Add limitStat to keep concurrent requests under control

Author: aredridel

lib/view.js

@@ -215,7 +215,7 @@ 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 +224,7 @@ 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 +235,31 @@ 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--;
+      }
+    }
+  }
+}