Split initialization_util into a Hermetic Library and a Variations Library

components/task_scheduler_util/initialization/browser_util.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 "components/task_scheduler_util/initialization/browser_util.h"
+
+#include <map>
+#include <string>
+#include <vector>

[fdoray, 2016/12/06 17:22:23]

<vector> already included in .h file

[robliao, 2016/12/07 00:03:54]

Done.

+
+#include "base/task_scheduler/initialization_util.h"
+#include "base/task_scheduler/switches.h"
+#include "base/task_scheduler/task_traits.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "build/build_config.h"
+
+namespace task_scheduler_util {
+namespace initialization {
+
+namespace {
+
+using StandbyThreadPolicy =
+    base::SchedulerWorkerPoolParams::StandbyThreadPolicy;
+using ThreadPriority = base::ThreadPriority;
+
+struct SchedulerWorkerPoolPredefinedParams {
+  const char* name;
+  ThreadPriority priority_hint;
+};
+
+}  // namespace
+
+std::vector<base::SchedulerWorkerPoolParams>
+BrowserWorkerPoolConfigurationToSchedulerWorkerPoolParams(
+    const BrowserWorkerPoolsConfiguration& config) {
+  constexpr SchedulerWorkerPoolPredefinedParams kAllPredefinedParams[] = {

[fdoray, 2016/12/06 17:22:23]

You could add a SingleWorkerPoolConfiguration* member to
SchedulerWorkerPoolPredefinedParams and rename it to
SingleWorkerPoolPredefinedAndVariationsParams:

 struct SingleWorkerPoolPredefinedAndVariationsParams {
   const char* name;
   ThreadPriority priority_hint;
   SingleWorkerPoolVariationParams* config;
 }

 {"Background", ThreadPriority::BACKGROUND, &config.background},
 {"BackgroundFileIO", ThreadPriority::BACKGROUND, &config.background_file_io},
 {"Foreground", ThreadPriority::NORMAL, &config.foreground},
 {"ForegroundFileIO", ThreadPriority::NORMAL, &config.foreground_file_io},

kAllPredefinedParams could no longer be constexpr, but it would be easier to
verify that SingleWorkerPoolConfiguration* are associated with the right
predefined params and you could use a range-based loop below.

[gab, 2016/12/06 19:16:07]

static per
https://groups.google.com/a/chromium.org/d/msg/chromium-dev/pF7nAmUQ2uw/-2PSZ...

[robliao, 2016/12/07 00:03:54]

This can't be static with the array inclusion change now.

[robliao, 2016/12/07 00:03:54]

I can live with that. Done.

+      {"Background", ThreadPriority::BACKGROUND},
+      {"BackgroundFileIO", ThreadPriority::BACKGROUND},
+      {"Foreground", ThreadPriority::NORMAL},
+      {"ForegroundFileIO", ThreadPriority::NORMAL},
+  };
+  static_assert(arraysize(kAllPredefinedParams) == WORKER_POOL_COUNT,
+                "Mismatched Worker Pool Types and Predefined Parameters");
+  constexpr size_t worker_pool_total_size =
+      sizeof(BrowserWorkerPoolsConfiguration);
+  constexpr size_t single_worker_pool_size =
+      sizeof(SingleWorkerPoolConfiguration);

[fdoray, 2016/12/06 17:22:23]

Compute this the same way as in BrowserWorkerPoolsConfiguration().

constexpr size_t kNumWorkerPoolsDefined =
    sizeof(BrowserWorkerPoolsConfiguration) /
    sizeof(SingleWorkerPoolConfiguration);

[robliao, 2016/12/07 00:03:54]

Done

+  static_assert(arraysize(kAllPredefinedParams) ==
+                    worker_pool_total_size / single_worker_pool_size,
+                "Mismatched Predefined Parameters and Browser Worker Pools");
+  const SingleWorkerPoolConfiguration* const all_pools[]{
+      &config.background, &config.background_file_io, &config.foreground,
+      &config.foreground_file_io,
+  };
+  static_assert(arraysize(kAllPredefinedParams) == arraysize(all_pools),

[fdoray, 2016/12/06 17:22:23]

Since most of the code in this file can be reused in child processes, I would:

1. Rename browser_util.cc -> util.cc.
2. Move the code below to a helper function:

std::vector<base::SchedulerWorkerPoolParams>
    WorkerPoolPredefinedAndVariationsParamsToSchedulerWorkerPoolParams(
        WorkerPoolPredefinedAndVariationsParams*
            worker_pool_predefined_and_variations_params,
        size_t worker_pool_predefined_and_variations_params_size);

3. In separate CLs, reuse the helper function to create vectors of
SchedulerWorkerPoolParams for child processes.

[robliao, 2016/12/07 00:03:54]

We can't do the rename because initialization/util.h clashes with
initialization_util.h. The include once guards are the same.
COMPONENTS_TASK_SCHEDULER_UTIL_INITIALIZATION_UTIL_H_. Let's table the name
until the helper refactor.

