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 <memory>
+#include <utility>
+
+#include "base/logging.h"
+#include "base/process/process_handle.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/unguessable_token.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;
+}
+
+}  // namespace
+
+CoordinationUnitImpl::CoordinationUnitImpl(
+    const CoordinationUnitID& id,
+    std::unique_ptr<service_manager::ServiceContextRef> service_ref) {
+  if (!id.id) {
+    id_ = CoordinationUnitID(id.type,
+                             base::UnguessableToken().Create().ToString());
+  } 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);
+}
+
+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::RecalcCoordinationPolicy() {
+  for (CoordinationUnitImpl* child : children_) {
+    child->RecalcCoordinationPolicy();
+  }
+
+  if (!policy_callback_) {
+    return;
+  }
+
+  bool background_priority = !SelfOrParentHasFlagSet(kTabVisible) &&
+                             !SelfOrParentHasFlagSet(kAudioPlaying);
+
+  // Send the priority to the client if it's new or changed.
+  if (!current_policy_) {
+    current_policy_ = mojom::CoordinationPolicy::New();
+  } else if ((current_policy_->use_background_priority ==
+              background_priority) &&
+             !SelfOrParentHasFlagSet(StateFlags::kTestState)) {
+    return;
+  }
+
+  // current_policy_ should be kept in sync with the policy we
+  // send to the client, to avoid redundant updates.
+  // TODO(oysteine): Once this object becomes more complex, make
+  // copying more robust.
+  mojom::CoordinationPolicyPtr policy = mojom::CoordinationPolicy::New();
+  policy->use_background_priority = background_priority;
+  current_policy_->use_background_priority = background_priority;
+
+  policy_callback_->SetCoordinationPolicy(std::move(policy));
+}
+
+void CoordinationUnitImpl::SendEvent(mojom::EventPtr event) {
+  switch (event->type) {
+    case mojom::EventType::kOnWebContentsShown:
+      state_flags_[kTabVisible] = true;
+      break;
+    case mojom::EventType::kOnWebContentsHidden:
+      state_flags_[kTabVisible] = false;
+      break;
+    case mojom::EventType::kOnProcessAudioStarted:
+      state_flags_[kAudioPlaying] = true;
+      break;
+    case mojom::EventType::kOnProcessAudioStopped:
+      state_flags_[kAudioPlaying] = false;
+      break;
+    case mojom::EventType::kTestEvent:
+      state_flags_[kTestState] = true;
+      break;
+    default:
+      return;
+  }
+
+  RecalcCoordinationPolicy();
+}
+
+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) {
+  // We don't recalculate the policy here as policies are only dependent
+  // on the current CU or its parents, not its children. In other words,
+  // policies only bubble down.
+  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);
+
+  RecalcCoordinationPolicy();
+}
+
+void CoordinationUnitImpl::RemoveParent(CoordinationUnitImpl* parent) {
+  size_t parents_removed = parents_.erase(parent);
+  DCHECK_EQ(1u, parents_removed);
+
+  RecalcCoordinationPolicy();
+}
+
+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::SetCoordinationPolicyCallback(
+    mojom::CoordinationPolicyCallbackPtr callback) {
+  callback.set_connection_error_handler(
+      base::Bind(&CoordinationUnitImpl::UnregisterCoordinationPolicyCallback,
+                 base::Unretained(this)));
+
+  policy_callback_ = std::move(callback);
+
+  RecalcCoordinationPolicy();
+}
+
+void CoordinationUnitImpl::UnregisterCoordinationPolicyCallback() {
+  policy_callback_.reset();
+  current_policy_.reset();
+}
+
+}  // namespace resource_coordinator