Rustでon-diskなB+Treeを作ったときの細かな話

by KOBA789

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KOBA789 RustͰ on-diskͳB+TreeΛ   ࡞ͬͨͱ͖ͷ ࡉ͔ͳ࿩

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KOBA789 ݱࡏਐߦܗͰແ৬ ‣ 3VTUྺ͸೥͘Β͍ ‣ ී௨ʹ΢ΣϒαʔόʔΛॻ͍ͨΓ ‣ %#.4Λॻ͍ͨΓ ‣ ϒϥ΢βͰಈ͘ճ࿏$"%Λॻ͍ͨΓ   8"4.λʔήοτ ‣ ࣗ࡞ΩʔϘʔυͷ   ϑΝʔϜ΢ΣΞΛॻ͍ͨΓ   ͍ΘΏΔ૊ΈࠐΈ3VTU ͓͢͢Ίͷ࢓ࣄʹؔ͢Δ৘ใ͸   ͍ͭͰ΋׻ܴ͍ͯ͠·͢ https://gihyo.jp/magazine/wdpress/archive/2021/vol122 ʲະঝ୚޿ࠂʳࡶࢽʹهࣄॻ͖·ͨ͠

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RustͰ on-diskͳB+TreeΛ   ࡞ͬͨͱ͖ͷ ࡉ͔ͳ࿩ ࠓճͷλΠτϧ   ʢ࠶ܝʣ

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RustͰ on-diskͳB+TreeΛ   ࡞ͬͨͱ͖ͷ ࡉ͔ͳ࿩ ͱ͸ʁ

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RustͰ on-diskͳB+TreeΛ   ࡞ͬͨͱ͖ͷ ࡉ͔ͳ࿩ ͱ͸ʁ " ಺༰ΛσΟεΫʹӬଓԽͰ͖ͨΓɺ   ϝϞϦΑΓେ͖ͳ಺༰ΛσΟεΫ্Ͱѻ͑ͨΓ͢Δ   #5SFF ˞ಠࣗͷఆٛͰ͢

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ͜͏͍͏#5SFFΛߟ͑Δ

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ͱΓ͋͑ͣ࣍ݩʹͭͿ͢

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σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ σΟεΫ͕͋Δͱ͢Δ

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σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ σΟεΫʹೖͬͨ

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σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU #5SFFΛૢ࡞͍ͨ͠

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σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU #5SFFΛૢ࡞͍ͨ͠ σΟεΫΛ௚઀ಡΈॻ͖͢Δͷ͸஗͍͠ෆศ

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ϝϞϦ σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU ϝϞϦʹόοϑΝΛ༻ҙ

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ϝϞϦ σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU

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ϝϞϦ σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU ϊʔυͷҰ෦ΛϝϞϦ΁

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ϝϞϦ σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU ಡΈॻ͖ ೖΕସ͑ όοϑΝϓʔϧϚωʔδϟ

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ Ұ෦ͷϊʔυͷΈ͕ϝϞϦʹ͋Δ#5SFFͱ͍͑Δ ന͍ϊʔυ͸σΟεΫʹ͔͠ͳ͍

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ϝϞϦ σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU ಡΈॻ͖ ೖΕସ͑ ͱ͜ΖͰɺ

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ϝϞϦ σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU ಡΈॻ͖ ೖΕସ͑ ϚϧνίΞΛ׆༻͍ͨ͠Ͱ͢ΑͶʁ CPU CPU CPU

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ϝϞϦ σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU ར༻தͷϊʔυΛόοϑΝ͔Β௥͍ग़ͨ͠Γ͢Δͱ͍ͨ΁Μͳ͜ͱʹ CPU CPU CPU ΛಡΈ͍ͨɻΛ௥͍ग़ͦ͏ ଴ͯίϥ ϊʔυ ར༻த

