Bug 220239 – WebKit IPC is slow to develop because changing .messages.in or the generator will cause rebuild

• Component: WebKit2
• Status: RESOLVED WONTFIX

[Kimmo Kinnunen]

WebKit IPC is slow to develop because changing .messages.in or the generator will cause rebuild.

It will rebuild all the files that depend on the generated content, even if the generated content has not changed.

[Kimmo Kinnunen]

Created attachment 416937 [details]
Patch

[Alexey Proskuryakov]

Comment on attachment 416937 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=416937&action=review

> Source/WebKit/ChangeLog:8
> +        Write the generated IPC files only if their content has changed.

Does this mean that the generated IPC files will be re-generated every time forever? If timestamps on the generated files are not updated, they will always be considered out of date by the build system.

[Kimmo Kinnunen]

(In reply to Alexey Proskuryakov from comment #2)
> > Source/WebKit/ChangeLog:8
> > +        Write the generated IPC files only if their content has changed.
> 
> Does this mean that the generated IPC files will be re-generated every time
> forever? If timestamps on the generated files are not updated, they will
> always be considered out of date by the build system.

Yes, you're right it does. My head was at stamp files.. Yeah, probably does not make sense to fix this with the current build system structure.

[Darin Adler]

Comment on attachment 416937 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=416937&action=review

>> Source/WebKit/ChangeLog:8
>> +        Write the generated IPC files only if their content has changed.
> 
> Does this mean that the generated IPC files will be re-generated every time forever? If timestamps on the generated files are not updated, they will always be considered out of date by the build system.

This is a recurring problem/pattern in make files. It’s surprisingly difficult to update files only if they are modified but avoid regenerating them every time we build; but if we could figure out how to do it, it’s the behavior we’d prefer for all generated files!