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From: Junio C Hamano <gitster@pobox.com>
To: Carlo Arenas <carenas@gmail.com>
Cc: Johannes Schindelin via GitGitGadget <gitgitgadget@gmail.com>,
	git@vger.kernel.org,
	Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: Re: [PATCH 1/1] pcre2: allow overriding the system allocator
Date: Mon, 05 Aug 2019 14:53:40 -0700
Message-ID: <xmqq36ifmg7v.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <CAPUEspgH1v1zo7smzQWCV4rX9pKVKLV84gDSfCPdT7LffQxUWw@mail.gmail.com> (Carlo Arenas's message of "Mon, 5 Aug 2019 09:19:24 -0700")

Carlo Arenas <carenas@gmail.com> writes:

> LGTM except from the suggestion below that might make the code more "standard"
> and probably be a good base for a similar PCRE1 fix
>>
>> +static pcre2_general_context *get_pcre2_context(void)
>> +{
>> +       static pcre2_general_context *context;
>> +
>> +       if (!context)
>> +               context = pcre2_general_context_create(pcre2_malloc,
>> +                                                      pcre2_free, NULL);
>> +
>> +       return context;
>> +}
>
> instead of using a static variable inside this helper function it
> might be better to use
> one extra field inside the (struct grep_pat *p), where all other
> variables are kept
>
> Additionally to being more consistent will avoid creating the global

"standard" and "more consistent" are good things, but I am not sure
I should agree with the argument without knowing what you are
comparing your suggested improvement with.  Whose standard practice
are we trying to be consistent with?  Keeping dynamic resources hooked
to "struct grep_pat" so that (1) different patterns could use different
settings when they desire and (2) the resources are not hidden behind
a function-scope static and can be discarded when we are done with
the pattern, which is the standard in our "grep" subsystem?

I think general context probably corresponds to a bit higher level
than individual grep_pat.  E.g. when running "grep -e foo -e bar",
do we expect resources needed by patterns "foo" and "bar" would want
to be allocated and freed by potentially separate <alloc,free>
function pairs?

> context for the
> most common case (when the locale is either C/POSIX or UTF-8) and therefore
> have a smaller impact on performance.

I am not sure about the impact on performance, but if it helps us
keep the subsystem reusable by avoiding function-scope static that
we cannot clear, that would be a good thing.  But "struct grep_pat"
may be a bit too fine-grained to control general context.


