mempool: add TTL configuration to mempool (#6715)

config/config.go

@@ -784,25 +784,47 @@ type MempoolConfig struct {
 	RootDir   string `mapstructure:"home"`
 	Recheck   bool   `mapstructure:"recheck"`
 	Broadcast bool   `mapstructure:"broadcast"`
+
 	// Maximum number of transactions in the mempool
 	Size int `mapstructure:"size"`
+
 	// Limit the total size of all txs in the mempool.
 	// This only accounts for raw transactions (e.g. given 1MB transactions and
 	// max-txs-bytes=5MB, mempool will only accept 5 transactions).
 	MaxTxsBytes int64 `mapstructure:"max-txs-bytes"`
+
 	// Size of the cache (used to filter transactions we saw earlier) in transactions
 	CacheSize int `mapstructure:"cache-size"`
+
 	// Do not remove invalid transactions from the cache (default: false)
 	// Set to true if it's not possible for any invalid transaction to become
 	// valid again in the future.
 	KeepInvalidTxsInCache bool `mapstructure:"keep-invalid-txs-in-cache"`
+
 	// Maximum size of a single transaction
 	// NOTE: the max size of a tx transmitted over the network is {max-tx-bytes}.
 	MaxTxBytes int `mapstructure:"max-tx-bytes"`
+
 	// Maximum size of a batch of transactions to send to a peer
 	// Including space needed by encoding (one varint per transaction).
 	// XXX: Unused due to https://github.com/tendermint/tendermint/issues/5796
 	MaxBatchBytes int `mapstructure:"max-batch-bytes"`
+
+	// TTLDuration, if non-zero, defines the maximum amount of time a transaction
+	// can exist for in the mempool.
+	//
+	// Note, if TTLNumBlocks is also defined, a transaction will be removed if it
+	// has existed in the mempool at least TTLNumBlocks number of blocks or if it's
+	// insertion time into the mempool is beyond TTLDuration.
+	TTLDuration time.Duration `mapstructure:"ttl-duration"`
+
+	// TTLNumBlocks, if non-zero, defines the maximum number of blocks a transaction
+	// can exist for in the mempool.
+	//
+	// Note, if TTLDuration is also defined, a transaction will be removed if it
+	// has existed in the mempool at least TTLNumBlocks number of blocks or if
+	// it's insertion time into the mempool is beyond TTLDuration.
+	TTLNumBlocks int64 `mapstructure:"ttl-num-blocks"`
 }
 
 // DefaultMempoolConfig returns a default configuration for the Tendermint mempool.
@@ -813,10 +835,12 @@ func DefaultMempoolConfig() *MempoolConfig {
 		Broadcast: true,
 		// Each signature verification takes .5ms, Size reduced until we implement
 		// ABCI Recheck
-		Size:        5000,
-		MaxTxsBytes: 1024 * 1024 * 1024, // 1GB
-		CacheSize:   10000,
-		MaxTxBytes:  1024 * 1024, // 1MB
+		Size:         5000,
+		MaxTxsBytes:  1024 * 1024 * 1024, // 1GB
+		CacheSize:    10000,
+		MaxTxBytes:   1024 * 1024, // 1MB
+		TTLDuration:  0 * time.Second,
+		TTLNumBlocks: 0,
 	}
 }
 
@@ -842,6 +866,13 @@ func (cfg *MempoolConfig) ValidateBasic() error {
 	if cfg.MaxTxBytes < 0 {
 		return errors.New("max-tx-bytes can't be negative")
 	}
+	if cfg.TTLDuration < 0 {
+		return errors.New("ttl-duration can't be negative")
+	}
+	if cfg.TTLNumBlocks < 0 {
+		return errors.New("ttl-num-blocks can't be negative")
+	}
+
 	return nil
 }
 

config/toml.go

@@ -399,6 +399,22 @@ max-tx-bytes = {{ .Mempool.MaxTxBytes }}
 # XXX: Unused due to https://github.com/tendermint/tendermint/issues/5796
 max-batch-bytes = {{ .Mempool.MaxBatchBytes }}
 
