core: total ordering flush (#212)

* Implement flush

* Panic for all errors from total-ordering

* Fix test failure

All DAGs generated by blocks-generator would trigger round switching.

* Add NewBlocksGeneratorConfig

* Add test caes for numChains changes

* Resize internal structures

* Perform total ordering based on current numChains

* Fix not a valid DAG checking

* Comparing blocks by height is not correct

* Fix blocks from future round are delivered first by revealer

* Make sure only picking one candidate in one chain.

Blocks on the same chain in different rounds would not
have acking relation.

* Fix stuffs

* Fix the issue that two candidates from the same chain are picked.

* Rework candidateChainMapping

* Add test case for phi, k changed

* Refine testing code for round change

* Add breakpoints in global vector

* Remove not a valid dag checking.

* Adding comments

* Add check to forward acking

* Fix vet failure

* Prepareing height record with breakpoint

* Fixup: add check to make sure delivered round IDs are increasing.

2 files changed, 24 insertions, 20 deletions

diff --git a/core/types/block.go b/core/types/block.go
index e384f95..63bcec4 100644
--- a/core/types/block.go
+++ b/core/types/block.go
@@ -146,31 +146,31 @@ func (b ByHash) Swap(i int, j int) {
 	b[i], b[j] = b[j], b[i]
 }
 
-// ByHeight is the helper type for sorting slice of blocks by height.
-type ByHeight []*Block
+// ByPosition is the helper type for sorting slice of blocks by position.
+type ByPosition []*Block
 
 // Len implements Len method in sort.Sort interface.
-func (bs ByHeight) Len() int {
+func (bs ByPosition) Len() int {
 	return len(bs)
 }
 
 // Less implements Less method in sort.Sort interface.
-func (bs ByHeight) Less(i int, j int) bool {
-	return bs[i].Position.Height < bs[j].Position.Height
+func (bs ByPosition) Less(i int, j int) bool {
+	return bs[j].Position.Newer(&bs[i].Position)
 }
 
 // Swap implements Swap method in sort.Sort interface.
-func (bs ByHeight) Swap(i int, j int) {
+func (bs ByPosition) Swap(i int, j int) {
 	bs[i], bs[j] = bs[j], bs[i]
 }
 
 // Push implements Push method in heap interface.
-func (bs *ByHeight) Push(x interface{}) {
+func (bs *ByPosition) Push(x interface{}) {
 	*bs = append(*bs, x.(*Block))
 }
 
 // Pop implements Pop method in heap interface.
-func (bs *ByHeight) Pop() (ret interface{}) {
+func (bs *ByPosition) Pop() (ret interface{}) {
 	n := len(*bs)
 	*bs, ret = (*bs)[0:n-1], (*bs)[n-1]
 	return
diff --git a/core/types/block_test.go b/core/types/block_test.go
index b03b785..49eaa86 100644
--- a/core/types/block_test.go
+++ b/core/types/block_test.go
@@ -104,18 +104,22 @@ func (s *BlockTestSuite) TestSortByHash() {
 	s.Equal(blocks[3].Hash, b3.Hash)
 }
 
-func (s *BlockTestSuite) TestSortByHeight() {
-	b0 := &Block{Position: Position{Height: 0}}
-	b1 := &Block{Position: Position{Height: 1}}
-	b2 := &Block{Position: Position{Height: 2}}
-	b3 := &Block{Position: Position{Height: 3}}
-
-	blocks := []*Block{b3, b2, b1, b0}
-	sort.Sort(ByHeight(blocks))
-	s.Equal(blocks[0].Hash, b0.Hash)
-	s.Equal(blocks[1].Hash, b1.Hash)
-	s.Equal(blocks[2].Hash, b2.Hash)
-	s.Equal(blocks[3].Hash, b3.Hash)
+func (s *BlockTestSuite) TestSortByPosition() {
+	b00 := &Block{Position: Position{Height: 0}}
+	b01 := &Block{Position: Position{Height: 1}}
+	b02 := &Block{Position: Position{Height: 2}}
+	b10 := &Block{Position: Position{Round: 1, Height: 0}}
+	b11 := &Block{Position: Position{Round: 1, Height: 1}}
+	b12 := &Block{Position: Position{Round: 1, Height: 2}}
+
+	blocks := []*Block{b12, b11, b10, b02, b01, b00}
+	sort.Sort(ByPosition(blocks))
+	s.Equal(blocks[0].Hash, b00.Hash)
+	s.Equal(blocks[1].Hash, b01.Hash)
+	s.Equal(blocks[2].Hash, b02.Hash)
+	s.Equal(blocks[3].Hash, b10.Hash)
+	s.Equal(blocks[4].Hash, b11.Hash)
+	s.Equal(blocks[5].Hash, b12.Hash)
 }
 
 func (s *BlockTestSuite) TestGenesisBlock() {