`Wrap(err)` in production

Transcript

1. Go(Un)Conference 4kg - @izumin5210 `Wra p ( e r r

   )` i n pro du ction

2. izumin5210 ‣ Wantedly People ‣ Web Engineer (serverside & frontend)

   ‣ Gopher & Rubyist

3. `Wrap(err)`
   ͯ͠·͔͢ʁ ࠓ೔
   AWrap(err)A
   ͨ͠ਓʙʁ
   

4. ෮श
   ͳΜͰ
   AWrap(err)A
   ͢Δͷʁ AWrap(err)A
   ͠ͳ͍ͱ͍͚ͳ͍ཧ༝෼͔Δਓʙʁ
   

5. func TestErrors_noWrapStdError(t *testing.T) { err := err1() if err !=

   nil { printError(t, err) } } func err1() error { return stderr() } func stderr() error { return stderrors.New("error!") }

6. func TestErrors_noWrapStdError(t *testing.T) { err := err1() if err !=

   nil { printError(t, err) } } func err1() error { return stderr() } func stderr() error { return stderrors.New("error!") } === RUN TestErrors_noWrapStdError --- PASS: TestErrors_noWrapStdError (0.00s) main.go:16: *** %#v ****************************************** main.go:17: &errors.errorString{s:"error!"} main.go:18: *** %+v ****************************************** main.go:19: error! main.go:20: *** stacktrace *********************************** main.go:20: /go/src/sandbox/main.go:16: main.TestErrors_noWrap main.go:20: /usr/local/go/src/testing/testing.go:777: testing. main.go:20: /usr/local/go/src/runtime/asm_amd64p32.s:968: runt PASS

7. func TestErrors_noWrapStdError(t *testing.T) { err := err1() if err !=

   nil { printError(t, err) } } func err1() error { return stderr() } func stderr() error { return stderrors.New("error!") } === RUN TestErrors_noWrapStdError --- PASS: TestErrors_noWrapStdError (0.00s) main.go:16: *** %#v ****************************************** main.go:17: &errors.errorString{s:"error!"} main.go:18: *** %+v ****************************************** main.go:19: error! main.go:20: *** stacktrace *********************************** main.go:20: /go/src/sandbox/main.go:16: main.TestErrors_noWrap main.go:20: /usr/local/go/src/testing/testing.go:777: testing. main.go:20: /usr/local/go/src/runtime/asm_amd64p32.s:968: runt PASS

8. func TestErrors_noWrapStdError(t *testing.T) { err := err1() if err !=

   nil { printError(t, err) } } func err1() error { return stderr() } func stderr() error { return stderrors.New("error!") } === RUN TestErrors_noWrapStdError --- PASS: TestErrors_noWrapStdError (0.00s) main.go:16: *** %#v ****************************************** main.go:17: &errors.errorString{s:"error!"} main.go:18: *** %+v ****************************************** main.go:19: error! main.go:20: *** stacktrace *********************************** main.go:20: /go/src/sandbox/main.go:16: main.TestErrors_noWrap main.go:20: /usr/local/go/src/testing/testing.go:777: testing. main.go:20: /usr/local/go/src/runtime/asm_amd64p32.s:968: runt PASS ΤϥʔΛฦͨؔ͠਺ͷ಺ଆͷελοΫτϨʔε͕ͱΕͳ͍

9. func TestErrors_Wrap(t *testing.T) { err := err2() if err !=

   nil { printError(t, err) } } func err2() error { err := stderr() return pkgerrors.Wrap(err, "wrapped") } func pkgerr() error { return pkgerrors.New("error!") }

10. func TestErrors_Wrap(t *testing.T) { err := err2() if err !=

    nil { printError(t, err) } } func err2() error { err := stderr() return pkgerrors.Wrap(err, "wrapped") } func pkgerr() error { return pkgerrors.New("error!") } === RUN TestErrors_Wrap --- PASS: TestErrors_Wrap (0.00s) main.go:47: *** %#v **************************************** main.go:48: wrapped: error! main.go:49: *** %+v **************************************** main.go:50: error! wrapped main.err2 /go/src/sandbox/main.go:30 main.TestErrors_Wrap /go/src/sandbox/main.go:21 testing.tRunner /usr/local/go/src/testing/testing.go:777 runtime.goexit /usr/local/go/src/runtime/asm_amd64p32.s:968 main.go:51: *** stacktrace ********************************* main.go:51: /go/src/sandbox/main.go:24: main.TestErrors_Wrap main.go:51: /usr/local/go/src/testing/testing.go:777: testin main.go:51: /usr/local/go/src/runtime/asm_amd64p32.s:968: ru PASS

