ECMAScriptの視点で見る WeakRefの“正しい”使い方

Ginza.js#7のLTです。

Transcript

1. &$."4DSJQUך鋔挿ד鋅׷
   8FBL3FGךˑ姻׃ְ˒⢪ְ倯
   (JO[BKT!VIZP@
   

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2. 荈䊹稱➜
   –ؿٗٝزؒٝسؒٝآص،!-*/&吳䒭⠓爡
   – +BWB4DSJQU娖䎃ֻ׵ְ
   –2JJUB蔓➂&$."4DSJQUةؚDPOUSJCVUJPO侧⡘
   – չ+BWB4DSJQUך \^׾椚鍑ׅ׷պ
   – չ➙ַ׵ד׮鷄ְאֽ׷ +BWB4DSJQUךչ垥彊ٓ؎ـٓٔպ׾㷕עպ
   – չ׉׹׉׹+BWB4DSJQUח䱰欽ׁ׸׉ֲז0QUJPOBM$IBJOJOH׾➙ׁ׵䗡䎿鍑铡պ זו
   !VIZP@
   

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3. !VIZP@
   5BCMFPG$POUFOUT
   8FBL3FGך䗁统
   &$."4DSJQUהؖك٦آ؝ؙٖءّٝךꟼ⤘
   8FBL3FGכ➬圫חוך״ֲח剅ַ׸׋ךַ
   8FBL3FGָ䧮ղח♷ִ׷⥂鏾כ⡦ַ
   

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4. !VIZP@
   8FBL3FGך䗁统
   –4UBHFفٗه٦ؠٕ
   –8FBL3FGؔـآؙؑزפך䓲⿫撑׾⡲䧭דֹ׷װא
   –'JOBMJ[BUJPO(SPVQؔـآؙؑزָؖك٦آ؝ؙٖز
   ׁ׸׋׵؝٦ٕغحؙㄎ׿דֻ׸׷װא
   ˟DG8FBL3FG+BWB4DSJQUח䓲⿫撑ָװ׏גֻ׷אְדח'JOBMJ[BUJPO׮ 2JJUB 㹑⠗
   

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5. !VIZP@
   8FBL3FGך⢽
   const ref = new WeakRef(new ArrayBuffer(1024 ** 3));
   console.log(ref.deref()); // ArrayBuffer
   setTimeout(()=> {
   gc();
   console.log(ref.deref()); // undefined
   }, 100);
   new WeakRef ⦼
   
   ד⦼פך䓲⿫撑׾⡲䧭
   䓲⿫撑ך⚥魦כderef
   ًاحسד铣׬
   ($ח״׏ג䓲⿫撑ָ
   ⥂䭯ׅ׷ؔـآؙؑز
   ָ嶊ִ׋
   

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6. !VIZP@
   8FBL3FGך⢽嶊ִזְ㜥さ
   const buf = new ArrayBuffer(1024 ** 3);
   const ref = new WeakRef(buf);
   console.log(ref.deref()); // ArrayBuffer
   console.log(ref.deref() === buf); // true
   setTimeout(()=> {
   gc();
   console.log(ref.deref()); // ArrayBuffer
   console.log(buf.byteLength); // 1073741824
   }, 100);
   㢌侧CVGח⦼׾Ⰵ׸׋
   䓲ֻזְ⿫撑
   䓲⿫撑ך⚥魦כ
   床׃׋⦼הずׄ
   ($䖓׮嶊ִגְזְ
   㢌侧buf׾鸐ׄג⦼ח
   ،ؙإأ〳腉זךד
   

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7. !VIZP@
   'JOBMJ[BUJPO(SPVQך⢽
   const group = new FinalizationGroup(
   iterator => console.log([...iterator]));
   let obj = new ArrayBuffer(1024 ** 3);
   group.register(obj, 'דְַر٦ة’);
   obj = null;
   gc(); // [‘דְַر٦ة’] ה邌爙ׁ׸׷
   ؔـآؙؑزָ($ׁ׸׋
   הֹחㄎעꟼ侧׾床ׅ
   'JOBMJ[BUJPO(SPVQך
   湊鋔㼎韋ח obj׾鷄⸇
   objפך⿫撑׾嶊ׅ
   objָ($〳腉חז׷
   objָ($ׁ׸ג؝٦ٕ
   غحָؙㄎל׸׷
   

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8. &$."4DSJQUה($
   

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9. !VIZP@
   &$."4DSJQUה($
   2הֿ׹דծ+4ך鎉铂➬圫&$."4DSJQUדכ
   ($כֿ׸תדוֲ䪔׻׸גְ׋ך
   ˟&$."4DSJQU +BWB4DSJQUך鎉铂➬圫׾㹀׭׷㕂ꥷ鋉呓կ
   չ+BWB4DSJQUպהչ&$."4DSJQUպך麩ְחכ长铡֮׷ָծ娖〷涸穗箮דせ⵸ָ麩ֲ׌ֽד䊴殯כ
   זְהְֲךָ涪邌罏ך䭯锷կ
   