+# ttl-duration, if non-zero, defines the maximum amount of time a transaction
+# can exist for in the mempool.
+#
+# Note, if ttl-num-blocks is also defined, a transaction will be removed if it
+# has existed in the mempool at least ttl-num-blocks number of blocks or if it's
+# insertion time into the mempool is beyond ttl-duration.
+ttl-duration = "{{ .Mempool.TTLDuration }}"
+
+# ttl-num-blocks, if non-zero, defines the maximum number of blocks a transaction
+# can exist for in the mempool.
+#
+# Note, if ttl-duration is also defined, a transaction will be removed if it
+# has existed in the mempool at least ttl-num-blocks number of blocks or if
+# it's insertion time into the mempool is beyond ttl-duration.
+ttl-num-blocks = {{ .Mempool.TTLNumBlocks }}
+
 #######################################################
 ###         State Sync Configuration Options        ###
 #######################################################

docs/nodes/configuration.md

@@ -275,9 +275,13 @@ dial-timeout = "3s"
 #######################################################
 [mempool]
 
+# Mempool version to use:
+#   1) "v0" - The legacy non-prioritized mempool reactor.
+#   2) "v1" (default) - The prioritized mempool reactor.
+version = "v1"
+
 recheck = true
 broadcast = true
-wal-dir = ""
 
 # Maximum number of transactions in the mempool
 size = 5000
@@ -304,6 +308,22 @@ max-tx-bytes = 1048576
 # XXX: Unused due to https://github.com/tendermint/tendermint/issues/5796
 max-batch-bytes = 0
 
+# ttl-duration, if non-zero, defines the maximum amount of time a transaction
+# can exist for in the mempool.
+#
+# Note, if ttl-num-blocks is also defined, a transaction will be removed if it
+# has existed in the mempool at least ttl-num-blocks number of blocks or if it's
+# insertion time into the mempool is beyond ttl-duration.
+ttl-duration = "0s"
+
+# ttl-num-blocks, if non-zero, defines the maximum number of blocks a transaction
+# can exist for in the mempool.
+#
+# Note, if ttl-duration is also defined, a transaction will be removed if it
+# has existed in the mempool at least ttl-num-blocks number of blocks or if
+# it's insertion time into the mempool is beyond ttl-duration.
+ttl-num-blocks = 0
+
 #######################################################
 ###         State Sync Configuration Options        ###
 #######################################################
@@ -421,7 +441,6 @@ max-open-connections = 3
 
