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(JUͷ಺෦σʔλߏ଄ 4IVIFJ,BHBXB .5FDI5BML

MTHJU '&5$)@)&"% )&"% DPOpH EFTDSJQUJPO IPPLT JOEFY JOGP MPHT PCKFDUT
QBDLFESFGT SFGT

USFFHJUPCKFDUT HJUPCKFDUT ᵓᴷᴷ ᴹᵋᴷᴷDGBFCCFG⒎DGFCGC ᵓᴷᴷ ᴹᵋᴷᴷCECBFDBFFFD⒎FG ᴹᵋᴷᴷEECCFBFECFDEB ᵓᴷᴷF ᴹᵋᴷᴷFFBFBEGGFCDFGD ᵓᴷᴷFC
ᴹᵋᴷᴷGGGFGEGECBBCBBGCFBCF ᵓᴷᴷJOGP ᵋᴷᴷQBDL

HJUPCKFDUT w ϑΝΠϧγεςϜΛར༻ͨ͠,FZ7BMVF4UPSFɻ w Ωʔ͸஋ͷ4)"ϋογϡɻ্ܻʢCZUFʣ͕ σΟϨΫτϦ໊ɺ࢒Γ͕ϑΝΠϧ໊ɻ DGBFCCFG⒎DGFCGC σΟϨΫτϦ໊ CZUF
ϑΝΠϧ໊ CZUF

PCKFDUͷछྨ CMPC USFF DPNNJU ϑΝΠϧͷத਎ σΟϨΫτϦ ͷΑ͏ͳ΋ͷ ͍ΘΏΔίϛοτ

PCKFDUͷߏ଄ CMPC a QVUT)FMMP 8PSMEaO PCKFDUͷ छྨ ۭന αΠζ
ψϧ จࣈ σʔλ 4)"ϋογϡ ϑΝΠϧ໊ ϑΝΠϧͷத਎ [MJCѹॖ ϔομ

HJUDBUpMFQTIBIBTI

CMPC QVUT)FMMP 8PSMEaO w ϑΝΠϧͷத਎ʮ͚ͩʯ͍࣋ͬͯΔɻ w ϑΝΠϧͷ໊લ͸͍࣋ͬͯͳ͍ɻ

USFF IFMMPKTa4)"ϋογϡʢόΠφϦʣ IFMMPSCa4)"ϋογϡʢόΠφϦʣ w USFFͱCMPCͷҰཡɻ w ֤ߦ͸໊લ΍ϞʔυʢύʔϛογϣϯʣΛ͍࣋ͬͯΔɻ w ຊ౰͸վߦͳ͠ɻ

DPNNJU USFFFBGD⒎FBBDFDDGEF BVUIPS4IVIFJ,BHBXBTIVIFJLBHBXB!HNBJMDPN DPNNJUUFS4IVIFJ,BHBXBTIVIFJLBHBXB!HNBJMDPN )FMMP 8PSME w USFF΁ͷࢀরΛҰ͍ͭ࣋ͬͯΔɻ
w ͋ͱ͸ॻ͍ͨਓͱίϛοτͨ͠ਓɺίϛοτϝοηʔδɻ

֤PCKFDUͷؔ܎ CMPC USFF DPNNJU CMPC IFMMPSC (FNpMF *OJUJBMDPNNJU

֤PCKFDUͷؔ܎ CMPC USFF DPNNJU DPNNJU USFF CMPC IFMMPSC
(FNpMF USFF MJC IFMMPSC (FNpMF *OJUJBMDPNNJU IFMMPSCΛMJC ʹೖΕͨ

֤PCKFDUͷؔ܎ CMPC USFF DPNNJU DPNNJU DPNNJU USFF
USFF CMPC IFMMPSC (FNpMF USFF CMPC MJC MJC IFMMPSC (FNpMF (FNpMF *OJUJBMDPNNJU IFMMPSCΛMJC ʹೖΕͨ ར༻ϥΠϒϥϦ Λߋ৽

Θ͔Δ͜ͱ w DPNNJU͚ͩͰ͸ͳ͘CMPC USFF΋4)"ϋογϡ Λ͍࣋ͬͯΔɻ w มΘΒͳ͍CMPC USFF͸USFF DPNNJUؒͰڞ༗͞Ε Δɻ
w ϑΝΠϧɾσΟϨΫτϦ໊͸CMPC USFFࣗ਎Ͱ͸ͳ ͘਌ͷUSFF͕͍࣋ͬͯΔɻ

