true; //we've made it here, lets go away
} catch (NoSuchElementException nse) {
System.out.println("Going for "+countValue+" was not hard enough. Trying harder");
options = ScanOptions.scanOptions().match(pattern).count(countValue*2).build();
}
}
Do note that the ScanCursor implementation of Spring Data REDIS will properly follow the SCAN instructions and loop correctly, as much as needed, to get to the end of the loop as per documentation. I've not found a way to change the scan options within the same cursor - so there may be a risk that if you get half-way through your results and get a NoSuchElementException, you'll start again (and essentially do some of the work twice).
Of course, better solutions are always welcome :)
My old code
ScanOptions.scanOptions().match("*" + query + "*").count(10).build();
Working code
ScanOptions.scanOptions().match("*" + query + "*").count(Integer.MAX_VALUE).build();
In SuperCollider: How do I downsample a control rate variable to a scalar value?
For instance, I have a scalar global called ~delay and a few functions care about that value. They assume it is a scalar. I wanted to set a envelope generator on that variable in order to change it via a control rate variable. Or use MouseX.kr, if I could convert a single value of MouseX.kr to a scalar value I would be happy.
Assume that I cannot refactor the code to allow for a k-rate global and thus I need to sample or downsample a single value from a control rate variable.
I can't do this:
MouseX.kr(1, 4, 1).rand.wait;
But I'd be happy with this:
downSample(MouseX.kr(1, 4, 1)).rand.wait;
Or
~mousex = MouseX.kr(1, 4, 1)
...
downSample(~mousex).rand.wait
This is the classic SuperCollider language-vs-server issue. You want to use MouseX (which represents the server's knowledge of mouse position) in a language-side calculation. ("Why the split? Why can't the language know it using the same object?" - well, imagine the two processes are running on different machines - different mice...)
To get the mouse position in the language, it's better to use one of:
Platform.getMouseCoords // SC up to 3.6
GUI.cursorPosition // SC recent versions
If you're sure you want to use server data in the language, then your own answer about sending via a Bus is one way to do it. Recent versions of SuperCollider have methods
Bus.getSynchronous
Bus.setSynchronous
which rely on the new "shared memory interface" between language and server. If the two are on the same machine, then this can be a nice way to do it which avoids the latency of asynchronously requesting the info.
After much research I came up with 1 solution: use a control Bus to grab values. We take a function as input (f) and then play it to a bus.
We then read from that bus by calling the get method on the bus and providing function that allows us to extract the value from the function thrown in.
~mkscalarfun = {
arg f={ 0 };
var last = 0.0;
var mbus = Bus.control(s, 1);
var pf = f.play(s,mbus);
var scalarf = {
mbus.get({|v| last = v;});
last;
};
scalarf; // This is a function
};
// Create a closure that includes the bus
~mousescalarf = ~mkscalarfun.({ MouseX.kr(1, 4, 1); });
~mousescalarf.();
~mousescalarf.().rand.wait;
I am not sure how idiomatic this solution or if it is appropriate or how well it performs.
One problem with this solution is that pf is hidden and thus you can't stop it.
One alternative is to use an OO solution where you make a class in your extension directory:
MakeScalarKR {
var last;
var mbus;
var pf;
var f;
*new { arg sbase,f;
^super.new.init(sbase,f)
}
init {
arg sbase,myf;
f = myf;
last = 0.0;
mbus = Bus.control(sbase, 1);
pf = f.play(sbase, mbus);
}
v {
mbus.get({|x| last=x;});
^last
}
free {
pf.free
}
}
Then you can invoke this class like so:
~mkr = MakeScalarKR(s,{ MouseX.kr(10,400,1) });
~mkr.v()
//Feedback Check
var generalFeedbackQuery = from feedbackElements in xml.Elements("feedback")
select new
{
Feedback = feedbackElements.Element("general").Value,
PostiveFeedback = feedbackElements.Element("positive").Value,
NegativeFeedback = feedbackElements.Element("negative").Value
};
Assert.AreEqual(actual.feedback, generalFeedbackQuery.ElementAt(0).Feedback);
Assert.AreEqual(actual.positiveFeedback, generalFeedbackQuery.ElementAt(0).PostiveFeedback);
Assert.AreEqual(actual.negativeFeedback, generalFeedbackQuery.ElementAt(0).NegativeFeedback);
Is it possible to check whether the query returned anything?
Like
if(generalFeedbackQuery.Count())....
This seems to work, but if you add a watch on the Count it doesn't seem to exist...
The best way of seeing whether or not anything was returned is to use Any(). That will stop and return true as soon as it gets any results, rather than looping through all of them.
(If you actually want the count, then Count() is indeed the right way to go. My guess is that the Watch window is confused by it being an extension method. You could explicitly call System.Linq.Enumerable.Count(generalFeedbackQuery) which may work.)