core: add upper bound on the queued transctions

core/tx_pool.go

@@ -20,6 +20,7 @@ import (
 	"errors"
 	"fmt"
 	"math/big"
+	"sort"
 	"sync"
 	"time"
 
@@ -44,8 +45,11 @@ var (
 	ErrNegativeValue      = errors.New("Negative value")
 )
 
-const (
-	maxQueued = 64 // max limit of queued txs per address
+var (
+	maxQueuedPerAccount = uint64(64)    // Max limit of queued transactions per address
+	maxQueuedInTotal    = uint64(65536) // Max limit of queued transactions from all accounts
+	maxQueuedLifetime   = 3 * time.Hour // Max amount of time transactions from idle accounts are queued
+	evictionInterval    = time.Minute   // Time interval to check for evictable transactions
 )
 
 type stateFn func() (*state.StateDB, error)
@@ -71,8 +75,10 @@ type TxPool struct {
 	pending map[common.Address]*txList         // All currently processable transactions
 	queue   map[common.Address]*txList         // Queued but non-processable transactions
 	all     map[common.Hash]*types.Transaction // All transactions to allow lookups
+	beats   map[common.Address]time.Time       // Last heartbeat from each known account
 
-	wg sync.WaitGroup // for shutdown sync
+	wg   sync.WaitGroup // for shutdown sync
+	quit chan struct{}
 
 	homestead bool
 }
@@ -83,6 +89,7 @@ func NewTxPool(config *ChainConfig, eventMux *event.TypeMux, currentStateFn stat
 		pending:      make(map[common.Address]*txList),
 		queue:        make(map[common.Address]*txList),
 		all:          make(map[common.Hash]*types.Transaction),
+		beats:        make(map[common.Address]time.Time),
 		eventMux:     eventMux,
 		currentState: currentStateFn,
 		gasLimit:     gasLimitFn,
@@ -90,10 +97,12 @@ func NewTxPool(config *ChainConfig, eventMux *event.TypeMux, currentStateFn stat
 		pendingState: nil,
 		localTx:      newTxSet(),
 		events:       eventMux.Subscribe(ChainHeadEvent{}, GasPriceChanged{}, RemovedTransactionEvent{}),
+		quit:         make(chan struct{}),
 	}
 
-	pool.wg.Add(1)
+	pool.wg.Add(2)
 	go pool.eventLoop()
+	go pool.expirationLoop()
 
 	return pool
 }
@@ -154,6 +163,7 @@ func (pool *TxPool) resetState() {
 
 func (pool *TxPool) Stop() {
 	pool.events.Unsubscribe()
+	close(pool.quit)
 	pool.wg.Wait()
 	glog.V(logger.Info).Infoln("Transaction pool stopped")
 }
@@ -290,7 +300,7 @@ func (pool *TxPool) add(tx *types.Transaction) error {
 	if pool.all[hash] != nil {
 		return fmt.Errorf("Known transaction: %x", hash[:4])
 	}
-	// Otherwise ensure basic validation passes nd queue it up
+	// Otherwise ensure basic validation passes and queue it up
 	if err := pool.validateTx(tx); err != nil {
 		return err
 	}
@@ -308,7 +318,7 @@ func (pool *TxPool) add(tx *types.Transaction) error {
 	return nil
 }
 
-// enqueueTx inserts a new transction into the non-executable transaction queue.
+// enqueueTx inserts a new transaction into the non-executable transaction queue.
 //
 // Note, this method assumes the pool lock is held!
 func (pool *TxPool) enqueueTx(hash common.Hash, tx *types.Transaction) {
@@ -355,6 +365,7 @@ func (pool *TxPool) promoteTx(addr common.Address, hash common.Hash, tx *types.T
 	pool.all[hash] = tx // Failsafe to work around direct pending inserts (tests)
 
 	// Set the potentially new pending nonce and notify any subsystems of the new tx
+	pool.beats[addr] = time.Now()
 	pool.pendingState.SetNonce(addr, list.last+1)
 	go pool.eventMux.Post(TxPreEvent{tx})
 }
@@ -412,8 +423,8 @@ func (pool *TxPool) RemoveBatch(txs types.Transactions) {
 	}
 }
 
