v0.33.0 tui tap for live view and console enhancements

internal/core/flow_test.go

@@ -1,6 +1,11 @@
 package core
 
-import "testing"
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+	"unsafe"
+)
 
 // A line's level is its first whole word, in any case, naming a level, not the
 // most severe one named; a wanted level skips the names of the others.
@@ -22,3 +27,41 @@ func TestLevelIsTheFirstWordNamingOne(t *testing.T) {
 		}
 	}
 }
+
+// A tapped record keeps at most TapEntryBytes of an entry's message, fields
+// and payload and TapNameBytes of its level, source and node, copied, so a
+// viewer's scrollback holds none of the source's line
+func TestTapClipsLongEntriesByCopying(t *testing.T) {
+	line := strings.Repeat("x", MaxLogEntryBytes)
+	payload, fields := []byte(line), json.RawMessage(line)
+	tap := NewTap(1)
+	tap.Offer(Tapped{Event: TransportEvent{Payload: payload, Entry: LogEntry{Message: line, Fields: fields, Level: line, Source: line, Node: line}}})
+	r := <-tap.Records()
+	e := r.Event.Entry
+	if len(e.Message) != TapEntryBytes || len(e.Fields) != TapEntryBytes || len(r.Event.Payload) != TapEntryBytes {
+		t.Fatalf("kept %d, %d and %d bytes, want %d", len(e.Message), len(e.Fields), len(r.Event.Payload), TapEntryBytes)
+	}
+	if len(e.Level) != TapNameBytes || len(e.Source) != TapNameBytes || len(e.Node) != TapNameBytes {
+		t.Fatalf("kept %d, %d and %d bytes of the names, want %d", len(e.Level), len(e.Source), len(e.Node), TapNameBytes)
+	}
+	for _, s := range []string{e.Message, e.Level, e.Source, e.Node} {
+		if unsafe.StringData(s) == unsafe.StringData(line) {
+			t.Fatal("a clipped part shares the source's line")
+		}
+	}
+	if &e.Fields[0] == &fields[0] || &r.Event.Payload[0] == &payload[0] {
+		t.Fatal("a clipped part shares the source's line")
+	}
+}
+
+// A full tap drops and counts without copying anything, so a tap nobody
+// reads costs a pipeline nothing
+func TestAFullTapCostsNothing(t *testing.T) {
+	line := strings.Repeat("x", MaxLogEntryBytes)
+	tap := NewTap(1)
+	rec := Tapped{Event: TransportEvent{Payload: []byte(line), Entry: LogEntry{Message: line, Fields: json.RawMessage(line), Level: line}}}
+	tap.Offer(rec)
+	if allocs := testing.AllocsPerRun(100, func() { tap.Offer(rec) }); allocs != 0 || tap.Dropped() != 101 {
+		t.Fatalf("%v allocations an offer, %d dropped", allocs, tap.Dropped())
+	}
+}