 # Instrumentation namespace
 namespace = "tendermint"
-
 ```
 
 ## Empty blocks VS no empty blocks

internal/mempool/v1/mempool.go

@@ -74,6 +74,14 @@ type TxMempool struct {
 	// thread-safe priority queue.
 	priorityIndex *TxPriorityQueue
 
+	// heightIndex defines a height-based, in ascending order, transaction index.
+	// i.e. older transactions are first.
+	heightIndex *WrappedTxList
+
+	// timestampIndex defines a timestamp-based, in ascending order, transaction
+	// index. i.e. older transactions are first.
+	timestampIndex *WrappedTxList
+
 	// A read/write lock is used to safe guard updates, insertions and deletions
 	// from the mempool. A read-lock is implicitly acquired when executing CheckTx,
 	// however, a caller must explicitly grab a write-lock via Lock when updating
@@ -101,6 +109,12 @@ func NewTxMempool(
 		txStore:       NewTxStore(),
 		gossipIndex:   clist.New(),
 		priorityIndex: NewTxPriorityQueue(),
+		heightIndex: NewWrappedTxList(func(wtx1, wtx2 *WrappedTx) bool {
+			return wtx1.height >= wtx2.height
+		}),
+		timestampIndex: NewWrappedTxList(func(wtx1, wtx2 *WrappedTx) bool {
+			return wtx1.timestamp.After(wtx2.timestamp) || wtx1.timestamp.Equal(wtx2.timestamp)
+		}),
 	}
 
 	if cfg.CacheSize > 0 {
@@ -279,6 +293,7 @@ func (txmp *TxMempool) CheckTx(
 			tx:        tx,
 			hash:      txHash,
 			timestamp: time.Now().UTC(),
+			height:    txmp.height,
 		}
 		txmp.initTxCallback(wtx, res, txInfo)
 
@@ -300,13 +315,11 @@ func (txmp *TxMempool) Flush() {
 	txmp.mtx.RLock()
 	defer txmp.mtx.RUnlock()
 
+	txmp.heightIndex.Reset()
+	txmp.timestampIndex.Reset()
+
 	for _, wtx := range txmp.txStore.GetAllTxs() {
-		if !txmp.txStore.IsTxRemoved(wtx.hash) {
-			txmp.txStore.RemoveTx(wtx)
-			txmp.priorityIndex.RemoveTx(wtx)
-			txmp.gossipIndex.Remove(wtx.gossipEl)
-			wtx.gossipEl.DetachPrev()
-		}
+		txmp.removeTx(wtx, false)
 	}
 
 	atomic.SwapInt64(&txmp.sizeBytes, 0)
@@ -444,6 +457,8 @@ func (txmp *TxMempool) Update(
 		}
 	}
 
+	txmp.purgeExpiredTxs(blockHeight)
+
 	// If there any uncommitted transactions left in the mempool, we either
 	// initiate re-CheckTx per remaining transaction or notify that remaining
 	// transactions are left.
@@ -550,7 +565,6 @@ func (txmp *TxMempool) initTxCallback(wtx *WrappedTx, res *abci.Response, txInfo
 			}
 
 			wtx.gasWanted = checkTxRes.CheckTx.GasWanted
-			wtx.height = txmp.height
 			wtx.priority = priority
 			wtx.sender = sender
 			wtx.peers = map[uint16]struct{}{
@@ -722,6 +736,8 @@ func (txmp *TxMempool) canAddTx(wtx *WrappedTx) error {
 func (txmp *TxMempool) insertTx(wtx *WrappedTx) {
 	txmp.txStore.SetTx(wtx)
 	txmp.priorityIndex.PushTx(wtx)
+	txmp.heightIndex.Insert(wtx)
+	txmp.timestampIndex.Insert(wtx)
 
 	// Insert the transaction into the gossip index and mark the reference to the
 	// linked-list element, which will be needed at a later point when the
@@ -739,6 +755,8 @@ func (txmp *TxMempool) removeTx(wtx *WrappedTx, removeFromCache bool) {
 
 	txmp.txStore.RemoveTx(wtx)
 	txmp.priorityIndex.RemoveTx(wtx)
+	txmp.heightIndex.Remove(wtx)
+	txmp.timestampIndex.Remove(wtx)
 
 	// Remove the transaction from the gossip index and cleanup the linked-list
 	// element so it can be garbage collected.