-// removeTx iterates removes a single transaction from the queue, moving all
-// subsequent transactions back to the future queue.
+// removeTx removes a single transaction from the queue, moving all subsequent
+// transactions back to the future queue.
 func (pool *TxPool) removeTx(hash common.Hash) {
 	// Fetch the transaction we wish to delete
 	tx, ok := pool.all[hash]
@@ -431,6 +442,8 @@ func (pool *TxPool) removeTx(hash common.Hash) {
 			// If no more transactions are left, remove the list and reset the nonce
 			if pending.Empty() {
 				delete(pool.pending, addr)
+				delete(pool.beats, addr)
+
 				pool.pendingState.SetNonce(addr, tx.Nonce())
 			} else {
 				// Otherwise update the nonce and postpone any invalidated transactions
@@ -465,6 +478,8 @@ func (pool *TxPool) promoteExecutables() {
 		return
 	}
 	// Iterate over all accounts and promote any executable transactions
+	queued := uint64(0)
+
 	for addr, list := range pool.queue {
 		// Drop all transactions that are deemed too old (low nonce)
 		for _, tx := range list.Forward(state.GetNonce(addr)) {
@@ -489,17 +504,51 @@ func (pool *TxPool) promoteExecutables() {
 			pool.promoteTx(addr, tx.Hash(), tx)
 		}
 		// Drop all transactions over the allowed limit
-		for _, tx := range list.Cap(maxQueued) {
+		for _, tx := range list.Cap(int(maxQueuedPerAccount)) {
 			if glog.V(logger.Core) {
 				glog.Infof("Removed cap-exceeding queued transaction: %v", tx)
 			}
 			delete(pool.all, tx.Hash())
 		}
+		queued += uint64(list.Len())
+
 		// Delete the entire queue entry if it became empty.
 		if list.Empty() {
 			delete(pool.queue, addr)
 		}
 	}
+	// If we've queued more transactions than the hard limit, drop oldest ones
+	if queued > maxQueuedInTotal {
+		// Sort all accounts with queued transactions by heartbeat
+		addresses := make(addresssByHeartbeat, 0, len(pool.queue))
+		for addr, _ := range pool.queue {
+			addresses = append(addresses, addressByHeartbeat{addr, pool.beats[addr]})
+		}
+		sort.Sort(addresses)
+
+		// Drop transactions until the total is below the limit
+		for drop := queued - maxQueuedInTotal; drop > 0; {
+			addr := addresses[len(addresses)-1]
+			list := pool.queue[addr.address]
+
+			addresses = addresses[:len(addresses)-1]
+
+			// Drop all transactions if they are less than the overflow
+			if size := uint64(list.Len()); size <= drop {
+				for _, tx := range list.Flatten() {
+					pool.removeTx(tx.Hash())
+				}
+				drop -= size
+				continue
+			}
+			// Otherwise drop only last few transactions
+			txs := list.Flatten()
+			for i := len(txs) - 1; i >= 0 && drop > 0; i-- {
+				pool.removeTx(txs[i].Hash())
+				drop--
+			}
+		}
+	}
 }
 
 // demoteUnexecutables removes invalid and processed transactions from the pools
@@ -540,10 +589,51 @@ func (pool *TxPool) demoteUnexecutables() {
 		// Delete the entire queue entry if it became empty.
 		if list.Empty() {
 			delete(pool.pending, addr)
+			delete(pool.beats, addr)
 		}
 	}
 }
 
+// expirationLoop is a loop that periodically iterates over all accounts with
+// queued transactions and drop all that have been inactive for a prolonged amount
+// of time.
+func (pool *TxPool) expirationLoop() {
+	defer pool.wg.Done()
+
+	evict := time.NewTicker(evictionInterval)
+	defer evict.Stop()
+
+	for {
+		select {
+		case <-evict.C:
+			pool.mu.Lock()
+			for addr := range pool.queue {
+				if time.Since(pool.beats[addr]) > maxQueuedLifetime {
+					for _, tx := range pool.queue[addr].Flatten() {
+						pool.removeTx(tx.Hash())
+					}
+				}
+			}
+			pool.mu.Unlock()
+
+		case <-pool.quit:
+			return
+		}
+	}
+}
+
+// addressByHeartbeat is an account address tagged with its last activity timestamp.
+type addressByHeartbeat struct {
+	address   common.Address
+	heartbeat time.Time
+}
+
+type addresssByHeartbeat []addressByHeartbeat
+
+func (a addresssByHeartbeat) Len() int           { return len(a) }
+func (a addresssByHeartbeat) Less(i, j int) bool { return a[i].heartbeat.Before(a[j].heartbeat) }
+func (a addresssByHeartbeat) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
+
 // txSet represents a set of transaction hashes in which entries
 //  are automatically dropped after txSetDuration time
 type txSet struct {