talked on Go Conference 2019 Spring https://gocon.jp/2019-spring-sessions#a1-s-case-studies-of-designing-developer-friendly-libraries
©2019 Wantedly, Inc.Case studies of designing developer friendly librariesGo Conference 2019 SpringMay 18, 2019 - Masayuki Izumi(@izumin5210)
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@izumin5210Application Engineer, Wantedly PeopleWantedly, Inc.
©2019 Wantedly, Inc.developer friendly ͳύοέʔδʁ
©2019 Wantedly, Inc.developer friendly ͳύοέʔδʁ͔͍͍ͭ͢ʁΘ͔Γ͍͢ʁগͳ͍ίʔυྔͰ͔͚Δʁͬͯͯͨͷ͍͠ʁ
©2019 Wantedly, Inc.developer friendly ͳύοέʔδʁ͔͍͍ͭ͢ʁΘ͔Γ͍͢ʁগͳ͍ίʔυྔͰ͔͚Δʁͬͯͯͨͷ͍͠ʁSimple?Easy?
©2019 Wantedly, Inc.1. Simple• ΄͔ͷͷͱབྷΈ߹ͬͯͳ͍• ઈରతɾ٬؍త2. Easy• ۙͰ͋Δɺ͠Έ͍͢• ૬ରతɾओ؍తSimple / Easy Simple Made Easy* https://speakerdeck.com/takeru0757/simple-is-not-easy?slide=49
©2019 Wantedly, Inc.SimpleͱEasyಉ͡Ͱͳ͍
©2019 Wantedly, Inc.Simpleͷରٛޠ͕EasyͳΘ͚Ͱͳ͍SimpleͷରComplexʁ
©2019 Wantedly, Inc.Easy͕ѱͳΘ͚Ͱͳ͍։ൃͷॳΛߴΊΔ
©2019 Wantedly, Inc.ͳʹ͕Easy͔ϢʔβͷίϯςΩετʹΑΔ
©2019 Wantedly, Inc.Simple͞ΛଛͳΘͳ͍ɺ͔ͭEasy ͳϥΠϒϥϦσβΠϯͷྫΛݟ͍ͯ͘Today’s goal
©2019 Wantedly, Inc.ڷʹै͏ઓུͦͷᶃ
©2019 Wantedly, Inc.ڷʹै͏Go քͷ׳शʹै͏“ڷʹೖͬͯڷʹै͑” ༨ܭͳࢥߟࣝΛཁٻ͠ͳ͍͍ͯ͘Α͏ʹɺ׳शʹै͏ FH AFSSPSAΛฦ͢ͱ͖Ҿͷ࠷ޙʹ ADPOUFYU$POUFYUAҾͷ࠷ॳʹ 'VODUJPOBMPQUJPOA8JUIA͔Β͡ΊΔʢॾઆ͋Γʣ ΤσΟλͷิͰPQUJPOͷҰཡ͕ݟΕͯศར
©2019 Wantedly, Inc.`context.Context`ਖ਼͓͘͠͏ context ωοτϫʔΫ*0ͳͲɺ͔͔࣌ؒΔॲཧ͕͋Δͱ͖ඞͣDPOUFYUΛ͢ʂ ωοτϫʔΫෆௐͰΊͬͪΌ͔͔࣌ؒΔ͔ˠλΠϜΞτ͍ͨ͠ $POUFYUΛར༻ͯ͠ϝτϦΫεऩूͳͲΛߦ͏πʔϧͷରԠʢޙड़ʣ HPPHMFDMPVEHPͳͲɺίϯετϥΫλͰDPOUFYUΛ ཁٻ͢Δύλʔϯ͋Δclient, err := pubsub.NewClient(ctx, "project-id")if err != nil {// ...}ڷʹै͏
©2019 Wantedly, Inc.`context.Context`ͱܭଌ DPOUFYUʹσʔλऩू༻ͷTUSVDUΛࠐΉύοέʔδ͕ଘࡏ͢Δ FHPQFODFOTVTHP OFXSFMJDHPBHFOU AIUUQ 3PVOE5SJQQFSAATUBUT)BOEMFSAͰDPOUFYU͔Β ΦϒδΣΫτΛऔΓग़͠ɺܭଌͨ͠σʔλΛॻ͖ࠐΉ ͜ͷΈΛਖ਼͘͠ಈ࡞ͤ͞ΔͨΊʹ$POUFYUൖॏཁfunc traceHandleRPC(ctx context.Context, rs stats.RPCStspan := trace.FromContext(ctx)switch rs := rs.(type) {case *stats.Begin:span.AddAttributes(trace.BoolAttribute("Client", rs.Client),trace.BoolAttribute("FailFast", rs.FailFast))case *stats.InPayload:// snip.case *stats.OutPayload:// snip.case *stats.End:// snip.span.End()}}https://github.com/census-instrumentation/opencensus-go/blob/v0.21.0/plugin/ocgrpc/trace_common.go#L84-L107ڷʹै͏
