graph/db: version channelCache by gossip version

Add a channelCacheKey struct keyed by {GossipVersion, chanID}, matching
the pattern already used by rejectCache. This prevents v1 and v2
channel data from colliding in the shared cache.

All callers in KVStore (always GossipVersion1) and SQLStore (version
from context) are updated to pass the version parameter.

This will be needed for later on when we update methods that use this
cache to be versioned (like ChannelUpdatesInHorizon).

graph/db/channel_cache_test.go

@@ -6,6 +6,7 @@ import (
 
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 	"github.com/lightningnetwork/lnd/graph/db/models"
+	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/routing/route"
 )
 
@@ -14,37 +15,39 @@ import (
 func TestChannelCache(t *testing.T) {
 	const cacheSize = 100
 
+	v := lnwire.GossipVersion1
+
 	// Create a new channel cache with the configured max size.
 	c := newChannelCache(cacheSize)
 
 	// As a sanity check, assert that querying the empty cache does not
 	// return an entry.
-	_, ok := c.get(0)
+	_, ok := c.get(v, 0)
 	if ok {
 		t.Fatalf("channel cache should be empty")
 	}
 
 	// Now, fill up the cache entirely.
 	for i := uint64(0); i < cacheSize; i++ {
-		c.insert(i, channelForInt(i))
+		c.insert(v, i, channelForInt(i))
 	}
 
 	// Assert that the cache has all of the entries just inserted, since no
 	// eviction should occur until we try to surpass the max size.
-	assertHasChanEntries(t, c, 0, cacheSize)
+	assertHasChanEntries(t, c, v, 0, cacheSize)
 
 	// Now, insert a new element that causes the cache to evict an element.
-	c.insert(cacheSize, channelForInt(cacheSize))
+	c.insert(v, cacheSize, channelForInt(cacheSize))
 
 	// Assert that the cache has this last entry, as the cache should evict
 	// some prior element and not the newly inserted one.
-	assertHasChanEntries(t, c, cacheSize, cacheSize)
+	assertHasChanEntries(t, c, v, cacheSize, cacheSize)
 
 	// Iterate over all inserted elements and construct a set of the evicted
 	// elements.
 	evicted := make(map[uint64]struct{})
 	for i := uint64(0); i < cacheSize+1; i++ {
-		_, ok := c.get(i)
+		_, ok := c.get(v, i)
 		if !ok {
 			evicted[i] = struct{}{}
 		}
@@ -58,35 +61,37 @@ func TestChannelCache(t *testing.T) {
 
 	// Remove the highest item which initially caused the eviction and
 	// reinsert the element that was evicted prior.
-	c.remove(cacheSize)
+	c.remove(v, cacheSize)
 	for i := range evicted {
-		c.insert(i, channelForInt(i))
+		c.insert(v, i, channelForInt(i))
 	}
 
 	// Since the removal created an extra slot, the last insertion should
 	// not have caused an eviction and the entries for all channels in the
 	// original set that filled the cache should be present.
-	assertHasChanEntries(t, c, 0, cacheSize)
+	assertHasChanEntries(t, c, v, 0, cacheSize)
 
 	// Finally, reinsert the existing set back into the cache and test that
 	// the cache still has all the entries. If the randomized eviction were
 	// happening on inserts for existing cache items, we expect this to fail
 	// with high probability.
 	for i := uint64(0); i < cacheSize; i++ {
-		c.insert(i, channelForInt(i))
+		c.insert(v, i, channelForInt(i))
 	}
-	assertHasChanEntries(t, c, 0, cacheSize)
+	assertHasChanEntries(t, c, v, 0, cacheSize)
 
 }
 
 // assertHasEntries queries the edge cache for all channels in the range [start,
 // end), asserting that they exist and their value matches the entry produced by
 // entryForInt.
-func assertHasChanEntries(t *testing.T, c *channelCache, start, end uint64) {
+func assertHasChanEntries(t *testing.T, c *channelCache,
+	v lnwire.GossipVersion, start, end uint64) {
+
 	t.Helper()
 
 	for i := start; i < end; i++ {
-		entry, ok := c.get(i)
+		entry, ok := c.get(v, i)
 		if !ok {
 			t.Fatalf("channel cache should contain chan %d", i)
 		}