graph/db: define and init the reject and chan caches

In this commit we add and initialise the reject and channel caches in
the SQLStore as is done in the KVStore. These are not used yet.

Author: ellemouton

graph/db/options.go

@@ -61,6 +61,44 @@ func WithPreAllocCacheNumNodes(n int) ChanGraphOption {
 	}
 }
 
+// SQLStoreOptions holds parameters for tuning and customizing a SQLStore
+// instance.
+type SQLStoreOptions struct {
+	// RejectCacheSize is the maximum number of rejectCacheEntries to hold
+	// in the rejection cache.
+	RejectCacheSize int
+
+	// ChannelCacheSize is the maximum number of ChannelEdges to hold in the
+	// channel cache.
+	ChannelCacheSize int
+}
+
+// DefaultSQLOptions returns a SQLStoreOptions populated with default values.
+func DefaultSQLOptions() *SQLStoreOptions {
+	return &SQLStoreOptions{
+		RejectCacheSize:  DefaultRejectCacheSize,
+		ChannelCacheSize: DefaultChannelCacheSize,
+	}
+}
+
+// SQLStoreOption defines the function signature for a functional option
+// that can be used to customize a SQLStoreOptions instance.
+type SQLStoreOption func(*SQLStoreOptions)
+
+// WithSQLStoreRejectCacheSize sets the RejectCacheSize to n.
+func WithSQLStoreRejectCacheSize(n int) SQLStoreOption {
+	return func(o *SQLStoreOptions) {
+		o.RejectCacheSize = n
+	}
+}
+
+// WithSQLStoreChannelCacheSize sets the ChannelCacheSize to n.
+func WithSQLStoreChannelCacheSize(n int) SQLStoreOption {
+	return func(o *SQLStoreOptions) {
+		o.ChannelCacheSize = n
+	}
+}
+
 // KVStoreOptions holds parameters for tuning and customizing a graph.DB.
 type KVStoreOptions struct {
 	// RejectCacheSize is the maximum number of rejectCacheEntries to hold

graph/db/sql_store.go

@@ -1,6 +1,8 @@
 package graphdb
 
 import (
+	"sync"
+
 	"github.com/lightningnetwork/lnd/sqldb"
 )
 
@@ -26,6 +28,14 @@ type BatchedSQLQueries interface {
 type SQLStore struct {
 	db BatchedSQLQueries
 
+	// cacheMu guards all caches (rejectCache and chanCache). If
+	// this mutex will be acquired at the same time as the DB mutex (ie if
+	// a transaction is starting) then the cacheMu MUST be acquired first to
+	// prevent deadlock.
+	cacheMu     sync.RWMutex
+	rejectCache *rejectCache
+	chanCache   *channelCache
+
 	// Temporary fall-back to the KVStore so that we can implement the
 	// interface incrementally.
 	*KVStore
@@ -37,9 +47,18 @@ var _ V1Store = (*SQLStore)(nil)
 
 // NewSQLStore creates a new SQLStore instance given an open BatchedSQLQueries
 // storage backend.
-func NewSQLStore(db BatchedSQLQueries, kvStore *KVStore) *SQLStore {
+func NewSQLStore(db BatchedSQLQueries, kvStore *KVStore,
+	options ...SQLStoreOption) *SQLStore {
+
+	opts := DefaultSQLOptions()
+	for _, o := range options {
+		o(opts)
+	}
+
 	return &SQLStore{
-		db:      db,
-		KVStore: kvStore,
+		db:          db,
+		KVStore:     kvStore,
+		rejectCache: newRejectCache(opts.RejectCacheSize),
+		chanCache:   newChannelCache(opts.ChannelCacheSize),
 	}
 }