WIN32下DELPHI中的多线程【深入VCL源码】（一）

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线xian程cheng的de基ji础chu知zhi识shi

线xian程cheng的de组zu成cheng。线xian程cheng有you两liang部bu分fen组zu成cheng。

1、一yi个ge是shi线xian程cheng的de内nei核gai对dui象xiang，操cao作zuo系xi统tong用yong它ta来lai对dui线xian程cheng实shi施shi管guan理li。内nei核gai对dui象xiang也ye是shi系xi统tong用yong来lai存cun放fang线xian程cheng统tong计ji信xin息xi的de地di方fang。

2、另ling一yi个ge是shi线xian程cheng堆dui栈zhan，它ta用yong于yu维wei护hu线xian程cheng在zai执zhi行xing代dai码ma时shi需xu要yao的de所suo有you函han数shu参shen数shu和he局ju部bu变bian量liang。

进jin程cheng从cong来lai不bu执zhi行xing任ren何he东dong西xi，它ta只zhi是shi线xian程cheng的de容rong器qi。线xian程cheng总zong是shi在zai某mou个ge进jin程cheng环huan境jing中zhong创chuang建jian的de，而er且qie它ta的de整zheng个ge寿shou命ming期qi都dou在zai该gai进jin程cheng中zhong。这zhe意yi味wei着zhe线xian程cheng在zai它ta的de进jin程cheng地di址zhi空kong间jian中zhong执zhi行xing代dai码ma，并bing且qie在zai进jin程cheng的de地di址zhi空kong间jian中zhong对dui数shu据ju进jin行xing操cao作zuo。因yin此ci，如ru果guo在zai单dan进jin程cheng环huan境jing中zhong，你ni有you两liang个ge或huo多duo个ge线xian程cheng正zheng在zai运yun行xing，那na么me这zhe两liang个ge线xian程cheng将jiang共gong享xiang单dan个ge地di址zhi空kong间jian。这zhe些xie线xian程cheng能neng够gou执zhi行xing相xiang同tong的de代dai码ma，对dui相xiang同tong的de数shu据ju进jin行xing操cao作zuo。这zhe些xie线xian程cheng还huan能neng共gong享xiang内nei核gai对dui象xiang句ju柄bing，因yin为wei句ju柄bing表biao依yi赖lai于yu每mei个ge进jin程cheng而er不bu是shi每mei个ge线xian程cheng存cun在zai。

线xian程cheng是shi一yi种zhong操cao作zuo系xi统tong对dui象xiang，它ta表biao示shi在zai进jin程cheng中zhong代dai码ma的de一yi条tiao执zhi行xing路lu径jing。在zai每mei一yi个geWi n32的de应ying用yong程cheng序xu中zhong都dou至zhi少shao有you一yi个ge线xian程cheng，它ta通tong常chang被bei称cheng为wei主zhu线xian程cheng或huo默mo认ren线xian程cheng。在zai应ying用yong程cheng序xu中zhong也ye可ke以yi自zi由you地di创chuang建jian别bie的de线xian程cheng去qu执zhi行xing其qi他ta任ren务wu。线xian程cheng技ji术shu使shi不bu同tong的de代dai码ma可ke以yi同tong时shi运yun行xing。当dang然ran，只zhi有you在zai多duoC P U的de计ji算suan机ji上shang，多duo个ge线xian程cheng才cai能neng够gou真zhen正zheng地di同tong时shi运yun行xing。在zai单dan个geCPU上shang，由you于yu操cao作zuo系xi统tong把baC P U的de时shi间jian分fen成cheng很hen短duan的de片pian段duan分fen配pei给gei每mei个ge线xian程cheng，这zhe样yang给gei人ren的de感gan觉jiao好hao像xiang是shi多duo个ge线xian程cheng真zhen的de同tong时shi运yun行xing，他ta们men只zhi是shi“看kan起qi来lai”同tong时shi在zai运yun行xing。

Win32是shi一yi种zhong抢qiang占zhan式shi操cao作zuo系xi统tong，操cao作zuo系xi统tong负fu责ze管guan理li哪na个ge线xian程cheng在zai什shen么me时shi候hou执zhi行xing。如ru果guo当dang线xian程cheng1暂zan停ting执zhi行xing时shi，线xian程cheng2才cai有you机ji会hui获huo得deC P U时shi间jian，我wo们men说shuo线xian程cheng1是shi抢qiang占zhan的de。如ru果guo某mou个ge线xian程cheng的de代dai码ma陷xian入ru死si循xun环huan，这zhe并bing不bu可ke怕pa，操cao作zuo系xi统tong仍reng会hui安an排pai时shi间jian给gei其qi他ta线xian程cheng。

