core: Change interface of Application.VerifyBlock (#246)

* Change interface of Application.VerifyBlock

7 files changed, 25 insertions, 10 deletions

diff --git a/core/interfaces.go b/core/interfaces.go
index 7b985cf..2ba8e0d 100644
--- a/core/interfaces.go
+++ b/core/interfaces.go
@@ -35,7 +35,7 @@ type Application interface {
 	PrepareWitness(consensusHeight uint64) (types.Witness, error)
 
 	// VerifyBlock verifies if the block is valid.
-	VerifyBlock(block *types.Block) bool
+	VerifyBlock(block *types.Block) types.BlockVerifyStatus
 
 	// BlockConfirmed is called when a block is confirmed and added to lattice.
 	BlockConfirmed(block types.Block)
diff --git a/core/lattice.go b/core/lattice.go
index 984203d..0357a8d 100644
--- a/core/lattice.go
+++ b/core/lattice.go
@@ -136,7 +136,8 @@ func (s *Lattice) SanityCheck(b *types.Block, checkRelation bool) (err error) {
 	}
 	// Verify data in application layer.
 	s.logger.Debug("Calling Application.VerifyBlock", "block", b)
-	if !s.app.VerifyBlock(b) {
+	// TODO(jimmy-dexon): handle types.VerifyRetryLater.
+	if s.app.VerifyBlock(b) == types.VerifyInvalidBlock {
 		err = ErrInvalidBlock
 		return err
 	}
diff --git a/core/nonblocking.go b/core/nonblocking.go
index 675675b..36135fd 100644
--- a/core/nonblocking.go
+++ b/core/nonblocking.go
@@ -129,7 +129,7 @@ func (nb *nonBlocking) PrepareWitness(height uint64) (types.Witness, error) {
 }
 
 // VerifyBlock cannot be non-blocking.
-func (nb *nonBlocking) VerifyBlock(block *types.Block) bool {
+func (nb *nonBlocking) VerifyBlock(block *types.Block) types.BlockVerifyStatus {
 	return nb.app.VerifyBlock(block)
 }
 
diff --git a/core/nonblocking_test.go b/core/nonblocking_test.go
index b1f1cb5..2ab40ea 100644
--- a/core/nonblocking_test.go
+++ b/core/nonblocking_test.go
@@ -54,8 +54,8 @@ func (app *slowApp) PrepareWitness(_ uint64) (types.Witness, error) {
 	return types.Witness{}, nil
 }
 
-func (app *slowApp) VerifyBlock(_ *types.Block) bool {
-	return true
+func (app *slowApp) VerifyBlock(_ *types.Block) types.BlockVerifyStatus {
+	return types.VerifyOK
 }
 
 func (app *slowApp) BlockConfirmed(block types.Block) {
@@ -103,7 +103,7 @@ func (app *noDebugApp) PrepareWitness(_ uint64) (types.Witness, error) {
 	panic("test")
 }
 
-func (app *noDebugApp) VerifyBlock(_ *types.Block) bool {
+func (app *noDebugApp) VerifyBlock(_ *types.Block) types.BlockVerifyStatus {
 	panic("test")
 }
 
diff --git a/core/test/app.go b/core/test/app.go
index a48b3c8..ba949b3 100644
--- a/core/test/app.go
+++ b/core/test/app.go
@@ -109,8 +109,8 @@ func (app *App) PrepareWitness(height uint64) (types.Witness, error) {
 }
 
 // VerifyBlock implements Application.
-func (app *App) VerifyBlock(block *types.Block) bool {
-	return true
+func (app *App) VerifyBlock(block *types.Block) types.BlockVerifyStatus {
+	return types.VerifyOK
 }
 
 // BlockConfirmed implements Application interface.
diff --git a/core/types/block.go b/core/types/block.go
index 9de4673..29b1c84 100644
--- a/core/types/block.go
+++ b/core/types/block.go
@@ -33,6 +33,20 @@ import (
 	"github.com/dexon-foundation/dexon-consensus-core/core/crypto"
 )
 
+// BlockVerifyStatus is the return code for core.Application.VerifyBlock
+type BlockVerifyStatus int
+
+// Enums for return value of core.Application.VerifyBlock.
+const (
+	// VerifyOK: Block is verified.
+	VerifyOK BlockVerifyStatus = iota
+	// VerifyRetryLater: Block is unable to be verified at this moment.
+	// Try again later.
+	VerifyRetryLater
+	// VerifyInvalidBlock: Block is an invalid one.
+	VerifyInvalidBlock
+)
+
 var (
 	// blockPool is the blocks cache to reuse allocated blocks.
 	blockPool = sync.Pool{
diff --git a/simulation/app.go b/simulation/app.go
index f8bbcc6..419bb0a 100644
--- a/simulation/app.go
+++ b/simulation/app.go
@@ -67,8 +67,8 @@ func (a *simApp) BlockConfirmed(block types.Block) {
 }
 
 // VerifyBlock implements core.Application.
-func (a *simApp) VerifyBlock(block *types.Block) bool {
-	return true
+func (a *simApp) VerifyBlock(block *types.Block) types.BlockVerifyStatus {
+	return types.VerifyOK
 }
 
 // getAckedBlocks will return all unconfirmed blocks' hash with lower Height