序

本文主要研究一下golang的zap的zapgrpc

zapgrpc

zap@v1.16.0/zapgrpc/zapgrpc.go

package zapgrpc // import "go.uber.org/zap/zapgrpc"

import "go.uber.org/zap"

// An Option overrides a Logger's default configuration.
type Option interface {
    apply(*Logger)
}

type optionFunc func(*Logger)

func (f optionFunc) apply(log *Logger) {
    f(log)
}

// WithDebug configures a Logger to print at zap's DebugLevel instead of
// InfoLevel.
func WithDebug() Option {
    return optionFunc(func(logger *Logger) {
        logger.print = (*zap.SugaredLogger).Debug
        logger.printf = (*zap.SugaredLogger).Debugf
    })
}

// NewLogger returns a new Logger.
//
// By default, Loggers print at zap's InfoLevel.
func NewLogger(l *zap.Logger, options ...Option) *Logger {
    logger := &Logger{
        log:    l.Sugar(),
        fatal:  (*zap.SugaredLogger).Fatal,
        fatalf: (*zap.SugaredLogger).Fatalf,
        print:  (*zap.SugaredLogger).Info,
        printf: (*zap.SugaredLogger).Infof,
    }
    for _, option := range options {
        option.apply(logger)
    }
    return logger
}

// Logger adapts zap's Logger to be compatible with grpclog.Logger.
type Logger struct {
    log    *zap.SugaredLogger
    fatal  func(*zap.SugaredLogger, ...interface{})
    fatalf func(*zap.SugaredLogger, string, ...interface{})
    print  func(*zap.SugaredLogger, ...interface{})
    printf func(*zap.SugaredLogger, string, ...interface{})
}

// Fatal implements grpclog.Logger.
func (l *Logger) Fatal(args ...interface{}) {
    l.fatal(l.log, args...)
}

// Fatalf implements grpclog.Logger.
func (l *Logger) Fatalf(format string, args ...interface{}) {
    l.fatalf(l.log, format, args...)
}

// Fatalln implements grpclog.Logger.
func (l *Logger) Fatalln(args ...interface{}) {
    l.fatal(l.log, args...)
}

// Print implements grpclog.Logger.
func (l *Logger) Print(args ...interface{}) {
    l.print(l.log, args...)
}

// Printf implements grpclog.Logger.
func (l *Logger) Printf(format string, args ...interface{}) {
    l.printf(l.log, format, args...)
}

// Println implements grpclog.Logger.
func (l *Logger) Println(args ...interface{}) {
    l.print(l.log, args...)
}

zapgrpc提供了对grpclog.Logger的适配，NewLogger将zap.Logger适配为zapgrpc.Logger，而该logger实现了grpclog.Logger接口

grpclog/logger

https://github.com/grpc/grpc-...

package grpclog

import "google.golang.org/grpc/internal/grpclog"

// Logger mimics golang's standard Logger as an interface.
//
// Deprecated: use LoggerV2.
type Logger interface {
    Fatal(args ...interface{})
    Fatalf(format string, args ...interface{})
    Fatalln(args ...interface{})
    Print(args ...interface{})
    Printf(format string, args ...interface{})
    Println(args ...interface{})
}

// SetLogger sets the logger that is used in grpc. Call only from
// init() functions.
//
// Deprecated: use SetLoggerV2.
func SetLogger(l Logger) {
    grpclog.Logger = &loggerWrapper{Logger: l}
}

// loggerWrapper wraps Logger into a LoggerV2.
type loggerWrapper struct {
    Logger
}

func (g *loggerWrapper) Info(args ...interface{}) {
    g.Logger.Print(args...)
}

func (g *loggerWrapper) Infoln(args ...interface{}) {
    g.Logger.Println(args...)
}

func (g *loggerWrapper) Infof(format string, args ...interface{}) {
    g.Logger.Printf(format, args...)
}

func (g *loggerWrapper) Warning(args ...interface{}) {
    g.Logger.Print(args...)
}

func (g *loggerWrapper) Warningln(args ...interface{}) {
    g.Logger.Println(args...)
}

func (g *loggerWrapper) Warningf(format string, args ...interface{}) {
    g.Logger.Printf(format, args...)
}

func (g *loggerWrapper) Error(args ...interface{}) {
    g.Logger.Print(args...)
}

func (g *loggerWrapper) Errorln(args ...interface{}) {
    g.Logger.Println(args...)
}

func (g *loggerWrapper) Errorf(format string, args ...interface{}) {
    g.Logger.Printf(format, args...)
}

func (g *loggerWrapper) V(l int) bool {
    // Returns true for all verbose level.
    return true
}

grpclog.Logger接口定义了Fatal(args ...interface{})、Fatalf(format string, args ...interface{})、Fatalln(args ...interface{})、Print(args ...interface{})、Printf(format string, args ...interface{})、Println(args ...interface{})方法；而grpclog.loggerWrapper会对grpclog.Logger进行适配，转而提供了Info、Infoln、Infof、Warning、Warningln、Warningf、Error、Errorln、Errorf方法

实例

func Example_initialization() {
    // Shared options for the logger, with a custom gRPC code to log level function.
    opts := []grpc_zap.Option{
        grpc_zap.WithLevels(customFunc),
    }
    // Make sure that log statements internal to gRPC library are logged using the zapLogger as well.
    grpc_zap.ReplaceGrpcLoggerV2(zapLogger)
    // Create a server, make sure we put the grpc_ctxtags context before everything else.
    _ = grpc.NewServer(
        grpc_middleware.WithUnaryServerChain(
            grpc_ctxtags.UnaryServerInterceptor(grpc_ctxtags.WithFieldExtractor(grpc_ctxtags.CodeGenRequestFieldExtractor)),
            grpc_zap.UnaryServerInterceptor(zapLogger, opts...),
        ),
        grpc_middleware.WithStreamServerChain(
            grpc_ctxtags.StreamServerInterceptor(grpc_ctxtags.WithFieldExtractor(grpc_ctxtags.CodeGenRequestFieldExtractor)),
            grpc_zap.StreamServerInterceptor(zapLogger, opts...),
        ),
    )
}

小结

zapgrpc提供了对grpclog.Logger的适配，NewLogger将zap.Logger适配为zapgrpc.Logger，而该logger实现了grpclog.Logger接口。

doc

• zap
• logging/zap