Code:
var sc = new TestScheduler();
Observable.Timer(TimeSpan.FromSeconds(5), sc)
.ToTask()
.ToObservable()
.Do(_ => Console.WriteLine("on next: " + Thread.CurrentThread.ManagedThreadId),
() => Console.WriteLine("on complete: " + Thread.CurrentThread.ManagedThreadId))
.Subscribe();
Console.WriteLine("call: " + Thread.CurrentThread.ManagedThreadId);
sc.AdvanceBy(TimeSpan.FromSeconds(5).Ticks);
Output:
call: 11
on next: 8
on complete: 8
If you remove both ToTask and ToObservable then everything will execute on the same thread. It seems to me that TPL schedules OnCompleted to Task Pool somehow, but I can't find it in the source code.
Can anybody help me understand what is going on here?
DotNetFiddle link: https://dotnetfiddle.net/epqTAG
Task.ToObservable() uses Task.ContinueWith() to add a Task continuation to trigger the observable when the task completes. By default, Task.ContinueWith() schedules the continuation on the task pool.
Rx.Net recently added an overload of ToObservable that accepts an IScheduler.
See the the Rx.Net github issue for more details.
Related
Every time a Protractor element locator fails, it prints an error and continues down a horrible path of endless cascading failures in my spec and suite. Every test that follows depends on the element locator finding its element, and depends on the current spec passing.
I would like to keep the web page under test open while I use the console. The goal is to debug the current state of the page and investigate why the element locator may have failed to find its target.
I'm not too concerned about failing the entire suite and exiting on the first spec failure (I've seen other answers on --fail-fast and stopping on first spec failure.) This is not the approach I would like to take. I want to set a breakpoint, and inspect the environment while the page is running.
Maybe there's something like a Jasmine option for doThisOnFailure: () => { debugger }, which would work for me I think.
I really do not like the solution of using a spec reporter to execute during afterEach and check the failed spec count on the Jasmine environment for the entire spec function. I want to immediately know when an element locator has failed and immediately break as soon as it has failed.
Maybe something really gross would work $('element').click().catch(() => { debugger }).
EDIT: Please, note that I am asking about breaking in a spec, not breaking at the end of the spec.
it('should execute deadly code', function () {
p.navigation.openStorageConfigTab()
$$('.bad-selector').get(0).click() /* IMPORTANT: I want to break here */
p.volume.navigateTo()
})
it('should not execute this spec', function () {
$$('.bad-selector').get(0).click()
})
And the output
✗ should execute deadly code
- Failed: Index out of bound. Trying to access element at index: 0, but there are only 0 elements that match locator By(css selector, .bad-selector)
✗ should not execute this spec
- Failed: Index out of bound. Trying to access element at index: 0, but there are only 0 elements that match locator By(css selector, .bad-selector)
I can recommend you the approach I use, and I hope you can take it from here
Overall approach is to wait until until you type close/ command in browser url:
await browser.waitForAngularEnabled(false);
await browser.wait(
async () => {
let url = await browser.getCurrentUrl();
return url.includes('close/');
},
5 * 60 * 1000,
'Keep-alive timeout reached, closing the session...'
);
The question is when you want to call it. I use the advantage of onComplete callback function in config file. When it's called, the browser is still available. So once all tests are completed, it doesn't exit for 5 minutes unless I submit close/ to the url field. Obviously that can be conditional, by adding something like if (DEBUG === true)
A downside of this setup is it's called when all tests are completed, and it's possible your spec has navigated away from the page where there was error. So what you can also do is to use advantage of jasmine reporter (if you use jasmine). Roughly, you just need to add this to your onPrepare func:
jasmine.getEnv().addReporter({
jasmineStarted: function(suiteInfo) {},
suiteStarted: function(result) {},
specStarted: function(result) {},
specDone: async function(spec) {
if (spec.status === 'failed') {
await browser.waitForAngularEnabled(false);
await browser.wait(
async () => {
let url = await browser.getCurrentUrl();
return url.includes('close/');
},
5 * 60 * 1000,
'Keep-alive timeout reached, closing the session...'
);
await browser.close();
process.exit(35);
}
},
suiteDone: function(result) {},
jasmineDone: function(result) {},
});
So if any it block has failed status, then it'll stop. BUT, I have not tested it, I'll leave it up to you. And second, I didn't think about what will happen to the rest of queued specs since you're redirected to non existing url close/, but I believe it'll still work for you. Worst case scenario, you can play around and make it continue or close the browser instance, as long as you understood the concept
P.S.
I modified the code to close the browser when you type close/, by adding
await browser.close();
process.exit(35);
I tested this code with the following scenarios:
happy path: all 5 it are successful
first element finder of second it block fails
second element finder of second it block fails
All passed. The code works as expected
I've built a Xamarin.Forms app that is using a DLL from a tierce app to send kind of SQL command (this is not SQL !)
Probleme is that it only provides synchronous methods and my app is then "not responding". How can I do an asynchronous method that will call the sycnhronous one and wait for its result without hanging the UI ?
I tried the following but it seems to be waitng forever like if thread was never stopping.
public async Task<ExecuteCommandResult> ExecuteMocaCommandAsync(String ps_command)
{
return await Task<ExecuteCommandResult>.Run(() =>
{
return ExecuteMocaCommand(ps_command);
}
);
}
and I'm calling it like this :
ExecuteCommandResult l_res = l_con.ExecuteMocaCommandAsync("list users where usr_id = '" + gs_UserName + "'").Result;
I'm clearly missing something and hope you can point me in the good direction.
