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 #pragma once
  18
  19 #include <limits.h>
  20
  21 namespace HPHP {
  22
  23 /*
  24  * The order in which we acquire blocking resources cannot produce
  25  * deadlock if paths respect a partial order on the resources.
  26  */
  27
  28 enum Rank {
  29   RankUnranked = -1, // Unranked locks can be inserted in any order.
  30   /*
  31    * Base rank locks are only ever acquired while no other locks are held.
  32    * In a wedding-cake diagram of the system, these are the upper layers of
  33    * frosting.
  34    */
  35   RankBase = 0,
  36
  37   /*
  38    * Fbml is currently the lowest ranked lock because we reenter the VM while
  39    * holding it. This is probably a bad idea and is not intended to be
  40    * permanent.
  41    */
  42   RankFbml = RankBase,
  43
  44   RankUnitInit,
  45   RankEvaledUnits,
  46   RankWriteLease,
  47   RankCodeCache,
  48   RankCodeMetadata,
  49
  50   RankStatCache,
  51
  52   RankUnitCache,
  53   RankStatCacheNode = RankUnitCache,
  54
  55   RankUnitHashCache,
  56
  57   RankInstanceBitsInit,
  58
  59   RankTreadmill,
  60
  61   /*
  62    * Leaf-rank locks are the deepest resources in the system; once you've
  63    * acquired one, you can acquire no further resources without releasing
  64    * one.
  65    */
  66   RankLeaf
  67 };
  68
  69 #ifndef NDEBUG
  70 extern Rank currentRank();
  71 extern void checkRank(Rank r);
  72 extern void pushRank(Rank r);
  73 extern void popRank(Rank r);
  74 extern void insertRank(Rank r);
  75 #else
  76 #define currentRank() RankBase
  77 #define checkRank(r) do { } while(0)
  78 #define pushRank(r) do { } while(0)
  79 #define popRank(r) do { } while(0)
  80 #define insertRank(r) do { } while(0)
  81 #endif
  82
  83 }