chore: Phase 10 remaining — QA WAL admission metrics tests

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

weed/storage/blockvol/qa_wal_admission_test.go

@@ -460,3 +460,261 @@ func TestQA_Admission_WriteLBAIntegration(t *testing.T) {
 	}
 	t.Logf("all %d writes succeeded with maxConcurrent=4", writers*writesPerWriter)
 }
+
+// =============================================================================
+// QA Adversarial Tests for WAL Admission Metrics (Item 2: WAL Visibility Hooks)
+//
+// These tests verify counter correctness under concurrent pressure, metrics
+// consistency across all code paths, and integration with EngineMetrics.
+// =============================================================================
+
+// TestQA_Admission_Metrics_ConcurrentCountersConsistent verifies that under
+// heavy concurrent load, Total >= Soft + Hard and Timeout <= Hard.
+func TestQA_Admission_Metrics_ConcurrentCountersConsistent(t *testing.T) {
+	m := NewEngineMetrics()
+	var pressure atomic.Int64
+	pressure.Store(50)
+
+	a := NewWALAdmission(WALAdmissionConfig{
+		MaxConcurrent: 8,
+		SoftWatermark: 0.7,
+		HardWatermark: 0.9,
+		WALUsedFn:     func() float64 { return float64(pressure.Load()) / 100.0 },
+		NotifyFn:      func() {},
+		ClosedFn:      func() bool { return false },
+		Metrics:       m,
+	})
+
+	// Oscillate pressure so writers hit all code paths.
+	stopOsc := make(chan struct{})
+	go func() {
+		zones := []int64{30, 80, 95, 50, 75, 92, 40, 85}
+		i := 0
+		for {
+			select {
+			case <-stopOsc:
+				return
+			default:
+				pressure.Store(zones[i%len(zones)])
+				i++
+				time.Sleep(time.Millisecond)
+			}
+		}
+	}()
+
+	var wg sync.WaitGroup
+	const writers = 16
+	const iters = 30
+
+	wg.Add(writers)
+	for i := 0; i < writers; i++ {
+		go func() {
+			defer wg.Done()
+			for j := 0; j < iters; j++ {
+				err := a.Acquire(50 * time.Millisecond)
+				if err == nil {
+					time.Sleep(time.Duration(rand.Intn(50)) * time.Microsecond)
+					a.Release()
+				}
+			}
+		}()
+	}
+	wg.Wait()
+	close(stopOsc)
+
+	total := m.WALAdmitTotal.Load()
+	soft := m.WALAdmitSoftTotal.Load()
+	hard := m.WALAdmitHardTotal.Load()
+	timeout := m.WALAdmitTimeoutTotal.Load()
+	waitCount, waitSumNs := m.WALAdmitWaitSnapshot()
+
+	// Every Acquire call records exactly one total count.
+	if total != writers*iters {
+		t.Fatalf("WALAdmitTotal = %d, want %d", total, writers*iters)
+	}
+
+	// soft and hard are mutually exclusive per call.
+	// But a call hitting hard also doesn't count as soft.
+	// Timeout is a subset of hard path calls.
+	if timeout > hard {
+		t.Fatalf("Timeout (%d) > Hard (%d): timeouts only happen in hard path", timeout, hard)
+	}
+
+	// Wait histogram count must equal total.
+	if waitCount != total {
+		t.Fatalf("WALAdmitWait count = %d, want %d (same as total)", waitCount, total)
+	}
+
+	// Sum of wait times must be non-negative.
+	if waitSumNs < 0 {
+		t.Fatalf("WALAdmitWait sum = %d, must be >= 0", waitSumNs)
+	}
+
+	t.Logf("total=%d soft=%d hard=%d timeout=%d waitCount=%d waitSumNs=%d",
+		total, soft, hard, timeout, waitCount, waitSumNs)
+}
+
+// TestQA_Admission_Metrics_SemaphoreWaitPathRecords verifies that metrics are
+// recorded even when the semaphore-wait path (not hard watermark) is the
+// bottleneck. The semaphore-wait code has a separate recordAdmit call.
+func TestQA_Admission_Metrics_SemaphoreWaitPathRecords(t *testing.T) {
+	m := NewEngineMetrics()
+	a := NewWALAdmission(WALAdmissionConfig{
+		MaxConcurrent: 1,
+		SoftWatermark: 0.7,
+		HardWatermark: 0.9,
+		WALUsedFn:     func() float64 { return 0.0 }, // no pressure
+		NotifyFn:      func() {},
+		ClosedFn:      func() bool { return false },
+		Metrics:       m,
+	})
+
+	// Fill semaphore.
+	a.sem <- struct{}{}
+
+	// Release after 10ms.
+	go func() {
+		time.Sleep(10 * time.Millisecond)
+		<-a.sem
+	}()
+
+	if err := a.Acquire(500 * time.Millisecond); err != nil {
+		t.Fatalf("Acquire: %v", err)
+	}
+	a.Release()
+
+	if m.WALAdmitTotal.Load() != 1 {