@@ -752,6 +770,56 @@ func (txmp *TxMempool) removeTx(wtx *WrappedTx, removeFromCache bool) {
 	}
 }
 
+// purgeExpiredTxs removes all transactions that have exceeded their respective
+// height and/or time based TTLs from their respective indexes. Every expired
+// transaction will be removed from the mempool entirely, except for the cache.
+//
+// NOTE: purgeExpiredTxs must only be called during TxMempool#Update in which
+// the caller has a write-lock on the mempool and so we can safely iterate over
+// the height and time based indexes.
+func (txmp *TxMempool) purgeExpiredTxs(blockHeight int64) {
+	now := time.Now()
+	expiredTxs := make(map[[mempool.TxKeySize]byte]*WrappedTx)
+
+	if txmp.config.TTLNumBlocks > 0 {
+		purgeIdx := -1
+		for i, wtx := range txmp.heightIndex.txs {
+			if (blockHeight - wtx.height) > txmp.config.TTLNumBlocks {
+				expiredTxs[mempool.TxKey(wtx.tx)] = wtx
+				purgeIdx = i
+			} else {
+				// since the index is sorted, we know no other txs can be be purged
+				break
+			}
+		}
+
+		if purgeIdx >= 0 {
+			txmp.heightIndex.txs = txmp.heightIndex.txs[purgeIdx+1:]
+		}
+	}
+
+	if txmp.config.TTLDuration > 0 {
+		purgeIdx := -1
+		for i, wtx := range txmp.timestampIndex.txs {
+			if now.Sub(wtx.timestamp) > txmp.config.TTLDuration {
+				expiredTxs[mempool.TxKey(wtx.tx)] = wtx
+				purgeIdx = i
+			} else {
+				// since the index is sorted, we know no other txs can be be purged
+				break
+			}
+		}
+
+		if purgeIdx >= 0 {
+			txmp.timestampIndex.txs = txmp.timestampIndex.txs[purgeIdx+1:]
+		}
+	}
+
+	for _, wtx := range expiredTxs {
+		txmp.removeTx(wtx, false)
+	}
+}
+
 func (txmp *TxMempool) notifyTxsAvailable() {
 	if txmp.Size() == 0 {
 		panic("attempt to notify txs available but mempool is empty!")

internal/mempool/v1/mempool_test.go

@@ -102,14 +102,10 @@ func checkTxs(t *testing.T, txmp *TxMempool, numTxs int, peerID uint16) []testTx
 		_, err := rng.Read(prefix)
 		require.NoError(t, err)
 
-		// sender := make([]byte, 10)
-		// _, err = rng.Read(sender)
-		// require.NoError(t, err)
-
 		priority := int64(rng.Intn(9999-1000) + 1000)
 
 		txs[i] = testTx{
-			tx:       []byte(fmt.Sprintf("sender-%d=%X=%d", i, prefix, priority)),
+			tx:       []byte(fmt.Sprintf("sender-%d-%d=%X=%d", i, peerID, prefix, priority)),
 			priority: priority,
 		}
 		require.NoError(t, txmp.CheckTx(context.Background(), txs[i].tx, nil, txInfo))
@@ -176,7 +172,7 @@ func TestTxMempool_Size(t *testing.T) {
 	txmp := setup(t, 0)
 	txs := checkTxs(t, txmp, 100, 0)
 	require.Equal(t, len(txs), txmp.Size())
-	require.Equal(t, int64(5490), txmp.SizeBytes())
+	require.Equal(t, int64(5690), txmp.SizeBytes())
 
 	rawTxs := make([]types.Tx, len(txs))
 	for i, tx := range txs {
@@ -193,14 +189,14 @@ func TestTxMempool_Size(t *testing.T) {
 	txmp.Unlock()
 
 	require.Equal(t, len(rawTxs)/2, txmp.Size())
-	require.Equal(t, int64(2750), txmp.SizeBytes())
+	require.Equal(t, int64(2850), txmp.SizeBytes())
 }
 
 func TestTxMempool_Flush(t *testing.T) {
 	txmp := setup(t, 0)
 	txs := checkTxs(t, txmp, 100, 0)
 	require.Equal(t, len(txs), txmp.Size())
-	require.Equal(t, int64(5490), txmp.SizeBytes())
+	require.Equal(t, int64(5690), txmp.SizeBytes())
 
 	rawTxs := make([]types.Tx, len(txs))
