select文の内部実装見つけました GeekGig #1, AUG 11 2021 さき(H.Saki) @saki-engineer

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TFMFDUจͰ͸ɺதʹDBTFจΛॻ͘͜ͱͰॲཧͷ෼ذΛ࣮ݱ͍ͯ͠Δɻ Select statements select文 var i1, i2 int var ch1, ch2 chan int select { case i1 = <-ch1: print("received ", i1, " from c1∖n") case ch2 <- i2: print("sent ", i2, " to c2∖n") default: print("no communication∖n") } νϟωϧDI͔Βͷड৴͕Մೳͳͱ͖࣮ߦ νϟωϧDI΁ͷૹ৴͕Մೳͳͱ͖࣮ߦ ͍ͣΕͰ΋ͳ͍৔߹ʹ࣮ߦ EFGBVMUDBTF͕ͳ͚Ε͹ϒϩοΫ

runtime/select.go runtime/select.go ߦ໨ʹʮ͜ͷϑΝΠϧʹ͸TFMFDUจͷ࣮૷ؚ͕·Ε͍ͯ·͢ʯͱͷهࡌ͋Γ

runtime/select.go runtime/select.go TFMFDUจຊମͷهड़͸ɺ-ͷ GVOD TFMFDUHP ͰߦΘΕ͍ͯΔɻ // selectgo implements the select statement. func selectgo(cas0 *scase, order0 *uint16, pc0 *uintptr, nsends, nrecvs int, block bool) (int, bool) { // (略) // 400行くらいある }

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Implementation of select statement select文の実装 ϒϩοΫ͠ͳͯ͘Α͍৔߹͔Β࣮૷͍ͯ͠Δ͜ͱ͕֬ೝͰ͖Δɻ TFMFDU͢Δର৅ͷத͔Βૹड৴Ͱ͖Δ νϟωϧ͕ͳ͍͔Λ୳͍ͯ͠ΔͬΆ͍ l νϟωϧ͔Βड৴ՄˠSFDW l όοϑΝ͔Βड৴ՄˠCVGSFDW l νϟωϧDMPTFࡁΈˠSDMPTF ͔ͳʁͱ͍͏Ծઆ͕༰қʹཱͭ

Implementation of select statement select文の実装 ͦͷ࣍ʹɺϒϩοΫʹೖΔ৔߹ͷॲཧΛॻ͍͍ͯΔɻ ૹड৴Ͱ͖Δνϟωϧ͕ͳ ͔ͬͨͱ͖ͷॲཧ͔ͳʁ HPQBSLؔ਺ͰҎԼͷॲཧΛ࣮ߦ͠ɺTFMFDUจͷCMPDLΛ࣮ݱ TFMFDUจΛ࣮ߦ͍ͯ͠Δΰʔϧʔνϯͷঢ়ଶΛSVOOJOH͔ΒXBJUJOHʹมߋ ֘౰ΰʔϧʔνϯΛεϨου͔ΒҰ୴੾Γ཭͢

Summary まとめ l TFMFDUจຊମͷ࣮૷͸SVOUJNFTFMFDUHPͷதͷTFMFDUHPؔ਺ ○ େମͷ(Pͷجװػೳ͸SVOUJNFύοέʔδͷதʹ͋Δ l ίʔυΛૉ௚ʹಡΈղ͔ͳͯ͘΋ɺ࣮૷ͷେ࿮Λ୳Δ͜ͱ͸Ͱ͖Δ ख͕͔ΓʹͳΔͷ͸ҎԼ ○ ίϝϯτ ○ ม਺ɾఆ਺ɾؔ਺໊ ○ ߏ଄ମͷϑΟʔϧυ໊ ○ ϥϕϧ໊ l ΈΜͳSVOUJNFύοέʔδΛಡ΋͏;&ˑ

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