From 39725a5322e141bba408ad2d9ff0b4bc25f39e92 Mon Sep 17 00:00:00 2001
From: Chris Peterson <cpeterson@mozilla.com>
Date: Mon, 2 Sep 2013 19:30:19 -0700
Subject: [PATCH] Bug 905221 - sizeof(nsEventQueue::Page) should be a power of
 two to avoid heap allocation slop. r=bsmedberg

---
 xpcom/threads/nsEventQueue.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/xpcom/threads/nsEventQueue.h b/xpcom/threads/nsEventQueue.h
index 7cb08bcad24d..f261a1bb83bf 100644
--- a/xpcom/threads/nsEventQueue.h
+++ b/xpcom/threads/nsEventQueue.h
@@ -60,7 +60,7 @@ private:
     return !mHead || (mHead == mTail && mOffsetHead == mOffsetTail);
   }
 
-  enum { EVENTS_PER_PAGE = 250 };
+  enum { EVENTS_PER_PAGE = 255 };
 
   // Page objects are linked together to form a simple deque.
 
@@ -69,6 +69,9 @@ private:
     nsIRunnable *mEvents[EVENTS_PER_PAGE];
   };
 
+  static_assert((sizeof(Page) & (sizeof(Page) - 1)) == 0,
+                "sizeof(Page) should be a power of two to avoid heap slop.");
+
   static Page *NewPage() {
     return static_cast<Page *>(calloc(1, sizeof(Page)));
   }