folly/wangle/concurrent/GlobalExecutor.cpp

   1 /*
   2  * Copyright 2015 Facebook, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at
   7  *
   8  *   http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #include <folly/experimental/Singleton.h>
  18 #include <folly/wangle/concurrent/IOExecutor.h>
  19 #include <folly/wangle/concurrent/IOThreadPoolExecutor.h>
  20 #include <folly/futures/InlineExecutor.h>
  21
  22 using namespace folly;
  23 using namespace folly::wangle;
  24
  25 namespace {
  26
  27 // lock protecting global CPU executor
  28 struct CPUExecutorLock {};
  29 Singleton<RWSpinLock, CPUExecutorLock> globalCPUExecutorLock;
  30 // global CPU executor
  31 Singleton<std::weak_ptr<Executor>> globalCPUExecutor;
  32 // default global CPU executor is an InlineExecutor
  33 Singleton<std::shared_ptr<InlineExecutor>> globalInlineExecutor(
  34     []{
  35       return new std::shared_ptr<InlineExecutor>(
  36           std::make_shared<InlineExecutor>());
  37     });
  38
  39 // lock protecting global IO executor
  40 struct IOExecutorLock {};
  41 Singleton<RWSpinLock, IOExecutorLock> globalIOExecutorLock;
  42 // global IO executor
  43 Singleton<std::weak_ptr<IOExecutor>> globalIOExecutor;
  44 // default global IO executor is an IOThreadPoolExecutor
  45 Singleton<std::shared_ptr<IOThreadPoolExecutor>> globalIOThreadPool(
  46     []{
  47       return new std::shared_ptr<IOThreadPoolExecutor>(
  48           std::make_shared<IOThreadPoolExecutor>(
  49               sysconf(_SC_NPROCESSORS_ONLN),
  50               std::make_shared<NamedThreadFactory>("GlobalIOThreadPool")));
  51     });
  52
  53 }
  54
  55 namespace folly { namespace wangle {
  56
  57 template <class Exe, class DefaultExe, class LockTag>
  58 std::shared_ptr<Exe> getExecutor(
  59     Singleton<std::weak_ptr<Exe>>& sExecutor,
  60     Singleton<std::shared_ptr<DefaultExe>>& sDefaultExecutor,
  61     Singleton<RWSpinLock, LockTag>& sExecutorLock) {
  62   std::shared_ptr<Exe> executor;
  63   auto singleton = sExecutor.get();
  64   auto lock = sExecutorLock.get();
  65
  66   {
  67     RWSpinLock::ReadHolder guard(lock);
  68     if ((executor = sExecutor->lock())) {
  69       return executor;
  70     }
  71   }
  72
  73
  74   RWSpinLock::WriteHolder guard(lock);
  75   executor = singleton->lock();
  76   if (!executor) {
  77     executor = *sDefaultExecutor.get();
  78     *singleton = executor;
  79   }
  80   return executor;
  81 }
  82
  83 template <class Exe, class LockTag>
  84 void setExecutor(
  85     std::shared_ptr<Exe> executor,
  86     Singleton<std::weak_ptr<Exe>>& sExecutor,
  87     Singleton<RWSpinLock, LockTag>& sExecutorLock) {
  88   RWSpinLock::WriteHolder guard(sExecutorLock.get());
  89   *sExecutor.get() = std::move(executor);
  90 }
  91
  92 std::shared_ptr<Executor> getCPUExecutor() {
  93   return getExecutor(
  94       globalCPUExecutor,
  95       globalInlineExecutor,
  96       globalCPUExecutorLock);
  97 }
  98
  99 void setCPUExecutor(std::shared_ptr<Executor> executor) {
 100   setExecutor(
 101       std::move(executor),
 102       globalCPUExecutor,
 103       globalCPUExecutorLock);
 104 }
 105
 106 std::shared_ptr<IOExecutor> getIOExecutor() {
 107   return getExecutor(
 108       globalIOExecutor,
 109       globalIOThreadPool,
 110       globalIOExecutorLock);
 111 }
 112
 113 void setIOExecutor(std::shared_ptr<IOExecutor> executor) {
 114   setExecutor(
 115       std::move(executor),
 116       globalIOExecutor,
 117       globalIOExecutorLock);
 118 }
 119
 120 }} // folly::wangle