+                "Mismatched Prefined Parameters and All Pools Array");
+  std::vector<base::SchedulerWorkerPoolParams> params_vector;
+  for (size_t i = 0; i < arraysize(kAllPredefinedParams); ++i) {
+    const auto& predefined_param = kAllPredefinedParams[i];
+    const auto& pool_config = all_pools[i];

[gab, 2016/12/06 19:16:07]

s/&/*/

[robliao, 2016/12/07 00:03:54]

Done.

+    params_vector.emplace_back(
+        predefined_param.name, predefined_param.priority_hint,
+        pool_config->standby_thread_policy, pool_config->threads,
+        pool_config->detach_period);
+  }
+  DCHECK_EQ(WORKER_POOL_COUNT, params_vector.size());
+  return params_vector;
+}
+
+// Returns the worker pool index for |traits| defaulting to
+// FOREGROUND or FOREGROUND_FILE_IO on unknown

[fdoray, 2016/12/06 17:22:23]

wrap

[gab, 2016/12/06 19:16:07]

"unknown priorities"? "non-background" priorities" maybe?

[robliao, 2016/12/07 00:03:54]

Went with "any other" priorities.

[robliao, 2016/12/07 00:03:54]

Done.

+// priorities.
+size_t BrowserWorkerPoolIndexForTraits(const base::TaskTraits& traits) {
+  const bool is_background =
+      traits.priority() == base::TaskPriority::BACKGROUND;
+  if (traits.with_file_io()) {

[fdoray, 2016/12/06 17:22:23]

no braces

[gab, 2016/12/06 19:16:07]

nit: no {}

[robliao, 2016/12/07 00:03:54]

Done.

[robliao, 2016/12/07 00:03:54]

Done.

+    return is_background ? BACKGROUND_FILE_IO : FOREGROUND_FILE_IO;
+  }
+  return is_background ? BACKGROUND : FOREGROUND;
+}
+
+std::vector<base::SchedulerWorkerPoolParams>
+GetDefaultBrowserSchedulerWorkerPoolParams() {
+  constexpr size_t kNumWorkerPoolsDefined =
+      sizeof(BrowserWorkerPoolsConfiguration) /
+      sizeof(SingleWorkerPoolConfiguration);
+  static_assert(kNumWorkerPoolsDefined == 4,
+                "Expected 4 worker pools in BrowserWorkerPoolsConfiguration");
+  BrowserWorkerPoolsConfiguration config;
+#if defined(OS_ANDROID) || defined(OS_IOS)
+  config.background.standby_thread_policy = StandbyThreadPolicy::ONE;
+  config.background.threads =
+      base::RecommendedMaxNumberOfThreadsInPool(2, 8, 0.1, 0);
+  config.background.detach_period = base::TimeDelta::FromSeconds(30);
+
+  config.background_file_io.standby_thread_policy = StandbyThreadPolicy::ONE;
+  config.background_file_io.threads =
+      base::RecommendedMaxNumberOfThreadsInPool(2, 8, 0.1, 0);
+  config.background_file_io.detach_period = base::TimeDelta::FromSeconds(30);
+
+  config.foreground.standby_thread_policy = StandbyThreadPolicy::ONE;
+  config.foreground.threads =
+      base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.3, 0);
+  config.foreground.detach_period = base::TimeDelta::FromSeconds(30);
+
+  config.foreground_file_io.standby_thread_policy = StandbyThreadPolicy::ONE;
+  config.foreground_file_io.threads =
+      base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.3, 0);
+  config.foreground_file_io.detach_period = base::TimeDelta::FromSeconds(30);
+#else
+  config.background.standby_thread_policy = StandbyThreadPolicy::ONE;
+  config.background.threads =
+      base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.1, 0);
+  config.background.detach_period = base::TimeDelta::FromSeconds(30);
+
+  config.background_file_io.standby_thread_policy = StandbyThreadPolicy::ONE;
+  config.background_file_io.threads =
+      base::RecommendedMaxNumberOfThreadsInPool(3, 8, 0.1, 0);
+  config.background_file_io.detach_period = base::TimeDelta::FromSeconds(30);
+
+  config.foreground.standby_thread_policy = StandbyThreadPolicy::ONE;
+  config.foreground.threads =
+      base::RecommendedMaxNumberOfThreadsInPool(8, 32, 0.3, 0);
+  config.foreground.detach_period = base::TimeDelta::FromSeconds(30);
+
+  config.foreground_file_io.standby_thread_policy = StandbyThreadPolicy::ONE;
+  config.foreground_file_io.threads =
+      base::RecommendedMaxNumberOfThreadsInPool(8, 32, 0.3, 0);
+  config.foreground_file_io.detach_period = base::TimeDelta::FromSeconds(30);
+#endif
+  return BrowserWorkerPoolConfigurationToSchedulerWorkerPoolParams(config);
+}
+
+}  // namespace initialization
+}  // namespace task_scheduler_util