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-rw-r--r--utils/trace/trace.go55
-rw-r--r--utils/trace/trace_test.go95
2 files changed, 150 insertions, 0 deletions
diff --git a/utils/trace/trace.go b/utils/trace/trace.go
new file mode 100644
index 0000000..3e15c5b
--- /dev/null
+++ b/utils/trace/trace.go
@@ -0,0 +1,55 @@
+package trace
+
+import (
+ "fmt"
+ "log"
+ "os"
+ "sync/atomic"
+)
+
+var (
+ // logger is the logger to use for tracing.
+ logger = newLogger()
+
+ // current is the targets that are enabled for tracing.
+ current atomic.Int32
+)
+
+func newLogger() *log.Logger {
+ return log.New(os.Stderr, "", log.Ltime|log.Lmicroseconds|log.Lshortfile)
+}
+
+// Target is a tracing target.
+type Target int32
+
+const (
+ // General traces general operations.
+ General Target = 1 << iota
+
+ // Packet traces git packets.
+ Packet
+)
+
+// SetTarget sets the tracing targets.
+func SetTarget(target Target) {
+ current.Store(int32(target))
+}
+
+// SetLogger sets the logger to use for tracing.
+func SetLogger(l *log.Logger) {
+ logger = l
+}
+
+// Print prints the given message only if the target is enabled.
+func (t Target) Print(args ...interface{}) {
+ if int32(t)&current.Load() != 0 {
+ logger.Output(2, fmt.Sprint(args...)) // nolint: errcheck
+ }
+}
+
+// Printf prints the given message only if the target is enabled.
+func (t Target) Printf(format string, args ...interface{}) {
+ if int32(t)&current.Load() != 0 {
+ logger.Output(2, fmt.Sprintf(format, args...)) // nolint: errcheck
+ }
+}
diff --git a/utils/trace/trace_test.go b/utils/trace/trace_test.go
new file mode 100644
index 0000000..6f8f140
--- /dev/null
+++ b/utils/trace/trace_test.go
@@ -0,0 +1,95 @@
+package trace
+
+import (
+ "bytes"
+ "io"
+ "log"
+ "testing"
+)
+
+func TestMain(m *testing.M) {
+ defer SetLogger(newLogger())
+ if code := m.Run(); code != 0 {
+ panic(code)
+ }
+}
+
+func setUpTest(t testing.TB, buf *bytes.Buffer) {
+ t.Cleanup(func() {
+ if buf != nil {
+ buf.Reset()
+ }
+ SetTarget(0)
+ })
+ w := io.Discard
+ if buf != nil {
+ w = buf
+ }
+ SetLogger(log.New(w, "", 0))
+}
+
+func TestEmpty(t *testing.T) {
+ var buf bytes.Buffer
+ setUpTest(t, &buf)
+ General.Print("test")
+ if buf.String() != "" {
+ t.Error("expected empty string")
+ }
+}
+
+func TestOneTarget(t *testing.T) {
+ var buf bytes.Buffer
+ setUpTest(t, &buf)
+ SetTarget(General)
+ General.Print("test")
+ if buf.String() != "test\n" {
+ t.Error("expected 'test'")
+ }
+}
+
+func TestMultipleTargets(t *testing.T) {
+ var buf bytes.Buffer
+ setUpTest(t, &buf)
+ SetTarget(General | Packet)
+ General.Print("a")
+ Packet.Print("b")
+ if buf.String() != "a\nb\n" {
+ t.Error("expected 'a\nb\n'")
+ }
+}
+
+func TestPrintf(t *testing.T) {
+ var buf bytes.Buffer
+ setUpTest(t, &buf)
+ SetTarget(General)
+ General.Printf("a %d", 1)
+ if buf.String() != "a 1\n" {
+ t.Error("expected 'a 1\n'")
+ }
+}
+
+func TestDisabledMultipleTargets(t *testing.T) {
+ var buf bytes.Buffer
+ setUpTest(t, &buf)
+ SetTarget(General)
+ General.Print("a")
+ Packet.Print("b")
+ if buf.String() != "a\n" {
+ t.Error("expected 'a\n'")
+ }
+}
+
+func BenchmarkDisabledTarget(b *testing.B) {
+ setUpTest(b, nil)
+ for i := 0; i < b.N; i++ {
+ General.Print("test")
+ }
+}
+
+func BenchmarkEnabledTarget(b *testing.B) {
+ setUpTest(b, nil)
+ SetTarget(General)
+ for i := 0; i < b.N; i++ {
+ General.Print("test")
+ }
+}