 	for i, tx := range txs {
@@ -225,7 +221,7 @@ func TestTxMempool_ReapMaxBytesMaxGas(t *testing.T) {
 	txmp := setup(t, 0)
 	tTxs := checkTxs(t, txmp, 100, 0) // all txs request 1 gas unit
 	require.Equal(t, len(tTxs), txmp.Size())
-	require.Equal(t, int64(5490), txmp.SizeBytes())
+	require.Equal(t, int64(5690), txmp.SizeBytes())
 
 	txMap := make(map[[mempool.TxKeySize]byte]testTx)
 	priorities := make([]int64, len(tTxs))
@@ -252,30 +248,30 @@ func TestTxMempool_ReapMaxBytesMaxGas(t *testing.T) {
 	reapedTxs := txmp.ReapMaxBytesMaxGas(-1, 50)
 	ensurePrioritized(reapedTxs)
 	require.Equal(t, len(tTxs), txmp.Size())
-	require.Equal(t, int64(5490), txmp.SizeBytes())
+	require.Equal(t, int64(5690), txmp.SizeBytes())
 	require.Len(t, reapedTxs, 50)
 
 	// reap by transaction bytes only
 	reapedTxs = txmp.ReapMaxBytesMaxGas(1000, -1)
 	ensurePrioritized(reapedTxs)
 	require.Equal(t, len(tTxs), txmp.Size())
-	require.Equal(t, int64(5490), txmp.SizeBytes())
-	require.Len(t, reapedTxs, 17)
+	require.Equal(t, int64(5690), txmp.SizeBytes())
+	require.GreaterOrEqual(t, len(reapedTxs), 16)
 
 	// Reap by both transaction bytes and gas, where the size yields 31 reaped
-	// transactions and the gas limit reaps 26 transactions.
+	// transactions and the gas limit reaps 25 transactions.
 	reapedTxs = txmp.ReapMaxBytesMaxGas(1500, 30)
 	ensurePrioritized(reapedTxs)
 	require.Equal(t, len(tTxs), txmp.Size())
-	require.Equal(t, int64(5490), txmp.SizeBytes())
-	require.Len(t, reapedTxs, 26)
+	require.Equal(t, int64(5690), txmp.SizeBytes())
+	require.Len(t, reapedTxs, 25)
 }
 
 func TestTxMempool_ReapMaxTxs(t *testing.T) {
 	txmp := setup(t, 0)
 	tTxs := checkTxs(t, txmp, 100, 0)
 	require.Equal(t, len(tTxs), txmp.Size())
-	require.Equal(t, int64(5490), txmp.SizeBytes())
+	require.Equal(t, int64(5690), txmp.SizeBytes())
 
 	txMap := make(map[[mempool.TxKeySize]byte]testTx)
 	priorities := make([]int64, len(tTxs))
@@ -302,21 +298,21 @@ func TestTxMempool_ReapMaxTxs(t *testing.T) {
 	reapedTxs := txmp.ReapMaxTxs(-1)
 	ensurePrioritized(reapedTxs)
 	require.Equal(t, len(tTxs), txmp.Size())
-	require.Equal(t, int64(5490), txmp.SizeBytes())
+	require.Equal(t, int64(5690), txmp.SizeBytes())
 	require.Len(t, reapedTxs, len(tTxs))
 
 	// reap a single transaction
 	reapedTxs = txmp.ReapMaxTxs(1)
 	ensurePrioritized(reapedTxs)
 	require.Equal(t, len(tTxs), txmp.Size())
-	require.Equal(t, int64(5490), txmp.SizeBytes())
+	require.Equal(t, int64(5690), txmp.SizeBytes())
 	require.Len(t, reapedTxs, 1)
 
 	// reap half of the transactions
 	reapedTxs = txmp.ReapMaxTxs(len(tTxs) / 2)
 	ensurePrioritized(reapedTxs)
 	require.Equal(t, len(tTxs), txmp.Size())
-	require.Equal(t, int64(5490), txmp.SizeBytes())
+	require.Equal(t, int64(5690), txmp.SizeBytes())
 	require.Len(t, reapedTxs, len(tTxs)/2)
 }
 
@@ -431,3 +427,53 @@ func TestTxMempool_ConcurrentTxs(t *testing.T) {
 	require.Zero(t, txmp.Size())
 	require.Zero(t, txmp.SizeBytes())
 }
+
+func TestTxMempool_ExpiredTxs_NumBlocks(t *testing.T) {
+	txmp := setup(t, 500)
+	txmp.height = 100
+	txmp.config.TTLNumBlocks = 10
+
+	tTxs := checkTxs(t, txmp, 100, 0)
+	require.Equal(t, len(tTxs), txmp.Size())
+	require.Equal(t, 100, txmp.heightIndex.Size())