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ϝϞϦ σΟεΫʢϑΝΠϧʣ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU ར༻தͷϊʔυΛόοϑΝ͔Β௥͍ग़ͨ͠Γ͢Δͱ͍ͨ΁Μͳ͜ͱʹ CPU CPU CPU ΛಡΈ͍ͨɻΛ௥͍ग़ͦ͏ ଴ͯίϥ ϊʔυ ར༻த ͜ͷ΁Μͷ   σʔλߏ଄ɾΞϧΰϦζϜΛ   3VTUͰͲ͏͢Δ͔ POEJTLಛ༗ͷ೉͕͋͠͞Δ

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3VTUͰPOEJTLͳ#5SFFΛ࡞Δͱ͖ͷݒ೦ࣄ߲ w όοϑΝϓʔϧϚωʔδϟͷ   σʔλߏ଄ͱΞϧΰϦζϜ w #5SFFͷϊʔυͷσʔλߏ଄ w #5SFFͷഉଞ੍ޚ

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όοϑΝϓʔϧϚωʔδϟͷ   σʔλߏ଄ͱΞϧΰϦζϜ

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ར༻தͷϊʔυΛอޢ͢Δʹ͸ $.6ͷߨٛͰ࢖ΘΕ͍ͯΔ#VT5VC $ ͱ͍͏࣮૷ͷ৔߹ ϊʔυʢϖʔδʣ಺ʹΧ΢ϯλΛ   ࣋ͬͯ؅ཧ͍ͯ͠Δ https://github.com/cmu-db/bustub/blob/master/src/include/storage/page/page.h ϐϯ 1JO ͸ʮར༻தʯͷҙຯ ˞3VTUͷ1JOͱ͸ؔ܎ͳ͍

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3VTUͰ͸Ͳ͏͢Δ͔ Ҋ$ಉ༷ʹΧ΢ϯλͰอޢ w ڞ༗ϝϞϦΛॻ͖׵͑ΔͨΊɺ   ౰વͷΑ͏ʹVOTBGF͕ొ৔ w ઈରʹόάΒͤΔࣗ৴͔͠ͳ͍ w ͜ΕͳΒ$Ͱॻ͚͹͍͍ w ଈߦͰϘπ

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3VTUͰ͸Ͳ͏͢Δ͔ Ҋ3X-PDLͰอޢ w ར༻த͸4IBSFEMPDLΛ͓࣋ͬͯ͘ w ௥͍ग़ͨ͘͠ͳͬͨΒ&YDMVTJWFMPDLΛऔΔ w (VBSEܥͷߏ଄ମ͸TUBUJD͡Όͳ͍ͷͰ   औΓճ͕͠ѱ͍

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3VTUͰ͸Ͳ͏͢Δ͔ Ҋ"SDͰอޢ w "SDʹ͸HFU@NVU NVU"SD5 ͱ͍͏   ϝιου͕͋Δ w ࢀরΧ΢ϯλ͕ͷͱ͖ʹ͚ͩNVU5͕औΕΔ w όοϑΝϓʔϧͷʮϐϯʯͱ૬ੑ͕Αͦ͞͏ͳػೳ w ͨͩ͠Ϩγʔό͸NVU w όοϑΝϓʔϧશମΛอޢ͢Δ.VUFY͕͋ΔͷͰ   Մมࢀর͕औΕΔ

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#5SFFͷϊʔυͷ   σʔλߏ଄

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#5SFFͷϊʔυͷߏ଄ ૉ๿ʹ΍Δͱɺ͜͏

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⚠ϊʔυ͸σΟεΫʹ   ॻ͖ग़ͤͳ͚Ε͹ͳΒͳ͍ ΋ͪΖΜɺಡΈग़͠΋Ͱ͖ͳ͚Ε͹ͳΒͳ͍

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2ߏ଄ମΛσΟεΫʹ   ॻ͖ग़͍ͨ͠ͱ͖ɺͲ͏͢Δʁ

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2ߏ଄ମΛσΟεΫʹ   ॻ͖ग़͍ͨ͠ͱ͖ɺͲ͏͢Δʁ TFSEF

