Ukufumana zonke iimatshisi zeregex bekuhlala kuyi-O(n²)

Iindleko ezifihlakeleyo zokuTshela iPateni

Kubaphuhlisi, amabinzana aqhelekileyo (regex) sisixhobo esiyimfuneko, imela yoMkhosi waseSwiss yokucazulula, ukuqinisekiswa, kunye nokukhupha ulwazi kwisicatshulwa. Ukusuka ekujongeni iifomati ze-imeyile ukukrazula idatha kwiilogi, i-regex sisisombululo sokuya. Nangona kunjalo, ngaphantsi kwale facade inamandla kukho umgibe wokusebenza oye wathwaxa iinkqubo amashumi eminyaka: olona xesha linzima lokufumana yonke imidlalo kumtya yi-O(n²). Olu bunzima bexesha le-quadratic lithetha ukuba njengoko umtya wokufakwayo ukhula ngokulandelelana, ixesha lokucubungula lingakhula ngokukhawuleza, likhokelela ekunciphiseni okungalindelekanga, ukuchithwa kwezixhobo, kunye nesiganeko esibizwa ngokuba yiReDoS(UkuLahlwa kweNkonzo rhoqo). Ukuqonda lo mda wendalo linyathelo lokuqala elibhekiselele kulwakhiwo olomeleleyo nolusebenzayo.

Kutheni iRegex iMatanisa i-O(n²)? Ingxaki yokuBamba umva

Ingcambu yokuntsokotha kwe-O(n²) ilele kwindlela esetyenziswa kakhulu ziinjini ze-regex: umva. Xa i-injini ye-regex, njengale isePerl, iPython, okanye iJava, izama ukufumana zonke iimatshisi ezinokwenzeka, ayiskeneli nje umtya kube kanye. Iphonononga iindlela ezahlukeneyo. Qwalasela ipateni elula efana `(a+)+b` esetyenziswa kuluhlu lwamagama ubukhulu becala "a", njengo "aaaaaaaaac". I-injini ngokunyoluka ithelekisa zonke ii-"a" kunye neyokuqala `a+`, emva koko izame ukutshatisa u-"b" wokugqibela. Xa isilela, ibuyisela umva—ingangqinelani neyokugqibela "a" kwaye izama `+` isilinganisi-manani kwiqela elingaphandle. Le nkqubo iyaphinda, inyanzelisa i-injini ukuba izame yonke indibaniselwano enokwenzeka yokuba ii-"a" zinokudityaniswa njani, nto leyo ekhokelela kuqhushumbo oludityanisiweyo lwamathuba. Inani leendlela emazijongwe yi-injini zinokulungelelana kwisikwere sobude bomtya, kungoko O(n²).

• Greedy Quantifiers: Iipateni ezifana `.*` okanye `.` sebenzisa umbhalo omninzi kangangoko kunokwenzeka ekuqaleni, okukhokelela kubuyiselo olubanzi xa iindawo ezilandelayo zepateni zisilela ukungqamana.
• Nested Quantifiers: Iintetho ezifana `(a+)+` okanye `(a*a*)*` zidala inani elichazayo leendlela zokwahlula umtya wokufaka, kwandisa kakhulu ixesha lokucubungula.
• Iipateni ezingacacanga: Xa umtya unokudityaniswa ngeendlela ezininzi ezithelelanayo, injini kufuneka ijonge ukuba kunokwenzeka ukufumana zonke iimatshisi.