+
+	// reap 5 txs at the next height -- no txs should expire
+	reapedTxs := txmp.ReapMaxTxs(5)
+	responses := make([]*abci.ResponseDeliverTx, len(reapedTxs))
+	for i := 0; i < len(responses); i++ {
+		responses[i] = &abci.ResponseDeliverTx{Code: abci.CodeTypeOK}
+	}
+
+	txmp.Lock()
+	require.NoError(t, txmp.Update(txmp.height+1, reapedTxs, responses, nil, nil))
+	txmp.Unlock()
+
+	require.Equal(t, 95, txmp.Size())
+	require.Equal(t, 95, txmp.heightIndex.Size())
+
+	// check more txs at height 101
+	_ = checkTxs(t, txmp, 50, 1)
+	require.Equal(t, 145, txmp.Size())
+	require.Equal(t, 145, txmp.heightIndex.Size())
+
+	// Reap 5 txs at a height that would expire all the transactions from before
+	// the previous Update (height 100).
+	//
+	// NOTE: When we reap txs below, we do not know if we're picking txs from the
+	// initial CheckTx calls or from the second round of CheckTx calls. Thus, we
+	// cannot guarantee that all 95 txs are remaining that should be expired and
+	// removed. However, we do know that that at most 95 txs can be expired and
+	// removed.
+	reapedTxs = txmp.ReapMaxTxs(5)
+	responses = make([]*abci.ResponseDeliverTx, len(reapedTxs))
+	for i := 0; i < len(responses); i++ {
+		responses[i] = &abci.ResponseDeliverTx{Code: abci.CodeTypeOK}
+	}
+
+	txmp.Lock()
+	require.NoError(t, txmp.Update(txmp.height+10, reapedTxs, responses, nil, nil))
+	txmp.Unlock()
+
+	require.GreaterOrEqual(t, txmp.Size(), 45)
+	require.GreaterOrEqual(t, txmp.heightIndex.Size(), 45)
+}

internal/mempool/v1/tx.go

@@ -1,6 +1,7 @@
 package v1
 
 import (
+	"sort"
 	"time"
 
 	"github.com/tendermint/tendermint/internal/libs/clist"
@@ -198,3 +199,84 @@ func (txs *TxStore) GetOrSetPeerByTxHash(hash [mempool.TxKeySize]byte, peerID ui
 	wtx.peers[peerID] = struct{}{}
 	return wtx, false
 }
+
+// WrappedTxList implements a thread-safe list of *WrappedTx objects that can be
+// used to build generic transaction indexes in the mempool. It accepts a
+// comparator function, less(a, b *WrappedTx) bool, that compares two WrappedTx
+// references which is used during Insert in order to determine sorted order. If
+// less returns true, a <= b.
+type WrappedTxList struct {
+	mtx  tmsync.RWMutex
+	txs  []*WrappedTx
+	less func(*WrappedTx, *WrappedTx) bool
+}
+
+func NewWrappedTxList(less func(*WrappedTx, *WrappedTx) bool) *WrappedTxList {
+	return &WrappedTxList{
+		txs:  make([]*WrappedTx, 0),
+		less: less,
+	}
+}
+
+// Size returns the number of WrappedTx objects in the list.
+func (wtl *WrappedTxList) Size() int {
+	wtl.mtx.RLock()
+	defer wtl.mtx.RUnlock()
+
+	return len(wtl.txs)
+}
+
+// Reset resets the list of transactions to an empty list.
+func (wtl *WrappedTxList) Reset() {
+	wtl.mtx.Lock()
+	defer wtl.mtx.Unlock()
+
+	wtl.txs = make([]*WrappedTx, 0)
+}
+
+// Insert inserts a WrappedTx reference into the sorted list based on the list's
+// comparator function.
+func (wtl *WrappedTxList) Insert(wtx *WrappedTx) {
+	wtl.mtx.Lock()
+	defer wtl.mtx.Unlock()
+
+	i := sort.Search(len(wtl.txs), func(i int) bool {
+		return wtl.less(wtl.txs[i], wtx)
+	})
+
+	if i == len(wtl.txs) {
+		// insert at the end
+		wtl.txs = append(wtl.txs, wtx)
+		return
+	}
+
+	// Make space for the inserted element by shifting values at the insertion
