How can I force a Zipkin span to be exportable?
In below code spans are sometimes exportable, sometimes not in a non repeatable manner.
It seems to me that if I comment first scopedSpan, than second manually created spanInScope is exportable, but how can first scopedSpan prevent second spanInScope from being exportable? How do they interfere?
#SneakyThrows
private void debugScopedSpan(final String label) {
ScopedSpan scopedSpan = tracer.startScopedSpan(label + "_1").tag("type", "manual");
try {
log.info("===== debugScopedSpan_1 {}", label);
} catch (RuntimeException | Error e) {
scopedSpan.error(e);
throw e;
} finally {
scopedSpan.finish();
}
// Why both above scopedSpan and below spanInScope cant be exportable at the same time??? How do they iterfere with each other?
Span trace = tracer.nextSpan().name(label+"_2").tag("type", "manual").start();
final Tracer.SpanInScope spanInScope = tracer.withSpanInScope(trace);
log.info("===== debugScopedSpan_2 {}", label);
spanInScope.close();
trace.finish();
}
It's because of sampling. Please create a bean of sampler type whose value can be Sampler.ALWAYS or set the probability property to 1.0
Related
Assume I have a class C that holds resources that need to be closed as member variables.
public class C {
private ClosableResource1 closableResource1;
private ClosableResource2 closableResource2;
.....
public C(){
closableResource1 = new ClosableResource1();
closableResource2 = new ClosableResource2();
.....
// some logic that can fail
}
close(){
closableResource1.close()
closableResource2.close()
.....
}
}
If the constructor succeeds I can be sure that close() will be called eventually by some entity manager and all the resources will be freed.
But how can I make sure I close the resources when the constructor fails? The failure can happen because I have additional logic in the constructor that can throw exception or I get some RuntimeException outside of my control?
Some things I though of:
Wrapping the constructor body with a try-catch block. Then, assuming I have a lot of closable members I'll have to have a big if statement in the catch block checking which resources were already initializing and only close them.
Offloading the ClosableResources creation to some init() function. Then I would have to make sure init() succeeded every time I try to use the object.
Is there some elegant solution? Or is this much more implementation specific then that?
You can do something like below:
public class C {
private List<AutoCloseable> closableResources = new ArrayList();
private ClosableResource1 closableResource1;
private ClosableResource2 closableResource2;
.....
public C() {
closableResource1 = new ClosableResource1();
closableResources.add(closableResource1)
closableResource2 = new ClosableResource2();
closableResources.add(closableResource2);
.....
try {
// some logic that can fail
} catch(Exception e) {
close();
}
}
close(){
for (AutoCloseable closableResource : closableResources) {
if (closableResource != null) {
closableResource.close();
}
}
}
}
Surrounding your code with try-catch and closing all your resources in catch is the correct solution here. Also read about method finalize() (Here is one tutorial). In general, I would recommend one method that cleans up all the resources (like you suggested method close(), I would call it though cleanup()) and call that method in your catch section and in your finalize() method
I asked and answered a very similar question here. It is very important that a constructor either succeeds or fails completely i.e. leaving no resources open. In order to achieve that I would follow each resource creation statement by a try-catch block. The catch block closes the resource and rethrows the exception so it is not lost:
public C() {
closableResource1 = new ClosableResource1();
closableResource2 = new ClosableResource2();
try {
// .....
// some logic that can fail and throw MyCheckedException or some RuntimeException
} catch (RuntimeException | MyCheckedException e) {
try {closableResource1.close();} catch (Exception ignore) {}
try {closableResource1.close();} catch (Exception ignore) {}
throw e;
}
}
If creating a resource can fail you need nested try-catch blocks as demonstrated here.
Here's a wild idea: create a class called something like DefusableCloser (that you can "defuse", like an explosive device being made safe):
class DefusableCloser implements AutoCloseable {
boolean active = true;
final AutoCloseable closeable;
DefusableCloser(AutoCloseable closeable) {
this.closeable = closeable;
}
#Override public void close() throws Exception {
if (active) closeable.close();
}
}
Now you can use this in a try-with-resources block:
c1 = new CloseableResource();
try (DefusableCloseable d1 = new DefusableCloseable(c1)) {
c2 = new CloseableResource();
try (DefusableCloseable d2 = new DefusableCloseable(c2)) {
// Do the other stuff which might fail...