创chuang建jian一yi个ge线xian程cheng

注zhu意yi：每mei个ge线xian程cheng必bi须xu拥yong有you一yi个ge进jin入ru点dian函han数shu，线xian程cheng从cong这zhe个ge进jin入ru点dian开kai始shi运yun行xing。线xian程cheng函han数shu可ke以yi使shi用yong任ren何he合he法fa的de名ming字zi。可ke以yi给gei线xian程cheng函han数shu传chuan递di单dan个ge参shen数shu，参shen数shu的de含han义yi由you你ni自zi己ji定ding义yi。线xian程cheng函han数shu必bi须xu由you一yi个ge返fan回hui值zhi，它ta将jiang成cheng为wei该gai线xian程cheng的de退tui出chu代dai码ma。线xian程cheng函han数shu应ying该gai尽jin可ke能neng的de使shi用yong函han数shu参shen数shu和he局ju部bu变bian量liang。线xian程cheng函han数shu类lei似si下xia面mian的de样yang子zi(Object Pascal)：

上shang面mian的de的de代dai码ma功gong能neng很hen简jian单dan，你ni可ke以yi在zai程cheng序xu中zhong直zhi接jie调tiao用yong，例li如ru这zhe样yang：

当dang你ni在zai一yi个ge窗chuang口kou中zhong用yong这zhe样yang的de方fang式shi调tiao用yong时shi，你ni会hui发fa现xian在zai执zhi行xing的de过guo程cheng中zhong，你ni将jiang无wu法fa在zai窗chuang口kou上shang进jin行xing其qi他ta操cao作zuo，因yin为wei它ta工gong作zuo于yu你ni程cheng序xu的de主zhu线xian程cheng之zhi中zhong。如ru果guo此ci时shi，你ni还huan希xi望wang窗chuang口kou可ke以yi进jin行xing其qi他ta操cao作zuo。怎zen么me办ban？让rang它ta在zai后hou台tai工gong作zuo，让rang它ta成cheng为wei另ling一yi个ge线xian程cheng，使shi得de不bu同tong的de代dai码ma可ke以yi同tong时shi运yun行xing。

做zuo法fa很hen简jian单dan，如ru果guo想xiang要yao创chuang建jian一yi个ge或huo多duo个ge辅fu助zhu线xian程cheng，只zhi需xu要yao让rang一yi个ge已yi经jing在zai运yun行xing的de线xian程cheng来lai调tiao用yongCreateThread，原yuan型xing如ru下xia：

当dangCreateThread，被bei调tiao用yong时shi，系xi统tong创chuang建jian一yi个ge线xian程cheng内nei核gai对dui象xiang。该gai线xian程cheng内nei核gai对dui象xiang不bu是shi线xian程cheng本ben身shen，而er是shi操cao作zuo系xi统tong用yong来lai管guan理li线xian程cheng的de较jiao小xiao的de数shu据ju结jie构gou。可ke以yi将jiang线xian程cheng内nei核gai对dui象xiang视shi为wei由you关guan于yu线xian程cheng的de统tong计ji信xin息xi组zu成cheng的de一yi个ge小xiao型xing数shu据ju结jie构gou。系xi统tong从cong进jin程cheng的de地di址zhi空kong间jian中zhong分fen配pei内nei存cun，供gong线xian程cheng的de堆dui栈zhan使shi用yong。新xin线xian程cheng运yun行xing的de进jin程cheng环huan境jing与yu创chuang建jian线xian程cheng的de环huan境jing相xiang同tong。因yin此ci，新xin线xian程cheng可ke以yi访fang问wen进jin程cheng的de内nei核gai对dui象xiang的de所suo有you句ju柄bing、进jin程cheng中zhong的de所suo有you内nei存cun和he在zai这zhe个ge相xiang同tong的de进jin程cheng中zhong的de所suo有you其qi他ta线xian程cheng的de堆dui栈zhan。这zhe使shi得de单dan个ge进jin程cheng中zhong的de多duo个ge线xian程cheng确que实shi能neng够gou非fei常chang容rong易yi地di互hu相xiang通tong信xin。

