dict.c: dictGetRandomKeys() visit pattern optimization.
dict.c: dictGetRandomKeys() visit pattern optimization.

We use the invariant that the original table ht[0] is never populated up
to the index before the current rehashing index.

Related to issue #2306.

davidradunz/redis,iandyh/redis,PradheepShrinivasan/redis,colstrom/redis,xuguruogu/redis,Aliceljm1/redis,shining-yang/redis,xlzhan/redis,healerkx/redis,pkdevbox/redis,rouzier/redis,jingjidejuren/redis,wprice/redis,spinlock/redis,rogerchina/redis,timothyohare/3rdPartySrc-redis,tellapart/redis,fengshao0907/redis,valdsJohn/redis,hgl888/redis,h0x91b/redis,RepmujNetsik/redis,ouyangkongtong/redis,pcarrier/redis,shining-yang/redis,OmarQunsul/graph-redis,zguangyu/redis,Wangyao14cyy/redis,weizijun/redis,wbailey5/redis,supasate/redis,ofirluzon/redis,netroby/redis,yossigo/redis,elkingtonmcb/redis,seandsky/redis,zczhuohuo/redis,wenxueliu/redis_comment,honestme/redis,MasahikoSawada/redis,h0x91b/redis,mcanthony/redis,harrisonfeng/redis,pedigree/redis,antirez/redis,yuhc/redis-benchmark-enhanced,qiyang0221/redis,wenxueliu/redis_comment,programmecat/redis,cnbin/redis,oranagra/redis,spinlock/redis,Soledad89/redis,weizijun/redis,duanx/redis,AplayER/redis,Markgorden/redis,clamoriniere1A/redis,xlzhan/redis,ytjiang/redis,tjschuck/redis,hawkchch/redis,honestme/redis,riyan8250/redis,zhcy/redis,h0x91b/redis,dayuoba/redis,csuhawk/redis,kaushik94/redis,brg-liuwei/redis,huyuezheng/redis,rogerlz/redis,jingjidejuren/redis,linfangrong/redis,flashbuckets/redis,mverrilli/redis,davidradunz/redis,shreesundara/redis,MasahikoSawada/redis,NBSW/redis,nuxeh/redis,abhiklodh/redis,YongMan/redis,arijitvt/redis,wangyikai/redis,gaoxianglong/redis,YongMan/redis,cloudrain21/redis,roth1002/redis,RepmujNetsik/redis,universsky/redis,arijitvt/redis,YuraLukashik/redis,seandsky/redis,hgl888/redis,charsyam/redis,StevenTsai/redis,StevenTsai/redis,arijitvt/redis,zczhuohuo/redis,allengaller/redis,citusdata/redis,dreamquster/redis,YongMan/redis,abhiklodh/redis,aim-for-better/redis,weizijun/redis,Sciumo/redis,JoeWoo/redis,supasate/redis,kensou97/redis,alenslan/redis,SyntaxStacks/redis,devaos/redis,blackmady/redis,NBSW/redis,thomasdarimont/redis,wenxueliu/redis_comment,ton31337/redis,antirez/redis,4396/redis,z-fork/redis,itugs/redis,ouyangkongtong/redis,citusdata/redis,francischan714/redis,mverrilli/redis,neomantra/redis,YongMan/redis,PKRoma/redis,cusspvz/redis,shreesundara/redis,janekmi/redis,4396/redis,davidradunz/redis,thomasdarimont/redis,tjschuck/redis,valdsJohn/redis,mingyaaaa/redis,ncopa/redis,ituncle/redis,citusdata/redis,rogerchina/redis,PradheepShrinivasan/redis,mcanthony/redis,saisai/redis,ipmobiletech/redis,h0x91b/redis,AALEKH/redis,rogerlz/redis,GitHubMota/redis,tellapart/redis,hedisdb/hedis,wprice/redis,GrimDerp/redis,PradheepShrinivasan/redis,ncopa/redis,riyan8250/redis,AALEKH/redis,190235047/redis,honestme/redis,zhcy/redis,Soledad89/redis,atreeyang/redis,universsky/redis,fengshao0907/redis,mengyou0304/redis,mengyou0304/redis,4396/redis,simplestbest/redis,roth1002/redis,itamarhaber/redis,mgk/redis,atreeyang/redis,Sciumo/redis,xlzhan/redis,tanghaodong25/redis,tjschuck/redis,seppo0010/redis,vincent-vivian-liu/redis,neomantra/redis,pmem/redis,AplayER/redis,YuraLukashik/redis,devaos/redis,jasonkying/redis,shining-yang/redis,twskipper/redis,AplayER/redis,ofirluzon/redis,ctripcorp/redis,OmarQunsul/graph-redis,colstrom/redis,wbailey5/redis,iandyh/redis,modulexcite/redis,CodeJuan/redis,july2993/redis,zczhuohuo/redis,francischan714/redis,nnog/redis,dayuoba/redis,mingyaaaa/redis,clamoriniere1A/redis,healerkx/redis,brg-liuwei/redis,Sciumo/redis,alenslan/redis,seandsky/redis,sunheehnus/redis,jingjidejuren/redis,ouyangkongtong/redis,RepmujNetsik/redis,twskipper/redis,JoeWoo/redis,taoguan/redis,hedisdb/hedis,nnog/redis,allengaller/redis,holstvoogd/redis,mingyaaaa/redis,holstvoogd/redis,190235047/redis,elkingtonmcb/redis,zguangyu/redis,AplayER/redis,aim-for-better/redis,thomasdarimont/redis,Soledad89/redis,supasate/redis,pedigree/redis,tellapart/redis,netroby/redis,ytjiang/redis,ituncle/redis,roth1002/redis,zguangyu/redis,yuhc/redis-benchmark-enhanced,Aliceljm1/redis,charsyam/redis,guker/redis,csuhawk/redis,mverrilli/redis,guker/redis,taoguan/redis,JoeWoo/redis,CodeJuan/redis,hornen/redis,rogerchina/redis,wangyikai/redis,twskipper/redis,aim-for-better/redis,programmecat/redis,wenxueliu/redis_comment,PradheepShrinivasan/redis,kaushik94/redis,netroby/redis,NBSW/redis,kaushik94/redis,izhoujie/redis,colstrom/redis,mcanthony/redis,cloudrain21/redis,zczhuohuo/redis,programmecat/redis,linfangrong/redis,july2993/redis,Markgorden/redis,ncopa/redis,ErikDubbelboer/redis,kmiku7/redis,pcarrier/redis,soloestoy/redis,GitHubMota/redis,gaoxianglong/redis,xuguruogu/redis,soloestoy/redis,Wangyao14cyy/redis,mgk/redis,190235047/redis,GrimDerp/redis,ofirluzon/redis,soloestoy/redis,YuraLukashik/redis,dreamquster/redis,harrisonfeng/redis,itamarhaber/redis,OmarQunsul/graph-redis,taoguan/redis,charsyam/redis,190235047/redis,blackmady/redis,nuxeh/redis,hornen/redis,ituncle/redis,hedisdb/hedis,oranagra/redis,abhiklodh/redis,duanx/redis,weizijun/redis,jasonkying/redis,jackyan/redis,takeshineshiro/redis,kmiku7/redis,itugs/redis,holstvoogd/redis,tanghaodong25/redis,hedisdb/hedis,soloestoy/redis,soveran/redis,PKRoma/redis,JoeWoo/redis,xujunhai1991/redis,mengyou0304/redis,dayuoba/redis,sunheehnus/redis,a-pavlov/redis,clamoriniere1A/redis,itamarhaber/redis,elkingtonmcb/redis,LongXQ/redis,jackyan/redis,oranagra/redis,elkingtonmcb/redis,wprice/redis,universsky/redis,ncopa/redis,atreeyang/redis,AALEKH/redis,zguangyu/redis,dayuoba/redis,devaos/redis,pmem/redis,itugs/redis,riyan8250/redis,mgk/redis,alenslan/redis,pcarrier/redis,soloestoy/redis,gaoxianglong/redis,simplestbest/redis,shreesundara/redis,ytjiang/redis,xlzhan/redis,vincent-vivian-liu/redis,pkdevbox/redis,YuanZhewei/redis,xujunhai1991/redis,zhcy/redis,pedigree/redis,RepmujNetsik/redis,LongXQ/redis,rouzier/redis,hornen/redis,izhoujie/redis,takeshineshiro/redis,xuguruogu/redis,tellapart/redis,yuhc/redis-benchmark-enhanced,ytjiang/redis,xuguruogu/redis,SyntaxStacks/redis,valdsJohn/redis,wbailey5/redis,cnbin/redis,citusdata/redis,ErikDubbelboer/redis,duanx/redis,aim-for-better/redis,allengaller/redis,pkdevbox/redis,ton31337/redis,soveran/redis,shining-yang/redis,honestme/redis,mcanthony/redis,ton31337/redis,sunheehnus/redis,kensou97/redis,taoguan/redis,hgl888/redis,mverrilli/redis,4396/redis,saisai/redis,saisai/redis,seandsky/redis,jasonkying/redis,flashbuckets/redis,mengyou0304/redis,kensou97/redis,izhoujie/redis,sunheehnus/redis,itamarhaber/redis,izhoujie/redis,clamoriniere1A/redis,StevenTsai/redis,YuraLukashik/redis,huyuezheng/redis,LongXQ/redis,neomantra/redis,guker/redis,ipmobiletech/redis,a-pavlov/redis,Wangyao14cyy/redis,nuxeh/redis,rouzier/redis,linfangrong/redis,pkdevbox/redis,cloudrain21/redis,Sciumo/redis,wangyikai/redis,Markgorden/redis,huyuezheng/redis,timothyohare/3rdPartySrc-redis,charsyam/redis,antirez/redis,shreesundara/redis,simplestbest/redis,rogerchina/redis,hornen/redis,itugs/redis,cloudrain21/redis,kensou97/redis,brg-liuwei/redis,nnog/redis,wprice/redis,YuanZhewei/redis,Aliceljm1/redis,a-pavlov/redis,mgk/redis,dreamquster/redis,atreeyang/redis,csuhawk/redis,charsyam/redis,devaos/redis,arijitvt/redis,MasahikoSawada/redis,mumingv/redis,jackyan/redis,flashbuckets/redis,fengshao0907/redis,ipmobiletech/redis,simplestbest/redis,ErikDubbelboer/redis,yossigo/redis,harrisonfeng/redis,qiyang0221/redis,GitHubMota/redis,timothyohare/3rdPartySrc-redis,kaushik94/redis,neomantra/redis,yuhc/redis-benchmark-enhanced,roth1002/redis,ipmobiletech/redis,huyuezheng/redis,SyntaxStacks/redis,gaoxianglong/redis,Markgorden/redis,z-fork/redis,dreamquster/redis,iandyh/redis,AALEKH/redis,SummonY/redis,seppo0010/redis,rogerlz/redis,wbailey5/redis,csuhawk/redis,SummonY/redis,mumingv/redis,oranagra/redis,z-fork/redis,riyan8250/redis,a-pavlov/redis,soveran/redis,modulexcite/redis,hawkchch/redis,tanghaodong25/redis,cusspvz/redis,oranagra/redis,zhiliaoniu/redis,programmecat/redis,CodeJuan/redis,GrimDerp/redis,guker/redis,badboy/redis,jasonkying/redis,timothyohare/3rdPartySrc-redis,qiyang0221/redis,zhiliaoniu/redis,cusspvz/redis,PKRoma/redis,yossigo/redis,hawkchch/redis,janekmi/redis,StevenTsai/redis,july2993/redis,ctripcorp/redis,colstrom/redis,abhiklodh/redis,vincent-vivian-liu/redis,francischan714/redis,duanx/redis,SummonY/redis,GrimDerp/redis,CodeJuan/redis,takeshineshiro/redis,NBSW/redis,ofirluzon/redis,mumingv/redis,rogerlz/redis,ituncle/redis,twskipper/redis,badboy/redis,supasate/redis,GitHubMota/redis,healerkx/redis,ctripcorp/redis,SummonY/redis,nuxeh/redis,cnbin/redis,flashbuckets/redis,netroby/redis,cusspvz/redis,ouyangkongtong/redis,modulexcite/redis,tanghaodong25/redis,soveran/redis,Aliceljm1/redis,ofirluzon/redis,ErikDubbelboer/redis,iandyh/redis,tjschuck/redis,badboy/redis,vincent-vivian-liu/redis,wangyikai/redis,xujunhai1991/redis,janekmi/redis,LongXQ/redis,valdsJohn/redis,zhcy/redis,cnbin/redis,holstvoogd/redis,antirez/redis,davidradunz/redis,YuanZhewei/redis,seppo0010/redis,pmem/redis,alenslan/redis,kmiku7/redis,thomasdarimont/redis,hgl888/redis,kmiku7/redis,badboy/redis,yossigo/redis,mumingv/redis,PKRoma/redis,blackmady/redis,jingjidejuren/redis,Wangyao14cyy/redis,qiyang0221/redis,OmarQunsul/graph-redis,pcarrier/redis,july2993/redis,Soledad89/redis,takeshineshiro/redis,hawkchch/redis,MasahikoSawada/redis,universsky/redis,spinlock/redis,francischan714/redis,brg-liuwei/redis,allengaller/redis,neomantra/redis,ton31337/redis,linfangrong/redis,YuanZhewei/redis,xujunhai1991/redis,harrisonfeng/redis,zhiliaoniu/redis,mingyaaaa/redis,nnog/redis,rouzier/redis,fengshao0907/redis,zhiliaoniu/redis,spinlock/redis,healerkx/redis,ctripcorp/redis,pmem/redis,seppo0010/redis,modulexcite/redis,saisai/redis,janekmi/redis,SyntaxStacks/redis,PKRoma/redis,pedigree/redis,jackyan/redis,blackmady/redis,yossigo/redis,z-fork/redis