// Finally, deactivate the closeables.
d1.active = d2.active = false;
}
}
If execution doesn't reach d1.active = d2.active = false;, the two closeables (or one, if the exception was in creating the second resource) will be closed. If execution does reach that line, they won't be closed and you can use them.
The advantage of doing it like this is that the exceptions will be correctly handled.
Note that the ordering is important: don't be tempted to create the two CloseableResources first, then the two DefusableCloseables: doing that won't handle an exception from creating the second CloseableResource. And don't put the creation of the CloseableResources into the TWR, as that would guarantee their closure.
For closing the resources in your class' close() method, you can also use try-with-resources to ensure that both resources are closed:
try (c1; c2) {}
You don't actually have to declare a new variable in the TWR syntax: you can just effectively say "close the resource for this existing variable afterwards", as shown here.
guys. Today I have done my custom realization for WebDriverEventListener. I need only onException() method which will create screenshot. But I got problem because I am using fluent wait.
new FluentWait<>(webDriver)
.withTimeout(Duration.ofSeconds(10))
.pollingEvery(Duration.ofMillis(500))
.ignoring(NoSuchElementException.class)
.until(someCondition)
So, finally, I have got screen for each ignoring(NoSuchElementException.class) - 20 screenshots for 1 fail ))). Had somebody the such problem or had someone resolve it?
when you use .ignoring(NoSuchElementException.class) you don't avoid that the exception is raised, you are just ignoring that exception. What is happening is that the exception is being raised by your FluentWait, but it is ignored (when you declare .ignoring(NoSuchElementException.class)).
You have three options here:
Capture the screen at the end of your test if the test failed [preferred].
Have a Try-Catch wherever you are using your FluentWait or any other Selenium code.
Use reflection to avoid capture when the event is raised from the method that implements the FluentWait.
This is an idea after what we have discussed:
private void ExceptionThrown(object sender, WebDriverExceptionEventArgs e)
{
if (e.ThrownException is NoSuchElementException)
{
// Get the stack trace from the current exception
StackTrace stackTrace = new StackTrace(e.ThrownException, true);
// Get the method stack frame index.
int stackTraceIndex = stackTrace.FrameCount - 1;
// Get the method name that caused the exception
string methodName = stackTrace.GetFrame(stackTraceIndex).GetMethod().Name;
if(methodName != "MyFindElement")
{
TakeSceenshot();
}
}
else
{
TakeSceenshot();
}
}
// This is an extension method of the DriverHelper interface
public IWebElement MyFindElement(this IWebDriver driver, By by, int timeOut = 0)
{
var wait = new WebDriverWait(driver, TimeSpan.FromSeconds(timeOut));
wait.IgnoreExceptionTypes(typeof(NoSuchElementException));
// I wait until the element exist
IWebElement result = wait.Until(drv => drv.FindElement(by) != null);
// it means that the element doesn't exist, so we throw the exception
if(result == null)
{
MyPersonalException(by);
}
}
// The parameter will help up to generate more accurate log
public void MyPersonalException(By by)
{
throw new NoSuchElementException(by.ToString());
}
This probably require changes in EventFiringWebDriver, because this class is without WebDriverWait instance and events for them. If you want avoid it, create bool variable in your EventFiringWebDriver extended class and check this value in your OnException like:
protected void OnException(WebDriverExceptionEventArgs e) {
if (IsWaitHandler)
return;
Your actions...
}
but this is not perfect solution.
I have a little ANTLR v4 grammer and I am implementing a visitor on it.
Lets say it is a simple calculator and every input must be terminated with a ";"
e.g. x=4+5;
If I do not put the ; at the end, then it is working too but I get a output the teminal.
line 1:56 missing ';' at '<EOF>'
Seems it can find the rule and more or less ignores the missing terminal ";".
I would prefer a strict error or an exception instead of this soft information.
The output is generated by the line
ParseTree tree = parser.input ()
Is there a way I can intensify the error-handling and check for that kind of error?
Yes, you can. Like you, I wanted a 100% perfect parse from user-submitted text and so created a strict error handler that prevents recovery from even simple errors.
