什么可以替代动态更改运行图？这是我的情况。我有图表将文章摄入DB。文章来自3种不同格式的插件。因此，我有几个流程
val converterFlow1: Flow[ImpArticle, Article, NotUsed]
val converterFlow2: Flow[NewsArticle, Article, NotUsed]
val sinkDB: Sink[Article, Future[Done]]
// These are being created every time I poll plugins
val sourceContentProvider : Source[ImpArticle, NotUsed]
val sourceNews : Source[NewsArticle, NotUsed]
val sourceCit : Source[Article, NotUsed]
val merged = Source.combine(
sourceContentProvider.via(converterFlow1),
sourceNews.via(converterFlow2),
sourceCit)(Merge(_))
val res = merged
.buffer(10, OverflowStrategy.backpressure)
.toMat(sinkDB)(Keep.both)
.run()
问题是我每24小时从内容提供商处获取一次数据，每2小时一次从新闻获取数据，最后一个来源可能随时来自，因为它来自人类。
我意识到图表是不可变的，但我如何定期将Source的新实例附加到我的图表中，以便我对摄取过程进行单点限制？
更新：您可以说我的数据是Source - s的流，在我的情况下有三个来源。但我不能改变它，因为我从外部类（所谓的插件）获取Source的实例。这些插件独立于我的摄取类。我不能将它们组合成一个巨大的类，以便有单Source。
答案 0 :(得分：3)
好的，一般来说，正确的方法是将来源流加入单一来源，即从Source[Source[T, _], Whatever]转到Source[T, Whatever]。这可以使用flatMapConcat或flatMapMerge来完成。因此，如果您可以获得Source[Source[Article, NotUsed], NotUsed]，则可以使用flatMap*个变种之一并获得最终Source[Article, NotUsed]。为你的每个来源做这件事（没有双关语），然后你的原始方法应该有用。
答案 1 :(得分：2)
我已根据Vladimir Matveev给出的答案实施了代码，并希望与其他人分享，因为它看起来像是我的常见用例。
我知道Viktor Klang提到的rep(1:4, c(1, 2, 3, 4))
[1] 1 2 2 3 3 3 4 4 4 4
，但我不知道 #include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
int main()
{
cv::Mat input = cv::imread("pallet.jpg");
// convert to grayscale (you could load as grayscale instead)
cv::Mat gray;
cv::cvtColor(input,gray, CV_BGR2GRAY);
// compute mask (you could use a simple threshold if the image is always as good as the one you provided)
cv::Mat mask;
cv::threshold(gray, mask, 0, 255, CV_THRESH_BINARY_INV | CV_THRESH_OTSU);
// find contours (if always so easy to segment as your image, you could just add the black/rect pixels to a vector)
std::vector<std::vector<cv::Point> > contours;
std::vector<cv::Vec4i> hierarchy;
cv::findContours(mask,contours, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE);
/// Draw contours and find biggest contour (if there are other contours in the image, we assume the biggest one is the desired rect)
// drawing here is only for demonstration!
int biggestContourIdx = -1;
float biggestContourArea = 0;
cv::Mat drawing = cv::Mat::zeros( mask.size(), CV_8UC3 );
for( int i = 0; i< contours.size(); i++ )
{
cv::Scalar color = cv::Scalar(0, 100, 0);
drawContours( drawing, contours, i, color, 1, 8, hierarchy, 0, cv::Point() );
float ctArea= cv::contourArea(contours[i]);
if(ctArea > biggestContourArea)
{
biggestContourArea = ctArea;
biggestContourIdx = i;
}
}
// if no contour found
if(biggestContourIdx < 0)
{
std::cout << "no contour found" << std::endl;
return 1;
}
// compute the rotated bounding rect of the biggest contour! (this is the part that does what you want/need)
cv::RotatedRect boundingBox = cv::minAreaRect(contours[biggestContourIdx]);
// one thing to remark: this will compute the OUTER boundary box, so maybe you have to erode/dilate if you want something between the ragged lines
// draw the rotated rect
cv::Point2f corners[4];
boundingBox.points(corners);
cv::line(drawing, corners[0], corners[1], cv::Scalar(255,255,255));
cv::line(drawing, corners[1], corners[2], cv::Scalar(255,255,255));
cv::line(drawing, corners[2], corners[3], cv::Scalar(255,255,255));
cv::line(drawing, corners[3], corners[0], cv::Scalar(255,255,255));
// display
cv::imshow("input", input);
cv::imshow("drawing", drawing);
cv::waitKey(0);
cv::imwrite("rotatedRect.png",drawing);
return 0;
}
。这真是太棒了。
Source.queue我仍然会检查flatMapConcat返回的implicit val system = ActorSystem("root")
implicit val executor = system.dispatcher
implicit val materializer = ActorMaterializer()
case class ImpArticle(text: String)
case class NewsArticle(text: String)
case class Article(text: String)
val converterFlow1: Flow[ImpArticle, Article, NotUsed] = Flow[ImpArticle].map(a => Article("a:" + a.text))
val converterFlow2: Flow[NewsArticle, Article, NotUsed] = Flow[NewsArticle].map(a => Article("a:" + a.text))
val sinkDB: Sink[Article, Future[Done]] = Sink.foreach { a =>
Thread.sleep(1000)
println(a)
}
// These are being created every time I poll plugins
val sourceContentProvider: Source[ImpArticle, NotUsed] = Source(List(ImpArticle("cp1"), ImpArticle("cp2")))
val sourceNews: Source[NewsArticle, NotUsed] = Source(List(NewsArticle("news1"), NewsArticle("news2")))
val sourceCit: Source[Article, NotUsed] = Source(List(Article("a1"), Article("a2")))
val (queue, completionFut) = Source
.queue[Source[Article, NotUsed]](10, backpressure)
.flatMapConcat(identity)
.buffer(2, OverflowStrategy.backpressure)
.toMat(sinkDB)(Keep.both)
.run()
queue.offer(sourceContentProvider.via(converterFlow1))
queue.offer(sourceNews.via(converterFlow2))
queue.offer(sourceCit)
queue.complete()
completionFut.onComplete {
case Success(res) =>
println(res)
system.terminate()
case Failure(ex) =>
ex.printStackTrace()
system.terminate()
}
Await.result(system.whenTerminated, Duration.Inf)
是否成功，但在我的情况下，这些来电很少见。
答案 2 :(得分：1)
如果您无法将其建模为Source[Source[_,_],_]，那么请考虑使用Source.queue[Source[T,_]](queueSize, overflowStrategy)：here
如果提交失败，那么你必须要小心的是。