下xia面mian来lai说shuo这zhe个ge函han数shu的de几ji个ge参shen数shu：

1、psa 此ci参shen数shu是shi指zhi向xiangSECURITY_ATTRIBUTES结jie构gou的de指zhi针zhen。如ru果guo想xiang要yao该gai线xian程cheng内nei核gai对dui象xiang的de默mo认ren安an全quan属shu性xing，可ke以yi（并bing且qie通tong常chang能neng够gou）传chuan递diNULL。如ru果guo希xi望wang所suo有you的de子zi进jin程cheng能neng够gou继ji承cheng该gai线xian程cheng对dui象xiang的de句ju柄bing，必bi须xu设she定ding一yi个geSECURITY_ATTRIBUTES结jie构gou，它ta的debInheritHandle(是shi否fou可ke继ji承cheng)成cheng员yuan被bei初chu始shi化hua为weiTrue，关guan于yuSECURITY_ATTRIBUTES，因yin为wei此ci文wen的de目mu的de不bu是shi介jie绍shao它ta，所suo以yi这zhe里li不bu做zuo详xiang细xi介jie绍shao，具ju体ti可ke以yi参shen考kaoMSDN。通tong常chang使shi用yong，我wo们men传chuan递dinull就jiu够gou了le。

2、cbStack 用yong于yu设she定ding线xian程cheng可ke以yi将jiang多duo少shao地di址zhi空kong间jian用yong于yu它ta自zi己ji的de堆dui栈zhan。当dang调tiao用yongCrateThread时shi，如ru果guo传chuan递di的de值zhi不bu是shi0，就jiu能neng使shi该gai函han数shu将jiang所suo有you的de存cun储chu器qi保bao留liu并bing分fen配pei给gei线xian程cheng的de堆dui栈zhan。由you于yu所suo有you的de存cun储chu器qi预yu先xian作zuo了le分fen配pei，因yin此ci可ke以yi确que保bao线xian程cheng拥yong有you指zhi定ding容rong量liang的de可ke用yong堆dui栈zhan存cun储chu器qi。通tong常chang状zhuang况kuang下xia，我wo们men会hui设she置zhi为wei0。

3、pfnStartAddr and pvParam，pfnStartAddr 参shen数shu用yong于yu指zhi明ming想xiang要yao新xin线xian程cheng执zhi行xing的de线xian程cheng函han数shu的de地di址zhi。线xian程cheng函han数shu的depvParam参shen数shu与yu原yuan先xian传chuan递di给geiCreateThread的depvParam参shen数shu是shi相xiang同tong的de。CreateThread使shi用yong该gai参shen数shu不bu做zuo别bie的de事shi情qing，只zhi是shi在zai线xian程cheng启qi动dong执zhi行xing时shi将jiang该gai参shen数shu传chuan递di给gei线xian程cheng函han数shu。该gai参shen数shu提ti供gong了le一yi个ge将jiang初chu始shi化hua值zhi传chuan递di给gei线xian程cheng函han数shu的de手shou段duan。该gai初chu始shi化hua数shu据ju既ji可ke以yi是shi数shu字zi值zhi，也ye可ke以yi是shi指zhi向xiang包bao含han其qi他ta信xin息xi的de一yi个ge数shu据ju结jie构gou的de指zhi针zhen。此ci时shi回hui头tou再zai去qu看kan我wo上shang面mian例li子zi上shang的deMyThread，你ni会hui发fa现xian它ta由you一yi个ge无wu类lei型xing的de指zhi针zhen参shen数shu（用yongC来lai描miao述shu，应ying该gai是shiPVOID），在zai创chuang建jian线xian程cheng时shi，这zhe个ge参shen数shu就jiu通tong过guopvParam来lai赋fu值zhi。

4、fdwcreate 此ci参shen数shu可ke以yi设she定ding用yong于yu控kong制zhi创chuang建jian线xian程cheng的de其qi他ta标biao志zhi。它ta可ke以yi是shi两liang个ge值zhi中zhong的de一yi个ge。如ru果guo该gai值zhi是shi0，那na么me线xian程cheng创chuang建jian后hou可ke以yi立li即ji进jin行xing调tiao度du。如ru果guo该gai值zhi是shiCREATE_ SUSPENDED，系xi统tong可ke以yi完wan整zheng地di创chuang建jian线xian程cheng并bing对dui它ta进jin行xing初chu始shi化hua，但dan是shi要yao暂zan停ting该gai线xian程cheng的de运yun行xing，这zhe样yang它ta就jiu无wu法fa进jin行xing调tiao度du。在zaiDELPHI的deWINDOWS.PAS单dan元yuan，你ni可ke以yi发fa现xian它ta的de定ding义yi