The first step is in removing the default error listeners and adding your own STRICT error handler:
AntlrInputStream inputStream = new AntlrInputStream(stream);
BailLexer lexer = new BailLexer(inputStream); // TALK ABOUT THIS AT BOTTOM
CommonTokenStream tokenStream = new CommonTokenStream(lexer);
LISBASICParser parser = new LISBASICParser(tokenStream);
parser.RemoveErrorListeners(); // UNHOOK ERROR HANDLER
parser.ErrorHandler = new StrictErrorStrategy(); // REPLACE WITH YOUR OWN
LISBASICParser.CalculationContext context = parser.calculation();
CalculationVisitor visitor = new CalculationVisitor();
visitor.VisitCalculation(context);
Here's my StrictErrorStrategy class. It inherits from the DefaultErrorStrategy class and overrides the two 'recovery' methods that are letting small errors like your semicolon error be recoverable:
public class StrictErrorStrategy : DefaultErrorStrategy
{
public override void Recover(Parser recognizer, RecognitionException e)
{
IToken token = recognizer.CurrentToken;
string message = string.Format("parse error at line {0}, position {1} right before {2} ", token.Line, token.Column, GetTokenErrorDisplay(token));
throw new Exception(message, e);
}
public override IToken RecoverInline(Parser recognizer)
{
IToken token = recognizer.CurrentToken;
string message = string.Format("parse error at line {0}, position {1} right before {2} ", token.Line, token.Column, GetTokenErrorDisplay(token));
throw new Exception(message, new InputMismatchException(recognizer));
}
public override void Sync(Parser recognizer) { }
}
Overriding these two methods allows you to stop (in this case with an exception that is caught elsewhere) on ANY parser error. And making the Sync method empty prevents the normal 're-sync after error' behavior from happening.
The final step is in catching all LEXER errors. You do this by creating a new class that inherits from your main lexer class; it overrides the Recover() method like so:
public class BailLexer : LISBASICLexer
{
public BailLexer(ICharStream input) : base(input) { }
public override void Recover(LexerNoViableAltException e)
{
string message = string.Format("lex error after token {0} at position {1}", _lasttoken.Text, e.StartIndex);
BasicEnvironment.SyntaxError = message;
BasicEnvironment.ErrorStartIndex = e.StartIndex;
throw new ParseCanceledException(BasicEnvironment.SyntaxError);
}
}
(Edit: In this code, BasicEnvironment is a high-level context object I used in the application to hold settings, errors, results, etc. So if you decide to use this, either do as another reader commented below, or substitute your own context/container.)
With this in place, even small errors during the lexing step will be caught as well. With these two overridden classes in place, the user of my app must supply absolutely perfect syntax to get a successful execution. There you go!
Because my ANTLR is in Java I add the answer here too. But it is the same idea as the accepted answer.
TempParser parser = new TempParser (tokens);
parser.removeErrorListeners ();
parser.addErrorListener (new BaseErrorListener ()
{
#Override
public void syntaxError (final Recognizer <?,?> recognizer, Object sym, int line, int pos, String msg, RecognitionException e)
{
throw new AssertionError ("ANTLR - syntax-error - line: " + line + ", position: " + pos + ", message: " + msg);
}
});
I want to make an application in javaFX 2 which opens as a smaller login window, then, when you put in correct data, it takes you to bigger main window. Both are designed in fxml and events are handled within java code.
Yes, I know, it is almost the same as the application in samples and I've tried to do what I want and it worked there.
Now, when I did the same in my project, I hit a problem when I want to change the value of stage.
As you can see in the code below, I have global variable and I set the value of primaryStage in start method to it. Just as a test, I print it out at end of start method and the value is set.
Then, when I try to use it when button is clicked(method buttonClick), the value of stage variable is null, therefore I cannot use it to resize window or anything else.
My question is why is stage variable value reseted despite that I don't use change anything between the two prints?
