Ɔndastand std::shared_mutex frɔm C++17

std::shared_mutex, we dɛn introduks insay C++17, na sinkronizashɔn primitiv we de alaw bɔku trɛd dɛn fɔ ol shered (rid) lɔk dɛn wan tɛm we dɛn de mek shɔ se dɛn gɛt ɛksklusiv akses fɔ rayt ɔpreshɔn. I de sɔlv wan pan di mɔs kɔmɔn kɔnkɔrɛns chalenj dɛn na di mɔdan C++ bay we i de gi divɛlɔpa dɛn wan klin, standad we fɔ impruv rida-rayta lɔk we dɛn nɔ rich fɔ tɔd-pati laybri ɔ pletfɔm-spɛsifi k API dɛn.

Wetin Eksaktli Na std::shared_mutex ɛn Wetin Mek Dɛn Ad am na C++17?

Bifo C++17, divɛlɔpa dɛn we bin nid rida-rayta sɛmantiks bin gɛt fɔ abop pan pletfɔm-spɛsifi k sɔlvishɔn dɛn lɛk pthread_rwlock_t pan POSIX sistem ɔ SRWLOCK pan Windows, ɔ dɛn go yuz tɔd-pati laybri dɛn lɛk Boost. Di C++17 standad kɔmiti bin no dis gap ɛn dɛn introduks std::shared_mutex na di hεda fɔ adrɛs am dairekt.

Di men aidia na stret: insay bɔku rial-wɔl program dɛm, dɛn kin rid data fa fawe pas aw dɛn rayt am. Wan standad std::mutex de serialize ɔl di akses — rid inklud — we de mek botlɛn we nɔ nid. std::shared_mutex de lif da ristrikshɔn de bay we i difrɛns bitwin tu lɔk mɔd dɛn:

we dɛn kɔl
• Shɛri (rid) lɔk — dɛn gɛt am bay lɔk_shɛri(); bɔku trɛd dɛn kin ol dis wan tɛm, we de mek i fayn fɔ rid wan tɛm.
• Eksklusiv (rayt) lɔk — we dɛn gɛt bay lɔk(); na wan trɛd nɔmɔ kin ol dis wan tɛm, ɛn dɛn nɔ alaw fɔ sheb lɔk we dɛn de ol am.
• std::shared_lock — na RAII wrap we de kɔl lock_shared() pan kɔnstrɔkshɔn ɛn unlock_shared() pan distrɔkshɔn, we de mek risɔs nɔ lik.
• std::unique_lock / std::lock_guard — dɛn yuz am wit di ɛksklusiv mɔd, fɔ mek shɔ se rayt ɔpreshɔn dɛn ful-ɔp fɔ protɛkt ɛn ɛksɛpshɔn-sef.

Dis dual-mode dizayn de mek std::shared_mutex na natura fit fɔ sɛnɛriɔ lɛk kesh, kɔnfigyushɔn rɛjista, ɛn ɛni data strɔkchɔ usay rid de domin di woklɔd.

Aw Yu De Yuz std::shared_mutex na Rial Kɔd Wit Kɔmɛnt?

Kɔmɛnt dɛn na kɔd we de yuz std::shared_mutex na patikyula valyu bikɔs kɔnkɔrɛns lɔjik na notoriously at fɔ rizin bɔt. Kɔmɛnt dɛn we dɛn put fayn fayn wan de mek wi no klia wan wetin mek dɛn pik wan patikyula kayn lɔk, we de ridyus di risk fɔ mek di wan dɛn we de mentenɛns tumara bambay aksidɛntli introduks data rɛs. Na dis na wan tipik patɛn:

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