Regards,
Yoz
The Task.Run looks good (though you can simplify it by changing Task<ExecuteCommandResult>.Run to just Task.Run). That's the proper way to push blocking work to a background thread in a UI application.
However, you can't use Result; that can deadlock. You'll need to call your method using await:
ExecuteCommandResult l_res = await l_con.ExecuteMocaCommandAsync("list users where usr_id = '" + gs_UserName + "'");
I'd like to implement websocket reconnect in webapp if internet connection is lost. In order to detect that internet is lost I use ping-pong approach, which means that I send from client ping-message and server returns me pong-message.
When webapp loaded I send init ping message and start to listen a reply on socket some kind of this:
this.websocket.onmessage = (evt) => {
try {
const websocketPayload: any = JSON.parse(evt.data);
if (websocketPayload.pong !== undefined && websocketPayload.pong == 1) {
this.pingPong$.next('pong');
}
It means that internet connection looks ok and we can continue. Also I have the follow code:
Observable.race(
Observable.of('timeout').delay(5000).repeat(),
this.pingPong$
).subscribe((data) => {
console.log("[ping-pong]:", data);
if (data == 'pong') {
Observable.interval(5000).take(1).subscribe(() => {
console.log("[ping-pong]:sending ping")
this.send({ping:1})
});
} else if (data == 'timeout'){
// show reconnect screen and start reconnect
console.error("It looks like websocket connection lost");
}
});
But!
When this.pingPong$ subject stops to emit events - .next() doesn't happen because of we can't get response when I break connection manually - I considered that in Observable.race this observable will be emitted
Observable.of('timeout').delay(5000).repeat()
But my subscribe never happens if this.pingPong$ stop emitting.
Why ?
Thank you
race picks and keeps subscribed to the first Observable that emits.
So if your this.pingPong$ starts emitting and then stops it makes no difference because race keeps subscribed to this.pingPong$. The other Observables don't matter any more. You might want emit one value from this.pingPong$ and the repeat the whole process. For example like the following:
Observable.race(
Observable.of('timeout').delay(5000).repeat(),
this.pingPong$
)
.pipe(
take(1), // complete the chain immediately
repeat() // resubscribe after take(1) completes the chain
)
.subscribe(...);
Obviously it mostly depends on what you want to do but I hope you get the point.
Consider a blocking function: this_thread::sleep_for(milliseconds(3000));
I'm trying to get the following behavior:
Trigger Blocking Function
|---------------------------------------------X
I want to trigger the blocking function and if it takes too long (more than two seconds), it should timeout.
I've done the following:
my_connection = observable<>::create<int>([](subscriber<int> s) {
auto s2 = observable<>::just(1, observe_on_new_thread()) |
subscribe<int>([&](auto x) {
this_thread::sleep_for(milliseconds(3000));
s.on_next(1);
});
}) |
timeout(seconds(2), observe_on_new_thread());
I can't get this to work. For starters, I think s can't on_next from a different thread.
So my question is, what is the correct reactive way of doing this? How can I wrap a blocking function in rxcpp and add a timeout to it?
Subsequently, I want to get an RX stream that behaves like this:
Trigger Cleanup
|------------------------X
(Delay) Trigger Cleanup
|-----------------X
Great question! The above is pretty close.
Here is an example of how to adapt blocking operations to rxcpp. It does libcurl polling to make http requests.
The following should do what you intended.
auto sharedThreads = observe_on_event_loop();
auto my_connection = observable<>::create<int>([](subscriber<int> s) {
this_thread::sleep_for(milliseconds(3000));
s.on_next(1);
s.on_completed();
}) |
subscribe_on(observe_on_new_thread()) |
//start_with(0) | // workaround bug in timeout
timeout(seconds(2), sharedThreads);
//skip(1); // workaround bug in timeout
my_connection.as_blocking().subscribe(
[](int){},
[](exception_ptr ep){cout << "timed out" << endl;}
);
subscribe_on will run the create on a dedicated thread, and thus create is allowed to block that thread.
timeout will run the timer on a different thread, that can be shared with others, and transfer all the on_next/on_error/on_completed calls to that same thread.
as_blocking will make sure that subscribe does not return until it has completed. This is only used to prevent main() from exiting - most often in test or example programs.
EDIT: added workaround for bug in timeout. At the moment, it does not schedule the first timeout until the first value arrives.
EDIT-2: timeout bug has been fixed, the workaround is not needed anymore.
How can I set the async operator of Observable to run in the main thread instead in another thread. Or at least set to get the result in the main thread once we finish.
#Test
public void retryWhen() {
Scheduler scheduler = Schedulers.newThread();
Single.just("single")
.map(word -> null)
.map(Object::toString)
.retryWhen(ot ->
ot.doOnNext(t -> System.out.println("Retry mechanism:" + t))
.filter(t -> t instanceof NullPointerException && cont < 5)
.flatMap(t -> Observable.timer(100, TimeUnit.MILLISECONDS,scheduler))
.doOnNext(t -> cont++)
.switchIfEmpty(Observable.error(new NullPointerException())))
.subscribeOn(scheduler)
.subscribe(System.out::println, System.out::println);
// new TestSubscriber()
// .awaitTerminalEvent(1000, TimeUnit.MILLISECONDS);
}
I´m trying observerOn and subscribeOn but both are used to set in which thread you want the execution. But in my case I want the execution or the end of it in the same thread where I run the test
Right now the only way to see the prints are just blocking and waiting for the execution.
Regards.
You could use Observable.toBlocking() to get a BlockingObservable and use that to extract your results in your tests.
If you don't specify observeOn/subscribeOn and no operator or Observable changes the thread, then when you subscribe to the observable it will do all the processing during the subscription.