Revert of TaskGraphRunner Group support

cc/raster/task_graph_work_queue.cc

 // Copyright 2014 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 "cc/raster/task_graph_work_queue.h"
 
 #include <algorithm>
-#include <map>
 #include <utility>
 
 #include "base/trace_event/trace_event.h"
 
 namespace cc {
-namespace {
-
-bool CompareTaskPriority(const TaskGraphWorkQueue::PrioritizedTask& a,
-                         const TaskGraphWorkQueue::PrioritizedTask& b) {
-  // In this system, numerically lower priority is run first.
-  return a.priority > b.priority;
-}
-
-class CompareTaskNamespacePriority {
- public:
-  explicit CompareTaskNamespacePriority(uint16_t category)
-      : category_(category) {}
-
-  bool operator()(const TaskGraphWorkQueue::TaskNamespace* a,
-                  const TaskGraphWorkQueue::TaskNamespace* b) {
-    DCHECK(!a->ready_to_run_tasks.at(category_).empty());
-    DCHECK(!b->ready_to_run_tasks.at(category_).empty());
-
-    // Compare based on task priority of the ready_to_run_tasks heap .front()
-    // will hold the max element of the heap, except after pop_heap, when max
-    // element is moved to .back().
-    return CompareTaskPriority(a->ready_to_run_tasks.at(category_).front(),
-                               b->ready_to_run_tasks.at(category_).front());
-  }
-
- private:
-  uint16_t category_;
-};
-}  // namespace
 
 TaskGraphWorkQueue::TaskNamespace::TaskNamespace() {}
 
 TaskGraphWorkQueue::TaskNamespace::~TaskNamespace() {}
 
 TaskGraphWorkQueue::TaskGraphWorkQueue() : next_namespace_id_(1) {}
 TaskGraphWorkQueue::~TaskGraphWorkQueue() {}
 
 NamespaceToken TaskGraphWorkQueue::GetNamespaceToken() {
   NamespaceToken token(next_namespace_id_++);
   DCHECK(namespaces_.find(token) == namespaces_.end());
   return token;
 }
 
 void TaskGraphWorkQueue::ScheduleTasks(NamespaceToken token, TaskGraph* graph) {
   TaskNamespace& task_namespace = namespaces_[token];
 
   // First adjust number of dependencies to reflect completed tasks.
   for (const scoped_refptr<Task>& task : task_namespace.completed_tasks) {
     for (DependentIterator node_it(graph, task.get()); node_it; ++node_it) {
       TaskGraph::Node& node = *node_it;
       DCHECK_LT(0u, node.dependencies);
       node.dependencies--;
     }
   }
 
   // Build new "ready to run" queue and remove nodes from old graph.
-  for (auto& ready_to_run_tasks_it : task_namespace.ready_to_run_tasks) {
-    ready_to_run_tasks_it.second.clear();
-  }
+  task_namespace.ready_to_run_tasks.clear();
   for (const TaskGraph::Node& node : graph->nodes) {
     // Remove any old nodes that are associated with this task. The result is
     // that the old graph is left with all nodes not present in this graph,
     // which we use below to determine what tasks need to be canceled.
     TaskGraph::Node::Vector::iterator old_it = std::find_if(
         task_namespace.graph.nodes.begin(), task_namespace.graph.nodes.end(),
         [node](const TaskGraph::Node& other) {
           return node.task == other.task;
         });
     if (old_it != task_namespace.graph.nodes.end()) {
       std::swap(*old_it, task_namespace.graph.nodes.back());
       task_namespace.graph.nodes.pop_back();
     }
 
     // Task is not ready to run if dependencies are not yet satisfied.
     if (node.dependencies)
       continue;
 
     // Skip if already finished running task.
     if (node.task->HasFinishedRunning())
       continue;
 
     // Skip if already running.
     if (std::find(task_namespace.running_tasks.begin(),
                   task_namespace.running_tasks.end(),
                   node.task) != task_namespace.running_tasks.end())
       continue;
 
-    task_namespace.ready_to_run_tasks[node.category].push_back(PrioritizedTask(
-        node.task, &task_namespace, node.category, node.priority));
+    task_namespace.ready_to_run_tasks.push_back(
+        PrioritizedTask(node.task, &task_namespace, node.priority));
   }
 
-  // Rearrange the elements in each vector within |ready_to_run_tasks| in such a
-  // way that they form a heap.
-  for (auto& it : task_namespace.ready_to_run_tasks) {
-    auto& ready_to_run_tasks = it.second;
-    std::make_heap(ready_to_run_tasks.begin(), ready_to_run_tasks.end(),
-                   CompareTaskPriority);
-  }
+  // Rearrange the elements in |ready_to_run_tasks| in such a way that they
+  // form a heap.
+  std::make_heap(task_namespace.ready_to_run_tasks.begin(),
+                 task_namespace.ready_to_run_tasks.end(), CompareTaskPriority);
 
   // Swap task graph.
   task_namespace.graph.Swap(graph);
 
