core: protect epoch checksum with its own mutex

client/core/core.go

@@ -173,6 +173,10 @@ type dexConnection struct {
 	// processed by a dex server.
 	inFlightOrders map[uint64]*InFlightOrder
 
+	// A map linking cancel order IDs to trade order IDs.
+	cancelsMtx sync.RWMutex
+	cancels    map[order.OrderID]order.OrderID
+
 	blindCancelsMtx sync.Mutex
 	blindCancels    map[order.OrderID]order.Preimage
 
@@ -253,6 +257,25 @@ func (dc *dexConnection) bondAssets() (map[uint32]*BondAsset, uint64) {
 	return bondAssets, cfg.BondExpiry
 }
 
+func (dc *dexConnection) registerCancelLink(cid, oid order.OrderID) {
+	dc.cancelsMtx.Lock()
+	dc.cancels[cid] = oid
+	dc.cancelsMtx.Unlock()
+}
+
+func (dc *dexConnection) deleteCancelLink(cid order.OrderID) {
+	dc.cancelsMtx.Lock()
+	delete(dc.cancels, cid)
+	dc.cancelsMtx.Unlock()
+}
+
+func (dc *dexConnection) cancelTradeID(cid order.OrderID) (order.OrderID, bool) {
+	dc.cancelsMtx.RLock()
+	defer dc.cancelsMtx.RUnlock()
+	oid, found := dc.cancels[cid]
+	return oid, found
+}
+
 // marketConfig is the market's configuration, as returned by the server in the
 // 'config' response.
 func (dc *dexConnection) marketConfig(mktID string) *msgjson.Market {
@@ -584,10 +607,12 @@ func (dc *dexConnection) findOrder(oid order.OrderID) (tracker *trackedTrade, pr
 	if tracker, found := dc.trades[oid]; found {
 		return tracker, tracker.preImg, false
 	}
-	// Search the cancel order IDs.
-	for _, tracker := range dc.trades {
-		if tracker.cancel != nil && tracker.cancel.ID() == oid {
-			return tracker, tracker.cancel.preImg, true
+
+	if tid, found := dc.cancelTradeID(oid); found {
+		if tracker, found := dc.trades[tid]; found {
+			return tracker, tracker.preImg, true
+		} else {
+			dc.log.Errorf("Did not find trade for cancel order ID %s", oid)
 		}
 	}
 	return
@@ -8087,6 +8112,7 @@ func (c *Core) newDEXConnection(acctInfo *db.AccountInfo, flag connectDEXFlag) (
 		ticker:            newDexTicker(defaultTickInterval), // updated when server config obtained
 		books:             make(map[string]*bookie),
 		trades:            make(map[order.OrderID]*trackedTrade),
+		cancels:           make(map[order.OrderID]order.OrderID),
 		inFlightOrders:    make(map[uint64]*InFlightOrder),
 		blindCancels:      make(map[order.OrderID]order.Preimage),
 		apiVer:            -1,
@@ -8899,7 +8925,7 @@ func handlePreimageRequest(c *Core, dc *dexConnection, msg *msgjson.Message) err
 	}
 
 	if len(req.Commitment) != order.CommitmentSize {
-		return fmt.Errorf("received preimage request for %v with no corresponding order submission response.", oid)
+		return fmt.Errorf("received preimage request for %s with no corresponding order submission response", oid)
 	}
 
 	// See if we recognize that commitment, and if we do, just wait for the
@@ -8992,15 +9018,14 @@ func acceptCsum(tracker *trackedTrade, isCancel bool, commitChecksum dex.Bytes)
 	// Do not allow csum to be changed once it has been committed to
 	// (initialized to something other than `nil`) because it is probably a
 	// malicious behavior by the server.
-	tracker.mtx.Lock()
-	defer tracker.mtx.Unlock()
-
+	tracker.csumMtx.Lock()
+	defer tracker.csumMtx.Unlock()
 	if isCancel {
-		if tracker.cancel.csum == nil {
-			tracker.cancel.csum = commitChecksum
+		if tracker.cancelCsum == nil {
+			tracker.cancelCsum = commitChecksum
 			return true
 		}
-		return bytes.Equal(commitChecksum, tracker.cancel.csum)
+		return bytes.Equal(commitChecksum, tracker.cancelCsum)
 	}
 	if tracker.csum == nil {
 		tracker.csum = commitChecksum
@@ -10721,25 +10746,39 @@ func (c *Core) checkEpochResolution(host string, mktID string) {
 	}
 	currentEpoch := dc.marketEpoch(mktID, time.Now())
 	lastEpoch := currentEpoch - 1
+
+	// Short path if we're already resolved.
+	dc.epochMtx.RLock()
+	resolvedEpoch := dc.resolvedEpoch[mktID]
+	dc.epochMtx.RUnlock()
+	if lastEpoch == resolvedEpoch {
+		return
+	}
+
 	ts, inFlights := dc.marketTrades(mktID)
 	for _, ord := range inFlights {
 		if ord.Epoch == lastEpoch {
 			return
 		}
 	}
 	for _, t := range ts {
+		// Is this order from the last epoch and still not booked or executed?
 		if t.epochIdx() == lastEpoch && t.status() == order.OrderStatusEpoch {
 			return
 		}
-		if t.cancel != nil && t.cancelEpochIdx() == lastEpoch {
-			t.mtx.RLock()
-			matched := t.cancel.matches.taker != nil
-			t.mtx.RUnlock()
-			if !matched {
-				return
-			}
+		// Does this order have an in-flight cancel order that is not yet
+		// resolved?
+		t.mtx.RLock()
+		unresolvedCancel := t.cancel != nil && t.cancelEpochIdx() == lastEpoch && t.cancel.matches.taker == nil
+		t.mtx.RUnlock()
+		if unresolvedCancel {
+			return
 		}
 	}
+
+	// We don't have any unresolved orders or cancel orders from the last epoch.
+	// Just make sure that not other thread has resolved the epoch and then send
+	// the notification.
 	dc.epochMtx.Lock()
 	sendUpdate := lastEpoch > dc.resolvedEpoch[mktID]
 	dc.resolvedEpoch[mktID] = lastEpoch