Re: [PATCH 4/5] strbuf_reset: don't write to slopbuf with ThreadSanitizer

[Junio C Hamano <gitster@pobox.com>]

Martin Ågren <martin.agren@gmail.com> writes:

>> diff --git a/strbuf.h b/strbuf.h
>> index 2075384e0b..1a77fe146a 100644
>> --- a/strbuf.h
>> +++ b/strbuf.h
>> @@ -147,7 +147,10 @@ static inline void strbuf_setlen(struct strbuf *sb, size_t len)
>>         if (len > (sb->alloc ? sb->alloc - 1 : 0))
>>                 die("BUG: strbuf_setlen() beyond buffer");
>>         sb->len = len;
>> -       sb->buf[len] = '\0';
>> +       if (sb->buf != strbuf_slopbuf)
>> +               sb->buf[len] = '\0';
>> +       else
>> +               assert(!strbuf_slopbuf[0]);
>>  }
>>
>>  /**
>
> When writing my patch, I used assert() and figured that with tsan, we're
> in some sort of "debug"-mode anyway. If we decide to always do the
> check, would it make sense to do "else if (strbuf_slopbuf[0]) BUG(..);"
> instead of the assert? Or, if we do prefer the assert, would the
> performance-worry be moot?

I wasn't thinking about performance impact of having an assert();
the use of it in the above was merely copied from yours ;-)