From 9daeea823b85c2a447afca73c4d35efe2d969cf1 Mon Sep 17 00:00:00 2001
From: luccioman <luccioman@users.noreply.github.com>
Date: Sat, 10 Nov 2018 22:00:49 +0100
Subject: Fixed concurrency issue on cache used for circles rendering

Without synchronization lock, concurrent rendering of images including
circles could lead to glitches as reported in issue #248
---
 .../net/yacy/visualization/CircleToolTest.java     | 119 +++++++++++++++++++++
 1 file changed, 119 insertions(+)
 create mode 100644 test/java/net/yacy/visualization/CircleToolTest.java

(limited to 'test/java')

diff --git a/test/java/net/yacy/visualization/CircleToolTest.java b/test/java/net/yacy/visualization/CircleToolTest.java
new file mode 100644
index 000000000..14fda8c23
--- /dev/null
+++ b/test/java/net/yacy/visualization/CircleToolTest.java
@@ -0,0 +1,119 @@
+// CircleToolTest.java
+// Copyright 2018 by luccioman; https://github.com/luccioman
+//
+// This is a part of YaCy, a peer-to-peer based web search engine
+//
+// LICENSE
+//
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 2 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+package net.yacy.visualization;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.ArrayList;
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+import org.bouncycastle.util.Arrays;
+import org.junit.Assert;
+import org.junit.Test;
+
+import net.yacy.peers.graphics.EncodedImage;
+
+/**
+ * Unit tests for the {@link CircleTool} class.
+ */
+public class CircleToolTest {
+
+	/**
+	 * Check circle function consistency when run on multiple concurrent threads.
+	 *
+	 * @throws Exception when an unexpected error occurred
+	 */
+	@Test
+	public void testCircleConcurrentConsistency() throws Exception {
+		final int concurrency = 20;
+		final int side = 600;
+		final String ext = "png";
+
+		final Callable<byte[]> drawTask = () -> {
+			final RasterPlotter raster = new RasterPlotter(side, side, RasterPlotter.DrawMode.MODE_SUB, "FFFFFF");
+			for (int radius = side / 4; radius < side / 2; radius++) {
+				raster.setColor(RasterPlotter.GREEN);
+				CircleTool.circle(raster, side / 2, side / 2, radius, 100);
+				raster.setColor(RasterPlotter.RED);
+				CircleTool.circle(raster, side / 2, side / 2, radius, 0, 45);
+			}
+
+			final EncodedImage image = new EncodedImage(raster, ext, true);
+			return image.getImage().getBytes();
+		};
+
+		/* Generate a reference image without concurrency */
+		CircleTool.clearcache();
+		final byte[] refImageBytes = drawTask.call();
+
+		/* Write the reference image to the file system to enable manual visual check */
+		final Path outputPath = Paths.get(System.getProperty("java.io.tmpdir", ""), "CircleToolTest." + ext);
+		try {
+			Files.write(outputPath, refImageBytes);
+			System.out.println("Wrote CircleTool.circle() test image to file " + outputPath.toAbsolutePath());
+		} catch (final IOException e) {
+			/*
+			 * Even if output file writing failed we do not make the test fail as this is
+			 * not the purpose of the test
+			 */
+			e.printStackTrace();
+		}
+
+		/*
+		 * Generate the same image multiple times in concurrent threads without initial
+		 * cache
+		 */
+		CircleTool.clearcache();
+		final ExecutorService executor = Executors.newFixedThreadPool(concurrency);
+		final ArrayList<Future<byte[]>> futures = new ArrayList<>();
+		for (int i = 0; i < concurrency; i++) {
+			futures.add(executor.submit(drawTask));
+		}
+		try {
+			for (final Future<byte[]> future : futures) {
+				/* Check that all concurrently generated images are equal to the reference */
+				final byte[] imageBytes = future.get();
+				if (!Arrays.areEqual(refImageBytes, imageBytes)) {
+					/* Write the image in error to file system to enable manual visual check */
+					final Path errOutputPath = Paths.get(System.getProperty("java.io.tmpdir", ""),
+							"CircleToolTestError." + ext);
+					try {
+						Files.write(errOutputPath, imageBytes);
+						System.out.println(
+								"Wrote CircleTool.circle() error image to file " + errOutputPath.toAbsolutePath());
+					} catch (final IOException e) {
+						e.printStackTrace();
+					}
+					Assert.fail();
+				}
+			}
+		} finally {
+			executor.shutdown();
+		}
+	}
+
+}
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