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10. !VIZP@
    &$."4DSJQUה($
    2הֿ׹דծ+4ך鎉铂➬圫&$."4DSJQUדכ
    ($כֿ׸תדוֲ䪔׻׸גְ׋ך
    " ⡦׮㹀纏ׁ׸גְתׇ׿ד׃׋
    ˟8FBL.BQך眍ח׍׳׏ה׌ֽ($פך鎉⿹ָ֮׷ָ/05&玎䏝
    ˟&$."4DSJQU +BWB4DSJQUך鎉铂➬圫׾㹀׭׷㕂ꥷ鋉呓կ
    չ+BWB4DSJQUպהչ&$."4DSJQUպך麩ְחכ长铡֮׷ָծ娖〷涸穗箮דせ⵸ָ麩ֲ׌ֽד䊴殯כ
    זְהְֲךָ涪邌罏ך䭯锷կ
    

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11. !VIZP@
    &$."4DSJQUה($
    2ז׈⡦׮㹀纏ׁ׸גְזַ׏׋ך
    " ($כفؚٗٓيך䮙⹛חⰋֻ䕦갟׾⿹רׁזְַ׵
    –($כⳢ椚禸ח״׷剑黝⻉חֺׅזְ湡涸ًٌٔ⢪欽ꆀ׾⵴幾
    –剑黝⻉דفؚٗٓيך䮙⹛ָ㢌׻׷ץֹדכזְ
    ˟($ָ䮠ת׷ְׇדفؚٗٓيךػؿؓ٦وٝأָ衅׍׋׶ׅ׷ַ׮׃׸זְָծ
    ػؿؓ٦وٝأכ鎉铂➬圫ד⥂鏾ׁ׸גְזְךד➙㔐כ莆㄂ז׃
    

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12. !VIZP@
    8FBL3FGך&$."4DSJQUפך䕦갟
    2ד׮8FBL3FGכفؚٗٓيך䮙⹛ח䕦갟ׅ׷״י
    

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13. !VIZP@
    8FBL3FGך&$."4DSJQUפך䕦갟
    2ד׮8FBL3FGכفؚٗٓيך䮙⹛ח䕦갟ׅ׷״י
    " ׉ֲדׅי
    אְח&$."4DSJQUחؖك٦آ؝ؙٖءّٝך嚊䙀ָ
    

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14. !VIZP@
    8FBL3FG➬圫ח鋅׷($
    IUUQTUDFTQSPQPTBMXFBLSFGT ״׶䒷欽
    

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15. !VIZP@
    8FBL3FG➬圫ח鋅׷($
    ˑֿך➬圫כؖك٦آ؝ؙٖءّٝח㼎׃ג⡦׵ך⥂鏾׮遤׻זְ˒
    IUUQTUDFTQSPQPTBMXFBLSFGT ״׶䒷欽
    

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16. !VIZP@
    ؖك٦آ؝ؙٖءّٝך➬圫♳ך㹀纏
    Ⳣ椚禸כ⟣䠐ךة؎ىؚٝדˑMJWFדזְ˒ؔـآؙؑز׾8FBL3FGַ׵
    嶊׃ג׮葺ְ⥂鏾כ搀ְ宕黅ח嶊ׁ׸זְ〳腉䚍׮֮׷
    • ˑMJWFדזְ˒ؔـآؙؑزؖك٦آ؝ؙٖءّٝך㼎韋ח
    ז׶䖤׷ؔـآؙؑزך䬄韋涸ז邌植
    

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17. !VIZP@
    MJWFזؔـآؙؑزך㹀纏
    㼛勻涸ח8FBL3FG⟃㢩ך䩛媮דفؚٗٓيַ׵錁庠
    ׁ׸׷ֿה
    ךזְؔـآؙؑز
    

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18. !VIZP@
    MJWFזؔـآؙؑزך㹀纏
    㼛勻涸ח8FBL3FG⟃㢩ך䩛媮דفؚٗٓيַ׵錁庠
    ׁ׸׷ֿה
    ךזְؔـآؙؑز
    錁庠הכ!!!!!!!!!!
    ˟׮׏ה׍ׯ׿ה׃׋㹀纏ח׃״ֲהְֲ陽锷כ֮׶תׅ
    

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19. תה׭
    

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20. !VIZP@
    ➬圫חֶֽ׷8FBL3FGך⥂鏾
    –($ָ饯ֿ׷⥂鏾כ搀ְⳢ椚禸⣛㶷
    –($㼎韋הז׷ؔـآؙؑزך⿑㺘ז㹀纏׮Ⳣ椚禸⣛㶷
    –׬׃׹8FBL3FGכ⥂鏾׾幾׵ׅ
    չفؚٗٓيָ⥂䭯ׅ׷ؔـآؙؑزכ($ׁ׸זְպהְֲ⥂鏾׾PQUPVU〳腉
    

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21. !VIZP@
    8FBL3FGך䠐纏
    8FBL3FGכ⥂鏾׾幾׵ׅ
    Ⳣ椚禸ךⵖ秈ָ幾׷
    剑黝⻉ך堣⠓ָ㟓⸇
    Ⱗ⡤涸חכًٌٔך⢪欽ꆀ⵴幾
    

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22. !VIZP@
    תה׭
    8FBL3FGכ剑黝⻉ָ׉ך㈓♧ך㶷㖈䠐纏ד֮׶ծ
    ➭ך湡涸ד⢪ֲךכ⡦ַָ呎劤涸חֶַ׃ְךד
    罋ִ湫׃ת׃׳ֲ
    'JOBMJ[BUJPO(SPVQ׮ず圫
    

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