doubly-linked free-lists for thread caches and page heaps

third_party/tcmalloc/chromium/src/thread_cache.cc

Index: third_party/tcmalloc/chromium/src/thread_cache.cc
diff --git a/third_party/tcmalloc/chromium/src/thread_cache.cc b/third_party/tcmalloc/chromium/src/thread_cache.cc
index b00e3b40f50a94775561cae571293beda6b7d493..d54bd84c610e9bb5c3b5ada03673f64f6060cac9 100644
--- a/third_party/tcmalloc/chromium/src/thread_cache.cc
+++ b/third_party/tcmalloc/chromium/src/thread_cache.cc
@@ -1,4 +1,4 @@
-// Copyright (c) 2008, Google Inc.
+// Copyright (c) 2011, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
@@ -153,7 +153,10 @@ void* ThreadCache::FetchFromCentralCache(size_t cl, size_t byte_size) {
   ASSERT((start == NULL) == (fetch_count == 0));
   if (--fetch_count >= 0) {
     size_ += byte_size * fetch_count;
-    list->PushRange(fetch_count, SLL_Next(start), end);
+    // Pop the top of the list and add the rest to the freelist

[jar (doing other things), 2011/08/20 02:40:30]

nit: This file they do use periods at the end of the sentences, you should too. 
I'd also expand on the comment:

Pop the top of the list to return, and add the rest to the freelist.

[bxx, 2011/08/24 00:19:24]

Done.  Although they do not consistently use periods at the end of the
sentences.

+    void *next = start;

[jar (doing other things), 2011/08/20 02:40:30]

Perhaps a better name than |next| would be |second|.
The code is perfect, but I had to read it a few times to be sure I understood
it... and I'm *guessing* the name didn't help. (or it could be I was tired... or
worse).

[bxx, 2011/08/24 00:19:24]

Done.

+    start = FL_Pop(&next);
+    list->PushRange(fetch_count, next, end);
   }
 
   // Increase max length slowly up to batch_size.  After that,