Impembelelo yokwenyani yeHlabathi: Ngakumbi Kunokwehla nje kokucotha

Le asiyongxaki yezemfundo kuphela. I-regex engasebenziyo inokuba neziphumo ezibi kwindawo yemveliso. Itshekhi yokuqinisekisa idatha ebonakala ingenabungozi inokuba ngumqobo xa kusetyenzwa iifayile ezinkulu okanye ukuphatha umthamo omkhulu wokufakwa komsebenzisi. Esona siphumo siyingozi kakhulu luhlaselo lwe-ReDoS, apho umdlali okhohlakeleyo ebonelela ngomtya owenziwe ngononophelo obangela ukuba kusebenze imeko embi kakhulu kwi-regex yesicelo sewebhu, ngokufanelekileyo ukuxhoma iseva kwaye iyenze ingafumaneki kubasebenzisi abasemthethweni. Kumashishini, oku kuguqulela ngokuthe ngqo kwixesha lokuphumla, ingeniso elahlekileyo, kunye negama elibi. Xa kusakhiwa iisistim ezintsonkothileyo, ngakumbi ezo zisetyenzwa ngedatha engathenjwayo, ukwazi le migibe yeregex yinxalenye ebalulekileyo yokhuseleko kunye nophicotho lokwenziwa komsebenzi.

"Sakhe saba nohlaziyo oluncinci loqwalaselo olwathi lwazisa i-regex yokwahlulahlula imitya yearhente yomsebenzisi. Ngaphantsi komthwalo oqhelekileyo, kwakulungile. Kodwa ngexesha le-traffic spike, kubangele ukusilela kwe-cascading okuthathe i-API yethu imizuzu. Umtyholi wayeyi-O(n²) regex esingazange sazi ukuba sinayo." - INjineli yeDevOps ephezulu

Ukwakha iiNkqubo eziNcinci ngeMewayz

Ke, sihamba njani ngaphaya kwesi sinyanzelo sisisiseko? Isisombululo siquka indibaniselwano yezixhobo ezingcono kunye nokukhetha kobuchule bokwakha. Okokuqala, abaphuhlisi banokusebenzisa abahlalutyi be-regex ukuchonga iipateni eziyingxaki kwaye bazibhale kwakhona ukuze zisebenze ngakumbi (umzekelo, ukusebenzisa izixhobo zokuchaza amanani okanye amaqela eathom). Ukwenziwa kokugqibela, iindlela ezizezinye zikhona eziqinisekisa ixesha lomgama, O(n), ukulungiselela uthelekiso lwepateni, nangona zingaxhaphakanga kumathala eencwadi asemgangathweni.

Apha kulapho i-OS yemodyuli yeshishini efana ne-Mewayz ibonelela ngenzuzo ebalulekileyo. I-Mewayz ikuvumela ukuba uhlukanise kwaye ubeke iliso kwiinkqubo ezibalulekileyo. Endaweni yokuba nesicelo se-monolithic apho i-regex enye ecothayo inokukhubaza inkqubo yonke, ungafaka i-microservice ezinikeleyo, eyedwa yokwahlulahlula kunye nokuqinisekisa. Ukuba kuvela umba wokusebenza, uqulethwe kwaye unokuqwalaselwa ngaphandle kokuchaphazela eminye imisebenzi yeshishini. Ngaphaya koko, izixhobo zokujonga ngaphakathi kweqonga leMewayz zinokukunceda ukuba uchonge oku kungasebenzi ngaphambi kokuba kube nefuthe kubathengi bakho, ukuguqula ingxaki enokubakho ibe ngumsebenzi olawulekayo. Ngokwakhela phezu kwesiseko esibhetyebhetye nesibonakalayo, uyaqinisekisa ukuba ingqiqo yeshishini lakho, kuqukwa nokusetyenzwa kwesicatshulwa esintsonkothileyo, ihlala isebenza kwaye ixhathisa.

Imibuzo Ebuzwa Rhoqo

Ixabiso Elifihliweyo Lothelekiso Lwepateni

Kubaphuhlisi, amabinzana aqhelekileyo (regex) sisixhobo esiyimfuneko, imela yoMkhosi waseSwiss yokucazulula, ukuqinisekiswa, kunye nokukhupha ulwazi kwisicatshulwa. Ukusuka ekujongeni iifomati ze-imeyile ukukrazula idatha kwiilogi, i-regex sisisombululo sokuya. Nangona kunjalo, ngaphantsi kwale facade inamandla kukho umgibe wokusebenza oye wathwaxa iinkqubo amashumi eminyaka: olona xesha linzima lokufumana yonke imidlalo kumtya yi-O(n²). Olu bunzima bexesha le-quadratic lithetha ukuba njengoko umtya wokufakwayo ukhula ngokulandelelana, ixesha lokucubungula lingakhula ngokukhawuleza, likhokelela ekunciphiseni okungalindelekanga, ukuchithwa kwezixhobo, kunye nento eyaziwa ngokuba yi-ReDoS (i-Regular Expression Denial of Service). Ukuqonda lo mda wendalo linyathelo lokuqala elibhekiselele kulwakhiwo olomeleleyo nolusebenzayo.

