From f470946379fb3480e2f97b571d81de94ad24c8bd Mon Sep 17 00:00:00 2001
From: Elle Mouton <elle.mouton@gmail.com>
Date: Thu, 18 Mar 2021 14:30:58 +0200
Subject: [PATCH] routing: add block cache to BtcdFilteredChainView

This commit makes the block cache available to BtcdFilteredChainView and
wraps its GetBlock method so that the block cache is used.
---
 chainreg/chainregistry.go           |  4 +++-
 routing/chainview/btcd.go           | 19 +++++++++++++++++--
 routing/chainview/interface_test.go |  5 ++++-
 3 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/chainreg/chainregistry.go b/chainreg/chainregistry.go
index e81258fd..dda18a80 100644
--- a/chainreg/chainregistry.go
+++ b/chainreg/chainregistry.go
@@ -555,7 +555,9 @@ func NewChainControl(cfg *Config) (*ChainControl, func(), error) {
 
 		// Finally, we'll create an instance of the default chain view to be
 		// used within the routing layer.
-		cc.ChainView, err = chainview.NewBtcdFilteredChainView(*rpcConfig)
+		cc.ChainView, err = chainview.NewBtcdFilteredChainView(
+			*rpcConfig, blockCache,
+		)
 		if err != nil {
 			log.Errorf("unable to create chain view: %v", err)
 			return nil, nil, err
diff --git a/routing/chainview/btcd.go b/routing/chainview/btcd.go
index c4d9c022..4e5a95b5 100644
--- a/routing/chainview/btcd.go
+++ b/routing/chainview/btcd.go
@@ -12,6 +12,7 @@ import (
 	"github.com/btcsuite/btcd/rpcclient"
 	"github.com/btcsuite/btcd/wire"
 	"github.com/btcsuite/btcutil"
+	"github.com/lightningnetwork/lnd/blockcache"
 	"github.com/lightningnetwork/lnd/channeldb"
 )
 
@@ -35,6 +36,9 @@ type BtcdFilteredChainView struct {
 	// chainView.
 	blockQueue *blockEventQueue
 
+	// blockCache is an LRU block cache.
+	blockCache *blockcache.BlockCache
+
 	// filterUpdates is a channel in which updates to the utxo filter
 	// attached to this instance are sent over.
 	filterUpdates chan filterUpdate
@@ -58,11 +62,14 @@ var _ FilteredChainView = (*BtcdFilteredChainView)(nil)
 
 // NewBtcdFilteredChainView creates a new instance of a FilteredChainView from
 // RPC credentials for an active btcd instance.
-func NewBtcdFilteredChainView(config rpcclient.ConnConfig) (*BtcdFilteredChainView, error) {
+func NewBtcdFilteredChainView(config rpcclient.ConnConfig,
+	blockCache *blockcache.BlockCache) (*BtcdFilteredChainView, error) {
+
 	chainView := &BtcdFilteredChainView{
 		chainFilter:     make(map[wire.OutPoint]struct{}),
 		filterUpdates:   make(chan filterUpdate),
 		filterBlockReqs: make(chan *filterBlockReq),
+		blockCache:      blockCache,
 		quit:            make(chan struct{}),
 	}
 
@@ -404,7 +411,7 @@ func (b *BtcdFilteredChainView) chainFilterer() {
 		case req := <-b.filterBlockReqs:
 			// First we'll fetch the block itself as well as some
 			// additional information including its height.
-			block, err := b.btcdConn.GetBlock(req.blockHash)
+			block, err := b.GetBlock(req.blockHash)
 			if err != nil {
 				req.err <- err
 				req.resp <- nil
@@ -486,3 +493,11 @@ func (b *BtcdFilteredChainView) FilteredBlocks() <-chan *FilteredBlock {
 func (b *BtcdFilteredChainView) DisconnectedBlocks() <-chan *FilteredBlock {
 	return b.blockQueue.staleBlocks
 }
+
+// GetBlock is used to retrieve the block with the given hash. This function
+// wraps the blockCache's GetBlock function.
+func (b *BtcdFilteredChainView) GetBlock(hash *chainhash.Hash) (
+	*wire.MsgBlock, error) {
+
+	return b.blockCache.GetBlock(hash, b.btcdConn.GetBlock)
+}
diff --git a/routing/chainview/interface_test.go b/routing/chainview/interface_test.go
index 875c0601..439b8d7f 100644
--- a/routing/chainview/interface_test.go
+++ b/routing/chainview/interface_test.go
@@ -906,7 +906,10 @@ var interfaceImpls = []struct {
 	{
 		name: "btcd_websockets",
 		chainViewInit: func(config rpcclient.ConnConfig, _ string) (func(), FilteredChainView, error) {
-			chainView, err := NewBtcdFilteredChainView(config)
+			blockCache := blockcache.NewBlockCache(10000)
+			chainView, err := NewBtcdFilteredChainView(
+				config, blockCache,
+			)
 			if err != nil {
 				return nil, nil, err
 			}