From 06309646c0f3650183290637e63b12f0f5a44458 Mon Sep 17 00:00:00 2001
From: Andrew Shaffer <andrew@weo.io>
Date: Tue, 17 May 2016 15:53:03 -0700
Subject: [PATCH] consolidate FSEventWatchers after reaching a threshhold of
 duplicate common path prefixes

---
 lib/fsevents-handler.js | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/lib/fsevents-handler.js b/lib/fsevents-handler.js
index f211346a..b16c28a2 100644
--- a/lib/fsevents-handler.js
+++ b/lib/fsevents-handler.js
@@ -34,6 +34,15 @@ function createFSEventsInstance(path, callback) {
 function setFSEventsListener(path, realPath, listener, rawEmitter) {
   var watchPath = sysPath.extname(path) ? sysPath.dirname(path) : path;
   var watchContainer;
+  var parentPath = parentOf(watchPath);
+
+  // If we've accumulated a substantial number of paths that
+  // could have been consolidated by watching one directory
+  // above the current one, create a watcher on the parent
+  // path instead, so that we do consolidate going forward.
+  if (couldConsolidate(parentPath)) {
+    watchPath = parentPath;
+  }
 
   var resolvedPath = sysPath.resolve(path);
   var hasSymlink = resolvedPath !== realPath;
@@ -89,9 +98,36 @@ function setFSEventsListener(path, realPath, listener, rawEmitter) {
   };
 }
 
+var consolidateThreshhold = 10;
+
+// Decide whether or not we should start a new higher-level
+// parent watcher
+function couldConsolidate(path) {
+  var candidates = {};
+  var keys = Object.keys(FSEventsWatchers)
+  var count = 0
+
+  for (var i = 0, len = keys.length; i < len; ++i) {
+    var watchPath = keys[i]
+    if (watchPath.indexOf(path) === 0) {
+      count++
+      if (count >= consolidateThreshhold) {
+        return true
+      }
+    }
+  }
+
+  return false
+}
+
+// Find the parent of a given path
+function parentOf (path) {
+  return path.split(sysPath.sep).slice(0, -1).join(sysPath.sep)
+}
+
 // returns boolean indicating whether fsevents can be used
 function canUse() {
-  return !!fsevents;
+  return fsevents && Object.keys(FSEventsWatchers).length < 128;
 }
 
 // determines subdirectory traversal levels from root to path