11. func TestErrors_Wrap(t *testing.T) { err := err2() if err !=

    nil { printError(t, err) } } func err2() error { err := stderr() return pkgerrors.Wrap(err, "wrapped") } func pkgerr() error { return pkgerrors.New("error!") } === RUN TestErrors_Wrap --- PASS: TestErrors_Wrap (0.00s) main.go:47: *** %#v **************************************** main.go:48: wrapped: error! main.go:49: *** %+v **************************************** main.go:50: error! wrapped main.err2 /go/src/sandbox/main.go:30 main.TestErrors_Wrap /go/src/sandbox/main.go:21 testing.tRunner /usr/local/go/src/testing/testing.go:777 runtime.goexit /usr/local/go/src/runtime/asm_amd64p32.s:968 main.go:51: *** stacktrace ********************************* main.go:51: /go/src/sandbox/main.go:24: main.TestErrors_Wrap main.go:51: /usr/local/go/src/testing/testing.go:777: testin main.go:51: /usr/local/go/src/runtime/asm_amd64p32.s:968: ru PASS

12. func TestErrors_Wrap(t *testing.T) { err := err2() if err !=

    nil { printError(t, err) } } func err2() error { err := stderr() return pkgerrors.Wrap(err, "wrapped") } func pkgerr() error { return pkgerrors.New("error!") } === RUN TestErrors_Wrap --- PASS: TestErrors_Wrap (0.00s) main.go:47: *** %#v **************************************** main.go:48: wrapped: error! main.go:49: *** %+v **************************************** main.go:50: error! wrapped main.err2 /go/src/sandbox/main.go:30 main.TestErrors_Wrap /go/src/sandbox/main.go:21 testing.tRunner /usr/local/go/src/testing/testing.go:777 runtime.goexit /usr/local/go/src/runtime/asm_amd64p32.s:968 main.go:51: *** stacktrace ********************************* main.go:51: /go/src/sandbox/main.go:24: main.TestErrors_Wrap main.go:51: /usr/local/go/src/testing/testing.go:777: testin main.go:51: /usr/local/go/src/runtime/asm_amd64p32.s:968: ru PASS ࠷ॳʹ
    8SBQ
    ͨ͠ͱ͜Ζ͔ΒͷτϨʔε͕औΓग़ͤΔ

13. func main() { err := auth() if err != nil

    { fmt.Fprintln(os.Stderr, errors.Wrap(err, "failed to authorization")) } } func auth() error { _, err := getUser() if err != nil { return errors.Wrap(err, "failed to get user") } return nil } func getUser() (*User, error) { return nil, errors.New("not found error") }

14. func main() { err := auth() if err != nil

    { fmt.Fprintln(os.Stderr, errors.Wrap(err, "failed to authorization")) } } func auth() error { _, err := getUser() if err != nil { return errors.Wrap(err, "failed to get user") } return nil } func getUser() (*User, error) { return nil, errors.New("not found error") } failed to authorization: failed to get user: not found error

15. func main() { err := auth() if err != nil

    { fmt.Fprintln(os.Stderr, errors.Wrap(err, "failed to authorization")) } } func auth() error { _, err := getUser() if err != nil { return errors.Wrap(err, "failed to get user") } return nil } func getUser() (*User, error) { return nil, errors.New("not found error") } failed to authorization: failed to get user: not found error Τϥʔϝοηʔδ΋ͲΜͲΜ
    BOOPUBUF
    Ͱ͖Δ
    ˠ
    Ͳ͏͍͏ίϯςΩετͰΤϥʔ͕ى͖ͯΔ͔͕Θ͔Γ΍͍͢ʂ

16. ‣ A8SBQ FSS A
    ͢Δ͜ͱͰʜ
     ελοΫτϨʔεΛΤϥʔͷൃੜݯ·ͰḪΔ͜ͱ͕Ͱ͖Δ
     ΤϥʔࣗମʹͲΜͲΜ৘ใΛ෇ՃͰ͖ΔͷͰɼݪҼΛ௥͏ͷʹ׆༻Ͱ͖Δ
    ‣ ৄ͘͠͸
    (P
    $POGFSFODF
    