©2019 Wantedly, Inc.Interceptor / Middleware ॲཧલޙʹϑοΫͰ͖ΔػߏΛ࡞Δύλʔϯ H31$ʹJOUFSDFQUPSͱ͍͏໊લͰ࣮͞Ε͍ͯΔ ॲཧͷલޙͰϏδωεϩδοΫʹؔͳ͍ॲཧΛ࣮ߦͰ͖Δ FHೝূ ϩΪϯά ΤϥʔϨϙʔτ ʜ* https://docs.pylonsproject.org/projects/pylons-webframework/en/latest/concepts.html#wsgi-middlewareڷʹै͏
©2019 Wantedly, Inc.֦ுੑΛอͭઓུͦͷᶄ
©2019 Wantedly, Inc.ͪΐͬͱෳࡶͳ͜ͱ͢ΔͱҟৗʹେมʹͳΔ&BTZͳͷΛ͏ͱ͖ʹΑ͘ى͜Δ͜ͱ
©2019 Wantedly, Inc.ͪΐͬͱෳࡶͳ͜ͱ͢ΔͱҟৗʹେมʹͳΔ&BTZͳͷΛ͏ͱ͖ʹΑ͘ى͜Δ͜ͱͳΔ֦͘ுੑΛอ͍ͪͨ
©2019 Wantedly, Inc.֦ுੑΛอͭRedigoͷྫgithub.com/gomodule/redigo 3FEJTΫϥΠΞϯτ A$POOAΠϯλϑΣʔεʹίϚϯυൃߦ༻ͷ ϝιου͕ੜ͍͑ͯΔtype Conn interface {// Close closes the connection.Close() error// Err returns a non-nil value when the connection is not usable.Err() error// Do sends a command to the server and returns the received reply.Do(commandName string, args ...interface{}) (reply interface{}, err// Send writes the command to the client's output buffer.Send(commandName string, args ...interface{}) error// Flush flushes the output buffer to the Redis server.Flush() error// Receive receives a single reply from the Redis serverReceive() (reply interface{}, err error)}
©2019 Wantedly, Inc.Redigoͷྫgithub.com/gomodule/redigo ࣮ࡍͷར༻Ͱɺ͍͍ͩͨDPOOFDUJPOQPPMΛ ͏͜ͱʹͳΔ pool := &redis.Pool{Dial: func () (redis.Conn, error) {return redis.Dial("tcp", addr)},}conn, err := pool.GetContext(ctx)֦ுੑΛอͭ
©2019 Wantedly, Inc.Redigoͷྫgithub.com/gomodule/redigo ࣮ࡍͷར༻Ͱɺ͍͍ͩͨ$POOFDUJPO1PPMΛ ͏͜ͱʹͳΔpool := &redis.Pool{DialContext: func (ctx context.Context) (redis.Conn, error) {return redis.Dial("tcp", addr)},}conn, err := pool.GetContext(ctx)֦ுੑΛอͭ
