Hodor

Hodor is the lib that holds the door before application closes in a crash, proving a last chance to inform someone that something was not good.

Why Hodor?

Sometimes you want to make your java application to say something on a crash situation and send a metric, one message or something similar, to make someone to know about the failure. Hodor wraps your application execution and catches Throwable, maybe this is not beautiful, but does the trick.

Usage

Hodor can hold the door for your application with or without @Annotations, it's your choice.

• Annotate or modify 'main'.
• Provide a 'HoldTheDoor' method to be called while crash.

What to add to 'HoldTheDoor' method?

Application failures may vary a lot but Hodor should manage all those special situations so consider seriously @HoldTheDoor annotated method content. Avoid doing heavy stuff there, it's not the place and might also fail.

Use this method to: write a log, send a metric, a message, etc, etc... in the end, simple operation(s) that might run without errors even in a OutOfMemory application crash scenario.

Using Annotation

• Add dependency to build.gradle

annotationProcessor 'info.developia:hodor:0.1'
implementation 'info.developia:hodor:0.1'

• Add @Hodor annotation to your current main method and create a method with your desired name but that accepts Throwable as argument.

package info.developia.application;

public class App {
    @Hodor
    public static void main(String[] args) {
        Application application = new Application();
    }
    @HoldTheDoor
    private static void sendSOS(Throwable t) {
        System.out.println("Sending a SOS!");
    }
}

• After your project gets built, check on 'build' at 'generated/sources/annotationProcessor/' folder and follow @Hodor annotated application class package. You will find a generated class with your class name ending with Hodor.

On our example, App class is on info.developia.application package, so class to find will be at:

build/generated/sources/annotationProcessor/info/developia/application/AppHodor.java

• Execute generated AppHodor.java on your IDE or modify your jar command to make AppHodor class as starting point.

You can find an AnnotatedApplication example.

Not using Annotation

• Add dependency to build.gradle

implementation 'info.developia:hodor:0.1'

• Move your main content to a new method with your desired name and add Hodor.holdTheDoor() to call it.

package info.developia.application;

public class App {
    public static void main(String[] args) {
        Hodor.holdTheDoor((a) -> App.application(args), (t) -> App.sendSOS(t));
    }
    
    public void application(String[] args){
        Application application = new Application();
    }
    
    private static void sendSOS(Throwable t) {
        System.out.println("Sending a SOS!");
    }
}

• Execute modified class on your IDE.

You can find an NonAnnotatedApplication example.