限制javafx gui更新 [英] Throttling javafx gui updates

问题描述

我随机地以高频率接收数据对象，并且需要使用这些来更新JavaFX GUI。但是，我不想用大量的runnables填充javafx事件队列（我使用Platform.RunLater）。

I receive data objects at random times at a high frequency, and need to update the JavaFX GUI with these. However, I don't want to fill the javafx event queue with a very large number of runnables (I use Platform.RunLater).

我一直在考虑如何最好实现限制算法。

I have been thinking of how to best implement a throttling algorithm.

• 最好有一个单独的GUIUpdater线程来检查新对象的阻塞队列，以及然后睡觉例如30ms，然后再次检查，在无限循环中？在这种情况下，阻塞队列是否是最佳数据结构？请注意我只需要最新的数据对象而且blockingQueue是一个FIFO队列，我似乎无法选择最新的条目。


• 或者 - 只是更新才会更好如果nanoTime-startTime> 30ms，使用Platform.RunLater的GUI？在这种情况下，我不需要单独的线程来执行Platform.RunLater调用。但是 - 如果在30ms未通过时收到更新，然后一段时间内未收到任何更新，则最后一次更新将不会显示在GUI中。

关于如何以简短有效的方式为JavaFX Platform.RunLater GUI更新设计限制算法的任何建议？

Any suggestions on how to design a throttling algorithm for JavaFX Platform.RunLater GUI updates in a short, efficient way?

推荐答案

这是 任务 用于实现 updateMessage（...）方法和其他类似方法。它提供了一个漂亮，强大的解决方案，以避免泛滥FX应用程序线程：

This is the idiom used in the Task class for implementing the updateMessage(...) method, and other similar methods. It provides a nice, robust solution to avoid flooding the FX Application Thread:

import java.util.concurrent.atomic.AtomicLong;

import javafx.application.Application;
import javafx.application.Platform;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;

public class ThrottlingCounter extends Application {

    @Override
    public void start(Stage primaryStage) {
        final AtomicLong counter = new AtomicLong(-1);
        final Label label = new Label();
        final Thread countThread = new Thread(new Runnable() {
            @Override
            public void run() {
                long count = 0 ;
                while (true) {
                    count++ ;
                    if (counter.getAndSet(count) == -1) {
                        updateUI(counter, label);
                    }
                }
            }
        });
        countThread.setDaemon(true);
        countThread.start();

        VBox root = new VBox();
        root.getChildren().add(label);
        root.setPadding(new Insets(5));
        root.setAlignment(Pos.CENTER);

        Scene scene = new Scene(root, 150, 100);
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    private void updateUI(final AtomicLong counter,
            final Label label) {
        Platform.runLater(new Runnable() {
            @Override
            public void run() {
                final String msg = String.format("Count: %,d", counter.getAndSet(-1));
                label.setText(msg);
            }
        });
    }

    public static void main(String[] args) {
        launch(args);
    }
}

AtomicLong 保存用于更新Label的当前值。计数不断增加并更新 AtomicLong ，但仅调度对 Platform.runLater（...）的调用它的当前值是-1。 Platform.runLater（...）使用中的当前值更新标签 AtomicLong 并将 AtomicLong 翻转回-1，表示它已准备好进行新的更新。

The AtomicLong holds the current value to be used to update the Label. The count continually increments and updates the AtomicLong, but only schedules a call to Platform.runLater(...) if it's current value is -1. The Platform.runLater(...) updates the Label with the current value from the AtomicLong and flips the AtomicLong back to -1, indicating that it's ready for a new update.

这里的效果是在FX应用程序线程准备好处理它们时安排对 Platform.runLater（...）的新调用。没有硬编码的时间间隔可能需要调整。

The effect here is to schedule new calls to Platform.runLater(...) whenever the FX Application Thread is ready to handle them. There's no hard-coded time interval which could need tuning.

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