render: improved threading stability

app/threading/threadticket.h

@@ -48,39 +48,91 @@ public:
     job_time_ = QDateTime::currentMSecsSinceEpoch();
   }
 
-  void WaitForFinished();
+  /**
+   * @brief Get the ticket's current state
+   *
+   * This function is thread safe, unless `lock` is set to false. Then the caller has responsibility
+   * of locking the mutex before and unlocking after this function is called.
+   */
+  bool IsRunning(bool lock = true);
 
+  /**
+   * @brief Determine how many times ticket has been finished
+   *
+   * This function is thread safe, unless `lock` is set to false. Then the caller has responsibility
+   * of locking the mutex before and unlocking after this function is called.
+   */
+  int GetFinishCount(bool lock = true);
+
+  /**
+   * @brief Check if this ticket has a result
+   *
+   * If this ticket is running, this will always return false.
+   */
+  bool HasResult();
+
+  /**
+   * @brief Get value, if any
+   */
   QVariant Get();
 
-  bool HasStarted();
-
-  bool IsFinished(bool lock = true);
-
-  bool WasCancelled();
+  /**
+   * @brief Wait for ticket to be finished
+   *
+   * If this ticket is not running, this function returns immediately.
+   */
+  void WaitForFinished();
+  void WaitForFinished(QMutex* mutex);
 
+  /**
+   * @brief Access this ticket's mutex
+   *
+   * Use if you're doing several operations on a ticket and need to ensure thread safety while
+   * doing so. Most of the time this isn't necessary since all functions are thread safe by default.
+   */
   QMutex* lock()
   {
     return &lock_;
   }
 
+  /**
+   * @brief Signal to the ticket that it is running
+   *
+   * If any value is set, it is cleared.
+   */
   void Start();
 
-  void Finish(QVariant result, bool cancelled);
+  /**
+   * @brief Finish ticket with no value
+   *
+   * Sets ticket to no longer running and assume it has received no result.
+   */
+  void Finish();
 
-  void Cancel();
+  /**
+   * @brief Finish ticket with value
+   *
+   * Sets ticket to no longer running and provide a value generated by the operation requested.
+   */
+  void Finish(QVariant result);
 
 signals:
+  /**
+   * @brief Emitted when finish has been called by any means (either cancelled or with a result)
+   */
   void Finished();
 
 private:
-  bool started_;
+  void FinishInternal(bool has_result, QVariant result);
 
-  bool finished_;
-
-  bool cancelled_;
+  bool is_running_;
 
   QVariant result_;
 
+  bool has_result_;
+
+  int finish_count_;
+
   QMutex lock_;
 
   QWaitCondition wait_;