hphp/runtime/vm/treadmill-inl.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 #ifndef incl_HPHP_TREADMILL_INL_H_
  17 #define incl_HPHP_TREADMILL_INL_H_
  18
  19 #include "hphp/runtime/base/rds-local.h"
  20
  21 #include <folly/Likely.h>
  22
  23 #include <atomic>
  24 #include <memory>
  25 #include <utility>
  26
  27 namespace HPHP { namespace Treadmill {
  28
  29 extern std::atomic<int64_t> g_nextThreadIdx;
  30 extern RDS_LOCAL_NO_CHECK(int64_t, rl_thisRequestIdx);
  31
  32 inline int64_t requestIdx() {
  33   if (UNLIKELY(*rl_thisRequestIdx == kInvalidRequestIdx)) {
  34     *rl_thisRequestIdx =
  35       g_nextThreadIdx.fetch_add(1, std::memory_order_relaxed);
  36   }
  37   return *rl_thisRequestIdx;
  38 }
  39
  40 //////////////////////////////////////////////////////////////////////
  41
  42 struct WorkItem;
  43 void enqueueInternal(std::unique_ptr<WorkItem>);
  44
  45 //////////////////////////////////////////////////////////////////////
  46
  47 using GenCount = int64_t;
  48
  49 struct WorkItem {
  50   WorkItem() = default;
  51   WorkItem(const WorkItem&) = delete;
  52   WorkItem& operator=(const WorkItem&) = delete;
  53   virtual ~WorkItem() {}
  54
  55   virtual void run() noexcept = 0;
  56
  57 private:
  58   friend void finishRequest();
  59   friend void enqueueInternal(std::unique_ptr<WorkItem>);
  60
  61 private:
  62   // Inherently racy. We get a lower bound on the generation;
  63   // presumably clients are aware of this, and are creating the
  64   // trigger for an object that was reachable strictly in the past.
  65   GenCount m_gen{0};
  66 };
  67
  68 template<class F>
  69 struct WorkItemImpl final : WorkItem {
  70   explicit WorkItemImpl(F&& f) : f(std::forward<F>(f)) {}
  71
  72   void run() noexcept override { f(); }
  73
  74 private:
  75   F f;
  76 };
  77
  78 template<class F>
  79 void enqueue(F&& f) {
  80   std::unique_ptr<WorkItemImpl<F>> p(new WorkItemImpl<F>(std::forward<F>(f)));
  81   enqueueInternal(std::move(p));
  82 }
  83
  84 //////////////////////////////////////////////////////////////////////
  85
  86 }}
  87
  88 #endif