Add the ability to print the startup time of each build step

[geoand]

This has been discussed a couple times and I myself could have
used it when I was looking into the Flyway startup times

[geoand]

@stuartwdouglas @gsmet I would like your opinion on this. Currently to enable this a user needs to set the system property both when building and when running the application, which means that under normal circumstances we don't pollute the bytecode with extra instructions, but I am pretty sure that this experience will puzzle users :).

For native, obviously only the main startup tasks will print there startup time (unless a user really knows what they are doing and goes to extreme of passing the system property with -J-D... to the native image generation as well..)

Also if we want this, it probably needs to be documented somewhere - the extension authors guide and / or the performance troubleshooting doc?

[stuartwdouglas]

I think that experience will be be a bit confusing.

I was thinking this could live in MainClassBuildStep, and just be abstracted into a function, so the only 'pollution' is a method call before each step (which is a noop if the property is not set). It should add basically 0 overhead. You can then store the enabled state and last step finish time in a static variable, so it should be very minimal.

[geoand]

@stuartwdouglas so IIUC you want to see the control of printing of the startup times be a build time property? So if a user builds the application with that property then the startup times will always be printed when the application is run?

I am thinking of another idea: Keep my initial approach, but when the application is built with the print startup times enabled, then by default it does print startup times, but you can opt-out of that behavior by setting the flag to false at runtime. How does that sound?

I pushed an update that does just that

[stuartwdouglas]

No, I meant that we always include the profiling code, but just do it in a way that adds basically no overhead.

[geoand]

PR updated. If you agree with the current approach, then I'll go ahead and squash the commits and take it out of draft

[geoand]

Commits squashed

[geoand]

I'll also add a small piece of documentation later on Done

[mkouba]

@geoand Hm, what's the difference compared to the debug output from the io.quarkus.builder? E.g. if you run your build with -X then you can see messages like:

[DEBUG] [io.quarkus.builder] Finished step "io.quarkus.arc.deployment.LifecycleEventsBuildStep#startupEvent" in 5 ms

[geoand]

@mkouba that is for build time build steps.

This PR introduces the ability to see the the time each generated startup task when you run the application

[mkouba]

Ah, I see. That makes sense.