From 00aa98419aaad08b846a8eef62b1824979b5da9a Mon Sep 17 00:00:00 2001
From: ptrus <ptrusr@gmail.com>
Date: Tue, 31 Mar 2020 16:14:01 +0200
Subject: [PATCH] go/runtime/client: use histroy for GetBlock(latest)

---
 go/roothash/api/history.go         |  3 +++
 go/runtime/client/client.go        | 11 ++++++-----
 go/runtime/history/history.go      | 17 +++++++++++++++++
 go/runtime/history/history_test.go | 12 ++++++++++++
 4 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/go/roothash/api/history.go b/go/roothash/api/history.go
index f467ae5c1d2..c7538f048b5 100644
--- a/go/roothash/api/history.go
+++ b/go/roothash/api/history.go
@@ -32,4 +32,7 @@ type BlockHistory interface {
 
 	// GetBlock returns the block at a specific round.
 	GetBlock(ctx context.Context, round uint64) (*block.Block, error)
+
+	// GetLatestBlock returns the block at latest round.
+	GetLatestBlock(ctx context.Context) (*block.Block, error)
 }
diff --git a/go/runtime/client/client.go b/go/runtime/client/client.go
index 9cb52a6d8ca..26f8fee4325 100644
--- a/go/runtime/client/client.go
+++ b/go/runtime/client/client.go
@@ -216,16 +216,17 @@ func (c *runtimeClient) WatchBlocks(ctx context.Context, runtimeID common.Namesp
 
 // Implements api.RuntimeClient.
 func (c *runtimeClient) GetBlock(ctx context.Context, request *api.GetBlockRequest) (*block.Block, error) {
-	if request.Round == api.RoundLatest {
-		return c.common.consensus.RootHash().GetLatestBlock(ctx, request.RuntimeID, consensus.HeightLatest)
-	}
-
 	rt, err := c.common.runtimeRegistry.GetRuntime(request.RuntimeID)
 	if err != nil {
 		return nil, err
 	}
 
-	return rt.History().GetBlock(ctx, request.Round)
+	switch request.Round {
+	case api.RoundLatest:
+		return rt.History().GetLatestBlock(ctx)
+	default:
+		return rt.History().GetBlock(ctx, request.Round)
+	}
 }
 
 func (c *runtimeClient) getTxnTree(blk *block.Block) *transaction.Tree {
diff --git a/go/runtime/history/history.go b/go/runtime/history/history.go
index 08b95243b08..4634fae4a0f 100644
--- a/go/runtime/history/history.go
+++ b/go/runtime/history/history.go
@@ -76,6 +76,10 @@ func (h *nopHistory) GetBlock(ctx context.Context, round uint64) (*block.Block,
 	return nil, errNopHistory
 }
 
+func (h *nopHistory) GetLatestBlock(ctx context.Context) (*block.Block, error) {
+	return nil, errNopHistory
+}
+
 func (h *nopHistory) Pruner() Pruner {
 	pruner, _ := NewNonePruner()(nil)
 	return pruner
@@ -144,6 +148,19 @@ func (h *runtimeHistory) GetBlock(ctx context.Context, round uint64) (*block.Blo
 	return annBlk.Block, nil
 }
 
+func (h *runtimeHistory) GetLatestBlock(ctx context.Context) (*block.Block, error) {
+	meta, err := h.db.metadata()
+	if err != nil {
+		return nil, err
+	}
+	annBlk, err := h.db.getBlock(meta.LastRound)
+	if err != nil {
+		return nil, err
+	}
+
+	return annBlk.Block, nil
+}
+
 func (h *runtimeHistory) Pruner() Pruner {
 	return h.pruner
 }
diff --git a/go/runtime/history/history_test.go b/go/runtime/history/history_test.go
index 1936833b8c5..a6b30fba620 100644
--- a/go/runtime/history/history_test.go
+++ b/go/runtime/history/history_test.go
@@ -41,6 +41,10 @@ func TestHistory(t *testing.T) {
 	require.Error(err, "GetBlock should fail for non-indexed block")
 	require.Equal(roothash.ErrNotFound, err)
 
+	_, err = history.GetLatestBlock(context.Background())
+	require.Error(err, "GetLatestBlock should fail for no indexed block")
+	require.Equal(roothash.ErrNotFound, err)
+
 	err = history.ConsensusCheckpoint(42)
 	require.NoError(err, "ConsensusCheckpoint")
 	err = history.ConsensusCheckpoint(40)
@@ -82,6 +86,10 @@ func TestHistory(t *testing.T) {
 	require.NoError(err, "GetBlock")
 	require.Equal(&putBlk, gotBlk, "GetBlock should return the correct block")
 
+	gotLatestBlk, err := history.GetLatestBlock(context.Background())
+	require.NoError(err, "GetLatestBlock")
+	require.Equal(&putBlk, gotLatestBlk, "GetLatestBlock should return the correct block")
+
 	// Close history and try to reopen and continue.
 	history.Close()
 
@@ -102,6 +110,10 @@ func TestHistory(t *testing.T) {
 	gotBlk, err = history.GetBlock(context.Background(), 10)
 	require.NoError(err, "GetBlock")
 	require.Equal(&putBlk, gotBlk, "GetBlock should return the correct block")
+
+	gotLatestBlk, err = history.GetLatestBlock(context.Background())
+	require.NoError(err, "GetLatestBlock")
+	require.Equal(&putBlk, gotLatestBlk, "GetLatestBlock should return the correct block")
 }
 
 type testPruneHandler struct {