interface+log: add new structured log methods

And let subLog implement the methods by calling its existing methods.
Note that subLog will not produce structured logs as of this commit. In
future, it can be updated to use an slog.Logger and this package can
implement a default slog.Handler.

Author: ellemouton

interface.go

@@ -4,6 +4,8 @@
 
 package btclog
 
+import "context"
+
 // Logger is an interface which describes a level-based logger.  A default
 // implementation of Logger is implemented by this package and can be created
 // by calling (*Backend).Logger.
@@ -56,6 +58,30 @@ type Logger interface {
 	// and writes to log with LevelCritical.
 	Critical(v ...any)
 
+	// TraceS writes a structured log with the given message and key-value
+	// pair attributes with LevelTrace to the log.
+	TraceS(ctx context.Context, msg string, attrs ...any)
+
+	// DebugS writes a structured log with the given message and key-value
+	// pair attributes with LevelDebug to the log.
+	DebugS(ctx context.Context, msg string, attrs ...any)
+
+	// InfoS writes a structured log with the given message and key-value
+	// pair attributes with LevelInfo to the log.
+	InfoS(ctx context.Context, msg string, attrs ...any)
+
+	// WarnS writes a structured log with the given message and key-value
+	// pair attributes with LevelWarn to the log.
+	WarnS(ctx context.Context, msg string, err error, attrs ...any)
+
+	// ErrorS writes a structured log with the given message and key-value
+	// pair attributes with LevelError to the log.
+	ErrorS(ctx context.Context, msg string, err error, attrs ...any)
+
+	// CriticalS writes a structured log with the given message and
+	// key-value pair attributes with LevelCritical to the log.
+	CriticalS(ctx context.Context, msg string, err error, attrs ...any)
+
 	// Level returns the current logging level.
 	Level() Level
 

log.go

@@ -34,8 +34,10 @@ package btclog
 
 import (
 	"bytes"
+	"context"
 	"fmt"
 	"io"
+	"log/slog"
 	"os"
 	"runtime"
 	"strings"
@@ -417,6 +419,63 @@ func (l *subLog) Criticalf(format string, args ...any) {
 	}
 }
 
+// TraceS writes a structured log with the given message and key-value pair
+// attributes with LevelTrace to the log.
+//
+// This is part of the Logger interface implementation.
+func (l *subLog) TraceS(_ context.Context, msg string, attrs ...any) {
+	l.Tracef(msg, attrs...)
+}
+
+// DebugS writes a structured log with the given message and key-value pair
+// attributes with LevelDebug to the log.
+//
+// This is part of the Logger interface implementation.
+func (l *subLog) DebugS(_ context.Context, msg string, attrs ...any) {
+	l.Debugf(msg, attrs...)
+}
+
+// InfoS writes a structured log with the given message and key-value pair
+// attributes with LevelInfo to the log.
+//
+// This is part of the Logger interface implementation.
+func (l *subLog) InfoS(_ context.Context, msg string, attrs ...any) {
+	l.Infof(msg, attrs...)
+}
+
+// WarnS writes a structured log with the given message and key-value pair
+// attributes with LevelWarn to the log.
+//
+// This is part of the Logger interface implementation.
+func (l *subLog) WarnS(_ context.Context, msg string, err error, attrs ...any) {
+	if err != nil {
+		attrs = append([]any{slog.String("err", err.Error())}, attrs...)
+	}
+	l.Warnf(msg, attrs...)
+}
+
+// ErrorS writes a structured log with the given message and key-value pair
+// attributes with LevelError to the log.
+//
+// This is part of the Logger interface implementation.
+func (l *subLog) ErrorS(_ context.Context, msg string, err error, attrs ...any) {
+	if err != nil {
+		attrs = append([]any{slog.String("err", err.Error())}, attrs...)
+	}
+	l.Errorf(msg, attrs...)
+}
+
+// CriticalS writes a structured log with the given message and key-value pair
+// attributes with LevelCritical to the log.
+//
+// This is part of the Logger interface implementation.
+func (l *subLog) CriticalS(_ context.Context, msg string, err error, attrs ...any) {
+	if err != nil {
+		attrs = append([]any{slog.String("err", err.Error())}, attrs...)
+	}
+	l.Criticalf(msg, attrs...)
+}
+
 // Level returns the current logging level
 //
 // This is part of the Logger interface implementation.