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pkg/storage/wal/manager.go

@@ -176,7 +176,9 @@ func (m *Manager) Append(r AppendRequest) (*AppendResult, error) {
 	return it.r, nil
 }
 
-func (m *Manager) Get() (*PendingItem, error) {
+// NextPending returns the next segment to be flushed. It returns nil if the
+// pending list is empty.
+func (m *Manager) NextPending() (*PendingItem, error) {
 	m.mu.Lock()
 	defer m.mu.Unlock()
 	if m.pending.Len() == 0 {
@@ -190,7 +192,7 @@ func (m *Manager) Get() (*PendingItem, error) {
 				m.available.Remove(el)
 			}
 		}
-		// If there are still no pending items, return nil.
+		// If the pending list is still empty return nil.
 		if m.pending.Len() == 0 {
 			return nil, nil
 		}
@@ -201,6 +203,8 @@ func (m *Manager) Get() (*PendingItem, error) {
 	return &PendingItem{Result: it.r, Writer: it.w}, nil
 }
 
+// Put resets the segment and puts it back in the available list to accept
+// writes. A PendingItem should not be put back until it has been flushed.
 func (m *Manager) Put(it *PendingItem) error {
 	m.mu.Lock()
 	defer m.mu.Unlock()

pkg/storage/wal/manager_test.go

@@ -45,7 +45,7 @@ func TestManager_Append(t *testing.T) {
 	}
 
 	// Flush the data and broadcast that the flush is successful.
-	it, err := m.Get()
+	it, err := m.NextPending()
 	require.NoError(t, err)
 	require.NotNil(t, it)
 	it.Result.SetDone(nil)
@@ -76,7 +76,7 @@ func TestManager_Append(t *testing.T) {
 	require.NotNil(t, res)
 
 	// Flush the data, but this time broadcast an error that the flush failed.
-	it, err = m.Get()
+	it, err = m.NextPending()
 	require.NoError(t, err)
 	require.NotNil(t, it)
 	it.Result.SetDone(errors.New("failed to flush"))
@@ -135,7 +135,7 @@ func TestManager_Append_ErrFull(t *testing.T) {
 	require.Nil(t, res)
 }
 
-func TestManager_Get(t *testing.T) {
+func TestManager_NextPending(t *testing.T) {
 	m, err := NewManager(Config{
 		MaxAge:         DefaultMaxAge,
 		MaxSegments:    1,
@@ -144,7 +144,7 @@ func TestManager_Get(t *testing.T) {
 	require.NoError(t, err)
 
 	// There should be no items as no data has been written.
-	it, err := m.Get()
+	it, err := m.NextPending()
 	require.NoError(t, err)
 	require.Nil(t, it)
 
@@ -165,7 +165,7 @@ func TestManager_Get(t *testing.T) {
 		Entries:   entries,
 	})
 	require.NoError(t, err)
-	it, err = m.Get()
+	it, err = m.NextPending()
 	require.NoError(t, err)
 	require.Nil(t, it)
 
@@ -181,12 +181,12 @@ func TestManager_Get(t *testing.T) {
 		Entries:   entries,
 	})
 	require.NoError(t, err)
-	it, err = m.Get()
+	it, err = m.NextPending()
 	require.NoError(t, err)
 	require.NotNil(t, it)
 
 	// Should not get the same item more than once.
-	it, err = m.Get()
+	it, err = m.NextPending()
 	require.NoError(t, err)
 	require.Nil(t, it)
 }
@@ -225,7 +225,7 @@ func TestManager_Put(t *testing.T) {
 	require.Equal(t, 1, m.pending.Len())
 
 	// Getting the pending segment should remove it from the list.
-	it, err := m.Get()
+	it, err := m.NextPending()
 	require.NoError(t, err)
 	require.NotNil(t, it)
 	require.Equal(t, 9, m.available.Len())