This code is sample of what I've tried, I've just cut out all code which is not crucial to understand how my application works.
public class App extends Application {
private Stage stage;
#FXML
private AnchorPane pane;
#Override
public void start(Stage primaryStage) {
try {
stage = primaryStage; // Set the value of primaryStage to stage
primaryStage.setScene(new Scene(openScene("Login"))); // Load Login window
primaryStage.show(); // Show the scene
} catch (IOException ex) {
Logger.getLogger(App.class.getName()).log(Level.SEVERE, null, ex);
}
System.out.println(stage);// <-- Here it has the value of primaryStage obviously
}
#FXML
void buttonClick(ActionEvent event) throws IOException {
// Note that even if I try to print here, the value of stage is still
// null, so the code doesn't affect it
// Also, this loads what I want, I just can't change the size.
try{
pane.getChildren().clear(); // Clear currently displayed content
pane.getChildren().add(openScene("MainScene")); // Display new content
System.out.println(stage); // <-- Here, output is null, but I don't know why
stage.setWidth(500); // This line throws error because stage = null
} catch (IOException ex) {
Logger.getLogger(App.class.getName()).log(Level.SEVERE, null, ex);
}
}
public Parent openScene(String name) throws IOException {
//Code from FXML login example
Parent parent = (Parent) FXMLLoader.load(PrijavnoOkno.class.getResource(name
+ ".fxml"), null, new JavaFXBuilderFactory());
return parent;
}
public static void main(String[] args) {
launch(args);
}
}
Although it is not clear by whom and where the buttonClick action method is called, I pressume it is a login button's action in Login.fxml. Also I assume you have defined the App (a.k.a PrijavnoOkno) as a controller of this Login.fxml.
According to these assumptions, there are 2 instances of App.class:
one created when the app starts up and where the stage variable is assigned with primary stage in start() method,
and another instance created by FXMLLoader (while loading Login.fxml) and where the stage variable is not assigned and thus NPE.
One of the right ways can be, create a new Controller class for Login.fxml, call your login action in it. Access the global stage (by making it static in App) from there.
I've got a rule like this:
declaration returns [RuntimeObject obj]:
DECLARE label value { $obj = new RuntimeObject($label.text, $value.text); };
Unfortunately, it throws an exception in the RuntimeObject constructor because $label.text is null. Examining the debug output and some other things reveals that the match against "label" actually failed, but the Antlr runtime "helpfully" continues with the match for the purpose of giving a more helpful error message (http://www.antlr.org/blog/antlr3/error.handling.tml).
Okay, I can see how this would be useful for some situations, but how can I tell Antlr to stop doing that? The defaultErrorHandler=false option from v2 seems to be gone.
I don't know much about Antlr, so this may be way off base, but the section entitled "Error Handling" on this migration page looks helpful.
It suggests you can either use #rulecatch { } to disable error handling entirely, or override the mismatch() method of the BaseRecogniser with your own implementation that doesn't attempt to recover. From your problem description, the example on that page seems like it does exactly what you want.
You could also override the reportError(RecognitionException) method, to make it rethrow the exception instead of print it, like so:
#parser::members {
#Override
public void reportError(RecognitionException e) {
throw new RuntimeException(e);
}
}
However, I'm not sure you want this (or the solution by ire_and_curses), because you will only get one error per parse attempt, which you can then fix, just to find the next error. If you try to recover (ANTLR does it okay) you can get multiple errors in one try, and fix all of them.
You need to override the mismatch and recoverFromMismatchedSet methods to ensure an exception is thrown immediately (examples are for Java):
#members {
protected void mismatch(IntStream input, int ttype, BitSet follow) throws RecognitionException {
throw new MismatchedTokenException(ttype, input);
}
public Object recoverFromMismatchedSet(IntStream input, RecognitionException e, BitSet follow) throws RecognitionException {
throw e;
}
}
then you need to change how the parser deals with those exceptions so they're not swallowed:
#rulecatch {
catch (RecognitionException e) {
throw e;
}
}
(The bodies of all the rule-matching methods in your parser will be enclosed in try blocks, with this as the catch block.)
For comparison, the default implementation of recoverFromMismatchedSet inherited from BaseRecognizer:
public Object recoverFromMismatchedSet(IntStream input, RecognitionException e, BitSet follow) throws RecognitionException {
if (mismatchIsMissingToken(input, follow)) {
reportError(e);
return getMissingSymbol(input, e, Token.INVALID_TOKEN_TYPE, follow);
}
throw e;
}
and the default rulecatch:
catch (RecognitionException re) {
reportError(re);
recover(input,re);
}