HJUSFGT w HJUSFGTIFBETNBTUFSͱ͔HJUSFGTUBHTWͱ͔ɻ w DPNNJUͷ4)"ϋογϡ͕ॻ͍ͯ͋Δ͚ͩɻ

HJUJOEFY w ࣍ͷDPNNJUʢͷUSFFʣΛ࡞ΔͨΊͷ৘ใ͕Ωϟογϡ͞Ε͍ͯΔɻ w มߋ͞ΕͨϑΝΠϧ͚ͩͰ͸ͳ͘શϑΝΠϧ͕ೖ͍ͬͯΔɻ w HJUMTpMFTͰ͸ݟ͑ͳ͍͕ɺ࠷ऴߋ৽೔࣌ͳͲ΋ೖ͍ͬͯΔɻ HJUMTpMFTTUBHF DDGEFECGCDBFDBECDCIFMMPKT D⒎BBFGDEEBGCE
IFMMPSC

ͦ͏͍͑͹ɾɾɾ w େ͖ͳϑΝΠϧʹҰߦ଍ͨ͠ΒɺผͷCMPC͕Ͱ͖ Δɻ w ͋Εɺ(JUͬͯϑΝΠϧΛࠩ෼Ͱ࣋ͬͯͳ͍ͷʁ

CFGPSF HJUPCKFDUT ᵓᴷᴷ ᴹᵋᴷᴷDGBFCCFG⒎DGFCGC ᵓᴷᴷ ᴹᵋᴷᴷDEBGEBFGDE ᵓᴷᴷ ᴹᵋᴷᴷCECBFDBFFFD⒎FG ᵓᴷᴷC ᴹᵋᴷᴷGFGFCECBFFGBFC
ᵓᴷᴷDD ᴹᵋᴷᴷGEFECGCDBFDBECDC ᵓᴷᴷE ᴹᵋᴷᴷGCDDEDEGDGFG ᵓᴷᴷEC ᴹᵋᴷᴷEECCFBFECFDEB ᵓᴷᴷF ᴹᵋᴷᴷFFBFBEGGFCDFGD ᵓᴷᴷFB ᴹᵋᴷᴷGD⒎FBBDFDDGEF ᵓᴷᴷFC ᴹᵋᴷᴷGGGFGEGECBBCBBGCFBCF ᵓᴷᴷJOGP ᵋᴷᴷQBDL HJUPCKFDUT ᵓᴷᴷJOGP ᴹᵋᴷᴷQBDLT ᵋᴷᴷQBDL ᵓᴷᴷQBDLFDGDGBFBBGBCFECFGGJEY ᵋᴷᴷQBDLFDGDGBFBBGBCFECFGGQBDL BGUFS

1BDLpMF w JEYͱQBDLͷϖΞɻQBDL͕ຊମͰJEY͕ΠϯσοΫ εɻ w ෳ਺ͷPCKFDU͕٧Ίࠐ·Ε͍ͯΔɻ w ඞཁʹԠͯ͡CMPCΛࠩ෼Ͱอ࣋ɻ w HJUWFSJGZQBDLWHJUPCKFDUTQBDLQBDLYYYJEYͰϦε
τ͕ݟΕΔɻ

QMVNCJOHDPNNBOET w HJUDBUpMF w HJUMTUSFF HJUNLUSFF HJUDPNNJUUSFF w HJUSFBEJOEFY HJUXSJUFJOEFY
HJUDPNNJUJOEFY

ࢀߟ w 1SP(JU(JU*OUFSOBMT  IUUQTHJUTDNDPNCPPLFOW w (JU$PNNVOJUZ#PPL*OUFSOBMTBOE1MVNCJOH  IUUQTTDIBDPOHJUIVCJPHJUCPPLJOEFYIUNM w HJU%PDVNFOUBUJPOUFDIOJDBM  IUUQTHJUIVCDPNHJUHJUUSFFNBTUFS%PDVNFOUBUJPOUFDIOJDBM

Git の内部データ構造

Git の内部データ構造

Shuhei Kagawa

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(JUͷ಺෦σʔλߏ଄ 4IVIFJ,BHBXB .5FDI5BML

MTHJU '&5$)@)&"% )&"% DPOpH EFTDSJQUJPO IPPLT JOEFY JOGP MPHT PCKFDUT

USFFHJUPCKFDUT HJUPCKFDUT ᵓᴷᴷ ᴹᵋᴷᴷDGBFCCFG⒎DGFCGC ᵓᴷᴷ ᴹᵋᴷᴷCECBFDBFFFD⒎FG ᴹᵋᴷᴷEECCFBFECFDEB ᵓᴷᴷF ᴹᵋᴷᴷFFBFBEGGFCDFGD ᵓᴷᴷFC

HJUPCKFDUT w ϑΝΠϧγεςϜΛར༻ͨ͠,FZ7BMVF4UPSFɻ w Ωʔ͸஋ͷ4)"ϋογϡɻ্ܻʢCZUFʣ͕ σΟϨΫτϦ໊ɺ࢒Γ͕ϑΝΠϧ໊ɻ DGBFCCFG⒎DGFCGC σΟϨΫτϦ໊ CZUF

