Update and add some comments

Signed-off-by: Silas Davis <[email protected]>

key_format.go

@@ -38,6 +38,7 @@ func (kf *KeyFormat) KeyBytes(segments ...[]byte) []byte {
 			panic(fmt.Errorf("length of segment %X provided to KeyFormat.Key() is longer than the %d bytes "+
 				"required by layout for segment %d", s, l, i))
 		}
+		// Big endian so pad on left if not given the full width for this segment
 		copy(key[n+(l-len(s)):n+l], s)
 		n += l
 	}
@@ -101,7 +102,7 @@ func scan(a interface{}, value []byte) {
 	case *[]byte:
 		*v = value
 	default:
-		panic(fmt.Errorf("KeyFormat.scan() does not support scanning value of type %T: %v", a, a))
+		panic(fmt.Errorf("KeyFormat scan() does not support scanning value of type %T: %v", a, a))
 	}
 }
 
@@ -122,6 +123,6 @@ func format(a interface{}) []byte {
 	case []byte:
 		return v
 	default:
-		panic(fmt.Errorf("KeyFormat.format() does not support formatting value of type %T: %v", a, a))
+		panic(fmt.Errorf("KeyFormat format() does not support formatting value of type %T: %v", a, a))
 	}
 }

nodedb.go

@@ -17,19 +17,19 @@ const (
 )
 
 var (
-	// All node keys are prefixed with this. This ensures no collision is
-	// possible with the other keys, and makes them easier to traverse.
-	nodeKeyFormat = NewKeyFormat('n', hashSize)
+	// All node keys are prefixed with the byte 'n'. This ensures no collision is
+	// possible with the other keys, and makes them easier to traverse. They are indexed by the node hash.
+	nodeKeyFormat = NewKeyFormat('n', hashSize) // n<hash>
 
 	// Orphans are keyed in the database by their expected lifetime.
 	// The first number represents the *last* version at which the orphan needs
 	// to exist, while the second number represents the *earliest* version at
 	// which it is expected to exist - which starts out by being the version
 	// of the node being orphaned.
-	orphanKeyFormat = NewKeyFormat('o', int64Size, int64Size, hashSize)
+	orphanKeyFormat = NewKeyFormat('o', int64Size, int64Size, hashSize) // o<last-version><first-version><hash>
 
-	// r/<version>
-	rootKeyFormat = NewKeyFormat('r', int64Size)
+	// Root nodes are indexed separately by their version
+	rootKeyFormat = NewKeyFormat('r', int64Size) // r<version>
 )
 
 type nodeDB struct {