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Groups > comp.lang.c++ > #86654
| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: Never use strncpy! |
| Date | 2022-09-27 18:07 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <tgv74b$3ilt$1@dont-email.me> (permalink) |
| References | (12 earlier) <tgn3ri$309ud$1@dont-email.me> <tgrlov$1ctg$1@gioia.aioe.org> <tgs31b$3nogl$1@dont-email.me> <tgth7s$3rvll$1@dont-email.me> <SBDYK.231093$51Rb.96992@fx45.iad> |
On 27/09/2022 16:17, Scott Lurndal wrote:
> "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> writes:
>> On 9/26/2022 4:39 AM, David Brown wrote:
>
>> // A RMW operation
>> int
>> fetch_add(
>> int& origin,
>> ) {
>> hash_lock(&origin);
>> int result = origin;
>> origin = result + 1;
>> hash_unlock(&origin);
>> return result;
>> }
>> ________________________
>>
>> Okay, we are atomic. There are other ways to get this done.
>>
>> https://en.cppreference.com/w/cpp/atomic/atomic/fetch_add
>
> GCC has had built-ins to generate atomic accesses (e.g. __sync_fetch_and_add)
> for many years now.
>
> On intel/amd these generate lock prefixes, on other architectures
> with atomic support (e.g. ARMv8 LDADD, et alia) those instructions
> will be generated.
For more demanding cases - sizes larger than the hardware supports
directly, or read-write-modify on RISC - gcc uses a library that does
much what Chris has shown here. The locks are simple busy-wait
user-space spin locks on an atomic flag, which are very efficient on
most systems (especially in the common case of no contention).
Unfortunately, this solution is worse than useless in some cases, such
as real-time systems and single-core systems.
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Never use strncpy! Juha Nieminen <nospam@thanks.invalid> - 2022-09-21 10:04 +0000
Re: Never use strncpy! "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2022-09-21 15:06 +0200
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-21 15:24 +0200
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-21 15:30 +0200
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-21 19:20 +0200
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-21 19:33 +0200
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-21 23:14 +0200
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-22 04:40 +0200
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-22 08:56 +0200
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-22 12:02 +0200
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-23 13:23 +0200
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-23 13:49 +0200
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-23 15:25 +0200
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-23 16:03 +0200
Re: Never use strncpy! scott@slp53.sl.home (Scott Lurndal) - 2022-09-23 14:34 +0000
Re: Never use strncpy! Michael S <already5chosen@yahoo.com> - 2022-09-23 08:19 -0700
Re: Never use strncpy! scott@slp53.sl.home (Scott Lurndal) - 2022-09-23 17:57 +0000
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-23 18:36 +0200
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-24 16:22 +0200
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-24 16:25 +0200
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-24 17:09 +0200
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-24 17:14 +0200
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-09-26 17:34 -0700
Re: Never use strncpy! Juha Nieminen <nospam@thanks.invalid> - 2022-09-26 07:53 +0000
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-26 10:21 +0200
Re: Never use strncpy! Juha Nieminen <nospam@thanks.invalid> - 2022-09-26 08:34 +0000
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-26 13:39 +0200
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-09-26 17:47 -0700
Re: Never use strncpy! scott@slp53.sl.home (Scott Lurndal) - 2022-09-27 14:17 +0000
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-27 18:07 +0200
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-09-27 12:42 -0700
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-28 09:32 +0200
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-09-28 13:34 -0700
Re: Never use strncpy! scott@slp53.sl.home (Scott Lurndal) - 2022-09-28 21:11 +0000
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-10-01 06:26 +0200
Re: Never use strncpy! scott@slp53.sl.home (Scott Lurndal) - 2022-10-01 17:01 +0000
