slogutil: export PrintRecovered

logutil/slogutil/defer.go

@@ -38,10 +38,7 @@ func CloseAndLog(ctx context.Context, l *slog.Logger, closer io.Closer, lvl slog
 // RecoverAndLog is a deferred helper that recovers from a panic and logs the
 // panic value into l along with the stacktrace.  l must not be nil.
 func RecoverAndLog(ctx context.Context, l *slog.Logger) {
-	v := recover()
-	if v != nil {
-		printRecovered(ctx, l, v)
-	}
+	PrintRecovered(ctx, l, recover())
 }
 
 // RecoverAndLogDefault is like [RecoverAndLog] but tries to get the logger from
@@ -57,24 +54,25 @@ func RecoverAndLogDefault(ctx context.Context) {
 		l = slog.Default()
 	}
 
-	printRecovered(ctx, l, v)
+	PrintRecovered(ctx, l, v)
 }
 
 // RecoverAndExit recovers a panic, logs it using l, and then exits with the
 // given exit code.  l must not be nil.
 func RecoverAndExit(ctx context.Context, l *slog.Logger, code osutil.ExitCode) {
-	v := recover()
-	if v == nil {
-		return
-	}
-
-	printRecovered(ctx, l, v)
+	PrintRecovered(ctx, l, recover())
 
 	os.Exit(code)
 }
 
-// printRecovered prints the recovered value.  l must not be nil.
-func printRecovered(ctx context.Context, l *slog.Logger, v any) {
+// PrintRecovered prints a message with the recovered value, if there is any, as
+// well as the stack.  If v is nil, PrintRecovered does nothing.  Otherwise, l
+// must not be nil.
+func PrintRecovered(ctx context.Context, l *slog.Logger, v any) {
+	if v == nil {
+		return
+	}
+
 	var args []any
 	if err, ok := v.(error); ok {
 		args = []any{KeyError, err}

logutil/slogutil/defer_example_test.go

@@ -1,9 +1,11 @@
 package slogutil_test
 
 import (
+	"bytes"
 	"context"
 	"fmt"
 	"log/slog"
+	"strings"
 
 	"github.com/AdguardTeam/golibs/errors"
 	"github.com/AdguardTeam/golibs/logutil/slogutil"
@@ -53,3 +55,28 @@ func ExampleCloseAndLog() {
 	// actual closer with error:
 	// DEBUG deferred closing err="close failed"
 }
+
+func ExamplePrintRecovered() {
+	ctx := context.Background()
+
+	output := &bytes.Buffer{}
+	l := slogutil.New(&slogutil.Config{
+		Output: output,
+	})
+
+	func() {
+		defer func() { slogutil.PrintRecovered(ctx, l, recover()) }()
+
+		l = l.With("extra", "parameters", "added", "later")
+
+		panic("test value")
+	}()
+
+	// Only print the first line, since the stack trace is not reproducible in
+	// examples.
+	lines := strings.Split(output.String(), "\n")
+	fmt.Println(lines[0])
+
+	// Output:
+	// ERROR recovered from panic extra=parameters added=later value="test value"
+}