Fix SlidingTimeWindowArraySample to expire metrics correctly

metrics/chunked_associative_array.go

@@ -172,9 +172,18 @@ func (caa *ChunkedAssociativeArray) Trim(startKey int64, endKey int64) {
 	})
 
 	// Remove chunks that only contain elements that are too small
-	for i := 0; i < indexAfterStartKey; i++ {
-		chunk := caa.chunks.PopFront()
-		caa.freeChunk(chunk)
+	if indexAfterStartKey == -1 {
+		// All chunks contain only elements that are too small, remove all
+		for caa.chunks.Len() > 0 {
+			chunk := caa.chunks.PopFront()
+			caa.freeChunk(chunk)
+		}
+	} else {
+		// Remove chunks before the first valid chunk
+		for i := 0; i < indexAfterStartKey; i++ {
+			chunk := caa.chunks.PopFront()
+			caa.freeChunk(chunk)
+		}
 	}
 }
 

metrics/sliding_time_window_expiry_test.go

@@ -0,0 +1,120 @@
+package metrics
+
+import (
+	"testing"
+	"time"
+)
+
+// TestSlidingTimeWindowExpiry verifies that values expire to 0 after the time window
+func TestSlidingTimeWindowExpiry(t *testing.T) {
+	// Create a sample with a 50ms window
+	window := 50 * time.Millisecond
+	sample := NewSlidingTimeWindowArraySample(window)
+
+	// Add some values
+	sample.Update(100)
+	sample.Update(200)
+	sample.Update(300)
+
+	// Verify initial values
+	snapshot1 := sample.Snapshot()
+	if snapshot1.Count() != 3 {
+		t.Errorf("Expected initial count of 3, got %d", snapshot1.Count())
+	}
+	if snapshot1.Mean() != 200 {
+		t.Errorf("Expected initial mean of 200, got %f", snapshot1.Mean())
+	}
+
+	// Wait for window to expire
+	time.Sleep(60 * time.Millisecond)
+
+	// Take snapshot after expiry
+	snapshot2 := sample.Snapshot()
+
+	// Should have count of 3 (from the implementation returning the actual count)
+	// but all values should be 0
+	percentiles := snapshot2.Percentiles([]float64{0.5, 0.95, 0.99})
+	for i, p := range percentiles {
+		if p != 0 {
+			t.Errorf("Expected percentile[%d] to be 0 after expiry, got %f", i, p)
+		}
+	}
+
+	if snapshot2.Min() != 0 {
+		t.Errorf("Expected min to be 0 after expiry, got %d", snapshot2.Min())
+	}
+
+	if snapshot2.Max() != 0 {
+		t.Errorf("Expected max to be 0 after expiry, got %d", snapshot2.Max())
+	}
+
+	if snapshot2.Mean() != 0 {
+		t.Errorf("Expected mean to be 0 after expiry, got %f", snapshot2.Mean())
+	}
+}
+
+// TestChunkedAssociativeArrayTrimAll verifies the fix for trimming all chunks
+func TestChunkedAssociativeArrayTrimAll(t *testing.T) {
+	array := NewChunkedAssociativeArray(3)
+
+	// Add values with small keys
+	array.Put(1, 100)
+	array.Put(2, 200)
+	array.Put(3, 300)
+	array.Put(4, 400)
+
+	// Verify values exist
+	values := array.Values()
+	if len(values) != 4 {
+		t.Errorf("Expected 4 values, got %d", len(values))
+	}
+
+	// Trim with startKey greater than all existing keys
+	// This should remove all chunks
+	array.Trim(1000, 2000)
+
+	// Should be empty now
+	values = array.Values()
+	if len(values) != 1 || values[0] != 0 {
+		t.Errorf("Expected [0] after trimming all, got %v", values)
+	}
+}
+
+// TestBoundedHistogramSampleExpiry verifies histogram expiry behavior
+func TestBoundedHistogramSampleExpiry(t *testing.T) {
+	// Create a histogram with 100ms window for faster testing
+	sample := NewSlidingTimeWindowArraySample(100 * time.Millisecond)
+	histogram := NewHistogram(sample)
+
+	// Add values
+	histogram.Update(1000)
+	histogram.Update(2000)
+	histogram.Update(3000)
+
+	// Check initial state
+	snapshot1 := histogram.Snapshot()
+	if snapshot1.Count() != 3 {
+		t.Errorf("Expected count of 3, got %d", snapshot1.Count())
+	}
+
+	// Wait for expiry
+	time.Sleep(110 * time.Millisecond)
+
+	// Check after expiry
+	snapshot2 := histogram.Snapshot()
+	percentiles := snapshot2.Percentiles([]float64{0.5, 0.99})
+
+	for i, p := range percentiles {
+		if p != 0 {
+			t.Errorf("Expected percentile[%d] to be 0 after expiry, got %f", i, p)
+		}
+	}
+
+	if snapshot2.Min() != 0 {
+		t.Errorf("Expected min to be 0 after expiry, got %d", snapshot2.Min())
+	}
+
+	if snapshot2.Max() != 0 {
+		t.Errorf("Expected max to be 0 after expiry, got %d", snapshot2.Max())
+	}
+}