[reference - do not submit] Always create four pools in TaskSchedulerImpl.

base/task_scheduler/task_scheduler.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/task_scheduler/task_scheduler.h"
 
-#include <algorithm>
-
-#include "base/bind.h"
 #include "base/logging.h"
-#include "base/sys_info.h"
+#include "base/task_scheduler/initialization_util.h"
 #include "base/task_scheduler/scheduler_worker_pool_params.h"
 #include "base/task_scheduler/task_scheduler_impl.h"
 #include "base/threading/platform_thread.h"
 #include "base/time/time.h"
 
 namespace base {
 
 namespace {
 
 // |g_task_scheduler| is intentionally leaked on shutdown.
 TaskScheduler* g_task_scheduler = nullptr;
 
 }  // namespace
 
+TaskSchedulerInitParams::TaskSchedulerInitParams(
+    const SchedulerWorkerPoolParams& background_worker_pool_params_in,
+    const SchedulerWorkerPoolParams& background_blocking_worker_pool_params_in,
+    const SchedulerWorkerPoolParams& foreground_worker_pool_params_in,
+    const SchedulerWorkerPoolParams& foreground_blocking_worker_pool_params_in)
+    : background_worker_pool_params(background_worker_pool_params_in),
+      background_blocking_worker_pool_params(
+          background_blocking_worker_pool_params_in),
+      foreground_worker_pool_params(foreground_worker_pool_params_in),
+      foreground_blocking_worker_pool_params(
+          foreground_blocking_worker_pool_params_in) {}
+
+bool TaskSchedulerInitParams::IsValid() const {
+  return background_worker_pool_params.IsValid() &&
+         background_blocking_worker_pool_params.IsValid() &&
+         foreground_worker_pool_params.IsValid() &&
+         foreground_blocking_worker_pool_params.IsValid();
+}
+
 #if !defined(OS_NACL)
 // static
 void TaskScheduler::CreateAndSetSimpleTaskScheduler(const std::string& name) {
-  constexpr int kMinNumThreads = 1;
-  std::vector<SchedulerWorkerPoolParams> worker_pool_params_vector;
-  worker_pool_params_vector.emplace_back(
-      name, ThreadPriority::NORMAL,
-      SchedulerWorkerPoolParams::StandbyThreadPolicy::LAZY,
-      std::max(kMinNumThreads, base::SysInfo::NumberOfProcessors()),
-      TimeDelta::FromSeconds(30));
+  using StandbyThreadPolicy = SchedulerWorkerPoolParams::StandbyThreadPolicy;
+
+  constexpr TimeDelta kSuggestedReclaimTime = TimeDelta::FromSeconds(30);
+  constexpr int kMaxNumBackgroundThreads = 1;
+  constexpr int kMaxNumBackgroundBlockingThreads = 2;
+  constexpr int kMaxNumForegroundThreadsLowerBound = 2;
+  constexpr int kMaxNumForegroundThreadsUpperBound = 32;
+  constexpr double kMaxNumForegroundThreadsCoresMultiplier = 1;
+  constexpr int kMaxNumForegroundThreadsOffset = 0;
+  constexpr int kMaxNumForegroundBlockingThreadsLowerBound = 2;
+  constexpr int kMaxNumForegroundBlockingThreadsUpperBound = 64;
+  constexpr double kMaxNumForegroundBlockingThreadsCoresMultiplier = 2;
+  constexpr int kMaxNumForegroundBlockingThreadsOffset = 0;
+
   CreateAndSetDefaultTaskScheduler(
-      worker_pool_params_vector,
-      Bind([](const TaskTraits&) -> size_t { return 0; }));
+      name, {{StandbyThreadPolicy::LAZY, kMaxNumBackgroundThreads,
+              kSuggestedReclaimTime},
+             {StandbyThreadPolicy::LAZY, kMaxNumBackgroundBlockingThreads,
+              kSuggestedReclaimTime},
+             {StandbyThreadPolicy::LAZY,
+              RecommendedMaxNumberOfThreadsInPool(
+                  kMaxNumForegroundThreadsLowerBound,
+                  kMaxNumForegroundThreadsUpperBound,
+                  kMaxNumForegroundThreadsCoresMultiplier,
+                  kMaxNumForegroundThreadsOffset),
+              kSuggestedReclaimTime},
+             {StandbyThreadPolicy::LAZY,
+              RecommendedMaxNumberOfThreadsInPool(
+                  kMaxNumForegroundBlockingThreadsLowerBound,
+                  kMaxNumForegroundBlockingThreadsUpperBound,
+                  kMaxNumForegroundBlockingThreadsCoresMultiplier,
+                  kMaxNumForegroundBlockingThreadsOffset),
+              kSuggestedReclaimTime}});
 }
 #endif  // !defined(OS_NACL)
 
-// static
 void TaskScheduler::CreateAndSetDefaultTaskScheduler(
-    const std::vector<SchedulerWorkerPoolParams>& worker_pool_params_vector,
-    const WorkerPoolIndexForTraitsCallback&
-        worker_pool_index_for_traits_callback) {
-  SetInstance(internal::TaskSchedulerImpl::Create(
-      worker_pool_params_vector, worker_pool_index_for_traits_callback));
+    const std::string& name,
+    const TaskSchedulerInitParams& init_params) {
+  SetInstance(internal::TaskSchedulerImpl::Create(name, init_params));
 }
 
 // static
 void TaskScheduler::SetInstance(std::unique_ptr<TaskScheduler> task_scheduler) {
   delete g_task_scheduler;
   g_task_scheduler = task_scheduler.release();
 }
 
 // static
 TaskScheduler* TaskScheduler::GetInstance() {
   return g_task_scheduler;
 }
 
 }  // namespace base