   // Determine what tasks in old graph need to be canceled.
   for (TaskGraph::Node::Vector::iterator it = graph->nodes.begin();
        it != graph->nodes.end(); ++it) {
     TaskGraph::Node& node = *it;
 
     // Skip if already finished running task.
     if (node.task->HasFinishedRunning())
       continue;
 
     // Skip if already running.
     if (std::find(task_namespace.running_tasks.begin(),
                   task_namespace.running_tasks.end(),
                   node.task) != task_namespace.running_tasks.end())
       continue;
 
     DCHECK(std::find(task_namespace.completed_tasks.begin(),
                      task_namespace.completed_tasks.end(),
                      node.task) == task_namespace.completed_tasks.end());
     task_namespace.completed_tasks.push_back(node.task);
   }
 
   // Build new "ready to run" task namespaces queue.
-  for (auto& ready_to_run_namespaces_it : ready_to_run_namespaces_) {
-    ready_to_run_namespaces_it.second.clear();
-  }
-  for (auto& namespace_it : namespaces_) {
-    auto& task_namespace = namespace_it.second;
-    for (auto& ready_to_run_tasks_it : task_namespace.ready_to_run_tasks) {
-      auto& ready_to_run_tasks = ready_to_run_tasks_it.second;
-      uint16_t category = ready_to_run_tasks_it.first;
-      if (!ready_to_run_tasks.empty()) {
-        ready_to_run_namespaces_[category].push_back(&task_namespace);
-      }
-    }
+  ready_to_run_namespaces_.clear();
+  for (auto& it : namespaces_) {
+    if (!it.second.ready_to_run_tasks.empty())
+      ready_to_run_namespaces_.push_back(&it.second);
   }
 
   // Rearrange the task namespaces in |ready_to_run_namespaces| in such a
   // way that they form a heap.
-  for (auto& it : ready_to_run_namespaces_) {
-    uint16_t category = it.first;
-    auto& task_namespace = it.second;
-    std::make_heap(task_namespace.begin(), task_namespace.end(),
-                   CompareTaskNamespacePriority(category));
-  }
+  std::make_heap(ready_to_run_namespaces_.begin(),
+                 ready_to_run_namespaces_.end(), CompareTaskNamespacePriority);
 }
 
-TaskGraphWorkQueue::PrioritizedTask TaskGraphWorkQueue::GetNextTaskToRun(
-    uint16_t category) {
-  TaskNamespace::Vector& ready_to_run_namespaces =
-      ready_to_run_namespaces_[category];
-  DCHECK(!ready_to_run_namespaces.empty());
+TaskGraphWorkQueue::PrioritizedTask TaskGraphWorkQueue::GetNextTaskToRun() {
+  DCHECK(!ready_to_run_namespaces_.empty());
 
-  // Take top priority TaskNamespace from |ready_to_run_namespaces|.
-  std::pop_heap(ready_to_run_namespaces.begin(), ready_to_run_namespaces.end(),
-                CompareTaskNamespacePriority(category));
-  TaskNamespace* task_namespace = ready_to_run_namespaces.back();
-  ready_to_run_namespaces.pop_back();
-
-  PrioritizedTask::Vector& ready_to_run_tasks =
-      task_namespace->ready_to_run_tasks[category];
-  DCHECK(!ready_to_run_tasks.empty());
+  // Take top priority TaskNamespace from |ready_to_run_namespaces_|.
+  std::pop_heap(ready_to_run_namespaces_.begin(),
+                ready_to_run_namespaces_.end(), CompareTaskNamespacePriority);
+  TaskNamespace* task_namespace = ready_to_run_namespaces_.back();
+  ready_to_run_namespaces_.pop_back();
+  DCHECK(!task_namespace->ready_to_run_tasks.empty());
 
   // Take top priority task from |ready_to_run_tasks|.
-  std::pop_heap(ready_to_run_tasks.begin(), ready_to_run_tasks.end(),
-                CompareTaskPriority);
-  PrioritizedTask task = ready_to_run_tasks.back();
-  ready_to_run_tasks.pop_back();
+  std::pop_heap(task_namespace->ready_to_run_tasks.begin(),
+                task_namespace->ready_to_run_tasks.end(), CompareTaskPriority);
+  PrioritizedTask task = task_namespace->ready_to_run_tasks.back();
+  task_namespace->ready_to_run_tasks.pop_back();
 
-  // Add task namespace back to |ready_to_run_namespaces| if not empty after
+  // Add task namespace back to |ready_to_run_namespaces_| if not empty after
   // taking top priority task.
-  if (!ready_to_run_tasks.empty()) {
-    ready_to_run_namespaces.push_back(task_namespace);
-    std::push_heap(ready_to_run_namespaces.begin(),
-                   ready_to_run_namespaces.end(),
-                   CompareTaskNamespacePriority(category));
+  if (!task_namespace->ready_to_run_tasks.empty()) {
+    ready_to_run_namespaces_.push_back(task_namespace);
+    std::push_heap(ready_to_run_namespaces_.begin(),
+                   ready_to_run_namespaces_.end(),
+                   CompareTaskNamespacePriority);
   }
 
