routing/chainview/bitcoind: improve filterMtx locking

In this commit, we modify the granularity of the locking
around the filterMtx in the bitcoind chainview, such that
we only lock once per block connected or filter update.
Currently, we acquire and release the lock for every
update to the map.

We also fix a bug that would cause us to not fully remove
all previous outpoints spent by a txn when doing manual
filter, as we previously would only remove the first output
detected.

routing/chainview/bitcoind.go

@@ -154,6 +154,7 @@ func (b *BitcoindFilteredChainView) onFilteredBlockConnected(height int32,
 	hash chainhash.Hash, txns []*wtxmgr.TxRecord) {
 
 	mtxs := make([]*wire.MsgTx, len(txns))
+	b.filterMtx.Lock()
 	for i, tx := range txns {
 		mtxs[i] = &tx.MsgTx
 
@@ -164,12 +165,11 @@ func (b *BitcoindFilteredChainView) onFilteredBlockConnected(height int32,
 			// that's okay since it would never be wise to consider
 			// the channel open again (since a spending transaction
 			// exists on the network).
-			b.filterMtx.Lock()
 			delete(b.chainFilter, txIn.PreviousOutPoint)
-			b.filterMtx.Unlock()
 		}
 
 	}
+	b.filterMtx.Unlock()
 
 	// We record the height of the last connected block added to the
 	// blockQueue such that we can scan up to this height in case of
@@ -246,19 +246,29 @@ func (b *BitcoindFilteredChainView) chainFilterer() {
 	// watched. Additionally, the chain filter will also be updated by
 	// removing any spent outputs.
 	filterBlock := func(blk *wire.MsgBlock) []*wire.MsgTx {
+		b.filterMtx.Lock()
+		defer b.filterMtx.Unlock()
+
 		var filteredTxns []*wire.MsgTx
 		for _, tx := range blk.Transactions {
+			var txAlreadyFiltered bool
 			for _, txIn := range tx.TxIn {
 				prevOp := txIn.PreviousOutPoint
-				if _, ok := b.chainFilter[prevOp]; ok {
-					filteredTxns = append(filteredTxns, tx)
-
-					b.filterMtx.Lock()
-					delete(b.chainFilter, prevOp)
-					b.filterMtx.Unlock()
-
-					break
+				if _, ok := b.chainFilter[prevOp]; !ok {
+					continue
 				}
+
+				delete(b.chainFilter, prevOp)
+
+				// Only add this txn to our list of filtered
+				// txns if it is the first previous outpoint to
+				// cause a match.
+				if txAlreadyFiltered {
+					continue
+				}
+
+				filteredTxns = append(filteredTxns, tx)
+				txAlreadyFiltered = true
 			}
 		}
 
@@ -304,11 +314,12 @@ func (b *BitcoindFilteredChainView) chainFilterer() {
 			// process.
 			log.Debugf("Updating chain filter with new UTXO's: %v",
 				update.newUtxos)
+
+			b.filterMtx.Lock()
 			for _, newOp := range update.newUtxos {
-				b.filterMtx.Lock()
 				b.chainFilter[newOp] = struct{}{}
-				b.filterMtx.Unlock()
 			}
+			b.filterMtx.Unlock()
 
 			// Apply the new TX filter to the chain client, which
 			// will cause all following notifications from and