©2019 Wantedly, Inc.Redigoͷྫgithub.com/gomodule/redigo ࣮ࡍͷར༻Ͱɺ͍͍ͩͨ$POOFDUJPO1PPMΛ ͏͜ͱʹͳΔ %JBM࣮ΛಠࣗఆٛͰ͖ΔΑ͏ʹͳ͍ͬͯΔͷͰɺASFEJT$POOAΛXSBQ͢Δ͜ͱͰϩΨʔϝτϦΫεऩूΛࠐΊΔ ࣅͨྫͱͯ͠AOFUIUUQ5SBOTQPSUAͳͲpool := &redis.Pool{DialContext: func (ctx context.Context) (redis.Conn, error) {conn, err := redis.Dial("tcp", addr)if err != nil {return nil, err}return redis.NewLoggingConn(conn, logger, "redis")},}conn, err := pool.GetContext(ctx)֦ுੑΛอͭ
©2019 Wantedly, Inc.google-cloud-go ͷྫcloud.google.com/go $MPVE%BUBTUPSF$MPVE1VC4VCͳͲɺ ($1Ͱఏڙ͞ΕΔ͋ΒΏΔαʔϏεͷΫϥΠΞϯτ͕ଘࡏ ͍͍ͩͨͷΫϥΠΞϯτίϯετϥΫλͰΦϓγϣϯΛड͚औΕΔΑ͏ʹͳ͍ͬͯΔclient, err := pubsub.NewClient(ctx, "project-id")if err != nil {// ...}֦ுੑΛอͭ
©2019 Wantedly, Inc.google-cloud-go ͷྫcloud.google.com/go ίϯετϥΫλʹͤΔΦϓγϣϯʹɺ௨৴ʹར༻͢ΔAHSQD$MJFOU$POOAAIUUQ$MJFOUAͳͲؚ·ΕΔ JOUFSDFQUPSTUBUTIBOEMFSͳͲ͕ඞཁʹͳΔϩΨʔܭଌܥͳͲࠐΈ์* https://godoc.org/google.golang.org/api/option#ClientOption֦ுੑΛอͭ
©2019 Wantedly, Inc.͋ΒΏΔͷΛࠩ͠ସ͑Մೳʹ͓ͯ͘͠ ͨͱ͑"1*ΫϥΠΞϯτͰ͋Εɺ HSQD$MJFOU$POOIUUQ$MJFOUʹΞΫηεՄೳͳύεΛ͓ͭͬͯ͘͘ͱศར ϝτϦΫεऩूࢄτϨʔγϯάͷεύϯੜͷϑοΫͳͲʹར༻Ͱ͖Δ ίϯετϥΫλͳͲʹGVODUJPOBMPQUJPOͳͲͷܗࣜͰͤΔΑ͏ʹ͓֦ͯ͘͠ுੑΛอͭ
©2019 Wantedly, Inc.Functional option ϥΠϒϥϦͳͲͰɺΦϓγϣϯΛࢦఆͤ͞ΔΑ͏ʹ͢ΔͨΊͷύλʔϯ DGCVJMEFSQBUUFSOtype Option func(*Config)func WithHTTPClient(client *http.Client) Option {return func(c *Config) {c.HTTPClient = client}}func NewClient(opts ...Option) Client {cfg := new(Config)for _, f := range opts {f(cfg)}// ...}֦ுੑΛอͭ
©2019 Wantedly, Inc.type Option func(*Config)func WithHTTPClient(client *http.Client) Option {return func(c *Config) {c.HTTPClient = client}}func NewClient(opts ...Option) Client {cfg := new(Config)for _, f := range opts {f(cfg)}// ...}func NewClientBuilder() *Builder {return &Builder{}}func (b *Builder) SetHTTPClient(client *http.Client) *Builder {b.HTTPClient = clientreturn b}func (b *Builder) Build() Client {// ...}Builder pattern Functional option pattern
©2019 Wantedly, Inc.type Option func(*Config)func WithHTTPClient(client *http.Client) Option {return func(c *Config) {c.HTTPClient = client}}func NewClient(opts ...Option) Client {cfg := new(Config)for _, f := range opts {f(cfg)}// ...}func NewClientBuilder() *Builder {return &Builder{}}func (b *Builder) SetHTTPClient(client *http.Client) *Builder {b.HTTPClient = clientreturn b}func (b *Builder) Build() Client {// ...}Builder pattern Functional option patternϢʔβ͕ಠࣗPQUJPOΛఆٛ͢Δ͜ͱՄೳͳͷͰɺݸਓతʹ'VODUJPOBMPQUJPOͷ΄͏͕͖
