Add limitStat to keep concurrent requests under control

expressjs · May 18, 2015 · 1fe4c1e · 1fe4c1e
1 parent 7b9270e
commit 1fe4c1e
Showing 1 changed file with 28 additions and 2 deletions.
diff --git a/lib/view.js b/lib/view.js
@@ -149,7 +149,7 @@ function resolveView(dir, file, ext, cb) {
 
   // <path>.<ext>
   path = join(dir, file);
-  fs.stat(path, function (err, stat) {
+  limitStat(path, function (err, stat) {
     if (err && err.code == 'ENOENT') {
       // Skip down
     } else if (!err && stat && stat.isFile()) {
@@ -158,7 +158,7 @@ function resolveView(dir, file, ext, cb) {
 
     // <path>/index.<ext>
     path = join(dir, basename(file, ext), 'index' + ext);
-    fs.stat(path, function (err, stat) {
+    limitStat(path, function (err, stat) {
       if (err && err.code == 'ENOENT') {
         return cb(null, null);
       } else if (!err && stat && stat.isFile()) {
@@ -169,3 +169,29 @@ function resolveView(dir, file, ext, cb) {
     });
   });
 }
+
+var pendingStats = [];
+var numPendingStats = 0;
+/**
+ * an fs.stat call that limits the number of outstanding requests to 10.
+ *
+ * @param {String} path
+ * @param {Function} cb
+ */
+function limitStat(path, cb) {
+  if (++numPendingStats > 10) {
+    pendingStats.push([path, cb]);
+  } else {
+    fs.stat(path, dequeue);
+  }
+
+  function dequeue(err, stat) {
+    cb(err, stat);
+    var next = pendingStats.shift();
+    if (next) {
+      fs.stat(next[0], next[1]);
+    } else {
+      numPendingStats--;
+    }
+  }
+}