lncfg/caches: adds Caches sub config

lncfg/caches.go

@@ -0,0 +1,45 @@
+package lncfg
+
+import "fmt"
+
+const (
+	// MinRejectCacheSize is a floor on the maximum capacity allowed for
+	// channeldb's reject cache. This amounts to roughly 125 KB when full.
+	MinRejectCacheSize = 5000
+
+	// MinChannelCacheSize is a floor on the maximum capacity allowed for
+	// channeldb's channel cache. This amounts to roughly 2 MB when full.
+	MinChannelCacheSize = 1000
+)
+
+// Caches holds the configuration for various caches within lnd.
+type Caches struct {
+	// RejectCacheSize is the maximum number of entries stored in lnd's
+	// reject cache, which is used for efficiently rejecting gossip updates.
+	// Memory usage is roughly 25b per entry.
+	RejectCacheSize int `long:"reject-cache-size" description:"Maximum number of entries contained in the reject cache, which is used to speed up filtering of new channel announcements and channel updates from peers. Each entry requires 25 bytes."`
+
+	// ChannelCacheSize is the maximum number of entries stored in lnd's
+	// channel cache, which is used reduce memory allocations in reply to
+	// peers querying for gossip traffic. Memory usage is roughly 2Kb per
+	// entry.
+	ChannelCacheSize int `long:"channel-cache-size" description:"Maximum number of entries contained in the channel cache, which is used to reduce memory allocations from gossip queries from peers. Each entry requires roughly 2Kb."`
+}
+
+// Validate checks the Caches configuration for values that are too small to be
+// sane.
+func (c *Caches) Validate() error {
+	if c.RejectCacheSize < MinRejectCacheSize {
+		return fmt.Errorf("reject cache size %d is less than min: %d",
+			c.RejectCacheSize, MinRejectCacheSize)
+	}
+	if c.ChannelCacheSize < MinChannelCacheSize {
+		return fmt.Errorf("channel cache size %d is less than min: %d",
+			c.ChannelCacheSize, MinChannelCacheSize)
+	}
+
+	return nil
+}
+
+// Compile-time constraint to ensure Caches implements the Validator interface.
+var _ Validator = (*Caches)(nil)