+	// index up one index.
+	//
+	// NOTE: The call to append does not allocate memory when cap(wtl.txs) > len(wtl.txs).
+	wtl.txs = append(wtl.txs[:i+1], wtl.txs[i:]...)
+	wtl.txs[i] = wtx
+}
+
+// Remove attempts to remove a WrappedTx from the sorted list.
+func (wtl *WrappedTxList) Remove(wtx *WrappedTx) {
+	wtl.mtx.Lock()
+	defer wtl.mtx.Unlock()
+
+	i := sort.Search(len(wtl.txs), func(i int) bool {
+		return wtl.less(wtl.txs[i], wtx)
+	})
+
+	// Since the list is sorted, we evaluate all elements starting at i. Note, if
+	// the element does not exist, we may potentially evaluate the entire remainder
+	// of the list. However, a caller should not be expected to call Remove with a
+	// non-existing element.
+	for i < len(wtl.txs) {
+		if wtl.txs[i] == wtx {
+			wtl.txs = append(wtl.txs[:i], wtl.txs[i+1:]...)
+			return
+		}
+
+		i++
+	}
+}

internal/mempool/v1/tx_test.go

@@ -2,6 +2,8 @@ package v1
 
 import (
 	"fmt"
+	"math/rand"
+	"sort"
 	"testing"
 	"time"
 
@@ -132,3 +134,97 @@ func TestTxStore_Size(t *testing.T) {
 
 	require.Equal(t, numTxs, txStore.Size())
 }
+
+func TestWrappedTxList_Reset(t *testing.T) {
+	list := NewWrappedTxList(func(wtx1, wtx2 *WrappedTx) bool {
+		return wtx1.height >= wtx2.height
+	})
+
+	require.Zero(t, list.Size())
+
+	for i := 0; i < 100; i++ {
+		list.Insert(&WrappedTx{height: int64(i)})
+	}
+
+	require.Equal(t, 100, list.Size())
+
+	list.Reset()
+	require.Zero(t, list.Size())
+}
+
+func TestWrappedTxList_Insert(t *testing.T) {
+	list := NewWrappedTxList(func(wtx1, wtx2 *WrappedTx) bool {
+		return wtx1.height >= wtx2.height
+	})
+
+	rng := rand.New(rand.NewSource(time.Now().UnixNano()))
+
+	var expected []int
+	for i := 0; i < 100; i++ {
+		height := rng.Int63n(10000)
+		expected = append(expected, int(height))
+		list.Insert(&WrappedTx{height: height})
+
+		if i%10 == 0 {
+			list.Insert(&WrappedTx{height: height})
+			expected = append(expected, int(height))
+		}
+	}
+
+	got := make([]int, list.Size())
+	for i, wtx := range list.txs {
+		got[i] = int(wtx.height)
+	}
+
+	sort.Ints(expected)
+	require.Equal(t, expected, got)
+}
+
+func TestWrappedTxList_Remove(t *testing.T) {
+	list := NewWrappedTxList(func(wtx1, wtx2 *WrappedTx) bool {
+		return wtx1.height >= wtx2.height
+	})
+
+	rng := rand.New(rand.NewSource(time.Now().UnixNano()))
+
+	var txs []*WrappedTx
+	for i := 0; i < 100; i++ {
+		height := rng.Int63n(10000)
+		tx := &WrappedTx{height: height}
+
+		txs = append(txs, tx)
+		list.Insert(tx)
+
+		if i%10 == 0 {
+			tx = &WrappedTx{height: height}
+			list.Insert(tx)
+			txs = append(txs, tx)
+		}
+	}
+
+	// remove a tx that does not exist
+	list.Remove(&WrappedTx{height: 20000})
+
+	// remove a tx that exists (by height) but not referenced
+	list.Remove(&WrappedTx{height: txs[0].height})
+
+	// remove a few existing txs
+	for i := 0; i < 25; i++ {
+		j := rng.Intn(len(txs))
+		list.Remove(txs[j])
+		txs = append(txs[:j], txs[j+1:]...)
+	}
+
+	expected := make([]int, len(txs))
+	for i, tx := range txs {
+		expected[i] = int(tx.height)
+	}
+
+	got := make([]int, list.Size())
+	for i, wtx := range list.txs {
+		got[i] = int(wtx.height)
+	}
+
+	sort.Ints(expected)
+	require.Equal(t, expected, got)
+}