    
    4QSJOH
    ͷ
    ,FZOPUF
    Λݟ·͠ΐ͏
    

     IUUQTEBWFDIFOFZOFUQBTUFHPDPOTQSJOHQEG

17. ‣ A8SBQ FSS A
    ͢Δ͜ͱͰʜ
     ελοΫτϨʔεΛΤϥʔͷൃੜݯ·ͰḪΔ͜ͱ͕Ͱ͖Δ
     ΤϥʔࣗମʹͲΜͲΜ৘ใΛ෇ՃͰ͖ΔͷͰɼݪҼΛ௥͏ͷʹ׆༻Ͱ͖Δ
    ‣ ৄ͘͠͸
    (P
    $POGFSFODF
    
    
    4QSJOH
    ͷ
    ,FZOPUF
    Λݟ·͠ΐ͏
    

     IUUQTEBWFDIFOFZOFUQBTUFHPDPOTQSJOHQEG ΄Μͱʹ͜Ε͚ͩͰ͍͍ͷ͔ʁ

18. ‣ ͜ͷͱ͖ͷεςʔλείʔυ͸ʁ
     %#
    ͕ࢮΜͰͨΒ
    *OUFSOBM
     ଘࡏ͠ͳ͍
    VTFS
    ͳΒ
    /PU'PVOE
     FUD func (s

    *server) GetUser(ctx context.Context, req *Get user, err := s.userRepo.GetUser(ctx, req.GetUserID() if err != nil { return nil, errors.Wrap(err, "failed to get user") } // snip }

19. ‣ Ͳ͏΍ͬͯΤϥʔΛ൑ผ͢Δ͔
     ఆ਺Խ
    ʢ4FOUJOFM
    FSSPST
     5ZQF
    ʹ͢Δ
    
    &SSPS
    UZQFT
    
    UZQF
    BTTFSUJPO
    ‣

    ਖ਼͍͔͠΋͠Εͳ͍͕ɼຖճఆٛ͢Δͷ͸
 ਖ਼௚ΊΜͲ͍͘͞ʜ switch errors.Cause(err).(type) { case *user.NotFoundError: return nil, status.Error(codes.NotFound, "user not f } if errors.Cause(err) == user.ErrNotFound { return nil, status.Error(codes.NotFound, "user not f }

20. ‣ ͜ͷΤϥʔ͸
    &SSPS
    SFQPSUFS
    ʹ౤͛Δ΂͖ʁ
    
     ࡶͳΞΫηεͰ
    
    /PU'PVOE
    ͳΒແࢹ͍ͨ͠
     ֤ʑͷϞδϡʔϧ͕উखʹ
    SFQPSU
    ͪ͠Ό͏ͱ
 Τϥʔ͕ॏෳ͢Δ͔΋
    ‣ લड़ͷ
    FSSPS
    UZQFT
    ʹʮSFQPSU
    ͢΂͖ʯϑϥάΛ
 ΋ͨͤΔͷ͔ʜʁ

    func (s *server) GetUser(ctx context.Context, req *Get user, err := s.userRepo.GetUser(ctx, req.GetUserID() if err != nil { return nil, errors.Wrap(err, "failed to get user") } // snip }

21. Go(Un)Conference 4kg - @izumin5210 `Wra p ( e r r

    )` i n p rod uct ion

22. ‣ *O
    PVS
    QSPEVDUJPO
     AHJUIVCDPNTSWDGBJMA
    Λར༻͍ͯ͠Δ
     QLHFSSPST
    ʹ͍͔ͭ͘ͷ
    NFUBEBUB
    Λ
 ௥Ճͨ͠΋ͷ
     AGBJM8SBQA
    ʹ
    BOOPUBUPS
    Λ౉͢͜ͱͰ
 ΤϥʔʹϚʔΩϯάͰ͖Δ

    func (r *repo) GetUser(ctx context.Context, id uint64) (*User, user, err := r.db.GetContext(ctx, &user, "...", id) if err == sql.ErrNoRows { return nil, fail.Wrap( err, fail.WithCode(appx.NotFound), fail.WithIgnorable(), ) } if err != nil { return nil, fail.Wrap(err, fail.WithCode(appx.Internal)) } // snip. }

23. ‣ AGBJM8JUI$PEF DPEF A
     εςʔλείʔυΛ౉͢
     AG&SS$PEFA
    ͷܗͰऔΓग़ͤΔ func (r