Kutheni iRegex iMatanisa i-O(n²)? Ingxaki yokuBamba umva

Ingcambu yokuntsokotha kwe-O(n²) ilele kwindlela esetyenziswa kakhulu ziinjini ze-regex: umva. Xa i-injini ye-regex, njengale isePerl, iPython, okanye iJava, izama ukufumana zonke iimatshisi ezinokwenzeka, ayiskeneli nje umtya kube kanye. Iphonononga iindlela ezahlukeneyo. Qwalasela ipateni elula efana `(a+)+b` esetyenziswa kuluhlu lwamagama ubukhulu becala "a", njengo "aaaaaaaaac". I-injini ngokunyoluka ithelekisa zonke ii-"a" kunye neyokuqala `a+`, emva koko izame ukutshatisa u-"b" wokugqibela. Xa isilela, ibuyisela umva—ingangqinelani neyokugqibela "a" kwaye izama `+` isilinganisi-manani kwiqela elingaphandle. Le nkqubo iyaphinda, inyanzelisa i-injini ukuba izame yonke indibaniselwano enokwenzeka yokuba ii-"a" zinokudityaniswa njani, nto leyo ekhokelela kuqhushumbo oludityanisiweyo lwamathuba. Inani leendlela emazijongwe yi-injini zinokulungelelana kwisikwere sobude bomtya, kungoko O(n²).

Impembelelo yeHlabathi yokwenyani: Ngaphezu nje kokucotha

Le asiyongxaki yezemfundo kuphela. I-regex engasebenziyo inokuba neziphumo ezibi kwindawo yemveliso. Itshekhi yokuqinisekisa idatha ebonakala ingenabungozi inokuba ngumqobo xa kusetyenzwa iifayile ezinkulu okanye ukuphatha umthamo omkhulu wokufakwa komsebenzisi. Esona siphumo siyingozi kakhulu luhlaselo lwe-ReDoS, apho umdlali okhohlakeleyo ebonelela ngomtya owenziwe ngononophelo obangela ukuba kusebenze imeko embi kakhulu kwi-regex yesicelo sewebhu, ngokufanelekileyo ukuxhoma iseva kwaye iyenze ingafumaneki kubasebenzisi abasemthethweni. Kumashishini, oku kuguqulela ngokuthe ngqo kwixesha lokuphumla, ingeniso elahlekileyo, kunye negama elibi. Xa kusakhiwa iisistim ezintsonkothileyo, ngakumbi ezo zisetyenzwa ngedatha engathenjwayo, ukwazi le migibe yeregex yinxalenye ebalulekileyo yokhuseleko kunye nophicotho lokwenziwa komsebenzi.

Ukwakha iiNkqubo eziNgcono ngeMewayz

Ke, sihamba njani ngaphaya kwesi sinyanzelo sisisiseko? Isisombululo siquka indibaniselwano yezixhobo ezingcono kunye nokukhetha kobuchule bokwakha. Okokuqala, abaphuhlisi banokusebenzisa abahlalutyi be-regex ukuchonga iipateni eziyingxaki kwaye bazibhale kwakhona ukuze zisebenze ngakumbi (umzekelo, ukusebenzisa izixhobo zokuchaza amanani okanye amaqela eathom). Ukwenziwa kokugqibela, iindlela ezizezinye zikhona eziqinisekisa ixesha lomgama, O(n), ukulungiselela uthelekiso lwepateni, nangona zingaxhaphakanga kumathala eencwadi asemgangathweni.