tracingpb: more fine grained redactability for tracing events

Prior to this patch, `RecordedSpan` and `Recording` only had a
`String` method to dump a representation, that would remove all
redaction markers and turn the result in an unsafe string.

This was making it hard to export recordings into logs while
preserving redactability of individual trace spans.

This patch improves the situation by introducing a `SafeFormat` method
which exposes the redactability of trace spans into a mixed string
that represents the recording.

Release note: None

pkg/util/tracing/tracingpb/recorded_span.go

@@ -12,7 +12,6 @@ package tracingpb
 
 import (
 	"fmt"
-	"strings"
 	"time"
 
 	"github.com/cockroachdb/cockroach/pkg/util/humanizeutil"
@@ -53,13 +52,17 @@ func (r Recording) Len() int {
 // LogMessageField is the field name used for the log message in a LogRecord.
 const LogMessageField = "event"
 
+// String implements fmt.Stringer.
 func (s *RecordedSpan) String() string {
-	sb := strings.Builder{}
-	sb.WriteString(fmt.Sprintf("=== %s (id: %d parent: %d)\n", s.Operation, s.SpanID, s.ParentSpanID))
+	return redact.Sprint(s).StripMarkers()
+}
+
+// SafeFormat implements redact.SafeFormatter.
+func (s *RecordedSpan) SafeFormat(w redact.SafePrinter, _ rune) {
+	w.Printf("=== %s (id: %d parent: %d)\n", redact.Safe(s.Operation), s.SpanID, s.ParentSpanID)
 	for _, ev := range s.Logs {
-		sb.WriteString(fmt.Sprintf("%s %s\n", ev.Time.UTC().Format(time.RFC3339Nano), ev.Msg()))
+		w.Printf("%s %s\n", redact.Safe(ev.Time.UTC().Format(time.RFC3339Nano)), ev.Msg())
 	}
-	return sb.String()
 }
 
 // Structured visits the data passed to RecordStructured for the Span from which

pkg/util/tracing/tracingpb/recording.go

@@ -16,7 +16,6 @@ import (
 	"regexp"
 	"sort"
 	"strconv"
-	"strings"
 	"time"
 
 	"github.com/cockroachdb/cockroach/pkg/util/protoutil"
@@ -140,20 +139,25 @@ type logRecord struct {
 // TODO(andrei): this should be unified with
 // SessionTracing.generateSessionTraceVTable().
 func (r Recording) String() string {
+	return redact.Sprint(r).StripMarkers()
+}
+
+// SafeFormat implements the redact.SafeFormatter interface.
+func (r Recording) SafeFormat(w redact.SafePrinter, _ rune) {
 	if len(r) == 0 {
-		return "<empty recording>"
+		w.SafeString("<empty recording>")
 	}
 
-	var buf strings.Builder
 	start := r[0].StartTime
 	writeLogs := func(logs []traceLogData) {
 		for _, entry := range logs {
-			fmt.Fprintf(&buf, "% 10.3fms % 10.3fms%s",
+			w.Printf("% 10.3fms % 10.3fms",
 				1000*entry.Timestamp.Sub(start).Seconds(),
-				1000*entry.timeSincePrev.Seconds(),
-				strings.Repeat("    ", entry.depth+1))
-			fmt.Fprint(&buf, entry.Msg.StripMarkers())
-			buf.WriteByte('\n')
+				1000*entry.timeSincePrev.Seconds())
+			for i := 0; i < entry.depth+1; i++ {
+				w.SafeString("    ")
+			}
+			w.Printf("%s\n", entry.Msg)
 		}
 	}
 
@@ -167,13 +171,12 @@ func (r Recording) String() string {
 	orphans := r.OrphanSpans()
 	if len(orphans) > 0 {
 		// This shouldn't happen.
-		buf.WriteString("orphan spans (trace is missing spans):\n")
+		w.SafeString("orphan spans (trace is missing spans):\n")
 		for _, o := range orphans {
 			logs := r.visitSpan(o, 0 /* depth */)
 			writeLogs(logs)
 		}
 	}
-	return buf.String()
 }
 
 // OrphanSpans returns the spans with parents missing from the recording.