    *repo) GetUser(ctx context.Context, id uint64) (*User, user, err := r.db.GetContext(ctx, &user, "...", id) if err == sql.ErrNoRows { return nil, fail.Wrap( err, fail.WithCode(appx.NotFound), fail.WithIgnorable(), ) } if err != nil { return nil, fail.Wrap(err, fail.WithCode(appx.Internal)) } // snip. } 1FSTJTUFODF
    MBZFS
    ʹ
    IUUQ
    
    H31$
    ͷ஌ࣝΛೖΕͨ͘ͳ͔ͬͨͨΊʢ࣮ଶ͸
    H31$
    ͷ
    ADPEFT$PEFA
    ͱಉҰʣ

24. ‣ AGBJM8JUI$PEF DPEF A
     εςʔλείʔυΛ౉͢
     AG&SS$PEFA
    ͷܗͰऔΓग़ͤΔ ‣ *O
    PVS
    QSPEVDUJPO
    

     ABQQY A
    ͸ࣾ಺Ͱಠࣗఆٛ ͨ͠
    $PEF
    ܕ
     JOUFSDFQUPS
    Ͱ͍͍ײ͡ʹ
    H31$
    ͷ
    DPEF
    ʹ
 Ϛοϐϯά͞ΕΔ func (r *repo) GetUser(ctx context.Context, id uint64) (*User, user, err := r.db.GetContext(ctx, &user, "...", id) if err == sql.ErrNoRows { return nil, fail.Wrap( err, fail.WithCode(appx.NotFound), fail.WithIgnorable(), ) } if err != nil { return nil, fail.Wrap(err, fail.WithCode(appx.Internal)) } // snip. } 1FSTJTUFODF
    MBZFS
    ʹ
    IUUQ
    
    H31$
    ͷ஌ࣝΛೖΕͨ͘ͳ͔ͬͨͨΊʢ࣮ଶ͸
    H31$
    ͷ
    ADPEFT$PEFA
    ͱಉҰʣ

25. func (r *repo) GetUser(ctx context.Context, id uint64) (*User, user, err

    := r.db.GetContext(ctx, &user, "...", id) if err == sql.ErrNoRows { return nil, fail.Wrap( err, fail.WithCode(appx.NotFound), fail.WithIgnorable(), ) } if err != nil { return nil, fail.Wrap(err, fail.WithCode(appx.Internal)) } // snip. } ‣ AGBJM8JUI*HOPSBCMF A
     ʮ͜Ε͸େͨ͜͠ͱͳ͍ΑʔʯϚʔΫ
     ʮ͚ͭ๨ΕͯΤϥʔʹؾ͚ͮͳ͍ʯ
 ͸ةݥͳͷͰɼGBMTF
    QPTJUJWF
    ʹ౗͍ͯ͠Δ

26. func (r *repo) GetUser(ctx context.Context, id uint64) (*User, user, err

    := r.db.GetContext(ctx, &user, "...", id) if err == sql.ErrNoRows { return nil, fail.Wrap( err, fail.WithCode(appx.NotFound), fail.WithIgnorable(), ) } if err != nil { return nil, fail.Wrap(err, fail.WithCode(appx.Internal)) } // snip. } ‣ AGBJM8JUI*HOPSBCMF A
     ʮ͜Ε͸େͨ͜͠ͱͳ͍ΑʔʯϚʔΫ
     ʮ͚ͭ๨ΕͯΤϥʔʹؾ͚ͮͳ͍ʯ
 ͸ةݥͳͷͰɼGBMTF
    QPTJUJWF
    ʹ౗͍ͯ͠Δ ‣ *O
    PVS
    QSPEVDUJPO
     ͜Ε͕
    AUSVFA
    ͳΤϥʔʹ͍ͭͯ͸ɼ
 JOUFSDFQUPS
    Ͱউखʹ
    SFQPSU
    ͞ΕΔ
     8SBQ
    ๨Εͯ΋
    SFQPSU
    ͞ΕΔ

27. ‣ AGBJM8JUI*HOPSBCMF A
     ʮ͜Ε͸େͨ͜͠ͱͳ͍ΑʔʯϚʔΫ
     ʮ͚ͭ๨ΕͯΤϥʔʹؾ͚ͮͳ͍ʯ
 ͸ةݥͳͷͰɼGBMTF
    QPTJUJWF
    ʹ౗͍ͯ͠Δ
    ‣ *O
    PVS
    QSPEVDUJPO
    