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2ߏ଄ମΛσΟεΫʹ   ॻ͖ग़͍ͨ͠ͱ͖ɺͲ͏͢Δʁ TFSEF γϦΞϥΠζޙͷσʔλ௕͕Θ͔Βͳ͍͠ ޮ཰΋ѱ͍ͷͰμϝ

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2ߏ଄ମΛσΟεΫʹ   ॻ͖ग़͍ͨ͠ͱ͖ɺͲ͏͢Δʁ "ͦͷ··ॻ͖ग़ͤΔ   σʔλߏ଄Λ͕Μ͹࣮ͬͯ૷͢Δ

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ͦͷ··ॻ͖ग़ͤΔσʔλߏ଄ ৗʹݻఆ௕ͷόΠτྻͷΈʹऩ·Δσʔλߏ଄ ϊʔυ ͖ͬ͞ొ৔ͨ͠ϊʔυ͘Μ

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ͦͷ··ॻ͖ग़ͤΔσʔλߏ଄ ৗʹݻఆ௕ͷόΠτྻͷΈʹऩ·Δσʔλߏ଄ ,# ࣮͸͜͏͍͏େ͖͞

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ͦͷ··ॻ͖ग़ͤΔσʔλߏ଄ ৗʹݻఆ௕ͷόΠτྻͷΈʹऩ·Δσʔλߏ଄ ,# ,FZ 7BMVF ͜Ε͸,FZ7BMVFͷϖΞ

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ͦͷ··ॻ͖ग़ͤΔσʔλߏ଄ ৗʹݻఆ௕ͷόΠτྻͷΈʹऩ·Δσʔλߏ଄ ,# ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF ௕͞͸όϥόϥ

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ͦͷ··ॻ͖ग़ͤΔσʔλߏ଄ ৗʹݻఆ௕ͷόΠτྻͷΈʹऩ·Δσʔλߏ଄ ,# ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF ͜ΕΛͦͷ··ෑ͖٧ΊΔͱ

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ͦͷ··ॻ͖ग़ͤΔσʔλߏ଄ ৗʹݻఆ௕ͷόΠτྻͷΈʹऩ·Δσʔλߏ଄ ,# ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF Φϑηοτ͕౳ִؒͰ͸ͳ͍ͷͰೋ෼୳ࡧͰ͖ͳ͍

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ͦͷ··ॻ͖ग़ͤΔσʔλߏ଄ ৗʹݻఆ௕ͷόΠτྻͷΈʹऩ·Δσʔλߏ଄ ,# ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF ࢓੾Γ௚͠

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ͦͷ··ॻ͖ग़ͤΔσʔλߏ଄ ৗʹݻఆ௕ͷόΠτྻͷΈʹऩ·Δσʔλߏ଄ ,# ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF ,FZ7BMVF͸ޙΖʹ٧Ίͯ

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ͦͷ··ॻ͖ग़ͤΔσʔλߏ଄ ৗʹݻఆ௕ͷόΠτྻͷΈʹऩ·Δσʔλߏ଄ ,# 1US ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF 1US 1US ݻఆ௕ͷϙΠϯλΛ಄ʹฒ΂Δ

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ͦͷ··ॻ͖ग़ͤΔσʔλߏ଄ ৗʹݻఆ௕ͷόΠτྻͷΈʹऩ·Δσʔλߏ଄ ,# 1US ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF 1US 1US ͜ΕΛ3VTUͰॻ͘

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ͱ͜ΖͰ͜ΕΛͲ͏΍ͬͯ   Ωϟετ͢Δͷ͔

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std::mem::transmute

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std::mem::transmute ͦΜͳةݥͳ΋ͷ࢖͏Θ͚ͳ͍

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ศརDSBUFl[FSPDPQZz ΞϥΠϝϯτͳͲΛߟྀͯ҆͠શʹܕΩϟετͰ͖Δ w (PPHMFͷ'VDITJBͰ࢖ΘΕ͍ͯΔͬΆ͍ w ࢖͍ํʹ͔ͳΓΫη͕͋Δ w υΩϡϝϯτ͸ۃΊͯগͳ͍ w αϯϓϧίʔυ͸'VDITJBͷωοτϫʔΫελοΫ

