Add caches to lotus-stats and splitcode

tools/stats/headbuffer/head_buffer.go

@@ -0,0 +1,56 @@
+package headbuffer
+
+import (
+	"container/list"
+
+	"github.com/filecoin-project/lotus/api"
+)
+
+type HeadChangeStackBuffer struct {
+	buffer *list.List
+	size   int
+}
+
+// NewHeadChangeStackBuffer buffer HeadChange events to avoid having to
+// deal with revert changes. Initialized size should be the average reorg
+// size + 1
+func NewHeadChangeStackBuffer(size int) *HeadChangeStackBuffer {
+	buffer := list.New()
+	buffer.Init()
+
+	return &HeadChangeStackBuffer{
+		buffer: buffer,
+		size:   size,
+	}
+}
+
+// Push adds a HeadChange to stack buffer. If the length of
+// the stack buffer grows larger than the initizlized size, the
+// oldest HeadChange is returned.
+func (h *HeadChangeStackBuffer) Push(hc *api.HeadChange) (rethc *api.HeadChange) {
+	if h.buffer.Len() >= h.size {
+		var ok bool
+
+		el := h.buffer.Front()
+		rethc, ok = el.Value.(*api.HeadChange)
+		if !ok {
+			// This shouldn't be possible, this method is typed and is the only place data
+			// pushed to the buffer.
+			panic("A cosmic ray made me do it")
+		}
+
+		h.buffer.Remove(el)
+	}
+
+	h.buffer.PushBack(hc)
+
+	return
+}
+
+// Pop removes the last added HeadChange
+func (h *HeadChangeStackBuffer) Pop() {
+	el := h.buffer.Back()
+	if el != nil {
+		h.buffer.Remove(el)
+	}
+}

tools/stats/headbuffer/head_buffer_test.go

@@ -0,0 +1,42 @@
+package headbuffer
+
+import (
+	"testing"
+
+	"github.com/filecoin-project/lotus/api"
+	"github.com/stretchr/testify/require"
+)
+
+func TestHeadBuffer(t *testing.T) {
+	t.Run("Straight Push through", func(t *testing.T) {
+		hb := NewHeadChangeStackBuffer(5)
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "1"}))
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "2"}))
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "3"}))
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "4"}))
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "5"}))
+
+		hc := hb.Push(&api.HeadChange{Type: "6"})
+		require.Equal(t, hc.Type, "1")
+	})
+
+	t.Run("Reverts", func(t *testing.T) {
+		hb := NewHeadChangeStackBuffer(5)
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "1"}))
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "2"}))
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "3"}))
+		hb.Pop()
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "3a"}))
+		hb.Pop()
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "3b"}))
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "4"}))
+		require.Nil(t, hb.Push(&api.HeadChange{Type: "5"}))
+
+		hc := hb.Push(&api.HeadChange{Type: "6"})
+		require.Equal(t, hc.Type, "1")
+		hc = hb.Push(&api.HeadChange{Type: "7"})
+		require.Equal(t, hc.Type, "2")
+		hc = hb.Push(&api.HeadChange{Type: "8"})
+		require.Equal(t, hc.Type, "3b")
+	})
+}