From: Sergey Matveev <stargrave@stargrave.org>
Date: Mon, 18 Sep 2023 13:35:09 +0000 (+0300)
Subject: log.slog handler
X-Git-Url: http://www.git.cypherpunks.ru/?p=gorecfile.git;a=commitdiff_plain;h=530284958d3d776e249514dccacaba53468ff24a

log.slog handler
---

diff --git a/README b/README
index 719e154..7d38e94 100644
--- a/README
+++ b/README
@@ -11,4 +11,7 @@ Limitations:
 * leading spaces in the first line of the value are ignored
 * trailing backslash at the end of lines is followed by space
 
+Also there is go.cypherpunks.ru/recfile/slog.NewRecfileHandler log/slog
+handler to write your logs in recfile format directly.
+
 It is free software: see the file COPYING for copying conditions.
diff --git a/go.mod b/go.mod
index 6a9343d..6f8d7f4 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,3 @@
 module go.cypherpunks.ru/recfile
 
-go 1.12
+go 1.21
diff --git a/slog/handler.go b/slog/handler.go
new file mode 100644
index 0000000..0a2acd4
--- /dev/null
+++ b/slog/handler.go
@@ -0,0 +1,128 @@
+package slog
+
+import (
+	"bytes"
+	"context"
+	"io"
+	"log/slog"
+	"sync"
+	"time"
+
+	"go.cypherpunks.ru/recfile"
+)
+
+type RecfileHandler struct {
+	W        io.Writer
+	Level    slog.Level
+	LevelKey string
+	MsgKey   string
+	TimeKey  string
+	attrs    []slog.Attr
+	group    string
+	m        *sync.Mutex
+}
+
+func NewRecfileHandler(
+	w io.Writer,
+	level slog.Level,
+	levelKey, msgKey, timeKey string,
+) *RecfileHandler {
+	return &RecfileHandler{
+		W:        w,
+		Level:    level,
+		LevelKey: levelKey,
+		MsgKey:   msgKey,
+		TimeKey:  timeKey,
+		m:        new(sync.Mutex),
+	}
+}
+
+func (h *RecfileHandler) Enabled(ctx context.Context, level slog.Level) bool {
+	return level >= h.Level
+}
+
+func (h *RecfileHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	return &RecfileHandler{
+		W:        h.W,
+		Level:    h.Level,
+		LevelKey: h.LevelKey,
+		MsgKey:   h.MsgKey,
+		TimeKey:  h.TimeKey,
+		attrs:    append(h.attrs, attrs...),
+		group:    h.group,
+		m:        h.m,
+	}
+}
+
+func (h *RecfileHandler) WithGroup(name string) slog.Handler {
+	neu := RecfileHandler{
+		W:        h.W,
+		Level:    h.Level,
+		LevelKey: h.LevelKey,
+		MsgKey:   h.MsgKey,
+		TimeKey:  h.TimeKey,
+		attrs:    h.attrs,
+		group:    h.group + name + "_",
+		m:        h.m,
+	}
+	return &neu
+}
+
+func writeValue(w *recfile.Writer, group string, attr slog.Attr) (err error) {
+	if attr.Value.Kind() == slog.KindAny {
+		multiline, ok := attr.Value.Any().([]string)
+		if ok {
+			if len(multiline) > 0 {
+				_, err = w.WriteFieldMultiline(group+attr.Key, multiline)
+				return
+			}
+			return
+		}
+	}
+	_, err = w.WriteFields(recfile.Field{
+		Name:  group + attr.Key,
+		Value: attr.Value.String(),
+	})
+	return
+}
+
+func (h *RecfileHandler) Handle(ctx context.Context, rec slog.Record) (err error) {
+	var b bytes.Buffer
+	w := recfile.NewWriter(&b)
+	_, err = w.RecordStart()
+	if err != nil {
+		panic(err)
+	}
+	var fields []recfile.Field
+	if h.LevelKey != "" {
+		fields = append(fields, recfile.Field{
+			Name:  h.LevelKey,
+			Value: rec.Level.String(),
+		})
+	}
+	if h.TimeKey != "" {
+		fields = append(fields, recfile.Field{
+			Name:  h.TimeKey,
+			Value: rec.Time.UTC().Format(time.RFC3339Nano),
+		})
+	}
+	fields = append(fields, recfile.Field{Name: h.MsgKey, Value: rec.Message})
+	_, err = w.WriteFields(fields...)
+	if err != nil {
+		return
+	}
+	for _, attr := range h.attrs {
+		writeValue(w, h.group, attr)
+	}
+	rec.Attrs(func(attr slog.Attr) bool { return writeValue(w, h.group, attr) == nil })
+	h.m.Lock()
+	n, err := h.W.Write(b.Bytes())
+	h.m.Unlock()
+	if err != nil {
+		return
+	}
+	if n != b.Len() {
+		return io.EOF
+	}
+	return
+}
diff --git a/slog/handler_test.go b/slog/handler_test.go
new file mode 100644
index 0000000..19fdd82
--- /dev/null
+++ b/slog/handler_test.go
@@ -0,0 +1,92 @@
+package slog
+
+import (
+	"bytes"
+	"log/slog"
+	"testing"
+	"time"
+
+	"go.cypherpunks.ru/recfile"
+)
+
+func TestBasic(t *testing.T) {
+	var buf bytes.Buffer
+	logger := slog.New(NewRecfileHandler(
+		&buf,
+		slog.LevelWarn,
+		"Urgency",
+		"Message",
+		"Time",
+	))
+	if !logger.Enabled(nil, slog.LevelWarn) {
+		t.FailNow()
+	}
+	logger.Info("won't catch me")
+	logger.Warn("catch me")
+
+	r := recfile.NewReader(&buf)
+	m, err := r.NextMap()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if m["Message"] != "catch me" {
+		t.FailNow()
+	}
+	if m["Urgency"] != "WARN" {
+		t.FailNow()
+	}
+	if _, err = time.Parse(time.RFC3339Nano, m["Time"]); err != nil {
+		t.FailNow()
+	}
+}
+
+func TestTrimmed(t *testing.T) {
+	var buf bytes.Buffer
+	logger := slog.New(NewRecfileHandler(&buf, slog.LevelWarn, "", "Message", ""))
+	logger.Warn("catch me")
+	r := recfile.NewReader(&buf)
+	m, err := r.NextMap()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if m["Message"] != "catch me" {
+		t.FailNow()
+	}
+	if m["Urgency"] != "" {
+		t.FailNow()
+	}
+	if m["Time"] != "" {
+		t.FailNow()
+	}
+}
+
+func TestFeatured(t *testing.T) {
+	var buf bytes.Buffer
+	logger := slog.New(NewRecfileHandler(&buf, slog.LevelInfo, "L", "M", "T"))
+	logger.WithGroup("grou").WithGroup("py").With("foo", "bar").With("bar", "baz").Info(
+		"catch me", "baz", []string{"multi", "line"},
+	)
+	r := recfile.NewReader(&buf)
+	m, err := r.NextMap()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if m["M"] != "catch me" {
+		t.Fatal("M")
+	}
+	if m["L"] != "INFO" {
+		t.Fatal("L")
+	}
+	if _, err = time.Parse(time.RFC3339Nano, m["T"]); err != nil {
+		t.Fatal("T")
+	}
+	if m["grou_py_foo"] != "bar" {
+		t.Fatal("foo")
+	}
+	if m["grou_py_bar"] != "baz" {
+		t.Fatal("bar")
+	}
+	if m["grou_py_baz"] != "multi\nline" {
+		t.Fatal("baz")
+	}
+}