mempool: Use median time for tx finality checks.

mempool/mempool.go

@@ -108,15 +108,17 @@ type Config struct {
 	// the current best chain.
 	BestHeight func() int64
 
+	// PastMedianTime defines the function to use in order to access the
+	// median time calculated from the point-of-view of the current chain
+	// tip within the best chain.
+	PastMedianTime func() time.Time
+
 	// SubsidyCache defines a subsidy cache to use.
 	SubsidyCache *blockchain.SubsidyCache
 
 	// SigCache defines a signature cache to use.
 	SigCache *txscript.SigCache
 
-	// TimeSource defines the timesource to use.
-	TimeSource blockchain.MedianTimeSource
-
 	// AddrIndex defines the optional address index instance to use for
 	// indexing the unconfirmed transactions in the memory pool.
 	// This can be nil if the address index is not enabled.
@@ -830,8 +832,9 @@ func (mp *TxPool) maybeAcceptTransaction(tx *dcrutil.Tx, isNew, rateLimit, allow
 	// Don't allow non-standard transactions if the network parameters
 	// forbid their relaying.
 	if !mp.cfg.Policy.RelayNonStd {
+		medianTime := mp.cfg.PastMedianTime()
 		err := checkTransactionStandard(tx, txType, nextBlockHeight,
-			mp.cfg.TimeSource, mp.cfg.Policy.MinRelayTxFee,
+			medianTime, mp.cfg.Policy.MinRelayTxFee,
 			mp.cfg.Policy.MaxTxVersion)
 		if err != nil {
 			// Attempt to extract a reject code from the error so

mempool/mempool_test.go

@@ -11,6 +11,7 @@ import (
 	"reflect"
 	"sync"
 	"testing"
+	"time"
 
 	"github.com/decred/dcrd/blockchain"
 	"github.com/decred/dcrd/chaincfg"
@@ -32,6 +33,7 @@ type fakeChain struct {
 	blocks        map[chainhash.Hash]*dcrutil.Block
 	currentHash   chainhash.Hash
 	currentHeight int64
+	medianTime    time.Time
 	scriptFlags   txscript.ScriptFlags
 }
 
@@ -133,6 +135,23 @@ func (s *fakeChain) SetHeight(height int64) {
 	s.Unlock()
 }
 
+// PastMedianTime returns the current median time associated with the fake chain
+// instance.
+func (s *fakeChain) PastMedianTime() time.Time {
+	s.RLock()
+	medianTime := s.medianTime
+	s.RUnlock()
+	return medianTime
+}
+
+// SetPastMedianTime sets the current median time associated with the fake chain
+// instance.
+func (s *fakeChain) SetPastMedianTime(medianTime time.Time) {
+	s.Lock()
+	s.medianTime = medianTime
+	s.Unlock()
+}
+
 // StandardVerifyFlags returns the standard verification script flags associated
 // with the fake chain instance.
 func (s *fakeChain) StandardVerifyFlags() (txscript.ScriptFlags, error) {
@@ -369,9 +388,9 @@ func newPoolHarness(chainParams *chaincfg.Params) (*poolHarness, []spendableOutp
 			BlockByHash:         chain.BlockByHash,
 			BestHash:            chain.BestHash,
 			BestHeight:          chain.BestHeight,
+			PastMedianTime:      chain.PastMedianTime,
 			SubsidyCache:        subsidyCache,
 			SigCache:            nil,
-			TimeSource:          blockchain.NewMedianTime(),
 			AddrIndex:           nil,
 			ExistsAddrIndex:     nil,
 		}),
@@ -394,6 +413,7 @@ func newPoolHarness(chainParams *chaincfg.Params) (*poolHarness, []spendableOutp
 		outputs = append(outputs, txOutToSpendableOut(coinbase, i))
 	}
 	harness.chain.SetHeight(int64(chainParams.CoinbaseMaturity) + curHeight)
+	harness.chain.SetPastMedianTime(time.Now())
 
 	return &harness, outputs, nil
 }

mempool/policy.go

@@ -7,6 +7,7 @@ package mempool
 
 import (
 	"fmt"
+	"time"
 
 	"github.com/decred/dcrd/blockchain"
 	"github.com/decred/dcrd/blockchain/stake"
@@ -363,7 +364,7 @@ func isDust(txOut *wire.TxOut, minRelayTxFee dcrutil.Amount) bool {
 // of recognized forms, and not containing "dust" outputs (those that are
 // so small it costs more to process them than they are worth).
 func checkTransactionStandard(tx *dcrutil.Tx, txType stake.TxType, height int64,
-	timeSource blockchain.MedianTimeSource, minRelayTxFee dcrutil.Amount,
+	medianTime time.Time, minRelayTxFee dcrutil.Amount,
 	maxTxVersion uint16) error {
 
 	// The transaction must be a currently supported version and serialize
@@ -382,8 +383,7 @@ func checkTransactionStandard(tx *dcrutil.Tx, txType stake.TxType, height int64,
 
 	// The transaction must be finalized to be standard and therefore
 	// considered for inclusion in a block.
-	adjustedTime := timeSource.AdjustedTime()
-	if !blockchain.IsFinalizedTransaction(tx, height, adjustedTime) {
+	if !blockchain.IsFinalizedTransaction(tx, height, medianTime) {
 		return txRuleError(wire.RejectNonstandard,
 			"transaction is not finalized")
 	}

mempool/policy_test.go

@@ -9,8 +9,8 @@ import (
 	"bytes"
 	"math/big"
 	"testing"
+	"time"
 
-	"github.com/decred/dcrd/blockchain"
 	"github.com/decred/dcrd/blockchain/stake"
 	"github.com/decred/dcrd/chaincfg"
 	"github.com/decred/dcrd/chaincfg/chainec"
@@ -514,12 +514,13 @@ func TestCheckTransactionStandard(t *testing.T) {
 		},
 	}
 
-	timeSource := blockchain.NewMedianTime()
+	medianTime := time.Now()
 	for _, test := range tests {
 		// Ensure standardness is as expected.
 		tx := dcrutil.NewTx(&test.tx)
 		err := checkTransactionStandard(tx, stake.DetermineTxType(&test.tx),
-			test.height, timeSource, DefaultMinRelayTxFee, maxTxVersion)
+			test.height, medianTime, DefaultMinRelayTxFee,
+			maxTxVersion)
 		if err == nil && test.isStandard {
 			// Test passes since function returned standard for a
 			// transaction which is intended to be standard.

server.go

@@ -2446,7 +2446,7 @@ func newServer(listenAddrs []string, db database.DB, chainParams *chaincfg.Param
 		BestHeight:      func() int64 { return bm.chain.BestSnapshot().Height },
 		SubsidyCache:    bm.chain.FetchSubsidyCache(),
 		SigCache:        s.sigCache,
-		TimeSource:      s.timeSource,
+		PastMedianTime:  func() time.Time { return bm.chain.BestSnapshot().MedianTime },
 		AddrIndex:       s.addrIndex,
 		ExistsAddrIndex: s.existsAddrIndex,
 	}