CREATE_SUSPENDED= $00000004;

5、pdwThreadId 最zui后hou一yi个ge参shen数shu必bi须xu是shiDword的de一yi个ge有you效xiao地di址zhi，CreateThread

使shi用yong这zhe个ge地di址zhi来lai存cun放fang系xi统tong分fen配pei给gei新xin线xian程cheng的deID.

有you了le上shang面mian这zhe些xie基ji础chu，下xia面mian我wo们men就jiu使shi用yongcreateThread来lai创chuang建jian刚gang才cai那na个geMyThread线xian程cheng（DELPHI7）;

执zhi行xing此ci段duan代dai码ma，你ni会hui发fa现xian，它ta依yi然ran会hui在zai屏ping幕mu指zhi定ding区qu域yu输shu出chu文wen字zi，和he最zui开kai始shi时shi我wo们men用yong把baMyThread在zai主zhu线xian程cheng中zhong运yun行xing不bu同tong的de是shi，此ci时shi，你ni依yi然ran可ke以yi对dui窗chuang口kou进jin行xing其qi他ta操cao作zuo。

看kan代dai码ma的de最zui后hou一yi行xing，它ta使shi用yong了lecreateThread，看kan它ta的de参shen数shu，第di一yi个genil以yi及ji第di二er个ge0意yi外wai着zhe，它ta使shi用yong默mo认ren的de安an全quan设she置zhi以yi及ji默mo认ren的de线xian程cheng堆dui栈zhan大da小xiao，第di三san个ge参shen数shu是shiMyThread的de地di址zhi（注zhu意yi@符fu号hao），然ran后hou我wo们men传chuan递di了leppi这zhe个gePinfo类lei型xing的de指zhi针zhen，使shi得de线xian程cheng函han数shu接jie受shou一yi个ge参shen数shu，如ru果guo你ni不bu准zhun备bei让rang线xian程cheng接jie受shou这zhe个ge参shen数shu，用yongnil，fdwcreate参shen数shu，我wo们men赋fu值zhi为wei0，意yi味wei着zhe我wo们men希xi望wang线xian程cheng立li即ji执zhi行xing，最zui后hou一yi个ge参shen数shu用yong来lai接jie受shou新xin线xian程cheng的deID。

让rang我wo们men来lai看kan看kanCreateThread都dou干gan了le些xie什shen么me。

上shang图tu显xian示shi了le系xi统tong在zai创chuang建jian线xian程cheng和he对dui线xian程cheng进jin行xing初chu始shi化hua时shi必bi须xu做zuo些xie什shen么me工gong作zuo。调tiao用yongCreateThread可ke使shi系xi统tong创chuang建jian一yi个ge线xian程cheng内nei核gai对dui象xiang。该gai对dui象xiang的de初chu始shi使shi用yong计ji数shu是shi2（在zai线xian程cheng停ting止zhi运yun行xing和he从congCreateThread返fan回hui的de句ju柄bing关guan闭bi之zhi前qian，线xian程cheng内nei核gai对dui象xiang不bu会hui被bei撤che消xiao）。线xian程cheng的de内nei核gai对dui象xiang的de其qi他ta属shu性xing也ye被bei初chu始shi化hua，暂zan停ting计ji数shu被bei设she置zhi为wei1，退tui出chu代dai码ma始shi终zhong为weiSTILL_ACTIVE（0 x 1 0 3），该gai对dui象xiang设she置zhi为wei未wei通tong知zhi状zhuang态tai。

