worker: some Subscribe NewTxsEvent changes of miner worker

1.remove the unnecessary NewTxsEvent subscriber, which was used for PoW resubmit check.
2.unsubscribe ASAP before another fillTransactions, to avoid block others.

miner/worker.go

@@ -188,8 +188,6 @@ type worker struct {
 
 	// Subscriptions
 	mux          *event.TypeMux
-	txsCh        chan core.NewTxsEvent
-	txsSub       event.Subscription
 	chainHeadCh  chan core.ChainHeadEvent
 	chainHeadSub event.Subscription
 	chainSideCh  chan core.ChainSideEvent
@@ -225,7 +223,6 @@ type worker struct {
 
 	// atomic status counters
 	running int32 // The indicator whether the consensus engine is running or not.
-	newTxs  int32 // New arrival transaction count since last sealing work submitting.
 
 	// External functions
 	isLocalBlock func(header *types.Header) bool // Function used to determine whether the specified block is mined by local miner.
@@ -253,7 +250,6 @@ func newWorker(config *Config, chainConfig *params.ChainConfig, engine consensus
 		remoteUncles:       make(map[common.Hash]*types.Block),
 		unconfirmed:        newUnconfirmedBlocks(eth.BlockChain(), sealingLogAtDepth),
 		pendingTasks:       make(map[common.Hash]*task),
-		txsCh:              make(chan core.NewTxsEvent, txChanSize),
 		chainHeadCh:        make(chan core.ChainHeadEvent, chainHeadChanSize),
 		chainSideCh:        make(chan core.ChainSideEvent, chainSideChanSize),
 		newWorkCh:          make(chan *newWorkReq),
@@ -265,8 +261,6 @@ func newWorker(config *Config, chainConfig *params.ChainConfig, engine consensus
 		resubmitIntervalCh: make(chan time.Duration),
 		recentMinedBlocks:  recentMinedBlocks,
 	}
-	// Subscribe NewTxsEvent for tx pool
-	worker.txsSub = eth.TxPool().SubscribeNewTxsEvent(worker.txsCh)
 	// Subscribe events for blockchain
 	worker.chainHeadSub = eth.BlockChain().SubscribeChainHeadEvent(worker.chainHeadCh)
 	worker.chainSideSub = eth.BlockChain().SubscribeChainSideEvent(worker.chainSideCh)
@@ -397,7 +391,6 @@ func (w *worker) newWorkLoop(recommit time.Duration) {
 			return
 		}
 		timer.Reset(recommit)
-		atomic.StoreInt32(&w.newTxs, 0)
 	}
 	// clearPending cleans the stale pending tasks.
 	clearPending := func(number uint64) {
@@ -442,10 +435,6 @@ func (w *worker) newWorkLoop(recommit time.Duration) {
 			if w.isRunning() && ((w.chainConfig.Ethash != nil) || (w.chainConfig.Clique != nil &&
 				w.chainConfig.Clique.Period > 0) || (w.chainConfig.Parlia != nil && w.chainConfig.Parlia.Period > 0)) {
 				// Short circuit if no new transaction arrives.
-				if atomic.LoadInt32(&w.newTxs) == 0 {
-					timer.Reset(recommit)
-					continue
-				}
 				commit(commitInterruptResubmit)
 			}
 
@@ -473,7 +462,6 @@ func (w *worker) newWorkLoop(recommit time.Duration) {
 // submit it or return task according to given parameters for various proposes.
 func (w *worker) mainLoop() {
 	defer w.wg.Done()
-	defer w.txsSub.Unsubscribe()
 	defer w.chainHeadSub.Unsubscribe()
 	defer w.chainSideSub.Unsubscribe()
 	defer func() {
@@ -539,24 +527,9 @@ func (w *worker) mainLoop() {
 				}
 			}
 
-		case ev := <-w.txsCh:
-			if w.isRunning() {
-				// Special case, if the consensus engine is 0 period clique(dev mode),
-				// submit sealing work here since all empty submission will be rejected
-				// by clique. Of course the advance sealing(empty submission) is disabled.
-				if (w.chainConfig.Clique != nil && w.chainConfig.Clique.Period == 0) ||
-					(w.chainConfig.Parlia != nil && w.chainConfig.Parlia.Period == 0) {
-					w.commitWork(nil, time.Now().Unix())
-				}
-			}
-
-			atomic.AddInt32(&w.newTxs, int32(len(ev.Txs)))
-
 		// System stopped
 		case <-w.exitCh:
 			return
-		case <-w.txsSub.Err():
-			return
 		case <-w.chainHeadSub.Err():
 			return
 		case <-w.chainSideSub.Err():
@@ -1221,6 +1194,9 @@ LOOP:
 				}
 			}
 		}
+		// if sub's channel if full, it will block other NewTxsEvent subscribers,
+		// so unsubscribe ASAP and Unsubscribe() is re-enterable, safe to call several time.
+		sub.Unsubscribe()
 	}
 	// get the most profitable work
 	bestWork := workList[0]