+		t.Fatalf("WALAdmitTotal = %d, want 1", m.WALAdmitTotal.Load())
+	}
+	// No pressure → no soft/hard flags.
+	if m.WALAdmitSoftTotal.Load() != 0 {
+		t.Fatalf("WALAdmitSoftTotal = %d, want 0", m.WALAdmitSoftTotal.Load())
+	}
+	if m.WALAdmitHardTotal.Load() != 0 {
+		t.Fatalf("WALAdmitHardTotal = %d, want 0", m.WALAdmitHardTotal.Load())
+	}
+
+	// Wait time should be >10ms (semaphore wait).
+	_, waitSum := m.WALAdmitWaitSnapshot()
+	if waitSum < int64(5*time.Millisecond) {
+		t.Fatalf("WALAdmitWait sum = %dns, expected >= 5ms from semaphore wait", waitSum)
+	}
+}
+
+// TestQA_Admission_Metrics_SemaphoreTimeoutRecords verifies that a timeout
+// during semaphore wait (not hard watermark) still records timedOut=true.
+func TestQA_Admission_Metrics_SemaphoreTimeoutRecords(t *testing.T) {
+	m := NewEngineMetrics()
+	a := NewWALAdmission(WALAdmissionConfig{
+		MaxConcurrent: 1,
+		SoftWatermark: 0.7,
+		HardWatermark: 0.9,
+		WALUsedFn:     func() float64 { return 0.0 }, // no pressure
+		NotifyFn:      func() {},
+		ClosedFn:      func() bool { return false },
+		Metrics:       m,
+	})
+
+	// Fill semaphore permanently.
+	a.sem <- struct{}{}
+
+	err := a.Acquire(10 * time.Millisecond)
+	if !errors.Is(err, ErrWALFull) {
+		t.Fatalf("expected ErrWALFull, got %v", err)
+	}
+
+	if m.WALAdmitTotal.Load() != 1 {
+		t.Fatalf("WALAdmitTotal = %d, want 1", m.WALAdmitTotal.Load())
+	}
+	if m.WALAdmitTimeoutTotal.Load() != 1 {
+		t.Fatalf("WALAdmitTimeoutTotal = %d, want 1 (semaphore timeout)", m.WALAdmitTimeoutTotal.Load())
+	}
+	// Hard should NOT be set — timeout was in semaphore path, not hard pressure path.
+	if m.WALAdmitHardTotal.Load() != 0 {
+		t.Fatalf("WALAdmitHardTotal = %d, want 0", m.WALAdmitHardTotal.Load())
+	}
+
+	<-a.sem // cleanup
+}
+
+// TestQA_Admission_Metrics_CloseDuringSemaphoreRecords verifies that volume
+// close during semaphore wait records metrics correctly (no timeout flag).
+func TestQA_Admission_Metrics_CloseDuringSemaphoreRecords(t *testing.T) {
+	m := NewEngineMetrics()
+	var closed atomic.Bool
+
+	a := NewWALAdmission(WALAdmissionConfig{
+		MaxConcurrent: 1,
+		SoftWatermark: 0.7,
+		HardWatermark: 0.9,
+		WALUsedFn:     func() float64 { return 0.0 },
+		NotifyFn:      func() {},
+		ClosedFn:      closed.Load,
+		Metrics:       m,
+	})
+
+	a.sem <- struct{}{}
+
+	go func() {
+		time.Sleep(10 * time.Millisecond)
+		closed.Store(true)
+	}()
+
+	err := a.Acquire(2 * time.Second)
+	if !errors.Is(err, ErrVolumeClosed) {
+		t.Fatalf("expected ErrVolumeClosed, got %v", err)
+	}
+
+	if m.WALAdmitTotal.Load() != 1 {
+		t.Fatalf("WALAdmitTotal = %d, want 1", m.WALAdmitTotal.Load())
+	}
+	// Close is NOT a timeout.
+	if m.WALAdmitTimeoutTotal.Load() != 0 {
+		t.Fatalf("WALAdmitTimeoutTotal = %d, want 0 (close, not timeout)", m.WALAdmitTimeoutTotal.Load())
+	}
+
+	<-a.sem
+}
+
+// TestQA_Admission_Metrics_Integration_WriteLBA verifies that real WriteLBA
+// calls produce correct admission metrics in the engine.
+func TestQA_Admission_Metrics_Integration_WriteLBA(t *testing.T) {
+	dir := t.TempDir()
+	cfg := DefaultConfig()
+	cfg.WALMaxConcurrentWrites = 4
+	cfg.FlushInterval = 5 * time.Millisecond
+	cfg.WALFullTimeout = 2 * time.Second
+
+	vol, err := CreateBlockVol(dir+"/test.blk", CreateOptions{
+		VolumeSize: 256 * 1024,
+		BlockSize:  4096,
+		WALSize:    128 * 1024,
+	}, cfg)
+	if err != nil {
+		t.Fatalf("CreateBlockVol: %v", err)
+	}
+	defer vol.Close()
+
+	// Write 20 blocks.
+	data := make([]byte, 4096)
+	for i := 0; i < 20; i++ {
+		data[0] = byte(i)
+		if err := vol.WriteLBA(uint64(i%64), data); err != nil {
+			t.Fatalf("WriteLBA %d: %v", i, err)
+		}
+	}
+
+	// Engine metrics should show 20 admits with 0 timeouts.
+	m := vol.Metrics
+	if m == nil {
+		t.Skip("volume has no metrics (nil)")
+	}
+
+	total := m.WALAdmitTotal.Load()
+	if total != 20 {
+		t.Fatalf("WALAdmitTotal = %d, want 20", total)
+	}
+	if m.WALAdmitTimeoutTotal.Load() != 0 {
+		t.Fatalf("WALAdmitTimeoutTotal = %d, want 0", m.WALAdmitTimeoutTotal.Load())
+	}
+}