Bug 226390 – Add a way to prefix output of `WTFReportBacktrace` to make log filtering easier

• Component: Tools / Tests
• Status: RESOLVED FIXED

[Devin Rousso]

Often times while debugging I add `WTFLogAlways("<DR> ...")` to various places as indicators that "logic has reached here". This is especially useful when debugging iOS as unlike macOS there's no console output from `run-safari`, meaning that I have to use system logging, which is often a deluge of unrelated information. Having "<DR>" as a prefix makes filtering through the system logging trivial as I can ignore logs that don't have it. Unfortunately, `WTFReportBacktrace` does not have a way to add this prefix, so it becomes much harder to find in the logs.

[Devin Rousso]

Created attachment 430042 [details]
Patch

[Devin Rousso]

Created attachment 430043 [details]
Patch

[Devin Rousso]

Created attachment 430062 [details]
Patch

[Megan Gardner]

Comment on attachment 430062 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=430062&action=review

> Source/WTF/wtf/Assertions.cpp:291
>  void WTFReportBacktrace()

Could you make it so this isn't duplicated code?

[Devin Rousso]

Comment on attachment 430062 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=430062&action=review

>> Source/WTF/wtf/Assertions.cpp:291
>>  void WTFReportBacktrace()
> 
> Could you make it so this isn't duplicated code?

I thought about doing this by having `WTFReportBacktrace` call `WTFReportBacktraceWithPrefix("")`, but I think the issue there is that we'd then want to adjust `framesToSkip`.  I'll take a stab at maybe using a `template` or something.

[Devin Rousso]

Comment on attachment 430062 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=430062&action=review

>>> Source/WTF/wtf/Assertions.cpp:291
>>>  void WTFReportBacktrace()
>> 
>> Could you make it so this isn't duplicated code?
> 
> I thought about doing this by having `WTFReportBacktrace` call `WTFReportBacktraceWithPrefix("")`, but I think the issue there is that we'd then want to adjust `framesToSkip`.  I'll take a stab at maybe using a `template` or something.

Turns out that I can't use a `template` because it's `extern "C"` :/

I did experiment with something like `#define WTFReportBacktrace() WTFReportBacktraceWithPrefix("")`, but it was pointed out to me that that could have issues if WebKit clients (e.g. Safari) depend on that symbol.

[EWS]

Committed r278474 (238492@main): <https://commits.webkit.org/238492@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 430062 [details].

[Radar WebKit Bug Importer]

<rdar://problem/78876754>

[Fujii Hironori]

Comment on attachment 430062 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=430062&action=review

> Source/WTF/wtf/StackTrace.h:104
> +    const char* m_prefix;

Adding a new member here is problematic.
Filed: Bug 230207 – StackTrace outputs a garbage prefix because WTF::StackTrace::m_prefix is filled with the stack content