Add limitStat to keep concurrent requests under control

Author: aredridel

lib/view.js

@@ -61,15 +61,11 @@ function View(name, options) {
     throw new Error('No default engine was specified and no extension was provided.');
   }
 
-  var fileName = name;
-
   if (!this.ext) {
     // get extension from default engine name
     this.ext = this.defaultEngine[0] !== '.'
       ? '.' + this.defaultEngine
       : this.defaultEngine;
-
-    fileName += this.ext;
   }
 
   if (!opts.engines[this.ext]) {
@@ -215,7 +211,7 @@ function resolveView(dir, file, ext, cb) {
   var path = join(dir, file);
 
   // <path>.<ext>
-  fs.stat(path, function (err, stat) {
+  limitStat(path, function (err, stat) {
     if (err && err.code !== 'ENOENT') {
       return cb(err);
     } else if (!err && stat && stat.isFile()) {
@@ -224,7 +220,7 @@ 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()) {
@@ -235,3 +231,31 @@ 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, cbAndDequeue(cb));
+  }
+
+  function cbAndDequeue(cb) {
+    return function (err, stat) {
+      cb(err, stat);
+      var next = pendingStats.shift();
+      if (next) {
+        fs.stat(next[0], cbAndDequeue(next[1]));
+      } else {
+        numPendingStats--;
+      }
+    }
+  }
+}