   // Add task to |running_tasks|.
   task_namespace->running_tasks.push_back(task.task);
 
   return task;
 }
 
 void TaskGraphWorkQueue::CompleteTask(const PrioritizedTask& completed_task) {
   TaskNamespace* task_namespace = completed_task.task_namespace;
   scoped_refptr<Task> task(completed_task.task);
 
   // Remove task from |running_tasks|.
   auto it = std::find(task_namespace->running_tasks.begin(),
                       task_namespace->running_tasks.end(), task);
   DCHECK(it != task_namespace->running_tasks.end());
   std::swap(*it, task_namespace->running_tasks.back());
   task_namespace->running_tasks.pop_back();
 
   // Now iterate over all dependents to decrement dependencies and check if they
   // are ready to run.
   bool ready_to_run_namespaces_has_heap_properties = true;
   for (DependentIterator it(&task_namespace->graph, task.get()); it; ++it) {
     TaskGraph::Node& dependent_node = *it;
 
     DCHECK_LT(0u, dependent_node.dependencies);
     dependent_node.dependencies--;
     // Task is ready if it has no dependencies. Add it to |ready_to_run_tasks_|.
     if (!dependent_node.dependencies) {
-      PrioritizedTask::Vector& ready_to_run_tasks =
-          task_namespace->ready_to_run_tasks[dependent_node.category];
-
-      bool was_empty = ready_to_run_tasks.empty();
-      ready_to_run_tasks.push_back(
-          PrioritizedTask(dependent_node.task, task_namespace,
-                          dependent_node.category, dependent_node.priority));
-      std::push_heap(ready_to_run_tasks.begin(), ready_to_run_tasks.end(),
+      bool was_empty = task_namespace->ready_to_run_tasks.empty();
+      task_namespace->ready_to_run_tasks.push_back(PrioritizedTask(
+          dependent_node.task, task_namespace, dependent_node.priority));
+      std::push_heap(task_namespace->ready_to_run_tasks.begin(),
+                     task_namespace->ready_to_run_tasks.end(),
                      CompareTaskPriority);
-
       // Task namespace is ready if it has at least one ready to run task. Add
       // it to |ready_to_run_namespaces_| if it just become ready.
       if (was_empty) {
-        TaskNamespace::Vector& ready_to_run_namespaces =
-            ready_to_run_namespaces_[dependent_node.category];
-
-        DCHECK(std::find(ready_to_run_namespaces.begin(),
-                         ready_to_run_namespaces.end(),
-                         task_namespace) == ready_to_run_namespaces.end());
-        ready_to_run_namespaces.push_back(task_namespace);
+        DCHECK(std::find(ready_to_run_namespaces_.begin(),
+                         ready_to_run_namespaces_.end(),
+                         task_namespace) == ready_to_run_namespaces_.end());
+        ready_to_run_namespaces_.push_back(task_namespace);
       }
       ready_to_run_namespaces_has_heap_properties = false;
     }
   }
 
   // Rearrange the task namespaces in |ready_to_run_namespaces_| in such a way
   // that they yet again form a heap.
   if (!ready_to_run_namespaces_has_heap_properties) {
-    for (auto& it : ready_to_run_namespaces_) {
-      uint16_t category = it.first;
-      auto& ready_to_run_namespaces = it.second;
-      std::make_heap(ready_to_run_namespaces.begin(),
-                     ready_to_run_namespaces.end(),
-                     CompareTaskNamespacePriority(category));
-    }
+    std::make_heap(ready_to_run_namespaces_.begin(),
+                   ready_to_run_namespaces_.end(),
+                   CompareTaskNamespacePriority);
   }
 
   // Finally add task to |completed_tasks_|.
   task_namespace->completed_tasks.push_back(task);
 }
 
 void TaskGraphWorkQueue::CollectCompletedTasks(NamespaceToken token,
                                                Task::Vector* completed_tasks) {
   TaskNamespaceMap::iterator it = namespaces_.find(token);
   if (it == namespaces_.end())
     return;
 
   TaskNamespace& task_namespace = it->second;
 
   DCHECK_EQ(0u, completed_tasks->size());
   completed_tasks->swap(task_namespace.completed_tasks);
   if (!HasFinishedRunningTasksInNamespace(&task_namespace))
     return;
 
   // Remove namespace if finished running tasks.
   DCHECK_EQ(0u, task_namespace.completed_tasks.size());
-  DCHECK(!HasReadyToRunTasksInNamespace(&task_namespace));
+  DCHECK_EQ(0u, task_namespace.ready_to_run_tasks.size());
   DCHECK_EQ(0u, task_namespace.running_tasks.size());
   namespaces_.erase(it);
 }
 
 bool TaskGraphWorkQueue::DependencyMismatch(const TaskGraph* graph) {
   // Value storage will be 0-initialized.
   base::hash_map<const Task*, size_t> dependents;
   for (const TaskGraph::Edge& edge : graph->edges)
     dependents[edge.dependent]++;
 
   for (const TaskGraph::Node& node : graph->nodes) {
     if (dependents[node.task] != node.dependencies)
       return true;
   }
 
   return false;
 }
 
 }  // namespace cc