©2019 Wantedly, Inc.ίʔυੜઓུͦͷᶅ
©2019 Wantedly, Inc.ܕΛ׆͔ͨ͢Ίͷίʔυੜ FH 03.42-#PJMFS YPʢ֎෦ʹ͋ΔεΩʔϚΛ(Pʹམͱ͠ࠐΉʣ %*XJSFʢܕΛݟͯґଘؔͷ%"(Λͭ͘Δʣ ͱ͘ʹ(Pͷ֎ʹܕఆ͕ٛ͋Δ߹ʢFH%# TXBHHFS QSPUPCVGʣʹ༗ޮ Ϣʔβ͕ੜޙͷίʔυΛฤू͢Δඞཁ͕ͳ͍Α͏ʹੜͯ͋͛͠Δͱྑ͍ ੜπʔϧ͕Ξοϓσʔτ͞Εͨͱ͖ʹैͰ͖ΔΑ͏ʹ// Code generated by protoc-gen-go. DO NOT EDIT.// source: content.protopackage api_pbimport (context "context"fmt "fmt"ADO NOT EDIT` ͬͯॻ͍͓ͯ͘ͱ͍ΖΜͳπʔϧͰແࢹͯ͠Β͑·͢// Code generated by protoc-gen-go. DO NOT EDIT.// source: content.protopackage api_pbimport (context "context"ίʔυੜ
©2019 Wantedly, Inc.Boilerplate ੜ FH TUSJOHFSΊΜͲ͍͘͞εχϖοτͷੜ HSBQJΞϓϦέʔγϣϯίʔυͷTDBGGPMEJOH ʮϢʔβ͕ฤू͢ΔίʔυʯʮϢʔβ͕৮Βͳ͍΄͏͕ྑ͍ίʔυʯΛ ͦΕͧΕผϑΝΠϧʹు͍͓ͯ͘ͷ͕ྑ͍ʢཧ༝͖ͬ͞ͱҰॹʣ ʮϢʔβ͕ฤू͢Δίʔυʯ࠷খݶʹཹΊΔ// NewBookServiceServer creates a new BookServiceServer instancefunc NewBookServiceServer() BookServiceServer {return &bookServiceServerImpl{}}type bookServiceServerImpl struct {}func (s *bookServiceServerImpl) ListBooks(ctx context.Context, r// TODO: Not yet implemented.return nil, status.Error(codes.Unimplemented, "TODO: You shoul}func (s *bookServiceServerImpl) GetBook(ctx context.Context, req// TODO: Not yet implemented.return nil, status.Error(codes.Unimplemented, "TODO: You shoul}func (s *bookServiceServerImpl) CreateBook(ctx context.Context,// TODO: Not yet implemented.return nil, status.Error(codes.Unimplemented, "TODO: You shoul}func (s *bookServiceServerImpl) UpdateBook(ctx context.Context,// TODO: Not yet implemented.return nil, status.Error(codes.Unimplemented, "TODO: You shoul}func (s *bookServiceServerImpl) DeleteBook(ctx context.Context,// TODO: Not yet implemented.return nil, status.Error(codes.Unimplemented, "TODO: You shoul}ίʔυੜ
©2019 Wantedly, Inc.উखʹ͍Ζ͍ΖΔઓུͦͷᶆ
©2019 Wantedly, Inc.͔͜͜Β༻๏༻ྔΛकͬͯਖ਼͍͘͠·͠ΐ͏ ⚠
