Global Resource Coordinator: Basic service internals

services/resource_coordinator/coordination_unit/coordination_unit_impl.cc

+// Copyright 2017 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 "services/resource_coordinator/coordination_unit/coordination_unit_impl.h"
+
+#include "base/logging.h"
+#include "base/process/process_handle.h"
+#include "base/strings/string_number_conversions.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+#include "services/resource_coordinator/public/cpp/coordination_unit_id.h"
+
+namespace resource_coordinator {
+
+namespace {
+
+using CUIDMap = std::unordered_map<CoordinationUnitID, CoordinationUnitImpl*>;
+
+CUIDMap* g_cu_map() {
+  static CUIDMap* instance = new CUIDMap();
+  return instance;

[dcheng, 2017/04/18 05:40:46]

Consider returning a ref, since this is never null.

[oystein (OOO til 10th of July), 2017/04/18 20:55:33]

Done.

+}
+
+}  // namespace
+
+CoordinationUnitImpl::CoordinationUnitImpl(
+    const CoordinationUnitID& id,
+    std::unique_ptr<service_manager::ServiceContextRef> service_ref) {
+  if (!id.id) {
+    static int next_id = 0;
+    id_ = CoordinationUnitID(id.type,
+                             base::IntToString(base::GetCurrentProcId()) + "." +

[dcheng, 2017/04/18 05:40:46]

I don't entirely understand the purpose of building this string and then hashing
it.

Why not just generate completely random IDs in this case? We have
mojo.common.mojom.UnguessableToken for this.

(I'm assuming this is to support the 'create initial token' vs 'get existing
token' use case, but perhaps that would also be useful to explicitly call out in
the comments)

[oystein (OOO til 10th of July), 2017/04/18 20:55:33]

UnguessableToken makes more sense; this was more an artifact from when I was
generating this client-side and wanted to ensure we didn't have collisions.
Done.

+                                 base::IntToString(++next_id));
+  } else {
+    id_ = id;
+  }
+
+  auto it = g_cu_map()->insert(std::make_pair(id_, this));
+  DCHECK(it.second);  // Inserted successfully
+
+  service_ref_ = std::move(service_ref);

[dcheng, 2017/04/18 05:40:46]

Nit: #include <utility>

[oystein (OOO til 10th of July), 2017/04/18 20:55:33]

Done.

