feat: add std logger

internal/log/handler.go

@@ -0,0 +1,116 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package log
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"log/slog"
+	"sync"
+	"time"
+)
+
+// ValueTextHandler is a [Handler] that writes Records to an [io.Writer] with values separated by spaces.
+type ValueTextHandler struct {
+	h   slog.Handler
+	mu  *sync.Mutex
+	out io.Writer
+}
+
+// NewValueTextHandler creates a [ValueTextHandler] that writes to out, using the given options.
+func NewValueTextHandler(out io.Writer, opts *slog.HandlerOptions) *ValueTextHandler {
+	if opts == nil {
+		opts = &slog.HandlerOptions{}
+	}
+	return &ValueTextHandler{
+		out: out,
+		h: slog.NewTextHandler(out, &slog.HandlerOptions{
+			Level:       opts.Level,
+			AddSource:   opts.AddSource,
+			ReplaceAttr: nil,
+		}),
+		mu: &sync.Mutex{},
+	}
+}
+
+func (h *ValueTextHandler) Enabled(ctx context.Context, level slog.Level) bool {
+	return h.h.Enabled(ctx, level)
+}
+
+func (h *ValueTextHandler) WithAttrs(attrs []slog.Attr) slog.Handler {
+	return &ValueTextHandler{h: h.h.WithAttrs(attrs), out: h.out, mu: h.mu}
+}
+
+func (h *ValueTextHandler) WithGroup(name string) slog.Handler {
+	return &ValueTextHandler{h: h.h.WithGroup(name), out: h.out, mu: h.mu}
+}
+
+// Handle formats its argument [Record] as a single line of space-separated values.
+// Example output format: 2024-11-12T15:08:11.451377-08:00 INFO "Initalized 0 sources.\n"
+func (h *ValueTextHandler) Handle(ctx context.Context, r slog.Record) error {
+	buf := make([]byte, 0, 1024)
+
+	// time
+	if !r.Time.IsZero() {
+		buf = h.appendAttr(buf, slog.Time(slog.TimeKey, r.Time))
+	}
+	// level
+	buf = h.appendAttr(buf, slog.Any(slog.LevelKey, r.Level))
+	// message
+	buf = h.appendAttr(buf, slog.String(slog.MessageKey, r.Message))
+
+	r.Attrs(func(a slog.Attr) bool {
+		buf = h.appendAttr(buf, a)
+		return true
+	})
+	buf = append(buf, "\n"...)
+
+	h.mu.Lock()
+	defer h.mu.Unlock()
+	_, err := h.out.Write(buf)
+	return err
+}
+
+// appendAttr is reponsible for formatting a single attribute
+func (h *ValueTextHandler) appendAttr(buf []byte, a slog.Attr) []byte {
+	// Resolve the Attr's value before doing anything else.
+	a.Value = a.Value.Resolve()
+	// Ignore empty Attrs.
+	if a.Equal(slog.Attr{}) {
+		return buf
+	}
+	switch a.Value.Kind() {
+	case slog.KindString:
+		// Quote string values, to make them easy to parse.
+		buf = fmt.Appendf(buf, "%q ", a.Value.String())
+	case slog.KindTime:
+		// Write times in a standard way, without the monotonic time.
+		buf = fmt.Appendf(buf, "%s ", a.Value.Time().Format(time.RFC3339Nano))
+	case slog.KindGroup:
+		attrs := a.Value.Group()
+		// Ignore empty groups.
+		if len(attrs) == 0 {
+			return buf
+		}
+		for _, ga := range attrs {
+			buf = h.appendAttr(buf, ga)
+		}
+	default:
+		buf = fmt.Appendf(buf, "%s ", a.Value)
+	}
+
+	return buf
+}

internal/log/log.go

@@ -0,0 +1,84 @@
+// Copyright 2024 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package log
+
+import (
+	"io"
+	"log/slog"
+	"strings"
+
+	"github.com/googleapis/genai-toolbox/toolbox"
+)
+
+// StdLogger is the standard logger
+type StdLogger struct {
+	outLogger *slog.Logger
+	errLogger *slog.Logger
+}
+
+// NewStdLogger create a Logger that uses out and err for informational and error messages.
+func NewStdLogger(out, err io.Writer, logLevel string) toolbox.Logger {
+	//Set log level
+	var programLevel = new(slog.LevelVar)
+	programLevel.Set(severityToLevel(logLevel))
+
+	handlerOptions := &slog.HandlerOptions{Level: programLevel}
+
+	return &StdLogger{
+		outLogger: slog.New(NewValueTextHandler(out, handlerOptions)),
+		errLogger: slog.New(NewValueTextHandler(err, handlerOptions)),
+	}
+}
+
+// Debug logs debug messages
+func (sl *StdLogger) Debug(msg string, keysAndValues ...interface{}) {
+	sl.outLogger.Debug(msg, keysAndValues...)
+}
+
+// Info logs debug messages
+func (sl *StdLogger) Info(msg string, keysAndValues ...interface{}) {
+	sl.outLogger.Info(msg, keysAndValues...)
+}
+
+// Warn logs warning messages
+func (sl *StdLogger) Warn(msg string, keysAndValues ...interface{}) {
+	sl.errLogger.Warn(msg, keysAndValues...)
+}
+
+// Error logs error messages
+func (sl *StdLogger) Error(msg string, keysAndValues ...interface{}) {
+	sl.errLogger.Error(msg, keysAndValues...)
+}
+
+const (
+	Debug = "DEBUG"
+	Info  = "INFO"
+	Warn  = "WARN"
+	Error = "ERROR"
+)
+
+// Returns severity level based on string.
+func severityToLevel(s string) slog.Level {
+	switch strings.ToUpper(s) {
+	case Debug:
+		return slog.LevelDebug
+	case Info:
+		return slog.LevelInfo
+	case Warn:
+		return slog.LevelWarn
+	default:
+		return slog.LevelError
+	}
+}