smb: fix metric types and names, extend 32-bit counters in smb and smbclient (#2710)

Signed-off-by: Claude <noreply@anthropic.com>
Co-authored-by: Claude <noreply@anthropic.com>

internal/utils/counter.go

@@ -39,3 +39,52 @@ func (c *Counter) AddValue(value uint32) {
 func (c *Counter) Value() float64 {
 	return c.totalValue
 }
+
+// Counter32 extends a raw 32-bit performance counter, such as a
+// PERF_COUNTER_COUNTER or the numerator of a PERF_AVERAGE_TIMER, beyond 2^32.
+// Unlike Counter, it starts at the raw value and follows a restart of the
+// source, so its value equals the raw value until the first wrap. It can only
+// detect one wrap between two samples.
+type Counter32 struct {
+	lastValue    uint32
+	totalValue   float64
+	restartBelow uint32
+}
+
+// NewCounter32 creates a Counter32 from the first raw value. If restartBelow is
+// not zero, a decrease from a raw value below restartBelow is taken as a
+// restart of the source instead of a wrap. Use it for counters that cannot
+// grow by 2^32-restartBelow between two samples, such as request counts.
+func NewCounter32(value float64, restartBelow uint32) Counter32 {
+	raw := toUint32(value)
+
+	return Counter32{
+		lastValue:    raw,
+		totalValue:   float64(raw),
+		restartBelow: restartBelow,
+	}
+}
+
+// Update adds a raw value and returns the extended value. reset reports that
+// the source restarted, for example because a share was reconnected; the raw
+// value is then taken as is. Any other decrease is a wrap, unless it starts
+// below restartBelow.
+func (c *Counter32) Update(value float64, reset bool) float64 {
+	raw := toUint32(value)
+
+	if reset || (raw < c.lastValue && c.lastValue < c.restartBelow) {
+		c.totalValue = float64(raw)
+	} else {
+		c.totalValue += float64(raw - c.lastValue)
+	}
+
+	c.lastValue = raw
+
+	return c.totalValue
+}
+
+// toUint32 converts through int64, so a sign-extended value keeps its low
+// 32 bits on every architecture.
+func toUint32(value float64) uint32 {
+	return uint32(int64(value))
+}

internal/utils/counter_test.go

@@ -55,3 +55,28 @@ func TestCounter(t *testing.T) {
 
 	require.Equal(t, float64(math.MaxUint32)*2-9, c.Value()) //nolint:testifylint
 }
+
+func TestCounter32(t *testing.T) {
+	t.Parallel()
+
+	c := utils.NewCounter32(100, 0)
+
+	require.Equal(t, 100.0, c.Update(100, false))                                    //nolint:testifylint
+	require.Equal(t, 150.0, c.Update(150, false))                                    //nolint:testifylint
+	require.Equal(t, float64(math.MaxUint32)-10, c.Update(math.MaxUint32-10, false)) //nolint:testifylint
+	require.Equal(t, float64(math.MaxUint32)+21, c.Update(20, false))                //nolint:testifylint
+	require.Equal(t, 5.0, c.Update(5, true))                                         //nolint:testifylint
+	require.Equal(t, 15.0, c.Update(15, false))                                      //nolint:testifylint
+	// Without restartBelow, any decrease is a wrap.
+	require.Equal(t, float64(math.MaxUint32)+4, c.Update(3, false)) //nolint:testifylint
+}
+
+func TestCounter32RestartBelow(t *testing.T) {
+	t.Parallel()
+
+	c := utils.NewCounter32(50, 1<<31)
+
+	require.Equal(t, 3.0, c.Update(3, false))                                        //nolint:testifylint
+	require.Equal(t, float64(math.MaxUint32)-10, c.Update(math.MaxUint32-10, false)) //nolint:testifylint
+	require.Equal(t, float64(math.MaxUint32)+21, c.Update(20, false))                //nolint:testifylint
+}