coding-standard编程参考.pdf

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1、GlusterFSCodingStandardsZResearchJuly14,2008•StructuredefinitionsshouldhaveacommentpermemberEverymemberinastructuredefinitionmusthaveacommentaboutitspurpose.Thecommentshouldbedescriptivewithoutbeingoverlyverbose.Bad:gf_lock_tlock;/*lock*/Good:DBTYPEaccess_mode;/*accessmodeforaccessing*thedatab

2、ases,canbe*DB_HASH,DB_BTREE*(optionaccess-mode)*/•DeclareallvariablesatthebeginningofthefunctionAlllocalvariablesinafunctionmustbedeclaredimmediatelyaftertheopeningbrace.Thismakesiteasytokeeptrackofmemorythatneedstobefreedduringexit.Italsohelpsdebugging,sincegdbcannothandlevariablesdec

3、laredinsideloopsorothersuchblocks.•AlwaysinitializelocalvariablesEverylocalvariableshouldbeinitializedtoasensibledefaultvalueatthepointofitsdeclaration.AllpointersshouldbeinitializedtoNULL,andallintegersshouldbezeroor(ifitmakessense)anerrorvalue.Good:intret=0;char*databuf=NULL;int_fd=-1;1•In

4、itializationshouldalwaysbedonewithacon-stantvalueNeveruseanon-constantexpressionastheinitializationvalueforavariable.Bad:pid_tpid=frame->root->pid;char*databuf=malloc(1024);•ValidateallargumentstoafunctionAllpointerargumentstoafunctionmustbecheckedforNULL.AmacronamedVALIDATE(incommon-utils.h

5、)takesoneargument,andifitisNULL,writesalogmessageandjumpstoalabelcallederraftersettingopretandoperrnoappropriately.Itisrecommendedtousethistemplate.Good:VALIDATE(frame);VALIDATE(this);VALIDATE(inode);•NeverrelyonprecedenceofoperatorsNeverwritecodethatreliesontheprecedenceofoperatorstoexecute

6、correctly.Suchcodecanbehardtoreadandsomeoneelsemightnotknowtheprecedenceofoperatorsasaccuratelyasyoudo.Bad:if(op_ret==-1&&errno!=ENOENT)Good:if((op_ret==-1)&&(errno!=ENOENT))•UseexactlymatchingtypesUseavariableoftheexacttypedeclaredinthemanualtoholdthereturnvalueofafunction.Donotusean“equiva

7、lent”type.Bad:intlen=strlen(path);Good:size_tlen=strlen(path);2•Neverwritecodesuchasfoo->bar->baz;checkeverypointerDonotwritecodethatblindlyfollowsachainofpointerreferences.AnypointerinthechainmaybeNULLandthuscauseacrash.Verifythateachpointerisnon-