Ukusebenza okugqwesileyo kwe-C++ singleton

Ukusukela iSingleton egqibeleleyo: Umngeni weC++ oZimayo

Kumhlaba omkhulu wendlela yoyilo lwesoftware, bambalwa abathe bavusa ingxoxo, ukusungula izinto ezintsha, kunye nempikiswano njengeSingleton. Injongo yayo ilula ngokukhohlisa: qinisekisa ukuba iklasi inomzekelo omnye kwaye ibonelele ngenqaku lehlabathi lokufikelela kuyo. Ukususela ekulawuleni uqwalaselo lolawulo lokufikelela kwisixhobo ekwabelwana ngaso njengechibi loqhagamshelwano lwesiseko sedatha, ipateni ye-Singleton ijongana nemfuno efanayo. Nangona kunjalo, kwi-C ++, ukufikelela kwi-Singleton ekhuselekileyo, esebenzayo, kwaye engenazo iingozi ezifihlakeleyo luhambo ngokuvela kolwimi ngokwalo. Kukufuna ukusebenza kunye nokuthembeka okubonisa intanda-bulumko ngasemva kwamaqonga afana ne-Mewayz, apho amacandelo emodyuli anamandla, asebenzayo ayimfuneko ekwakhiweni kwenkqubo ezinzileyo yokusebenza kweshishini. Uphumezo "olungcono" aluyompendulo enye kodwa lulungelelwano lweemfuno ezithe ngqo kumxholo weprojekthi yakho.

I-Naive Beginning kunye neeNgozi zokuThinta imisonto emininzi

Olona phumezo luthe ngqo lwe-Singleton lusebenzisa umsebenzi omileyo owenza umzekelo kwifowuni yokuqala. Nangona kunjalo, le ndlela yakudala inesiphene esibalulekileyo kwihlabathi elinemisonto emininzi. Ukuba imisonto emininzi ngaxeshanye khangela ukuba umzekelo ukhona, bonke bangayifumana ilize kwaye baqhubele phambili ngokwenza ezabo iimeko, ezikhokelela ekwaphulweni okucacileyo komgaqo-siseko wepatheni. Ngelixa ukongeza isitshixo se-mutex esijikeleze ingqiqo yokudala isombulula umdyarho wedatha, yazisa umqobo obalulekileyo wokusebenza. Umnxeba ngamnye oya kwi-eceace-getter, nasemva kokuba i-Singleton iqaliswe ngokupheleleyo, ingenisa ngaphezulu kokutshixa kunye nokuvula, okungeyomfuneko kwaye kuyabiza. Oku kufana nokwakha inkqubo yeshishini apho wonke umqeshwa kufuneka acele isitshixo segumbi ixesha elide emva kokuba umnyango uvuliwe ngokusisigxina-inkcitho yexesha kunye nezibonelelo. Kwinkqubo yeemodyuli ezikumgangatho ophezulu ezifana neMewayz, ukungasebenzi kakuhle kwinqanaba elingundoqo akunakwamkeleka.

Isisombululo se-C++ sanamhlanje: `std::call_once` kunye ne-Magic Statics

Umgangatho we-C++11 uze nezixhobo ezinamandla eziphucule ngokumangalisayo ukusetyenziswa kwe-Singleton. Eyona ndlela inamandla kwaye icetyiswa ngokubanzi namhlanje ixhasa inqaku elithi "Magic Static". Ngokubhengeza umzekelo we-Singleton njengoguquguquko olumileyo ngaphakathi komsebenzi (endaweni yokuba udidi olumileyo), sisebenzisa isiqinisekiso solwimi sokuba iinguqu ezimileyo ziqaliswa ngendlela ekhuselekileyo yomsonto. Umqambi uphatha izitshixo eziyimfuneko phantsi kwe-hood, kodwa kuphela ngexesha lokuqalisa kokuqala. Iifowuni ezilandelayo zikhawuleza njengokutshekisha isalathisi esilula. Le ndlela yokusebenza, isetyenziswa rhoqo kusetyenziswa `std::call_once` kulawulo olucacileyo, ibonelela ngokuqalisa ukonqena nokusebenza okuphezulu.

• Ukuqaliswa kwe-Tread-Safe Initialization: Iqinisekiswa ngumgangatho we-C++, isusa iimeko zogqatso ekudalweni.
• I-Lazy Instantiation: Umzekelo wenziwa kuphela xa ufuneka kuqala, ukugcina izixhobo.
• I-Minimal Runtime Overhead: Emva kokuqaliswa, iindleko zokufikelela kumzekelo azinamsebenzi.
• Ulula: Ikhowudi icocekile, kulula ukuyiqonda, kwaye kunzima ukuyiphatha kakubi.

