core: refactor witness data processing flow (#124)

Since witness data need to include data from application after it
processed a block (e.g. stateRoot).  We should make the process of
witness data asynchronous.

An interface `BlockProcessedChan()` is added to the application
interface to return a channel for notifying the consensus core when a
block is processed. The notification object includes a byte slice
(witenss data) which will be include in the final witness data object.

1 files changed, 8 insertions, 0 deletions

diff --git a/core/test/app.go b/core/test/app.go
index e9ef871..617bc38 100644
--- a/core/test/app.go
+++ b/core/test/app.go
@@ -89,6 +89,7 @@ type App struct {
 	deliveredLock      sync.RWMutex
 	WitnessAckSequence []*types.WitnessAck
 	witnessAckLock     sync.RWMutex
+	witnessResultChan  chan types.WitnessResult
 }
 
 // NewApp constructs a TestApp instance.
@@ -99,6 +100,7 @@ func NewApp() *App {
 		TotalOrderedByHash: make(map[common.Hash]*AppTotalOrderRecord),
 		Delivered:          make(map[common.Hash]*AppDeliveredRecord),
 		DeliverSequence:    common.Hashes{},
+		witnessResultChan:  make(chan types.WitnessResult),
 	}
 }
 
@@ -155,6 +157,12 @@ func (app *App) DeliverBlock(blockHash common.Hash, timestamp time.Time) {
 	app.DeliverSequence = append(app.DeliverSequence, blockHash)
 }
 
+// BlockProcessedChan returns a channel to receive the block hashes that have
+// finished processing by the application.
+func (app *App) BlockProcessedChan() <-chan types.WitnessResult {
+	return app.witnessResultChan
+}
+
 // WitnessAckDeliver implements Application interface.
 func (app *App) WitnessAckDeliver(witnessAck *types.WitnessAck) {
 	app.witnessAckLock.Lock()