lnutils+lntemp: move SyncMap to lnutils

This commit moves the `SyncMap` from `lntemp/node` into `lnutils` so it
can be used by other packages.

lnutils/sync_map.go

@@ -0,0 +1,53 @@
+package lnutils
+
+import "sync"
+
+// SyncMap wraps a sync.Map with type parameters such that it's easier to
+// access the items stored in the map since no type assertion is needed. It
+// also requires explicit type definition when declaring and initiating the
+// variables, which helps us understanding what's stored in a given map.
+type SyncMap[K comparable, V any] struct {
+	sync.Map
+}
+
+// Store puts an item in the map.
+func (m *SyncMap[K, V]) Store(key K, value V) {
+	m.Map.Store(key, value)
+}
+
+// Load queries an item from the map using the specified key. If the item
+// cannot be found, an empty value and false will be returned. If the stored
+// item fails the type assertion, a nil value and false will be returned.
+func (m *SyncMap[K, V]) Load(key K) (V, bool) {
+	result, ok := m.Map.Load(key)
+	if !ok {
+		return *new(V), false // nolint: gocritic
+	}
+
+	item, ok := result.(V)
+	return item, ok
+}
+
+// Delete removes an item from the map specified by the key.
+func (m *SyncMap[K, V]) Delete(key K) {
+	m.Map.Delete(key)
+}
+
+// LoadAndDelete queries an item and deletes it from the map using the
+// specified key.
+func (m *SyncMap[K, V]) LoadAndDelete(key K) (V, bool) {
+	result, loaded := m.Map.LoadAndDelete(key)
+	if !loaded {
+		return *new(V), loaded // nolint: gocritic
+	}
+
+	item, ok := result.(V)
+	return item, ok
+}
+
+// Range iterates the map.
+func (m *SyncMap[K, V]) Range(visitor func(K, V) bool) {
+	m.Map.Range(func(k any, v any) bool {
+		return visitor(k.(K), v.(V))
+	})
+}