Micro-optimize memfs readdir. NFC

Author: sbc100

src/library_memfs.js

@@ -76,7 +76,7 @@ addToLibrary({
       if (FS.isDir(node.mode)) {
         node.node_ops = MEMFS.ops_table.dir.node;
         node.stream_ops = MEMFS.ops_table.dir.stream;
-        node.contents = {};
+        node.contents = new Map();
       } else if (FS.isFile(node.mode)) {
         node.node_ops = MEMFS.ops_table.file.node;
         node.stream_ops = MEMFS.ops_table.file.stream;
@@ -95,7 +95,7 @@ addToLibrary({
       node.atime = node.mtime = node.ctime = Date.now();
       // add the new node to the parent
       if (parent) {
-        parent.contents[name] = node;
+        parent.contents.set(name, node);
         parent.atime = parent.mtime = parent.ctime = node.atime;
       }
       return node;
@@ -198,36 +198,30 @@ addToLibrary({
             new_node = FS.lookupNode(new_dir, new_name);
           } catch (e) {
           }
-          if (new_node) {
-            for (var i in new_node.contents) {
-              throw new FS.ErrnoError({{{ cDefs.ENOTEMPTY }}});
-            }
+          if (new_node && new_node.contents.size) {
+            throw new FS.ErrnoError({{{ cDefs.ENOTEMPTY }}});
           }
         }
         // do the internal rewiring
-        delete old_node.parent.contents[old_node.name];
-        new_dir.contents[new_name] = old_node;
+        old_node.parent.contents.delete(old_node.name);
+        new_dir.contents.set(new_name, old_node);
         old_node.name = new_name;
         new_dir.ctime = new_dir.mtime = old_node.parent.ctime = old_node.parent.mtime = Date.now();
       },
       unlink(parent, name) {
-        delete parent.contents[name];
+        parent.contents.delete(name);
         parent.ctime = parent.mtime = Date.now();
       },
       rmdir(parent, name) {
         var node = FS.lookupNode(parent, name);
-        for (var i in node.contents) {
+        if (node.contents.size) {
           throw new FS.ErrnoError({{{ cDefs.ENOTEMPTY }}});
         }
         delete parent.contents[name];
         parent.ctime = parent.mtime = Date.now();
       },
       readdir(node) {
-        var entries = ['.', '..'];
-        for (var key of Object.keys(node.contents)) {
-          entries.push(key);
-        }
-        return entries;
+        return ['.', '..', ...node.contents.keys()];
       },
       symlink(parent, newname, oldpath) {
         var node = MEMFS.createNode(parent, newname, 0o777 | {{{ cDefs.S_IFLNK }}}, 0);

test/other/codesize/test_codesize_cxx_ctors1.gzsize

@@ -1 +1 @@
-8484
+8473

test/other/codesize/test_codesize_cxx_ctors1.jssize

@@ -1 +1 @@
-20746
+20708

test/other/codesize/test_codesize_cxx_ctors2.gzsize

@@ -1 +1 @@
-8467
+8457

test/other/codesize/test_codesize_cxx_ctors2.jssize

@@ -1 +1 @@
-20714
+20676

test/other/codesize/test_codesize_cxx_except.gzsize

@@ -1 +1 @@
-9507
+9494

test/other/codesize/test_codesize_cxx_except.jssize

@@ -1 +1 @@
-24589
+24551

test/other/codesize/test_codesize_cxx_except_wasm.gzsize

@@ -1 +1 @@
-8449
+8442

test/other/codesize/test_codesize_cxx_except_wasm.jssize

@@ -1 +1 @@
-20640
+20602

test/other/codesize/test_codesize_cxx_except_wasm_exnref.gzsize

@@ -1 +1 @@
-8449
+8442