tracer

Documentation

Overview

Package tracer starts an opencensus span with a logger automatically signed with the current calling function.

An additional method is provided to explicitly sign anonymous functions.

Index

• func RegisterPrefix(custom string)
• func StartNamedSpan(ctx context.Context, rt Loggable, signature string, fields ...zap.Field) (context.Context, *trace.Span, log.Logger)
• func StartSpan(ctx context.Context, rt Loggable, fields ...zap.Field) (context.Context, *trace.Span, log.Logger)
• type Loggable

Examples

• StartNamedSpan
• StartSpan

Functions

func RegisterPrefix

func RegisterPrefix(custom string)

RegisterPrefix sets a package level prefix at initialization time.

The default value is "function".

func StartNamedSpan

func StartNamedSpan(ctx context.Context, rt Loggable, signature string, fields ...zap.Field) (context.Context, *trace.Span, log.Logger)

StartNamedSpan is used inside anonymous functions. The caller may specify a signature.

Example

package main

import (
	"context"

	"github.com/fredbi/go-trace/log"
	"github.com/fredbi/go-trace/tracer"
	"go.uber.org/zap"
)

type Runtime struct {
	logger log.Factory
}

func (r Runtime) Logger() log.Factory {
	return r.logger
}

func main() {
	lg, _ := zap.NewDevelopment()
	rt := Runtime{logger: log.NewFactory(lg)}
	ctx := context.Background()

	// StartNamedSpan should be used in anonymous functions like so.
	handleFunc := func() {
		_, span, logger := tracer.StartNamedSpan(ctx, rt, "signature", zap.String("field", "fred"))
		defer span.End()

		logger.Info("test")
	}

	handleFunc()
}

func StartSpan

func StartSpan(ctx context.Context, rt Loggable, fields ...zap.Field) (context.Context, *trace.Span, log.Logger)

StartSpan returns an opencensus span and logger that prepends the caller's signature.

This spares us the boiler plate of repeatedly adding the prefix and function signatures in trace spans and logger.

Example

package main

import (
	"context"

	"github.com/fredbi/go-trace/log"
	"github.com/fredbi/go-trace/tracer"
	"go.uber.org/zap"
)

type Runtime struct {
	logger log.Factory
}

func (r Runtime) Logger() log.Factory {
	return r.logger
}

func main() {
	lg, _ := zap.NewProduction()
	rt := Runtime{logger: log.NewFactory(lg)}
	ctx := context.Background()

	// Instantiate a span and its associated span logger.
	//
	// This span is automatically signed with the current function, annotated with the source file and line
	_, span, logger := tracer.StartSpan(ctx, rt, zap.String("field", "fred"))
	defer span.End()

	logger.Info("test")

	// Should get something like:
	// 2023-11-01T17:19:58.615+0100	INFO	log/logger.go:35	test	{
	//	"function": "tracer.TestStartSpan",
	//	"source_file": ".../github.com/fredbi/go-trace/tracer/tracer_test.go",
	//	"source_line": 28,
	//	"field": "fred"
	//	}
}

Types

type Loggable

type Loggable interface {
	Logger() log.Factory
}

Loggable is a log factory provider