| // 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. |
| |
| #ifndef CC_RASTER_TASK_H_ |
| #define CC_RASTER_TASK_H_ |
| |
| #include <stdint.h> |
| |
| #include <vector> |
| |
| #include "base/memory/ref_counted.h" |
| #include "cc/base/cc_export.h" |
| |
| namespace cc { |
| class Task; |
| |
| // This class provides states to manage life cycle of a task and given below is |
| // how it is used by TaskGraphWorkQueue to process life cycle of a task. |
| // Task is in NEW state when it is created. When task is added to |
| // |ready_to_run_tasks| then its state is changed to SCHEDULED. Task can be |
| // canceled from NEW state (not yet scheduled to run) or from SCHEDULED state, |
| // when new ScheduleTasks() is triggered and its state is changed to CANCELED. |
| // When task is about to run it is added |running_tasks| and its state is |
| // changed to RUNNING. Once task finishes running, its state is changed to |
| // FINISHED. Both CANCELED and FINISHED tasks are added to |completed_tasks|. |
| // ╔═════╗ |
| // +------║ NEW ║------+ |
| // | ╚═════╝ | |
| // v v |
| // ┌───────────┐ ╔══════════╗ |
| // │ SCHEDULED │------> ║ CANCELED ║ |
| // └───────────┘ ╚══════════╝ |
| // | |
| // v |
| // ┌─────────┐ ╔══════════╗ |
| // │ RUNNING │-------> ║ FINISHED ║ |
| // └─────────┘ ╚══════════╝ |
| class CC_EXPORT TaskState { |
| public: |
| bool IsScheduled() const; |
| bool IsRunning() const; |
| bool IsFinished() const; |
| bool IsCanceled() const; |
| |
| // Functions to change the state of task. These functions should be called |
| // only from TaskGraphWorkQueue where the life cycle of a task is decided or |
| // from tests. These functions are not thread-safe. Caller is responsible for |
| // thread safety. |
| void Reset(); // Sets state to NEW. |
| void DidSchedule(); |
| void DidStart(); |
| void DidFinish(); |
| void DidCancel(); |
| |
| private: |
| friend class Task; |
| |
| // Let only Task class create the TaskState. |
| TaskState(); |
| ~TaskState(); |
| |
| enum class Value : uint16_t { NEW, SCHEDULED, RUNNING, FINISHED, CANCELED }; |
| |
| Value value_; |
| }; |
| |
| // A task which can be run by a TaskGraphRunner. To run a Task, it should be |
| // inserted into a TaskGraph, which can then be scheduled on the |
| // TaskGraphRunner. |
| class CC_EXPORT Task : public base::RefCountedThreadSafe<Task> { |
| public: |
| typedef std::vector<scoped_refptr<Task>> Vector; |
| |
| TaskState& state() { return state_; } |
| |
| // Subclasses should implement this method. RunOnWorkerThread may be called |
| // on any thread, and subclasses are responsible for locking and thread |
| // safety. |
| virtual void RunOnWorkerThread() = 0; |
| |
| protected: |
| friend class base::RefCountedThreadSafe<Task>; |
| |
| Task(); |
| virtual ~Task(); |
| |
| private: |
| TaskState state_; |
| }; |
| |
| // A task dependency graph describes the order in which to execute a set |
| // of tasks. Dependencies are represented as edges. Each node is assigned |
| // a category, a priority and a run count that matches the number of |
| // dependencies. Priority range from 0 (most favorable scheduling) to UINT16_MAX |
| // (least favorable). Categories range from 0 to UINT16_MAX. It is up to the |
| // implementation and its consumer to determine the meaning (if any) of a |
| // category. A TaskGraphRunner implementation may chose to prioritize certain |
| // categories over others, regardless of the individual priorities of tasks. |
| struct CC_EXPORT TaskGraph { |
| struct Node { |
| typedef std::vector<Node> Vector; |
| |
| Node(Task* task, |
| uint16_t category, |
| uint16_t priority, |
| uint32_t dependencies) |
| : task(task), |
| category(category), |
| priority(priority), |
| dependencies(dependencies) {} |
| |
| Task* task; |
| uint16_t category; |
| uint16_t priority; |
| uint32_t dependencies; |
| }; |
| |
| struct Edge { |
| typedef std::vector<Edge> Vector; |
| |
| Edge(const Task* task, Task* dependent) |
| : task(task), dependent(dependent) {} |
| |
| const Task* task; |
| Task* dependent; |
| }; |
| |
| TaskGraph(); |
| TaskGraph(const TaskGraph& other); |
| ~TaskGraph(); |
| |
| void Swap(TaskGraph* other); |
| void Reset(); |
| |
| Node::Vector nodes; |
| Edge::Vector edges; |
| }; |
| |
| } // namespace cc |
| |
| #endif // CC_RASTER_TASK_H_ |