+}
+
+CoordinationUnitImpl::~CoordinationUnitImpl() {
+  g_cu_map()->erase(id_);
+
+  for (CoordinationUnitImpl* child : children_) {
+    child->RemoveParent(this);
+  }
+
+  for (CoordinationUnitImpl* parent : parents_) {
+    parent->RemoveChild(this);
+  }
+}
+
+bool CoordinationUnitImpl::SelfOrParentHasFlagSet(StateFlags state) {
+  const base::Optional<bool>& state_flag = state_flags_[state];
+  if (state_flag && *state_flag)
+    return true;
+
+  for (CoordinationUnitImpl* parent : parents_) {
+    if (parent->SelfOrParentHasFlagSet(state))
+      return true;
+  }
+
+  return false;
+}
+
+void CoordinationUnitImpl::RecalcPolicy() {
+  for (CoordinationUnitImpl* child : children_) {
+    child->RecalcPolicy();
+  }
+
+  if (!policy_callback_) {
+    return;
+  }
+
+  bool background_priority = !SelfOrParentHasFlagSet(TAB_VISIBLE) &&
+                             !SelfOrParentHasFlagSet(AUDIO_PLAYING);
+
+  // Send the priority to the client if it's new or changed.
+  if (!current_policy_)
+    current_policy_ = mojom::Policy::New();
+  else if ((current_policy_->use_background_priority == background_priority) &&
+           !SelfOrParentHasFlagSet(StateFlags::TEST_STATE)) {
+    return;
+  }
+
+  mojom::PolicyPtr policy = mojom::Policy::New();
+  policy->use_background_priority = background_priority;
+  current_policy_->use_background_priority = background_priority;
+
+  policy_callback_->SetPolicy(std::move(policy));
+}
+
+void CoordinationUnitImpl::SendEvent(mojom::EventPtr event) {
+  switch (event->type) {
+    case mojom::EventType::ON_WEBCONTENTS_SHOWN:
+      state_flags_[TAB_VISIBLE] = true;
+      break;
+    case mojom::EventType::ON_WEBCONTENTS_HIDDEN:
+      state_flags_[TAB_VISIBLE] = false;
+      break;
+    case mojom::EventType::ON_PROCESS_AUDIO_STARTED:
+      state_flags_[AUDIO_PLAYING] = true;
+      break;
+    case mojom::EventType::ON_PROCESS_AUDIO_STOPPED:
+      state_flags_[AUDIO_PLAYING] = false;
+      break;
+    case mojom::EventType::TEST_EVENT:
+      state_flags_[TEST_STATE] = true;
+      break;
+    default:
+      return;
+  }
+
+  RecalcPolicy();
+}
+
+void CoordinationUnitImpl::GetID(const GetIDCallback& callback) {
+  callback.Run(id_);
+}
+
+void CoordinationUnitImpl::Duplicate(mojom::CoordinationUnitRequest request) {
+  bindings_.AddBinding(this, std::move(request));
+}
+
+void CoordinationUnitImpl::AddChild(const CoordinationUnitID& child_id) {
+  if (child_id == id_)
+    return;
+
+  auto child_iter = g_cu_map()->find(child_id);
+  if (child_iter != g_cu_map()->end()) {
+    CoordinationUnitImpl* child = child_iter->second;
+    if (HasParent(child) || HasChild(child))
+      return;
+
+    DCHECK(child->id_ == child_id);
+    DCHECK(child != this);
+
+    if (AddChild(child)) {
+      child->AddParent(this);
+    }
+  }
+}
+
+bool CoordinationUnitImpl::AddChild(CoordinationUnitImpl* child) {
+  return children_.count(child) ? false : children_.insert(child).second;
+}
+
+void CoordinationUnitImpl::RemoveChild(CoordinationUnitImpl* child) {
+  size_t children_removed = children_.erase(child);
+  DCHECK_EQ(1u, children_removed);
+}
+
+void CoordinationUnitImpl::AddParent(CoordinationUnitImpl* parent) {
+  DCHECK_EQ(0u, parents_.count(parent));
+  parents_.insert(parent);
+
+  RecalcPolicy();
+}
+
+void CoordinationUnitImpl::RemoveParent(CoordinationUnitImpl* parent) {
+  size_t parents_removed = parents_.erase(parent);
+  DCHECK_EQ(1u, parents_removed);
+
+  RecalcPolicy();
+}
+
+bool CoordinationUnitImpl::HasParent(CoordinationUnitImpl* unit) {
+  for (CoordinationUnitImpl* parent : parents_) {
+    if (parent == unit || parent->HasParent(unit))
+      return true;
+  }
+
+  return false;
+}
+
+bool CoordinationUnitImpl::HasChild(CoordinationUnitImpl* unit) {
+  for (CoordinationUnitImpl* child : children_) {
+    if (child == unit || child->HasChild(unit))
+      return true;
+  }
+
+  return false;
+}
+
+void CoordinationUnitImpl::SetPolicyCallback(
+    mojom::PolicyCallbackPtr callback) {
+  callback.set_connection_error_handler(base::Bind(
+      &CoordinationUnitImpl::UnregisterPolicyCallback, base::Unretained(this)));
+
+  policy_callback_ = std::move(callback);
+
+  RecalcPolicy();
+}
+
+void CoordinationUnitImpl::UnregisterPolicyCallback() {
+  policy_callback_.reset();
+  current_policy_.reset();
+}
+
+}  // namespace resource_coordinator