Try to avoid unnecessary allocations in enum-types' String methods

2 files changed, 109 insertions, 80 deletions

diff --git a/lib/btrfs/btrfsprim/itemtype.go b/lib/btrfs/btrfsprim/itemtype.go
index dba7ced..f33179a 100644
--- a/lib/btrfs/btrfsprim/itemtype.go
+++ b/lib/btrfs/btrfsprim/itemtype.go
@@ -42,42 +42,72 @@ const (
 )
 
 func (t ItemType) String() string {
-	names := map[ItemType]string{
-		BLOCK_GROUP_ITEM_KEY:     "BLOCK_GROUP_ITEM",
-		CHUNK_ITEM_KEY:           "CHUNK_ITEM",
-		DEV_EXTENT_KEY:           "DEV_EXTENT",
-		DEV_ITEM_KEY:             "DEV_ITEM",
-		DIR_INDEX_KEY:            "DIR_INDEX",
-		DIR_ITEM_KEY:             "DIR_ITEM",
-		EXTENT_CSUM_KEY:          "EXTENT_CSUM",
-		EXTENT_DATA_KEY:          "EXTENT_DATA",
-		EXTENT_DATA_REF_KEY:      "EXTENT_DATA_REF",
-		EXTENT_ITEM_KEY:          "EXTENT_ITEM",
-		FREE_SPACE_BITMAP_KEY:    "FREE_SPACE_BITMAP",
-		FREE_SPACE_EXTENT_KEY:    "FREE_SPACE_EXTENT",
-		FREE_SPACE_INFO_KEY:      "FREE_SPACE_INFO",
-		INODE_ITEM_KEY:           "INODE_ITEM",
-		INODE_REF_KEY:            "INODE_REF",
-		METADATA_ITEM_KEY:        "METADATA_ITEM",
-		ORPHAN_ITEM_KEY:          "ORPHAN_ITEM",
-		PERSISTENT_ITEM_KEY:      "PERSISTENT_ITEM",
-		QGROUP_INFO_KEY:          "QGROUP_INFO",
-		QGROUP_LIMIT_KEY:         "QGROUP_LIMIT",
-		QGROUP_RELATION_KEY:      "QGROUP_RELATION",
-		QGROUP_STATUS_KEY:        "QGROUP_STATUS",
-		ROOT_BACKREF_KEY:         "ROOT_BACKREF",
-		ROOT_ITEM_KEY:            "ROOT_ITEM",
-		ROOT_REF_KEY:             "ROOT_REF",
-		SHARED_BLOCK_REF_KEY:     "SHARED_BLOCK_REF",
-		SHARED_DATA_REF_KEY:      "SHARED_DATA_REF",
-		TREE_BLOCK_REF_KEY:       "TREE_BLOCK_REF",
-		UNTYPED_KEY:              "UNTYPED",
-		UUID_RECEIVED_SUBVOL_KEY: "UUID_KEY_RECEIVED_SUBVOL",
-		UUID_SUBVOL_KEY:          "UUID_KEY_SUBVOL",
-		XATTR_ITEM_KEY:           "XATTR_ITEM",
+	switch t {
+	case BLOCK_GROUP_ITEM_KEY:
+		return "BLOCK_GROUP_ITEM"
+	case CHUNK_ITEM_KEY:
+		return "CHUNK_ITEM"
+	case DEV_EXTENT_KEY:
+		return "DEV_EXTENT"
+	case DEV_ITEM_KEY:
+		return "DEV_ITEM"
+	case DIR_INDEX_KEY:
+		return "DIR_INDEX"
+	case DIR_ITEM_KEY:
+		return "DIR_ITEM"
+	case EXTENT_CSUM_KEY:
+		return "EXTENT_CSUM"
+	case EXTENT_DATA_KEY:
+		return "EXTENT_DATA"
+	case EXTENT_DATA_REF_KEY:
+		return "EXTENT_DATA_REF"
+	case EXTENT_ITEM_KEY:
+		return "EXTENT_ITEM"
+	case FREE_SPACE_BITMAP_KEY:
+		return "FREE_SPACE_BITMAP"
+	case FREE_SPACE_EXTENT_KEY:
+		return "FREE_SPACE_EXTENT"
+	case FREE_SPACE_INFO_KEY:
