I'm currently using LTTng for such performances issues, and I want to use TRACEPOINT_EVENT_CLASS and TRACEPOINT_EVENT_INSTANCE as well.
But I don't understand the 2.10 version's documentation. I wonder why we need to define TP_ARGS in each event instance as well as defining it in the event class.
Because we can't modify TP_FIELDS to change the type of any field, or compose it from many arguments.
The TP_ARGS() portion of a TRACEPOINT_EVENT_INSTANCE is used to validate that each instance matches the TRACEPOINT_EVENT_CLASS. See ust-tracepoint-event.h for more context.
I recommend that you repost your question on our mailing list/irc channel so that we can have an actual discussion regarding this. The maintainer of lttng-ust and lttng-modules, Compudj will surely provide more context and might even be open to the introduction of a new macro allowing event instance declaration without the TP_ARGS() portion.
Related
I'm looking to share an EF Context between "data manager" objects to ensure change tracking occurs under one context as opposed to handling multiple contexts...so I'm looking into named context... but in review of this documentation, I felt it wasn't clear, and I want to ensure my assumption is correct, and if so, update the documentation: here PRISM documents the resolution of named instances via a constructor:
My assumption is that the named typed "carservice" is matched to the named parameter in the constructor to select which concrete class should be reference to that parameter based on the IVehicleService.
Is my assumption correct - either way I'll create a pull request to clarify the documentation..Either way, answering the question here will add reference to clarification/handling of named instances in PRISM.
It seems this is NOT correct assumption, and it's not possible in Unity - I refactored to avoid.
One solution that I didn't try was to simply another interface (came to mind much later), was inheriting from an existing interface, and registers the "new" interface to use a specific constructor. As I'm new to Unity, I thought I would mention. I'm answering my own question, as I can't don't think I can give credit to a comment, and I HATE leaving questions unanswered on this site!
Question
Is there an official recommended way to create a custom RxJs Subject?
Use Case
I have a need for a QueueSubject, i.e. a Subject that queues all values passed to its next method until there is a subscriber. This is different from the built-in ReplaySubject because the ReplaySubject does not clear its buffer upon a subscription.
What I have learned so far
An exact implementation of what I need is available in this GitHub project by James Pike. The reason for my question despite this perfectly available solution is that the _subscribe method is an internal method. It is even marked as #deprecated, therefore if a linter is used, a linter rule exception needs to be added to the class to suppress the deprecation warning.
I did not find anything in the documentation about how to create a custom Subject.
You can use any Subject implementation as a reference for your own custom one, for example this one on Github.
Concerning _subscribe: You can override it with your custom class, but never call it directly from an outside consumer class (this is why it is annotated with #deprecated). The function is called by the Subject class internally following the Template Method Pattern.
In summary: Your linked implementation looks valid to me.
One way of doing seemed to be to use the java.lang.Compiler
I tried to use the java.lang.Compiler inside Eclipse anddid not understand the Object any parameters for the methods of that class? And putting in a class did not seem to work either.
Compiler.command(any) // what is meant by any? What are valid objects to put there?
Compiler.compileClass(clazz) // Nothing happens when I out a class in there?
Compiler.compileClasses(string) // hm?
How to can I print a hello message with a Compiler inside Eclipse...?
Reading the documentation is a very important skill you need to learn.
Whenever you come across a class or a method that you don't know the functionality of, simply look at the documentation first.
Here is the docs for java.lang.Compiler: https://docs.oracle.com/javase/7/docs/api/java/lang/Compiler.html
This is the first sentence of the document:
The Compiler class is provided to support Java-to-native-code compilers and related services. By design, the Compiler class does nothing; it serves as a placeholder for a JIT compiler implementation.
So, the answer to your question is, it does nothing. According to the documentation, it does nothing. It is used to start up the Java compiler when the JVM starts. You are not meant to use this.
I'm wondering why protocols are used in swift. In every case I've had to use one so far (UICollectionViewDelegate, UICollectionViewDataSource) I've noted that they don't even have to be added to the class declaration for my code to work. All they do is make it such that your class needs to have certain methods in it so that it can compile. Beats me why this is useful other then as a little post it note to help you keep track of what your classes do.
I'm assuming I'm wrong though. Would anyone care to point out why to me please?
A protocol defines a blueprint of methods, properties, and other requirements that suit a particular task or piece of functionality. The protocol doesn’t actually provide an implementation for any of these requirements—it only describes what an implementation will look like.
So it's basically an interface, right?
You use an interface when you want to define a "contract" for your code. In most cases, the purpose of this is to enable multiple implementations of that contract. For example, you can provide a real implementation, and a fake one for testing.
Further Reading
Protocols
What is the point of an Interface?
It allows flexible linkage between parts of code. Once the protocol is defined it can be used by code that doesn't need to know what will be done when the methods are called or exactly what object (or struct or enum) is actually being used. An alternative approach could be setting callbacks or blocks but by using a protocol as complete set of behaviours can be grouped and documented.
Some other code will typically create the concrete instance and pass it to the code expecting the protocol (sometimes the concrete instance will pass itself). In some cases neither the implementation of the code using it need to be aware of each other and it can all be set up by some other code to keep it reusable and testable.
It might be possible to do this in some languages by duck typing which is to say that a runtime inspection could allow a object to act in such a context without particular declaration but this is probably not possible to do at compile time in all cases and it could also be error prone if worked out implicitly.
i would like to ask a little question about task adaptor in q2.
i have a class that extends TaskAdaptor and an xml class with to instantiate it.
so my question is, how do i get the object instance created by the xml in java?
Thank you very much for any help provided.
You use the NameRegistrar to get a reference to your object, but please keep in mind that the TaskAdaptor was created in the early Q2 days in order to reuse Tasks created to run under QSP (QSP was the original version, Q2 stands for 'QSP version 2').
I don't think we have any of those old tasks in the jPOS system now, so I wonder why you need the TaskAdaptor; if you have Tasks of your own, it might be easier to upgrade them to full QBeans (just by extending QBeanSupport or implementing the simple QBean interface).
Please take a look at http://jpos.org/doc/proguide-draft.pdf, there's a chapter about writing your own jPOS Services (aka QBeans).