From c1c003e4ff36c22d67662ca661fc78cde850d401 Mon Sep 17 00:00:00 2001
From: gary rong <garyrong0905@gmail.com>
Date: Tue, 28 Aug 2018 21:59:05 +0800
Subject: consensus, miner: stale block mining support (#17506)

* consensus, miner: stale block supporting

* consensus, miner: refactor seal signature

* cmd, consensus, eth: add miner noverify flag

* cmd, consensus, miner: polish
---
 consensus/clique/clique.go | 39 +++++++++++++++++++++++----------------
 1 file changed, 23 insertions(+), 16 deletions(-)

(limited to 'consensus/clique/clique.go')

diff --git a/consensus/clique/clique.go b/consensus/clique/clique.go
index 3730c91f6..547290984 100644
--- a/consensus/clique/clique.go
+++ b/consensus/clique/clique.go
@@ -590,17 +590,17 @@ func (c *Clique) Authorize(signer common.Address, signFn SignerFn) {
 
 // Seal implements consensus.Engine, attempting to create a sealed block using
 // the local signing credentials.
-func (c *Clique) Seal(chain consensus.ChainReader, block *types.Block, stop <-chan struct{}) (*types.Block, error) {
+func (c *Clique) Seal(chain consensus.ChainReader, block *types.Block, results chan<- *types.Block, stop <-chan struct{}) error {
 	header := block.Header()
 
 	// Sealing the genesis block is not supported
 	number := header.Number.Uint64()
 	if number == 0 {
-		return nil, errUnknownBlock
+		return errUnknownBlock
 	}
 	// For 0-period chains, refuse to seal empty blocks (no reward but would spin sealing)
 	if c.config.Period == 0 && len(block.Transactions()) == 0 {
-		return nil, errWaitTransactions
+		return errWaitTransactions
 	}
 	// Don't hold the signer fields for the entire sealing procedure
 	c.lock.RLock()
@@ -610,10 +610,10 @@ func (c *Clique) Seal(chain consensus.ChainReader, block *types.Block, stop <-ch
 	// Bail out if we're unauthorized to sign a block
 	snap, err := c.snapshot(chain, number-1, header.ParentHash, nil)
 	if err != nil {
-		return nil, err
+		return err
 	}
 	if _, authorized := snap.Signers[signer]; !authorized {
-		return nil, errUnauthorized
+		return errUnauthorized
 	}
 	// If we're amongst the recent signers, wait for the next block
 	for seen, recent := range snap.Recents {
@@ -621,8 +621,7 @@ func (c *Clique) Seal(chain consensus.ChainReader, block *types.Block, stop <-ch
 			// Signer is among recents, only wait if the current block doesn't shift it out
 			if limit := uint64(len(snap.Signers)/2 + 1); number < limit || seen > number-limit {
 				log.Info("Signed recently, must wait for others")
-				<-stop
-				return nil, nil
+				return nil
 			}
 		}
 	}
@@ -635,21 +634,29 @@ func (c *Clique) Seal(chain consensus.ChainReader, block *types.Block, stop <-ch
 
 		log.Trace("Out-of-turn signing requested", "wiggle", common.PrettyDuration(wiggle))
 	}
-	log.Trace("Waiting for slot to sign and propagate", "delay", common.PrettyDuration(delay))
-
-	select {
-	case <-stop:
-		return nil, nil
-	case <-time.After(delay):
-	}
 	// Sign all the things!
 	sighash, err := signFn(accounts.Account{Address: signer}, sigHash(header).Bytes())
 	if err != nil {
-		return nil, err
+		return err
 	}
 	copy(header.Extra[len(header.Extra)-extraSeal:], sighash)
+	// Wait until sealing is terminated or delay timeout.
+	log.Trace("Waiting for slot to sign and propagate", "delay", common.PrettyDuration(delay))
+	go func() {
+		select {
+		case <-stop:
+			return
+		case <-time.After(delay):
+		}
 
-	return block.WithSeal(header), nil
+		select {
+		case results <- block.WithSeal(header):
+		default:
+			log.Warn("Sealing result is not read by miner", "sealhash", c.SealHash(header))
+		}
+	}()
+
+	return nil
 }
 
 // CalcDifficulty is the difficulty adjustment algorithm. It returns the difficulty
-- 
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