I want to change a synchronous method to asynchronous

[Ruanjq98]

I would like to modify the Foo#performTask () method by rebasing it。

The code is as follows:

public class ByteBuddyExample {
    public static class Foo {
        public void performTask() {
            System.out.println("Performing task...");
        }
    }

    public static class AsyncAdvice {
        @Advice.OnMethodEnter(skipOn = Advice.OnNonDefaultValue.class)
        public static boolean enter(@Advice.This Foo foo, @Advice.Origin Method method) {
            CompletableFuture.runAsync(new Runnable() {
                @Override
                public void run() {
                    runAsyncMethod(foo, method);
                }
            });
            return true;
        }

        public static void runAsyncMethod(Foo foo, Method method) {
            try {
                System.out.println("Async task started...");
                method.invoke(foo);  // 调用原有方法
                System.out.println("Async task completed.");
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    public static void main(String[] args) throws IOException, InterruptedException {
        ByteBuddyAgent.install();

        new ByteBuddy().rebase(Foo.class)
            .visit(Advice.to(AsyncAdvice.class).on(ElementMatchers.named("performTask")))
            .make()
            .load(Foo.class.getClassLoader(), ClassReloadingStrategy.fromInstalledAgent())
            .saveIn(new File("./"));

        Foo foo = new Foo();
        foo.performTask();

        Thread.sleep(2000);
    }
}

The enhanced performTask method is invoked cyclically.

The saved byte information is as follows:

public class ByteBuddyExample$Foo {
    public ByteBuddyExample$Foo() {
    }

    public void performTask() {
        CompletableFuture.runAsync(new ByteBuddyExample.AsyncAdvice.1(this, ByteBuddyExample$Foo.class.getMethod("performTask")));
        boolean var1 = true;
        if (!var1) {
            System.out.println("Performing task...");
        }
    }
}

verison：1.14.6

My question is, if I use rebase, won't it generate a private performTask method? How can I achieve the above?

I hope someone will reply. Thank you very much.

[raphw]

Add a ThreadLocal<Boolean> which you set to true in runAsyncMethod. In the advice, you check if the ThreadLocal is set to true. If so, you set it back to false but also return false from the advice so that the original code is not skipped for this particular execution.

[Ruanjq98]

This feels so inelegant. Why can't it be done like AOP?

[raphw]

Because this would require to make a lot of assumptions, such as how to rebase the method or store the thread local.