  parent reply	other threads:[~2019-08-05 21:53 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-05 11:51 [PATCH 0/1] Fix a problem with PCRE2 and nedmalloc, found via Azure Pipelines Johannes Schindelin via GitGitGadget
2019-08-05 11:51 ` [PATCH 1/1] pcre2: allow overriding the system allocator Johannes Schindelin via GitGitGadget
2019-08-05 16:19   ` Carlo Arenas
2019-08-05 16:27     ` Carlo Arenas
2019-08-05 19:32       ` Johannes Schindelin
2019-08-05 19:26     ` Johannes Schindelin
2019-08-05 21:53     ` Junio C Hamano [this message]
2019-08-06  6:24       ` Carlo Arenas
2019-08-06  8:50       ` [PATCH 0/3] grep: no leaks (WIP) Carlo Marcelo Arenas Belón
2019-08-06  8:50         ` [PATCH 1/3] grep: make PCRE1 aware of custom allocator Carlo Marcelo Arenas Belón
2019-08-08 13:54           ` Johannes Schindelin
2019-08-08 15:19             ` Carlo Arenas
2019-08-06  8:50         ` [PATCH 2/3] grep: make PCRE2 " Carlo Marcelo Arenas Belón
2019-08-08 13:56           ` Johannes Schindelin
2019-08-08 14:32             ` Carlo Arenas
2019-08-06  8:50         ` [PATCH 3/3] grep: avoid leak of chartables in PCRE2 Carlo Marcelo Arenas Belón
2019-08-06 16:36         ` [RFC PATCH v3 0/3] grep: no leaks or crashes (windows testing needed) Carlo Marcelo Arenas Belón
2019-08-06 16:36           ` [RFC PATCH v3 1/3] grep: make PCRE1 aware of custom allocator Carlo Marcelo Arenas Belón
2019-08-06 16:36           ` [RFC PATCH v3 2/3] grep: make PCRE2 " Carlo Marcelo Arenas Belón
2019-08-07  5:38             ` René Scharfe
2019-08-07  9:49               ` Carlo Arenas
2019-08-07 13:02                 ` René Scharfe
2019-08-07 13:08                   ` [PATCH 1/2] nedmalloc: do assignments only after the declaration section René Scharfe
2019-08-07 13:09                   ` [PATCH 2/2] nedmalloc: avoid compiler warning about unused value René Scharfe
2019-08-08  2:35                   ` [RFC PATCH v3 2/3] grep: make PCRE2 aware of custom allocator Carlo Arenas
2019-08-08  7:07                     ` René Scharfe
2019-08-08 12:38                       ` Carlo Arenas
2019-08-08 14:29                         ` René Scharfe
2019-08-08 20:18                           ` Johannes Schindelin
2019-08-07 18:15                 ` Junio C Hamano
2019-08-06 16:36           ` [RFC PATCH v3 3/3] grep: avoid leak of chartables in PCRE2 Carlo Marcelo Arenas Belón
2019-08-06 16:48           ` [RFC PATCH v3 0/3] grep: no leaks or crashes (windows testing needed) Junio C Hamano
2019-08-07 21:39           ` [RFC PATCH v4 " Carlo Marcelo Arenas Belón
2019-08-07 21:39             ` [RFC PATCH v4 1/3] grep: make PCRE1 aware of custom allocator Carlo Marcelo Arenas Belón
2019-08-07 21:39             ` [RFC PATCH v4 2/3] grep: make PCRE2 " Carlo Marcelo Arenas Belón
2019-08-07 22:28               ` Junio C Hamano
2019-08-07 21:39             ` [RFC PATCH v4 3/3] grep: avoid leak of chartables in PCRE2 Carlo Marcelo Arenas Belón
2019-08-09  3:02             ` [RFC PATCH v5 0/3] grep: almost no more leaks, hopefully no crashes Carlo Marcelo Arenas Belón
2019-08-09  3:02               ` [RFC PATCH v5 1/3] grep: make PCRE1 aware of custom allocator Carlo Marcelo Arenas Belón
2019-08-09  3:02               ` [RFC PATCH v5 2/3] grep: make PCRE2 " Carlo Marcelo Arenas Belón
2019-08-27  9:07                 ` Johannes Schindelin
2019-08-27 11:51                   ` Carlo Arenas
2019-10-03  5:02                     ` Junio C Hamano
2019-10-03  8:08                       ` Johannes Schindelin
2019-10-03 11:17                         ` Carlo Arenas
2019-10-03 18:23                           ` Johannes Schindelin
2019-10-03 22:57                           ` Junio C Hamano
2019-08-09  3:02               ` [RFC PATCH v5 3/3] grep: avoid leak of chartables in PCRE2 Carlo Marcelo Arenas Belón
2019-08-09 11:24               ` [RFC PATCH v5 0/3] grep: almost no more leaks, hopefully no crashes Carlo Arenas
2019-08-09 17:01                 ` René Scharfe
2019-08-09 17:46                   ` Junio C Hamano
2019-08-09 21:26                   ` Johannes Schindelin
2019-08-10  3:03                     ` [PATCH] SQUASH Carlo Marcelo Arenas Belón
2019-08-10  7:57                       ` René Scharfe
2019-08-10  8:42                         ` Carlo Arenas
2019-08-10 19:47                           ` René Scharfe
2019-08-12  7:35                             ` Carlo Arenas
2019-08-12 12:14                               ` René Scharfe
2019-08-12 12:28                                 ` Carlo Arenas
2019-08-10 13:57                       ` Johannes Schindelin
2019-08-10  3:05                     ` [RFC PATCH v5 0/3] grep: almost no more leaks, hopefully no crashes Carlo Arenas
2019-08-10  7:56                       ` René Scharfe
2019-08-10 12:40                         ` Carlo Arenas
2019-08-10 21:16                           ` René Scharfe
2019-08-08 20:21           ` [RFC PATCH v3 0/3] grep: no leaks or crashes (windows testing needed) Johannes Schindelin
2019-08-09  6:52             ` Carlo Arenas
2019-08-09 21:13               ` Johannes Schindelin

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