fs: use async directory processing in cp()

The readdir() functions do not scale well, which is why opendir(), etc. were introduced. This is exacerbated in the current cp() implementation, which calls readdir() recursively. This commit updates cp() to use the opendir() style iteration. PR-URL: #41351 Reviewed-By: Luigi Pinca <[email protected]> Reviewed-By: Tierney Cyren <[email protected]> Reviewed-By: Matteo Collina <[email protected]> Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: Juan José Arboleda <[email protected]> Reviewed-By: Mohammed Keyvanzadeh <[email protected]>
nodejs · Jan 14, 2022 · d4a6f2c · d4a6f2c
1 parent 1f6c4e8
commit d4a6f2c
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Showing 2 changed files with 22 additions and 14 deletions.
diff --git a/lib/internal/fs/cp/cp-sync.js b/lib/internal/fs/cp/cp-sync.js
@@ -32,7 +32,7 @@ const {
   existsSync,
   lstatSync,
   mkdirSync,
-  readdirSync,
+  opendirSync,
   readlinkSync,
   statSync,
   symlinkSync,
@@ -275,14 +275,22 @@ function mkDirAndCopy(srcMode, src, dest, opts) {
 }
 
 function copyDir(src, dest, opts) {
-  readdirSync(src).forEach((item) => copyDirItem(item, src, dest, opts));
-}
+  const dir = opendirSync(src);
+
+  try {
+    let dirent;
 
-function copyDirItem(item, src, dest, opts) {
-  const srcItem = join(src, item);
-  const destItem = join(dest, item);
-  const { destStat } = checkPathsSync(srcItem, destItem, opts);
-  return startCopy(destStat, srcItem, destItem, opts);
+    while ((dirent = dir.readSync()) !== null) {
+      const { name } = dirent;
+      const srcItem = join(src, name);
+      const destItem = join(dest, name);
+      const { destStat } = checkPathsSync(srcItem, destItem, opts);
+
+      startCopy(destStat, srcItem, destItem, opts);
+    }
+  } finally {
+    dir.closeSync();
+  }
 }
 
 function onLink(destStat, src, dest) {

diff --git a/lib/internal/fs/cp/cp.js b/lib/internal/fs/cp/cp.js
@@ -41,7 +41,7 @@ const {
   copyFile,
   lstat,
   mkdir,
-  readdir,
+  opendir,
   readlink,
   stat,
   symlink,
@@ -325,11 +325,11 @@ async function mkDirAndCopy(srcMode, src, dest, opts) {
 }
 
 async function copyDir(src, dest, opts) {
-  const dir = await readdir(src);
-  for (let i = 0; i < dir.length; i++) {
-    const item = dir[i];
-    const srcItem = join(src, item);
-    const destItem = join(dest, item);
+  const dir = await opendir(src);
+
+  for await (const { name } of dir) {
+    const srcItem = join(src, name);
+    const destItem = join(dest, name);
     const { destStat } = await checkPaths(srcItem, destItem, opts);
     await startCopy(destStat, srcItem, destItem, opts);
   }