Le bhalansi yokhuseleko, ukusebenza kakuhle, kunye nokulula ngumgangatho wegolide wezicelo ezininzi. Iqinisekisa ukuba imodyuli engundoqo, efana nenkonzo phakathi kweMewayz OS, iqiniswe ngokuthembekileyo kwaye iqhuba ngokupheleleyo kumjikelo wobomi wesicelo.

Xa uMsebenzi uPhakamileyo: I-Meyers Singleton

Ukuphunyezwa okuthe ngqo kwepateni ye-"Magic Static" intle kakhulu kwaye iyasebenza ithiywe ngentshatsheli yayo, uScott Meyers. I-Meyers Singleton ihlala ithathwa njengesona sisombululo sisebenza ngokubanzi kwi-C++ yanamhlanje. Ikufutshane ngokumangalisayo:

"I-Meyers Singleton mhlawumbi yeyona ndlela isebenzayo yokuphumeza i-Singleton kwi-C++ kuba iphakamisa ukuqaliswa kwe-static komqambi, ukubonelela ukusebenza kakuhle emva komnxeba wokuqala."

Le pateni ifanelekile kwiiSingletons ezifikelelwa rhoqo emva kokuqaliswa. Iimpawu zayo zokusebenza zihambelana neemfuno zenkqubo efana ne-Mewayz, apho iinkonzo ezingundoqo kufuneka zifikeleleke ngokukhawuleza ngaphandle kokwazisa ukubambezeleka, ukuqinisekisa ukuba ukuhamba komsebenzi omkhulu woshishino kuhlala kungekho mthungo kwaye kuphendula.

Isiphelo: Ukukhetha Isixhobo esiLungileyo soMsebenzi

Ukufuna eyona "yeyona" C++ ukusebenza kweSingleton ifikelela kuvuthondaba kwiipateni zangoku ezinikwe amandla nguC++11 nangaphaya. Ngelixa i-Meyers Singleton ilolona khetho lubalaseleyo, eyona "yeyona ilungileyo" ukusebenza ekugqibeleni ixhomekeke kwimiqobo yakho ethile. Kwiimeko apho nexabiso lesalathisi liphezulu kakhulu, i-Singleton eyakhiwe ngononophelo ebekwe kwindawo yamagama yehlabathi inokuqwalaselwa, nangona oku kuncama ukuqaliswa kobuvila. Undoqo kukuqonda urhwebo. Kanye njengokuba iMewayz ibonelela ngezixhobo zeemodyuli onokuthi uziqwalasele ukuze usebenze kakuhle, ukhetho lwakho lwepateni ye-Singleton kufuneka ibe sisigqibo sangabom esisekwe kwiimfuno zesicelo sakho sokhuseleko lomsonto, ukuqalisa ixesha, kunye nokufikelela rhoqo. Ngokukhetha uphumezo lwangoku, olunyanzeliswe ngumqokeleli, uyakha isiseko esomeleleyo nesisebenza kakhulu njengeenkqubo ojonge ukuzenza.

Imibuzo Ebuzwa Rhoqo

Ukusukela iSingleton egqibeleleyo: Umngeni weC++ oZimayo

Kumhlaba omkhulu wendlela yoyilo lwesoftware, bambalwa abathe bavusa ingxoxo, ukusungula izinto ezintsha, kunye nempikiswano njengeSingleton. Injongo yayo ilula ngokukhohlisa: qinisekisa ukuba iklasi inomzekelo omnye kwaye ibonelele ngenqaku lehlabathi lokufikelela kuyo. Ukususela ekulawuleni uqwalaselo lolawulo lokufikelela kwisixhobo ekwabelwana ngaso njengechibi loqhagamshelwano lwesiseko sedatha, ipateni ye-Singleton ijongana nemfuno efanayo. Nangona kunjalo, kwi-C ++, ukufikelela kwi-Singleton ekhuselekileyo, esebenzayo, kwaye engenazo iingozi ezifihlakeleyo luhambo ngokuvela kolwimi ngokwalo. Kukufuna ukusebenza kunye nokuthembeka okubonisa intanda-bulumko ngasemva kwamaqonga afana ne-Mewayz, apho amacandelo emodyuli anamandla, asebenzayo ayimfuneko ekwakhiweni kwenkqubo ezinzileyo yokusebenza kweshishini. Uphumezo "olungcono" aluyompendulo enye kodwa lulungelelwano lweemfuno ezithe ngqo kumxholo weprojekthi yakho.

