From: Jeff Hostetler <git@jeffhostetler.com>
Date: Thu, 21 Mar 2019 17:43:07 GMT
Subject: Re: [PATCH v2 1/1] trace2: write to directory targets
Message-ID: <51e88650-8667-df1f-13ef-4537f2e70346@jeffhostetler.com>
In-Reply-To: <xmqqmulpt22e.fsf@gitster-ct.c.googlers.com>



On 3/20/2019 10:04 PM, Junio C Hamano wrote:
> Josh Steadmon <steadmon@google.com> writes:
> 
[...]
>> +/*
>> + * How many attempts we will make at creating a random trace output path.
>> + */
>> +#define MAX_RANDOM_ATTEMPTS 10
> 
> With the updated design, randomness is no longer the primary
> property of this new feature.  The fact that the names are
> automatically assigned is.  It could be that the source of tr2_sid
> may (or may not) be some randomness, but the point is that the
> caller in this patch does not care how tr2_sid is computed.
> 
> I'd call this max-attempts (or max-autopath-attempts, but that is
> rather long, and I do not think inside the scope of "tr2_dst" that
> is about "destination", there will be anything but the destination
> path we'd "attempt" with a reasonable maximum value to compute, so
> the "-autopath" clarification would not buy us much)....
> 
>>   static int tr2_dst_want_warning(void)
>>   {
>>   	static int tr2env_dst_debug = -1;
>> @@ -36,6 +42,53 @@ void tr2_dst_trace_disable(struct tr2_dst *dst)
>>   	dst->need_close = 0;
>>   }
>>   
>> +static int tr2_dst_try_random_path(struct tr2_dst *dst, const char *tgt_prefix)
> 
> .... and I'd call this s/random/auto/ instead, if I were writing
> this patch following the updated design.

I agree with Junio WRT the s/random/auto/ suggestions.

[...]
>> +	for (attempt_count = 0; attempt_count < MAX_RANDOM_ATTEMPTS; attempt_count++) {
>> +		strbuf_reset(&final_path);
>> +		strbuf_addbuf(&final_path, &base_path);
>> +		strbuf_addf(&final_path, ".%d", attempt_count);

Since the last component of the SID is already very unique and
we're unlikely to have collisions, maybe change the above line to:

		if (attempt_count > 0)
			strbuf_addf(&final_path, ".%d", attempt_count);

and in reality expect to never have files with the suffix.

Unless, that is, they turned on more than one of GIT_TR2,
GIT_TR2_PERF, or GIT_TR2_EVENT and pointed them at the same
directory, but I'm not sure if I care about that edge case
or not.

>> +		fd = open(final_path.buf, O_WRONLY | O_CREAT | O_EXCL, 0666);
[...]

Nice.  Thanks for looking into this.
Jeff