README
¶
console-slog
A handler for slog that prints colorized logs, similar to zerolog's console writer output, but without sacrificing performances.
Example
package main
import (
"errors"
"log/slog"
"os"
"github.com/phsym/console-slog"
)
func main() {
logger := slog.New(
console.NewHandler(os.Stderr, &console.HandlerOptions{Level: slog.LevelDebug}),
)
slog.SetDefault(logger)
slog.Info("Hello world!", "foo", "bar")
slog.Debug("Debug message")
slog.Warn("Warning message")
slog.Error("Error message", "err", errors.New("the error"))
logger = logger.With("foo", "bar").
WithGroup("the-group").
With("bar", "baz")
logger.Info("group info", "attr", "value")
}
When setting console.HandlerOptions.AddSource to true:
console.NewHandler(os.Stderr, &console.HandlerOptions{Level: slog.LevelDebug, AddSource: true})
Performances
See benchmark file for details.
The handler itself performs quite well compared to std-lib's handlers. It does no allocation:
goos: linux
goarch: amd64
pkg: github.com/phsym/console-slog
cpu: Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
BenchmarkHandlers/dummy-4 128931026 8.732 ns/op 0 B/op 0 allocs/op
BenchmarkHandlers/console-4 849837 1294 ns/op 0 B/op 0 allocs/op
BenchmarkHandlers/std-text-4 542583 2097 ns/op 4 B/op 2 allocs/op
BenchmarkHandlers/std-json-4 583784 1911 ns/op 120 B/op 3 allocs/op
However, the go 1.21.0 slog.Logger adds some overhead:
goos: linux
goarch: amd64
pkg: github.com/phsym/console-slog
cpu: Intel(R) Core(TM) i5-6300U CPU @ 2.40GHz
BenchmarkLoggers/dummy-4 1239873 893.2 ns/op 128 B/op 1 allocs/op
BenchmarkLoggers/console-4 483354 2338 ns/op 128 B/op 1 allocs/op
BenchmarkLoggers/std-text-4 368828 3141 ns/op 132 B/op 3 allocs/op
BenchmarkLoggers/std-json-4 393322 2909 ns/op 248 B/op 4 allocs/op
Documentation
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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type ConsoleHandler ¶
type ConsoleHandler struct {
// contains filtered or unexported fields
}
func NewHandler ¶
func NewHandler(out io.Writer, opts *HandlerOptions) *ConsoleHandler
type HandlerOptions ¶
type HandlerOptions struct {
// AddSource causes the handler to compute the source code position
// of the log statement and add a SourceKey attribute to the output.
AddSource bool
// Level reports the minimum record level that will be logged.
// The handler discards records with lower levels.
// If Level is nil, the handler assumes LevelInfo.
// The handler calls Level.Level for each record processed;
// to adjust the minimum level dynamically, use a LevelVar.
Level slog.Leveler
}
HandlerOptions are options for a ConsoleHandler. A zero HandlerOptions consists entirely of default values.
Source Files
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