+		return "FREE_SPACE_INFO"
+	case INODE_ITEM_KEY:
+		return "INODE_ITEM"
+	case INODE_REF_KEY:
+		return "INODE_REF"
+	case METADATA_ITEM_KEY:
+		return "METADATA_ITEM"
+	case ORPHAN_ITEM_KEY:
+		return "ORPHAN_ITEM"
+	case PERSISTENT_ITEM_KEY:
+		return "PERSISTENT_ITEM"
+	case QGROUP_INFO_KEY:
+		return "QGROUP_INFO"
+	case QGROUP_LIMIT_KEY:
+		return "QGROUP_LIMIT"
+	case QGROUP_RELATION_KEY:
+		return "QGROUP_RELATION"
+	case QGROUP_STATUS_KEY:
+		return "QGROUP_STATUS"
+	case ROOT_BACKREF_KEY:
+		return "ROOT_BACKREF"
+	case ROOT_ITEM_KEY:
+		return "ROOT_ITEM"
+	case ROOT_REF_KEY:
+		return "ROOT_REF"
+	case SHARED_BLOCK_REF_KEY:
+		return "SHARED_BLOCK_REF"
+	case SHARED_DATA_REF_KEY:
+		return "SHARED_DATA_REF"
+	case TREE_BLOCK_REF_KEY:
+		return "TREE_BLOCK_REF"
+	case UNTYPED_KEY:
+		return "UNTYPED"
+	case UUID_RECEIVED_SUBVOL_KEY:
+		return "UUID_KEY_RECEIVED_SUBVOL"
+	case UUID_SUBVOL_KEY:
+		return "UUID_KEY_SUBVOL"
+	case XATTR_ITEM_KEY:
+		return "XATTR_ITEM"
+	default:
+		return fmt.Sprintf("%d", t)
 	}
-	if name, ok := names[t]; ok {
-		return name
-	}
-	return fmt.Sprintf("%d", t)
 }
diff --git a/lib/btrfs/btrfsprim/objid.go b/lib/btrfs/btrfsprim/objid.go
index 8ca1fbb..1aea030 100644
--- a/lib/btrfs/btrfsprim/objid.go
+++ b/lib/btrfs/btrfsprim/objid.go
@@ -54,13 +54,45 @@ const (
 	EMPTY_SUBVOL_DIR_OBJECTID ObjID = 2
 )
 
+var (
+	objidCommonNames = map[ObjID]string{
+		BALANCE_OBJECTID:         "BALANCE",
+		ORPHAN_OBJECTID:          "ORPHAN",
+		TREE_LOG_OBJECTID:        "TREE_LOG",
+		TREE_LOG_FIXUP_OBJECTID:  "TREE_LOG_FIXUP",
+		TREE_RELOC_OBJECTID:      "TREE_RELOC",
+		DATA_RELOC_TREE_OBJECTID: "DATA_RELOC_TREE",
+		EXTENT_CSUM_OBJECTID:     "EXTENT_CSUM",
+		FREE_SPACE_OBJECTID:      "FREE_SPACE",
+		FREE_INO_OBJECTID:        "FREE_INO",
+		MULTIPLE_OBJECTIDS:       "MULTIPLE",
+	}
+	objidDevTreeNames = map[ObjID]string{
+		DEV_STATS_OBJECTID: "DEV_STATS",
+	}
+	objidChunkTreeNames = map[ObjID]string{
+		DEV_ITEMS_OBJECTID:        "DEV_ITEMS",
+		FIRST_CHUNK_TREE_OBJECTID: "FIRST_CHUNK_TREE",
+	}
+	objidRootTreeNames = map[ObjID]string{
+		ROOT_TREE_OBJECTID:        "ROOT_TREE",
+		EXTENT_TREE_OBJECTID:      "EXTENT_TREE",
+		CHUNK_TREE_OBJECTID:       "CHUNK_TREE",
+		DEV_TREE_OBJECTID:         "DEV_TREE",
+		FS_TREE_OBJECTID:          "FS_TREE",
+		ROOT_TREE_DIR_OBJECTID:    "ROOT_TREE_DIR",
+		CSUM_TREE_OBJECTID:        "CSUM_TREE",
+		QUOTA_TREE_OBJECTID:       "QUOTA_TREE",
+		UUID_TREE_OBJECTID:        "UUID_TREE",