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LayoutVerifiedͱ͍͏   εϚʔτϙΠϯλܦ༝Ͱૢ࡞͢Δ new_from_prefixϝιου͸   ϔομͱϘσΟʹ෼͔Ε͍ͯΔ   σʔλߏ଄ʹ࢖͑Δ

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1US ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF 1US 1US OVN@TMPUT IFBEFS CPEZ

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new_sliceϝιουͰ   ϙΠϯλͷεϥΠεΛ੾Γग़͍ͯ͠Δ

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1US ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF 1US 1US OVN@TMPUT QPJOUFST IFBEFS CPEZ

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1US ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF 1US 1US OVN@TMPUT QPJOUFST IFBEFS CPEZ ͜ͷਤΛΑ͘ݟͯ΄͍͠

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1US ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF 1US 1US OVN@TMPUT QPJOUFST IFBEFS CPEZ QPJOUFST͸CPEZΛआ༻͍ͯ͠Δ

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1US ,FZ 7BMVF ,FZ 7BMVF ,FZ 7BMVF 1US 1US OVN@TMPUT QPJOUFST IFBEFS CPEZ QPJOUFST͸CPEZΛआ༻͍ͯ͠Δ ͭ·Γɺ,FZ7BMVFϖΞΛมߋ͢Δͱ͖ʹ͸   ͍͍ͪͪQPJOUFSTΛख์͞ͳ͚Ε͹ͳΒͳ͍ ͩΔ͍   ʢ͔ͨ͠ͳ͠ʣ

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#5SFFͷഉଞ੍ޚ

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU CPU

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU CPU Modify Modify 💥 😩 😩

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU CPU ϩοΫ͸্͔ΒॱʹऔΔ

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϩοΫ͸্͔ΒॱʹऔΔ CPU CPU

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϩοΫ͸্͔ΒॱʹऔΔ CPU CPU

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϩοΫ͕औΕͨΒɺ্ͷϩοΫ͸ख์ͯ͠΋Α͍ CPU CPU

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ଞͷεϨου͕ಈ͚ͯฒྻ౓্͕͕Δ CPU CPU

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU CPU ಉ༷ʹଓ͚Δ

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ Լͷϊʔυ͕ᷓΕͦ͏ͳ৔߹͸ɺ্ͷϩοΫΛख์ͯ͠͸ͳΒͳ͍   ʢॻ͖ࠐΈͷ৔߹ʣ CPU CPU

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ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ ϊʔυ CPU CPU ͜ΕΛ3VTUͰ࣮૷͢Δ

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#5SFFͷഉଞ੍ޚ ૉ๿ʹ࣮૷

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#5SFFͷഉଞ੍ޚ ૉ๿ʹ࣮૷

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#5SFFͷഉଞ੍ޚ ૉ๿ʹ࣮૷ page:   Arc> ro_page:   RwLockReadGuard<_, Page> next_page:   Arc> ro_next_page:   RwLockReadGuard<_, Page> next_pageΛಈ͔͍͕ͨ͠ かといってRwLockReadGuardΛ   ख์͢Θ͚ʹ͸͍͔ͳ͍ ro_page͕pageΛɺ   ro_next_page͕next_pageΛ   ࢀর͍ͯ͠ΔͷͰಈ͔ͤͳ͍

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͜Ε͸Α͋͘Δ4UBCMF"EESFTT໰୊ "SDͷࢦ͢ϙΠϯλ͸ෆมͳΜ͔ͩΒNPWFͤͯ͘͞Ε w PXOJOH@SFGΫϨʔτͳͲͰ   ղܾ͕ࢼΈΒΕ͍ͯΔ w ࠓճ͸3X-PDL3FBE(VBSEʹ   ಛघͳϝιουΛੜ΍ͯ͠ճආ

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0XOFE3X-PDL3FBE(VBSE ΊͬͪΌVOTBGF͚ͩͲ͔ͨ͠ͳ͍

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