I-Naive Beginning kunye neeNgozi zokuFumana imisonto emininzi

Olona phumezo luthe ngqo lwe-Singleton lusebenzisa umsebenzi omileyo owenza umzekelo kwifowuni yokuqala. Nangona kunjalo, le ndlela yakudala inesiphene esibalulekileyo kwihlabathi elinemisonto emininzi. Ukuba imisonto emininzi ngaxeshanye khangela ukuba umzekelo ukhona, bonke bangayifumana ilize kwaye baqhubele phambili ngokwenza ezabo iimeko, ezikhokelela ekwaphulweni okucacileyo komgaqo-siseko wepatheni. Ngelixa ukongeza isitshixo se-mutex esijikeleze ingqiqo yokudala isombulula umdyarho wedatha, yazisa umqobo obalulekileyo wokusebenza. Umnxeba ngamnye oya kwi-eceace-getter, nasemva kokuba i-Singleton iqaliswe ngokupheleleyo, ingenisa ngaphezulu kokutshixa kunye nokuvula, okungeyomfuneko kwaye kuyabiza. Oku kufana nokwakha inkqubo yeshishini apho wonke umqeshwa kufuneka acele isitshixo segumbi ixesha elide emva kokuba umnyango uvuliwe ngokusisigxina-inkcitho yexesha kunye nezibonelelo. Kwinkqubo yeemodyuli ezikumgangatho ophezulu ezifana neMewayz, ukungasebenzi kakuhle kwinqanaba elingundoqo akunakwamkeleka.

Isisombululo se-C++ sanamhlanje: `std::call_once` kunye ne-Magic Statics

Umgangatho we-C++11 uze nezixhobo ezinamandla eziphucule ngokumangalisayo ukusetyenziswa kwe-Singleton. Eyona ndlela inamandla kwaye icetyiswa ngokubanzi namhlanje ixhasa inqaku elithi "Magic Static". Ngokubhengeza umzekelo we-Singleton njengoguquguquko olumileyo ngaphakathi komsebenzi (endaweni yokuba udidi olumileyo), sisebenzisa isiqinisekiso solwimi sokuba iinguqu ezimileyo ziqaliswa ngendlela ekhuselekileyo yomsonto. Umqambi uphatha izitshixo eziyimfuneko phantsi kwe-hood, kodwa kuphela ngexesha lokuqalisa kokuqala. Iifowuni ezilandelayo zikhawuleza njengokutshekisha isalathisi esilula. Le ndlela yokusebenza, isetyenziswa rhoqo kusetyenziswa `std::call_once` kulawulo olucacileyo, ibonelela ngokuqalisa ukonqena nokusebenza okuphezulu.

Xa uMsebenzi uPhakamileyo: I-Meyers Singleton

Ukuphunyezwa okuthe ngqo kwepateni ye-"Magic Static" intle kakhulu kwaye iyasebenza ithiywe ngentshatsheli yayo, uScott Meyers. I-Meyers Singleton ihlala ithathwa njengesona sisombululo sisebenza ngokubanzi kwi-C++ yanamhlanje. Ikufutshane ngokumangalisayo:

Isiphelo: Ukukhetha Isixhobo esiLungileyo soMsebenzi

Ukufuna eyona "yeyona" C++ ukusebenza kweSingleton ifikelela kuvuthondaba kwiipateni zangoku ezinikwe amandla nguC++11 nangaphaya. Ngelixa i-Meyers Singleton ilolona khetho lubalaseleyo, eyona "yeyona ilungileyo" ukusebenza ekugqibeleni ixhomekeke kwimiqobo yakho ethile. Kwiimeko apho nexabiso lesalathisi liphezulu kakhulu, i-Singleton eyakhiwe ngononophelo ebekwe kwindawo yamagama yehlabathi inokuqwalaselwa, nangona oku kuncama ukuqaliswa kobuvila. Undoqo kukuqonda urhwebo. Kanye njengokuba iMewayz ibonelela ngezixhobo zeemodyuli onokuthi uziqwalasele ukuze usebenze kakuhle, ukhetho lwakho lwepateni ye-Singleton kufuneka ibe sisigqibo sangabom esisekwe kwiimfuno zesicelo sakho sokhuseleko lomsonto, ukuqalisa ixesha, kunye nokufikelela rhoqo. Ngokukhetha uphumezo lwangoku, olunyanzeliswe ngumqokeleli, uyakha isiseko esomeleleyo nesisebenza kakhulu njengeenkqubo ojonge ukuzenza.