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

third_party/tcmalloc/chromium/src/common.cc

-// Copyright (c) 2008, Google Inc.
+// Copyright (c) 2011, Google Inc.
 // All rights reserved.
 // 
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 // 
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 // copyright notice, this list of conditions and the following disclaimer
@@ skipping 143 matching lines @@
     }
     next_size = max_size_in_class + kAlignment;
   }
 
   // Double-check sizes just to be safe
   for (size_t size = 0; size <= kMaxSize; size++) {
     const int sc = SizeClass(size);
     if (sc <= 0 || sc >= kNumClasses) {
       CRASH("Bad size class %d for %" PRIuS "\n", sc, size);
     }
-    if (sc > 1 && size <= class_to_size_[sc-1]) {
+    if (sc > FIRST_SIZE_CLASS && size <= class_to_size_[sc-1]) {

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

The name seems bad, since it is actually the first usable, and not the first
size class (unless the code is changed much more).

Perhaps:
FIRST_USABLE_SIZE_CLASS

For completeness, you may as well add something to test the low values, such as:
if (AVOID_8_BYTE_CLASSES &&
    (sc == FIRST_USABLE_SIZE_CLASS) == (size <= 16))
   CRASH(...)

Then again.. they didn't have tests for this... so it is your call.

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

Done.

       CRASH("Allocating unnecessarily large class %d for %" PRIuS
             "\n", sc, size);
     }
     const size_t s = class_to_size_[sc];
     if (size > s) {
       CRASH("Bad size %" PRIuS " for %" PRIuS " (sc = %d)\n", s, size, sc);
     }
     if (s == 0) {
       CRASH("Bad size %" PRIuS " for %" PRIuS " (sc = %d)\n", s, size, sc);
     }
@@ skipping 32 matching lines @@
   return result;
 }
 
 uint64_t metadata_system_bytes() { return metadata_system_bytes_; }
 
 void increment_metadata_system_bytes(size_t bytes) {
   metadata_system_bytes_ += bytes;
 }
 
 }  // namespace tcmalloc