In my code I have scheduled a runnable task using the schedule method of task schedular. I went through this link - https://docs.spring.io/spring-cloud-sleuth/docs/current-SNAPSHOT/reference/html/integrations.html#sleuth-runnablecallable-integration. I implemented this way. The current state is - for any schedule a trace is created, and the same trace id is being used for all the runs invoked by this schedule, though spans are new. But I want that each run should have it's own unique trace id. There is a method of tracer which creates a new trace, but is there any way to do this in sleuth by which I can avoid manual creation of a new trace? I am using the 2.0.x version.
I created a new trace using newtrace method of tracer which returns a span.
Started this span.
Then added this span in the currentscope using withspaninscope method.
Started scoped span for the runnable task and finished both of these spans.
It worked.
Related
I have more question while migrating the dialog from V3 to V4. below is our code.
In v3, we were using
Microsoft.Bot.Builder.Dialogs.Conversation.SendAsync(conversationContext.CurrentActivity, new RootDialog());
public class RootDialog : IDialog {
public RootDialog()
{
.....
}
public async Task StartAsync(IDialogContext context)
{
context.Wait(this.MessageReceivedAsync);
}
public virtual async Task MessageReceivedAsync(IDialogContext context, IAwaitable<IMessageActivity> result)
{
}
In the MessageReceivedAsync, we used the context.Wait(), context.Done() and context.PostAsync().
Can you recommend how to replace in the V4? And what's the alertnative for Microsoft.Bot.Builder.Dialogs.Conversation.SendAsync in V4?
These APIs are all gone. Here are the explanations of their replacements in V4:
context.Wait(…)
This method was used to tell the dialog system what method to invoke next on your class when a new activity arrived and is now gone. Instead you now subclass Dialog and override several methods for various lifecycle events:
BeginDialogAsync - called when the dialog is first pushed on the stack by bot code or another dialog calling BeginDialogAsync on the DialogContext.
ContinueDialogAsync - called when a new activity comes in and the bot calls ContinueDialog on the DialogContext.
ResumeDialogAsync - called when another dialog on the stack has completed and a dialog that was previously on the stack is now at the top of the stack.
RepromptDialogAsync - called when an explicit request has been made to reprompt the user. This is basically a way to tell the dialog that nothing has changed, but that it should pick up from where it left off again by sending whatever activity it last sent.
EndDialogAsync - called when the dialog has indicated its done and is being popped off the stack.
context.Done()/.Fail()
This was one of the way you reported the status of your dialog, but this is now accomplished by returning a DialogTurnResult from most of the aforementioned lifecycle methods. One of the properties is named Status and is of type DialogTurnStatus which has values that indicate the current state of the dialog. For example:
Waiting - the dialog sent some activities and is awaiting more input and should remain at the top of the stack.
Complete - the dialog has completed it's work and should be ended and popped off the stack. When this state is returned, callers can also investigate the output of the dialog (if it has one) which is passed back via the DialogTurnResult::Result property.
Cancelled - the dialog was cancelled part of the way through its work.
context.PostAsync()/Conversation.SendAsync
These were both used to respond back to the user. Both are now replaced by calling SendActivityAsync on the ITurnContext that is accessible via the Context property of the DialogContext instance that is passed into most of the aforementioned lifecycle methods as a parameter. NOTE: a couple of the lifecycle methods actually receive an ITurnContext parameter directly and then you just use that.
I would like someone to explain to me what is Device.BeginInvokeOnMainThread and what is it for?
And also some examples of cases where it's used.
Just to add an example.
Imagine you have an async method DoAnyWorkAsync if you call it (just as an example) this way:
DoAnyWorkAsync().ContinueWith ((arg) => {
StatusLabel.Text = "Async operation completed...";
});
StatusLabel is a label you have in the XAML.
The code above will not show the message in the label once the async operation had finished, because the callback is in another thread different than the UI thread and because of that it cannot modify the UI.
If the same code you update it a bit, just enclosing the StatusLabel text update within Device.BeginInvokeOnMainThread like this:
DoAnyWorkAsync().ContinueWith ((arg) => {
Device.BeginInvokeOnMainThread (() => {
StatusLabel.Text = "Async operation completed...";
});
});
there will not be any problem.
Try it yourself, replacing DoAnyWorkAsync() with Task.Delay(2000).
The simple answer is: Background thread cannot modify UI elements because most UI operations in iOS and Android are not thread-safe; therefore, you need to invoke UI thread to execute the code that modifies UI such MyLabel.Text="New Text".
The detailed answer can be found in Xamarin document:
For iOS:
IOSPlatformServices.BeginInvokeOnMainThread() Method simply calls NSRunLoop.Main.BeginInvokeOnMainThread
public void BeginInvokeOnMainThread(Action action)
{
NSRunLoop.Main.BeginInvokeOnMainThread(action.Invoke);
}
https://developer.xamarin.com/api/member/Foundation.NSObject.BeginInvokeOnMainThread/p/ObjCRuntime.Selector/Foundation.NSObject/
You use this method from a thread to invoke the code in the specified object that is exposed with the specified selector in the UI thread. This is required for most operations that affect UIKit or AppKit as neither one of those APIs is thread safe.
The code is executed when the main thread goes back to its main loop for processing events.
