hphp/util/rank.h

   1 /*
   2    +----------------------------------------------------------------------+
   3    | HipHop for PHP                                                       |
   4    +----------------------------------------------------------------------+
   5    | Copyright (c) 2010-present Facebook, Inc. (http://www.facebook.com)  |
   6    +----------------------------------------------------------------------+
   7    | This source file is subject to version 3.01 of the PHP license,      |
   8    | that is bundled with this package in the file LICENSE, and is        |
   9    | available through the world-wide-web at the following url:           |
  10    | http://www.php.net/license/3_01.txt                                  |
  11    | If you did not receive a copy of the PHP license and are unable to   |
  12    | obtain it through the world-wide-web, please send a note to          |
  13    | license@php.net so we can mail you a copy immediately.               |
  14    +----------------------------------------------------------------------+
  15 */
  16
  17 #ifndef incl_HPHP_RANK_H_
  18 #define incl_HPHP_RANK_H_
  19
  20 #include <limits.h>
  21
  22 namespace HPHP {
  23
  24 /*
  25  * The order in which we acquire blocking resources cannot produce
  26  * deadlock if paths respect a partial order on the resources.
  27  */
  28
  29 enum Rank {
  30   RankUnranked = -1, // Unranked locks can be inserted in any order.
  31   /*
  32    * Base rank locks are only ever acquired while no other locks are held.
  33    * In a wedding-cake diagram of the system, these are the upper layers of
  34    * frosting.
  35    */
  36   RankBase = 0,
  37
  38   /*
  39    * Fbml is currently the lowest ranked lock because we reenter the VM while
  40    * holding it. This is probably a bad idea and is not intended to be
  41    * permanent.
  42    */
  43   RankFbml = RankBase,
  44
  45   RankUnitInit,
  46   RankEvaledUnits,
  47   RankWriteLease,
  48   RankCodeCache,
  49   RankCodeMetadata,
  50
  51   RankStatCache,
  52
  53   RankUnitCache,
  54   RankStatCacheNode = RankUnitCache,
  55
  56   RankInstanceBitsInit,
  57
  58   RankTreadmill,
  59
  60   /*
  61    * Leaf-rank locks are the deepest resources in the system; once you've
  62    * acquired one, you can acquire no further resources without releasing
  63    * one.
  64    */
  65   RankLeaf
  66 };
  67
  68 #ifdef DEBUG
  69 extern Rank currentRank();
  70 extern void checkRank(Rank r);
  71 extern void pushRank(Rank r);
  72 extern void popRank(Rank r);
  73 extern void insertRank(Rank r);
  74 #else
  75 #define currentRank() RankBase
  76 #define checkRank(r) do { } while(0)
  77 #define pushRank(r) do { } while(0)
  78 #define popRank(r) do { } while(0)
  79 #define insertRank(r) do { } while(0)
  80 #endif
  81
  82 }
  83
  84 #endif