©2019 Wantedly, Inc.͍͍ײ͡ʹΔࣾϥΠϒϥϦ 8): αʔόΛຊ൪ڥͰಈ͔͢ʹɺ"1.ͱBDDFTTMPHͱFSSPSSFQPSUͱʜ Δ͜ͱ͕͍ͬͺ͍͋Δ Θ͢Εͦ͏ 8)"5 ڥมΛೖΕΔ͚ͩͰ͍͍ײ͡ʹશͯಈ͘Α͏ʹ͍ͨ͠func run() error {defer servicex.Close()ctx := context.Background()s := grapiserver.New(grpcx.WithDefault(),grapiserver.WithServers(NewContentServiceServer(),),)return s.Serve()}উखʹ͍Ζ͍ΖΔ
©2019 Wantedly, Inc.͍͍ײ͡ʹΔࣾϥΠϒϥϦ ڥมಡΈग़͠dॾʑͷॳظԽΛATFSWJDFYAͱ͍͏ύοέʔδͷ AJOJU AͰશ෦উखʹΔ AJOJU AͳͷͰJNQPSU͑͞͞Ε͍ͯΕΑ͍ ˠAEFGFSTFSWJDFY$MPTF AΛॻ͔ͤΔ͚ͩͰΑ͍ ʢCMBOLJNQPSU͡Όͳ͍ͷखͰॻ͘ͷΊΜͲ͍͔͘͞Βʣfunc run() error {defer servicex.Close()ctx := context.Background()s := grapiserver.New(grpcx.WithDefault(),grapiserver.WithServers(NewContentServiceServer(),),)return s.Serve()}func init() {loadEnv()initErrorReporter()initLogger()// ...}উखʹ͍Ζ͍ΖΔ
©2019 Wantedly, Inc.$PNQPVOEGVODPQUJPO 1SPEVDUJPOSFBEZͳαʔόʹඞਢͷػೳ͕શͯ༗ޮʹͳΔΑ͏ͳ ΧελϜGVODUJPOBMPQUJPOΛͭ͘Δ 'VODUJPOBMPQUJPO͍͍͕ͩͨ AGVOD $POpHA͔AGVOD $POpH$POpHAͳͷͰɺ߹Ͱ͖Δfunc WithDefault() grapiserver.Option {opts := []grapiserver.Option{grapiserver.WithGrpcServerUnaryInterceptors(grpc_ctxtags.UnaryServerInterceptor(ctxtagsOptioClientMetadataUnaryServerInterceptor(),AccessLoggingUnaryServerInterceptor(),grpc_zap.UnaryServerInterceptor(zap.L(), ...),ErrorsUnaryServerInterceptor(),RecoveryUnaryServerInterceptor(),AuthUnaryServerInterceptor(),),// ...}return func(c *grapiserver.Config) {for _, f := range opts {f(c)}}}func run() error {defer servicex.Close()ctx := context.Background()s := grapiserver.New(grpcx.WithDefault(),grapiserver.WithServers(উखʹ͍Ζ͍ΖΔ
©2019 Wantedly, Inc.͜Μͳʹউखͳ͜ͱͯ͠ྑ͍ͷ͔ʁ ϏδωεϩδοΫʹؔΘΔΑ͏ͳίʔυͩͱμϝ ڞ༗ίʔυଟ͚Εଟ͍΄ͲΑ͘ͳ͍ͬͯʮϚΠΫϩαʔϏεΞʔΩςΫνϟʯʹॻ͍ͯͨ ͱ͍͑ɺ͜ͷࣾϥΠϒϥϦ͕ղܾ͢ΔͷϏδωεϩδοΫͱશવผͷϨΠϠͰ͋Γɺ ΧελϚΠζཉٻߴ͘ͳ͍ՕॴͳͷͰΪϦΪϦηʔϑʢʁʣ ͱ͍͑։ൃऀͷखݩͷڥͰมͳಈ͖Λ͠ͳ͍Α͏ɺࡉ৺ͷҙΛ͍࣮ͭͭউखʹ͍Ζ͍ΖΔ
lڷʹೖͬͯڷʹै͑z ͪΌΜͱ(Pͷ׳शʹԊͬͨ"1*ʹ͠Α͏ ֦ுੑΛอͭ ͍͜͠ͱΛΖ͏ͱͨ͠ͱ͖ʹࠔΒͳ͍Α͏ʹ͠Α͏ ࠷ѱίΞʹͳͬͯΔύοέʔδʹ৮ΕΒΕΔΑ͏ʹ͠Α͏ ίʔυੜΛ͏·͘͏͜ͱΛݕ౼͠Α͏ ͍͗͢ɾ͍ॴʹཁҙʂ Ϣʔβ͕ݶΒΕΔɺดͨ͡ίϯςΩετɺϏδωεϩδοΫ͕བྷ·ͳ͍ͳΒɺ উखʹ৭ʑΔύοέʔδ͋Γ͔ʂʁ
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