For Android:
Many People think on Xamarin.Android BeginInvokeOnMainThread() method use Activity.runOnUiThread(), BUT this is NOT the case, and there is a difference between using runOnUiThread() and Handler.Post():
public final void runOnUiThread(Runnable action) {
if (Thread.currentThread() != mUiThread) {
mHandler.post(action);//<-- post message delays action until UI thread is scheduled to handle messages
} else {
action.run();//<--action is executed immediately if current running thread is UI thread.
}
}
The actual implementation of Xamarin.Android BeginInvokeOnMainThread() method can be found in AndroidPlatformServices.cs class
public void BeginInvokeOnMainThread(Action action)
{
if (s_handler == null || s_handler.Looper != Looper.MainLooper)
{
s_handler = new Handler(Looper.MainLooper);
}
s_handler.Post(action);
}
https://developer.android.com/reference/android/os/Handler.html#post(java.lang.Runnable)
As you can see, you action code is not executed immediately by Handler.Post(action). It is added to the Looper's message queue, and is handled when the UI thread's scheduled to handle its message.
You can only update the UI from the main UI thread. If you are running code on a background thread and need to update the UI, BeginInvokeOnMainThread() allows you to force your code to run on the main thread, so you can update the UI.
As explained above, any UI updates must happen in the main thread or an exception will occur.
Though there's a peculiarity with Xamarin.Forms, one can manilpulate UI elements (e.g. create Labels and add them to StackLayout's Children collection) off the main thread without any failures as long as this part of UI is detached from UI elements currently displayed. This approach can be used to boost performance by creating Xamarin.Forms controls and setting their child/parent relations in-memory/off-screen in a separate thread BUT in order to attach them to displayed container (e.g. assign ContentPage's Content property) you will have to do this in Device.BeginInvokeOnMainThread().
While analysing the relationship between UI thread and background thread in some situation, we should be aware of the following:
BeginInvokeOnMainThread method as described in the docs, merely queues the invocation and returns immediately to the caller. So in this case, UI thread and background thread which submitted some work to UI thread, might work in parallel.
However, there is also InvokeOnMainThread which, as described in the docs, waits for the UI thread to execute the method, and does not return until the code pointed by action has completed. So in this case, background thread waits for UI thread to finish executing the given work, and then background thread continues execution.
I have a Behat FeatureContext with some custom steps, and I'd like to do the following:
Initialize a variable/array/object when the test suite starts,
Have that variable/array/object available within the scope of each Scenario in the test suite,
Have values stored in the variable/array/object updated after all of the steps in each Scenario execute,
When test suite execution is complete, persist the values (writing out to a log file would be perfect).
Can this be done, and how would you go about structuring this? I'm attempting to do this using #BeforeSuite, #BeforeScenario and #AfterScenario hooks but have not yet been successful (my OOP is a little rusty).
I want to get the remaining early start and remaining early finish properties of an Activity while reading a Primavera .xer file. I have seen that the class PrimaveraPMFileReader in the mpxj library sets these properties to the task object, but am trying to import xer file and so the reader used is PrimaveraXERFileReader class. With the XER reader, the task instances are not set any properties that am looking for.
After going through the code of PrimaveraPMFileWriter and also some methods of the Task class of mpxj library, I have realized that to get remaining early start of a task in primavera, you need to use the getResume() API of the Task class of mpxj.
Here is my problem , I have created a SortableCollection : ObservableCollection
and added a sort method (sort colors).
When I sort The collection with the principal Thread , it works every thing is fine and works
But When I try to sort this customCollection by using an item in the collection I have an expetion : (The calling thread cannot access this object because a different thread owns it).
I have looked in web and I found several solution , One Solution
This type of solution put the collection multithread for insertion , removing moving operation.
But not for the custom sort.
Thanks for help,
WPF classes have thread affinity. What this means is that all changes to those objects must be in the same thread where they were created. It truly is difficult to create a user interface API that is thread-safe, so Microsoft chose to keep it singlethreaded and force run-time checking to make sure of it.
That said, there are a few options you have to perform your sort in a background thread, and then apply it in the UI thread. The first option is to copy your SortableCollection into a plain old List or Array and perform the sort in the background. Once the background thread is complete, you use a Dispatcher to execute code in the UI thread. Every UI element in WPF extends System.Windows.Threading.DispatcherObject and most extend System.Windows.Freezable. The DispatcherObject is where you get the Dispatcher to execute code in the UI thread.
Logically, the execution would be something like this:
public void BackgroundSort()
{
List<T> items = new List<T>(this.ToArray());
BackgroundSortDelegate del = Sort;
del.BeginInvoke(SortCompleted, del);
}
private void SortCompleted(IAsyncResult result)
{
BackgroundSortDelegate del = result.AsyncState as BackgroundSortDelegate;
List<T> items = del.EndInvoke(result);
this.Dispatcher.Invoke(()=>{this.Collection = items;});
}
The short explanation of what happened is that the background worker/delegate is using a copy of the items in this list. Once the sort is complete, we are calling the Dispatcher object and invoking an action. In that action we are assigning the new sorted list back to our object.
The key to assigning the result of any background work within the UI thread is to use the UI's Dispatcher object. There's actually probably a half dozen ways to invoke a background worker in C#, but the approach to get your work in a background thread into the UI thread is the same.