一yi旦dan内nei核gai对dui象xiang创chuang建jian完wan成cheng，系xi统tong就jiu分fen配pei用yong于yu线xian程cheng的de堆dui栈zhan的de内nei存cun。该gai内nei存cun是shi从cong进jin程cheng的de地di址zhi空kong间jian分fen配pei而er来lai的de，因yin为wei线xian程cheng并bing不bu拥yong有you它ta自zi己ji的de地di址zhi空kong间jian。然ran后hou系xi统tong将jiang两liang个ge值zhi写xie入ru新xin线xian程cheng的de堆dui栈zhan的de上shang端duan（线xian程cheng堆dui栈zhan总zong是shi从cong内nei存cun的de高gao地di址zhi向xiang低di地di址zhi建jian立li）。写xie入ru堆dui栈zhan的de第di一yi个ge值zhi是shi传chuan递di给geiCreateThread的depvParam参shen数shu的de值zhi。紧jin靠kao它ta的de下xia面mian是shi传chuan递di给geiCreateThread的depfnStartAddr参shen数shu的de值zhi。每mei个ge线xian程cheng都dou有you它ta自zi己ji的de一yi组zuC P U寄ji存cun器qi，称cheng为wei线xian程cheng的de上shang下xia文wen。该gai上shang下xia文wen反fan映yang了le线xian程cheng上shang次ci运yun行xing时shi该gai线xian程cheng的deCPU寄ji存cun器qi的de状zhuang态tai。线xian程cheng的de这zhe组zuC P U寄ji存cun器qi保bao存cun在zai一yi个geCONTEXT结jie构gou。CONTEXT结jie构gou本ben身shen则ze包bao含han在zai线xian程cheng的de内nei核gai对dui象xiang中zhong。

指zhi令ling指zhi针zhen和he堆dui栈zhan指zhi针zhen寄ji存cun器qi是shi线xian程cheng上shang下xia文wen中zhong两liang个ge最zui重chong要yao的de寄ji存cun器qi。线xian程cheng总zong是shi在zai进jin程cheng的de上shang下xia文wen中zhong运yun行xing的de。因yin此ci，这zhe些xie地di址zhi都dou用yong于yu标biao识shi拥yong有you线xian程cheng的de进jin程cheng地di址zhi空kong间jian中zhong的de内nei存cun。当dang线xian程cheng的de内nei核gai对dui象xiang被bei初chu始shi化hua时shi，CONTEXT结jie构gou的de堆dui栈zhan指zhi针zhen寄ji存cun器qi被bei设she置zhi为wei线xian程cheng堆dui栈zhan上shang用yong来lai放fang置zhipfnStartAddr的de地di址zhi。当dang线xian程cheng完wan全quan初chu始shi化hua后hou，系xi统tong就jiu要yao查cha看kanCREATE_SUSPENDED标biao志zhi是shi否fou已yi经jing传chuan递di给geiCreateThread。如ru果guo该gai标biao志zhi没mei有you传chuan递di，系xi统tong便bian将jiang线xian程cheng的de暂zan停ting计ji数shu递di减jian为wei0，该gai线xian程cheng可ke以yi调tiao度du到dao一yi个ge进jin程cheng中zhong。然ran后hou系xi统tong用yong上shang次ci保bao存cun在zai线xian程cheng上shang下xia文wen中zhong的de值zhi加jia载zai到dao实shi际ji的deC P U寄ji存cun器qi中zhong。这zhe时shi线xian程cheng就jiu可ke以yi执zhi行xing代dai码ma，并bing对dui它ta的de进jin程cheng的de地di址zhi空kong间jian中zhong的de数shu据ju进jin行xing操cao作zuo。

在zai这zhe里li，我wo还huan要yao简jian单dan的de描miao述shu一yi下xiaCONTEXT结jie构gou，因yin为weiWIN32是shi抢qiang占zhan式shi操cao作zuo系xi统tong，一yi个ge线xian程cheng几ji乎hu不bu可ke能neng永yong远yuan的de占zhan据juCPU，也ye就jiu是shi说shuo，它ta会hui在zai一yi定ding时shi间jian后hou（在zaiWINDOWS中zhong，大da概gai式shi20ms的de时shi间jian），被beiCPU放fang在zai一yi边bian，一yi段duan时shi间jian之zhi后hou，才cai可ke以yi重chong新xin获huo得deCPU时shi间jian片pian，此ci时shi就jiu有you一yi个ge问wen题ti，线xian程cheng现xian在zai执zhi行xing到dao了le那na里li，CPU在zai再zai次ci分fen配pei给gei它ta时shi间jian片pian执zhi行xing的de时shi候hou，必bi须xu知zhi道dao这zhe些xie信xin息xi，难nan道dao要yao从cong0开kai始shi吗ma？CONTEXT结jie构gou的de作zuo用yong就jiu是shi用yong来lai解jie决jue这zhe个ge问wen题ti。