     ͜Ε͕
    AUSVFA
    ͳΤϥʔʹ͍ͭͯ͸ɼ
 JOUFSDFQUPS
    Ͱউखʹ
    SFQPSU
    ͞ΕΔ
     8SBQ
    ๨Εͯ΋
    SFQPSU
    ͞ΕΔ func (r *repo) GetUser(ctx context.Context, id uint64) (*User, user, err := r.db.GetContext(ctx, &user, "...", id) if err == sql.ErrNoRows { return nil, fail.Wrap( err, fail.WithCode(appx.NotFound), fail.WithIgnorable(), ) } if err != nil { return nil, fail.Wrap(err, fail.WithCode(appx.Internal)) } // snip. }
    ͜Ε͸
    JOUFSDFQUPS
    Ͱ
    SFQPSU
    ͞ΕΔ

28. ‣ 0UIFS
    BOOPUBUPST
    A8JUI5BHTA
    A8JUI1BSBNTA
    FUD
    ‣ AHJUIVCDPNTSWDHSQDFSSPSTA
     H31$
    ͷ
    JOUFSDFQUPS
    Ͱ
    GBJM&SSPS
    Λ͍͍ײ͡ʹϋϯυϧ͢Δ࣮૷
    ‣ ࣾ಺ڞ௨ϥΠϒϥϦ
    ATFSWJDFYA
    

     ͜͜Ͱ
    AHSQDFSSPSTA
    Λ͍͍ײ͡ʹηοτͯ͠ɼ͍͍ײ͡ʹ
    FSSPS
    SFQPSU
    ͢Δ࢓૊ΈΛ࡞͍ͬͯΔ
     AHSBQJA
    ͷ
    0QUJPO
    Λఏڙ͍ͯͯ͠ɼߦ௥ه
    
    ؀ڥม਺ΛೖΕΔ͚ͩͰ͢΂͕ͯ༗ޮԽ͞ΕΔ HJUIVCDPNJ[VNJOHSBQJ
    
    H31$
    
    HSQDHBUFXBZ
    Λར༻ͨ͠
    8FC
    
    GSBNFXPSL
    
    DPEF
    HFOFSBUPS

29. ‣ 8SBQ
    ๨Εͯ΋
    SFQPSU
    ͞ΕΔͱ͸͍͑ʜ
     SFQPSU
    ͞ΕΔϝλσʔλ͕ݮΔͷ͸ࠔΔ
     ͔ͩΒͱ͍ͬͯຖճϨϏϡʔͰࢦఠ͢Δͷʜʁ

30. ‣ 8SBQ
    ๨Εͯ΋
    SFQPSU
    ͞ΕΔͱ͸͍͑ʜ
     SFQPSU
    ͞ΕΔϝλσʔλ͕ݮΔͷ͸ࠔΔ
     ͔ͩΒͱ͍ͬͯຖճϨϏϡʔͰࢦఠ͢Δͷʜʁ ‣ *O
    PVS
    QSPEVDUJPO
     AHJUIVCDPNTSWDXSBQFSSA
    ͱ͍͏ɼ


    8SBQ
    ๨Εݕग़πʔϧΛ࡞ͬͨ
     ASFWJFXEPHA
    ͱҰॹʹಈ͔͍ͯ͠Δ

31. ‣ A8SBQ FSS A
    ͸
    ΤϥʔͷίϯςΩετΛ఻ൖͤ͞Δͷʹॏཁ
     4UBDLUSBDF
    ͳͲ΋ؚΉ
    *O
    PVS
    QSPEVDUJPO
    
    ‣ AHJUIVCDPNTSWDGBJMA
    

    ͪΐͬͱϦονͳ
    A8SBQ FSS A
    Ͱɼ͍ΖΜͳ෇Ճ৘ใΛΤϥʔʹ৐͍ͤͯΔ
     ڞ௨ϥΠϒϥϦͷ
    JOUFSDFQUPS
    ͰɼXSBQQFE
    FSSPS
    ͷ෇Ճ৘ใ͔Β
    FSSPS
    SFQPSU
    Λ͍ͯ͠Δ
    ‣ AHJUIVCDPNTSWDXSBQFSSA
     A8SBQ FSS A
    Λ๨ΕΛݕ஌͢ΔπʔϧΛ࢖ͬͯɼ1VMM
    3FRVFTU
    ͰࣗಈϨϏϡʔ͍ͯ͠Δ