Re: Never use strncpy! Michael S <already5chosen@yahoo.com> - 2022-10-02 15:32 -0700
Re: Never use strncpy! scott@slp53.sl.home (Scott Lurndal) - 2022-10-03 14:01 +0000
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-10-03 13:49 -0700
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-10-02 12:46 -0700
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-10-03 04:14 +0200
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-10-02 19:43 -0700
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-10-02 19:48 -0700
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-10-03 04:53 +0200
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-10-02 19:58 -0700
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-10-03 08:27 +0200
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-10-03 13:49 -0700
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-10-04 10:53 -0700
Re: Never use strncpy! "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2022-10-02 12:44 -0700
Re: Never use strncpy! Juha Nieminen <nospam@thanks.invalid> - 2022-09-22 05:59 +0000
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-22 09:32 +0200
Re: Never use strncpy! Muttley@dastardlyhq.com - 2022-09-21 15:42 +0000
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-21 18:10 +0200
Re: Never use strncpy! Muttley@dastardlyhq.com - 2022-09-21 16:19 +0000
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-21 18:27 +0200
Re: Never use strncpy! Muttley@dastardlyhq.com - 2022-09-23 14:47 +0000
Re: Never use strncpy! scott@slp53.sl.home (Scott Lurndal) - 2022-09-21 16:12 +0000
Re: Never use strncpy! Philipp Klaus Krause <pkk@spth.de> - 2022-09-23 19:52 +0200
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-24 16:25 +0200
Re: Never use strncpy! scott@slp53.sl.home (Scott Lurndal) - 2022-09-21 14:00 +0000
Re: Never use strncpy! Juha Nieminen <nospam@thanks.invalid> - 2022-09-22 06:03 +0000
Re: Never use strncpy! Philipp Klaus Krause <pkk@spth.de> - 2022-09-23 19:50 +0200
Re: Never use strncpy! Juha Nieminen <nospam@thanks.invalid> - 2022-09-26 07:54 +0000
Re: Never use strncpy! Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-21 15:56 +0100
Re: Never use strncpy! Muttley@dastardlyhq.com - 2022-09-21 15:36 +0000
Re: Never use strncpy! Frederick Virchanza Gotham <cauldwell.thomas@gmail.com> - 2022-09-21 08:59 -0700
Re: Never use strncpy! Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-09-21 13:23 -0700
Re: Never use strncpy! Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-21 21:49 +0100
Re: Never use strncpy! Richard Damon <Richard@Damon-Family.org> - 2022-09-21 19:18 -0400
Re: Never use strncpy! Ben Bacarisse <ben.usenet@bsb.me.uk> - 2022-09-22 00:39 +0100
Re: Never use strncpy! Richard Damon <Richard@Damon-Family.org> - 2022-09-21 20:45 -0400
Re: Never use strncpy! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-21 18:00 -0700
Re: Never use strncpy! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-21 17:55 -0700
Re: Never use strncpy! Juha Nieminen <nospam@thanks.invalid> - 2022-09-22 06:09 +0000
Re: Never use strncpy! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-22 11:44 -0700
Re: Never use strncpy! Richard Damon <Richard@Damon-Family.org> - 2022-09-22 23:33 -0400
Re: Never use strncpy! Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-09-22 19:00 -0700
Re: Never use strncpy! Andrey Tarasevich <andreytarasevich@hotmail.com> - 2022-09-22 19:04 -0700
Re: Never use strncpy! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-22 22:49 -0700
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-24 11:38 +0200
Re: Never use strncpy! Muttley@dastardlyhq.com - 2022-09-24 09:43 +0000
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-24 11:59 +0200
Re: Never use strncpy! Richard Damon <Richard@Damon-Family.org> - 2022-09-24 06:27 -0400
Re: Never use strncpy! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-24 11:53 -0700
Re: Never use strncpy! Bonita Montero <Bonita.Montero@gmail.com> - 2022-09-24 20:58 +0200
Re: Never use strncpy! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-21 16:01 -0700
Re: Never use strncpy! David Brown <david.brown@hesbynett.no> - 2022-09-22 09:37 +0200
Re: Never use strncpy! Manfred <noname@add.invalid> - 2022-10-01 01:24 +0200
Re: Never use strncpy! Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2022-09-30 16:43 -0700
Re: Never use strncpy! Lynn McGuire <lynnmcguire5@gmail.com> - 2022-09-22 21:03 -0500
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