PCKFDUͷछྨ CMPC USFF DPNNJU ϑΝΠϧͷத਎ σΟϨΫτϦ ͷΑ͏ͳ΋ͷ ͍ΘΏΔίϛοτ

PCKFDUͷߏ଄ CMPC a QVUT)FMMP 8PSMEaO PCKFDUͷ छྨ ۭന αΠζ

HJUDBUpMFQTIBIBTI

CMPC QVUT)FMMP 8PSMEaO w ϑΝΠϧͷத਎ʮ͚ͩʯ͍࣋ͬͯΔɻ w ϑΝΠϧͷ໊લ͸͍࣋ͬͯͳ͍ɻ

USFF IFMMPKTa4)"ϋογϡʢόΠφϦʣ IFMMPSCa4)"ϋογϡʢόΠφϦʣ w USFFͱCMPCͷҰཡɻ w ֤ߦ͸໊લ΍ϞʔυʢύʔϛογϣϯʣΛ͍࣋ͬͯΔɻ w ຊ౰͸վߦͳ͠ɻ

DPNNJU USFFFBGD⒎FBBDFDDGEF BVUIPS4IVIFJ,BHBXBTIVIFJLBHBXB!HNBJMDPN DPNNJUUFS4IVIFJ,BHBXBTIVIFJLBHBXB!HNBJMDPN )FMMP 8PSME w USFF΁ͷࢀরΛҰ͍ͭ࣋ͬͯΔɻ

֤PCKFDUͷؔ܎ CMPC USFF DPNNJU CMPC IFMMPSC (FNpMF *OJUJBMDPNNJU

֤PCKFDUͷؔ܎ CMPC USFF DPNNJU DPNNJU USFF CMPC IFMMPSC

֤PCKFDUͷؔ܎ CMPC USFF DPNNJU DPNNJU DPNNJU USFF

Θ͔Δ͜ͱ w DPNNJU͚ͩͰ͸ͳ͘CMPC USFF΋4)"ϋογϡ Λ͍࣋ͬͯΔɻ w มΘΒͳ͍CMPC USFF͸USFF DPNNJUؒͰڞ༗͞Ε Δɻ

HJUSFGT w HJUSFGTIFBETNBTUFSͱ͔HJUSFGTUBHTWͱ͔ɻ w DPNNJUͷ4)"ϋογϡ͕ॻ͍ͯ͋Δ͚ͩɻ

HJUJOEFY w ࣍ͷDPNNJUʢͷUSFFʣΛ࡞ΔͨΊͷ৘ใ͕Ωϟογϡ͞Ε͍ͯΔɻ w มߋ͞ΕͨϑΝΠϧ͚ͩͰ͸ͳ͘શϑΝΠϧ͕ೖ͍ͬͯΔɻ w HJUMTpMFTͰ͸ݟ͑ͳ͍͕ɺ࠷ऴߋ৽೔࣌ͳͲ΋ೖ͍ͬͯΔɻ HJUMTpMFTTUBHF DDGEFECGCDBFDBECDCIFMMPKT D⒎BBFGDEEBGCE

ͦ͏͍͑͹ɾɾɾ w େ͖ͳϑΝΠϧʹҰߦ଍ͨ͠ΒɺผͷCMPC͕Ͱ͖ Δɻ w ͋Εɺ(JUͬͯϑΝΠϧΛࠩ෼Ͱ࣋ͬͯͳ͍ͷʁ

HJUHD

CFGPSF HJUPCKFDUT ᵓᴷᴷ ᴹᵋᴷᴷDGBFCCFG⒎DGFCGC ᵓᴷᴷ ᴹᵋᴷᴷDEBGEBFGDE ᵓᴷᴷ ᴹᵋᴷᴷCECBFDBFFFD⒎FG ᵓᴷᴷC ᴹᵋᴷᴷGFGFCECBFFGBFC

1BDLpMF w JEYͱQBDLͷϖΞɻQBDL͕ຊମͰJEY͕ΠϯσοΫ εɻ w ෳ਺ͷPCKFDU͕٧Ίࠐ·Ε͍ͯΔɻ w ඞཁʹԠͯ͡CMPCΛࠩ෼Ͱอ࣋ɻ w HJUWFSJGZQBDLWHJUPCKFDUTQBDLQBDLYYYJEYͰϦε

QMVNCJOHDPNNBOET w HJUDBUpMF w HJUMTUSFF HJUNLUSFF HJUDPNNJUUSFF w HJUSFBEJOEFY HJUXSJUFJOEFY

ࢀߟ w 1SP(JU(JUOUFSOBMT  IUUQTHJUTDNDPNCPPLFOW w (JU$PNNVOJUZ#PPLOUFSOBMTBOE1MVNCJOH  IUUQTTDIBDPOHJUIVCJPHJUCPPLJOEFYIUNM w HJU%PDVNFOUBUJPOUFDIOJDBM  IUUQTHJUIVCDPNHJUHJUUSFFNBTUFS%PDVNFOUBUJPOUFDIOJDBM