Kotlin Coroutinesで共有リソースに正しくアクセスする

by Mori Atsushi

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.PSJ"UTVTIJ ,PUMJO$PSPVUJOFTͰ   ڞ༗Ϧιʔεʹਖ਼͘͠ΞΫηε͢Δ ,PUMJO'FTU ,PUMJOݴޠɾϓϩάϥϛϯά

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LINEϠϑʔגࣜձࣾ / Android  2019೥౓ ະ౿εʔύʔΫϦΤʔλ Mori Atsushi X: @at_sushi_at IUUQTHJUIVCDPNNPSJBUTVTIJ

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$PSPVUJOFͷىಈ

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ࠓճͷΰʔϧ Kotlin CoroutinesΛ࢖ͬͯɺ  ࣗ৴Λ࣋ͬͯڞ༗ϦιʔεΛѻ͑ΔΑ͏ʹ͢Δ 1. ڝ߹ঢ়ଶ͕ൃੜ͢Δཧ༝ͱղܾํ๏ 2. ୯ҰεϨουͷࡍʹؾΛ͚ͭΔ΂͖఺ 3. ԋश໰୊ 🚀

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ڝ߹ঢ়ଶ͕ൃੜ͢Δཧ༝ͱ  ղܾํ๏ 1

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࠶ܝ

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஋ΛಡΈऔͬͯॻ͖ࠐΉ

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ݪҼɿಉ࣌ʹߋ৽͕૸Δ J εϨου εϨου UFNQ UFNQ J J

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ϒϩοΫ಺͸ಉ࣌ʹ͔ͭ͠ॲཧ͞Εͳ͍

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MutexʹΑΔϩοΫ J εϨου εϨου UFNQ UFNQ J NVUFY ϩοΫ J ϩοΫղআ ϩοΫதͷͨΊ଴ػ ϩοΫղআ ϩοΫ

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૿΍ͨ͠΋ͷΛฦؔ͢਺ εϨου҆શͳ*OUFHFS ѻ͍͍ͨσʔλʹରԠͨ͠λΠϓ͕ଘࡏ͠ͳ͍৔߹͸࢖͑ͳ͍ ,PUMJO/BUJWFͰ͸"UPNJD*OU͕࢖͑Δ

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ϒϩοΫ಺͸ಉ࣌ʹ͔ͭ͠ॲཧ͞Εͳ͍

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ؔ਺͸ಉ࣌ʹ͔̍ͭ͠ॲཧ͞Εͳ͍

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MutexͱSynchronizedͷҧ͍ MutexɿϒϩοΫ͞Ε͍ͯΔؒɺͦͷCoroutine͸தஅঢ়ଶʹͳΔ SynchronizedɿϒϩοΫ͞Ε͍ͯΔؒɺεϨουΛઐ༗͠ଓ͚Δ CoroutinesΛ࢖͍ͬͯΔ৔߹ → Mutex  suspendͰͳ͍ؔ਺ → Synchronized

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ෳ਺ͷεϨουͰಉ͡ϦιʔεΛ  ѻ͏৔߹ɿ  - AtomicInteger౳ͷεϨου҆શͳ  λΠϓΛ࢖͏ - Mutex΍SynchronizedͰϩοΫ͢Δ 💡

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୯ҰεϨουͷࡍʹ  ؾΛ͚ͭΔ΂͖఺ 2

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Dispatcherͷछྨ Dispatchers.Main: UIॲཧ Dispatchers.Default: όοΫάϥϯυॲཧ  Dispatchers.IO: ωοτϫʔΫ΍DBΞΫηε౳

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Dispatcherͷछྨ Dispatchers.Main: UIॲཧ Dispatchers.Default: όοΫάϥϯυॲཧ  Dispatchers.IO: ωοτϫʔΫ΍DBΞΫηε౳ εϨου ෳ਺εϨου ෳ਺εϨου

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εϨου͔ͩΒڝ߹ঢ়ଶ͸ى͖ͳ͍ʁ

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ճݺ͹ΕΔ

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ݪҼɿFetchதʹॲཧ͞ΕΔͨΊ MBTU'FUDIFE"U.JMMJT $PSPVUJOF $PSPVUJOF GFUDI ʜ GFUDI ʜ

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౓ͷΈݺ͹ΕΔ ϩοΫͯ͠ಉ࣌ʹ࣮ߦ͞Εͳ͍Α͏ʹ͢Δ

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౓ͷΈݺ͹ΕΔ 4VTQFOEؔ਺ͷݺͼग़͠લʹߋ৽͢Δ ϝΠϯεϨου͔Βݺͼग़͢ඞཁ͕͋Δ͜ͱΛ໌ࣔ BOESPJEYBOOPUBUJPO

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ίϯύΠϧΤϥʔ suspendؔ਺ʹSynchronized͸࢖͑ͳ͍

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୯ҰεϨουͰಉ͡ϦιʔεΛ  ѻ͏৔߹ɿ  - ಡΈࠐΈͱॻ͖ࠐΈͷؒʹsuspend ؔ਺͕ೖΔ৔߹ʹ஫ҙ͕ඞཁ - MutexͰϩοΫՄೳ 💡

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ԋश໰୊ 3

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ෳ਺εϨουͰݺͼग़͍ͨ͠ ԋश̍

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.VUFYͰϩοΫ͢Δ

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εϨου҆શͳ   .VUBCMF4UBUF'MPXVQEBUF Λ࢖͏

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GVODUJPO͸ෳ਺ճ   ݺͼग़͞ΕΔՄೳੑ͕͋Δ function಺ʹ෭࡞༻Λ࣋ͨͤͯ͸͍͚ͳ͍

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FNJU͸ ෳ਺εϨου͔Β҆શʹݺͼग़ͤΔ ͜͜͸ಉ͡εϨουʹͳΔ $IBOOFMͰ΋Մ

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ԋश2 TVTQFOEGVODUJPO

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.VUFYͰϩοΫ͢Δ

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.VUFYͰϩοΫ͢Δ ҟͳΔIDͷϢʔβʔΛಉ࣌ʹऔಘͰ͖ͳ͍

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*%͝ͱʹϩοΫΛ࡞੒͢Δ *%͝ͱͷϩοΫΛऔಘ͢ΔͨΊʹ   ϩοΫ͢Δඞཁ͕͋Δ

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%FGGFSFEΛ࡞Δ͚ͩͳͷͰTVTQFOEঢ়ଶʹͳΒͳ͍ ΞϓϦέʔγϣϯείʔϓͷ$PSPVUJOF4DPQF 6TFSͷ୅ΘΓʹ%FGGFSFEΛอ࣋͢Δ .BQͷૢ࡞͸ϩοΫதʹߦ͏

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εϨου҆શͳ.VUBCMF.BQ IUUQTHJUIVCDPNUPVDIMBC4UBUFMZ +7.ͳΒ$PODVSSFOU)BTI.BQ͕࢖͑Δ

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ඇಉظॲཧ͸૝૾Ҏ্ʹෳࡶ  - Ͱ͖Δ͚ͩ1εϨουͰѻ͑ΔΑ͏ʹ͢Δ - ෳ਺Coroutine͔ΒΞΫηε͞ΕΔڞ༗ Ϧιʔε͸Ͱ͖Δ͚ͩݮΒ͢ - ෳ਺ͷղܾࡦ͔Βγϯϓϧͳ΋ͷΛબͿ 🚀