+		FREE_SPACE_TREE_OBJECTID:  "FREE_SPACE_TREE",
+		BLOCK_GROUP_TREE_OBJECTID: "BLOCK_GROUP_TREE",
+	}
+)
+
 func (id ObjID) Format(tree ObjID) string {
 	switch tree {
 	case DEV_TREE_OBJECTID:
-		names := map[ObjID]string{
-			DEV_STATS_OBJECTID: "DEV_STATS",
-		}
-		if name, ok := names[id]; ok {
+		if name, ok := objidDevTreeNames[id]; ok {
 			return name
 		}
 		return fmt.Sprintf("%d", int64(id))
@@ -75,51 +107,18 @@ func (id ObjID) Format(tree ObjID) string {
 	case UUID_TREE_OBJECTID:
 		return fmt.Sprintf("%#016x", uint64(id))
 	case CHUNK_TREE_OBJECTID:
-		names := map[ObjID]string{
-			BALANCE_OBJECTID:         "BALANCE",
-			ORPHAN_OBJECTID:          "ORPHAN",
-			TREE_LOG_OBJECTID:        "TREE_LOG",
-			TREE_LOG_FIXUP_OBJECTID:  "TREE_LOG_FIXUP",
-			TREE_RELOC_OBJECTID:      "TREE_RELOC",
-			DATA_RELOC_TREE_OBJECTID: "DATA_RELOC_TREE",
-			EXTENT_CSUM_OBJECTID:     "EXTENT_CSUM",
-			FREE_SPACE_OBJECTID:      "FREE_SPACE",
-			FREE_INO_OBJECTID:        "FREE_INO",
-			MULTIPLE_OBJECTIDS:       "MULTIPLE",
-
-			DEV_ITEMS_OBJECTID:        "DEV_ITEMS",
-			FIRST_CHUNK_TREE_OBJECTID: "FIRST_CHUNK_TREE",
+		if name, ok := objidCommonNames[id]; ok {
+			return name
 		}
-		if name, ok := names[id]; ok {
+		if name, ok := objidChunkTreeNames[id]; ok {
 			return name
 		}
 		return fmt.Sprintf("%d", int64(id))
 	default:
-		names := map[ObjID]string{
-			BALANCE_OBJECTID:         "BALANCE",
-			ORPHAN_OBJECTID:          "ORPHAN",
-			TREE_LOG_OBJECTID:        "TREE_LOG",
-			TREE_LOG_FIXUP_OBJECTID:  "TREE_LOG_FIXUP",
-			TREE_RELOC_OBJECTID:      "TREE_RELOC",
-			DATA_RELOC_TREE_OBJECTID: "DATA_RELOC_TREE",
-			EXTENT_CSUM_OBJECTID:     "EXTENT_CSUM",
-			FREE_SPACE_OBJECTID:      "FREE_SPACE",
-			FREE_INO_OBJECTID:        "FREE_INO",
-			MULTIPLE_OBJECTIDS:       "MULTIPLE",
-
-			ROOT_TREE_OBJECTID:        "ROOT_TREE",
-			EXTENT_TREE_OBJECTID:      "EXTENT_TREE",
-			CHUNK_TREE_OBJECTID:       "CHUNK_TREE",
-			DEV_TREE_OBJECTID:         "DEV_TREE",
-			FS_TREE_OBJECTID:          "FS_TREE",
-			ROOT_TREE_DIR_OBJECTID:    "ROOT_TREE_DIR",
-			CSUM_TREE_OBJECTID:        "CSUM_TREE",
-			QUOTA_TREE_OBJECTID:       "QUOTA_TREE",
-			UUID_TREE_OBJECTID:        "UUID_TREE",
-			FREE_SPACE_TREE_OBJECTID:  "FREE_SPACE_TREE",
-			BLOCK_GROUP_TREE_OBJECTID: "BLOCK_GROUP_TREE",
+		if name, ok := objidCommonNames[id]; ok {
+			return name
 		}
-		if name, ok := names[id]; ok {
+		if name, ok := objidRootTreeNames[id]; ok {
 			return name
 		}
 		return fmt.Sprintf("%d", int64(id))