core: test locals support in txpool queue limits, fix

The commit reworks the transaction pool queue limitation tests
to cater for testing local accounts, also testing the nolocal flag.

In addition, it also fixes a panic if local transactions exceeded
the global queue allowance (no accounts left to drop from) and also
fixes queue eviction to operate on all accounts, not just the one
being updated.

core/tx_list.go

@@ -477,7 +477,7 @@ func (l *txPricedList) Underpriced(tx *types.Transaction, local *accountSet) boo
 }
 
 // Discard finds a number of most underpriced transactions, removes them from the
-// priced list and returs them for further removal from the entire pool.
+// priced list and returns them for further removal from the entire pool.
 func (l *txPricedList) Discard(count int, local *accountSet) types.Transactions {
 	drop := make(types.Transactions, 0, count) // Remote underpriced transactions to drop
 	save := make(types.Transactions, 0, 64)    // Local underpriced transactions to keep

core/tx_pool.go

@@ -716,7 +716,6 @@ func (pool *TxPool) promoteExecutables(state *state.StateDB, accounts []common.A
 		}
 	}
 	// Iterate over all accounts and promote any executable transactions
-	queued := uint64(0)
 	for _, addr := range accounts {
 		list := pool.queue[addr]
 		if list == nil {
@@ -754,8 +753,6 @@ func (pool *TxPool) promoteExecutables(state *state.StateDB, accounts []common.A
 				log.Trace("Removed cap-exceeding queued transaction", "hash", hash)
 			}
 		}
-		queued += uint64(list.Len())
-
 		// Delete the entire queue entry if it became empty.
 		if list.Empty() {
 			delete(pool.queue, addr)
@@ -833,19 +830,22 @@ func (pool *TxPool) promoteExecutables(state *state.StateDB, accounts []common.A
 		pendingRateLimitCounter.Inc(int64(pendingBeforeCap - pending))
 	}
 	// If we've queued more transactions than the hard limit, drop oldest ones
+	queued := uint64(0)
+	for _, list := range pool.queue {
+		queued += uint64(list.Len())
+	}
 	if queued > pool.config.GlobalQueue {
 		// Sort all accounts with queued transactions by heartbeat
 		addresses := make(addresssByHeartbeat, 0, len(pool.queue))
 		for addr := range pool.queue {
-			// Don't drop locals
-			if !pool.locals.contains(addr) {
+			if !pool.locals.contains(addr) { // don't drop locals
 				addresses = append(addresses, addressByHeartbeat{addr, pool.beats[addr]})
 			}
 		}
 		sort.Sort(addresses)
 
-		// Drop transactions until the total is below the limit
-		for drop := queued - pool.config.GlobalQueue; drop > 0; {
+		// Drop transactions until the total is below the limit or only locals remain
+		for drop := queued - pool.config.GlobalQueue; drop > 0 && len(addresses) > 0; {
 			addr := addresses[len(addresses)-1]
 			list := pool.queue[addr.address]