Merge pull request #835 from chiliec/sorted-config-file

Write yacy.conf with alphabetically sorted keys

source/net/yacy/kelondro/util/FileUtils.java

@@ -56,6 +56,7 @@ import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.TreeMap;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.zip.GZIPInputStream;
 
@@ -539,7 +540,7 @@ public final class FileUtils {
         final Object lock = SAVE_MAP_LOCKS.computeIfAbsent(lockKey, k -> new Object());
         synchronized (lock) {
             /* Take the snapshot in write order so delayed callers cannot persist stale state. */
-            final Map<String, String> propsCopy = new HashMap<>(props);
+            final Map<String, String> propsCopy = new TreeMap<>(props);
             File tf = null;
             PrintWriter pw = null;
             try {

test/java/net/yacy/kelondro/util/FileUtilsTest.java

@@ -23,12 +23,18 @@ package net.yacy.kelondro.util;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
+import java.io.File;
 import java.io.FilterInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.StringReader;
 import java.io.StringWriter;
 import java.nio.charset.StandardCharsets;
+import java.nio.file.Files;
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
 
 import org.junit.Assert;
 import org.junit.BeforeClass;
@@ -258,4 +264,31 @@ public class FileUtilsTest {
 			Assert.assertEquals(sourceBytes.length, FileUtils.read(source, sourceBytes.length + 10).length);
 		}
 	}
+
+	/**
+	 * Test saving a map to a file writes keys in a stable alphabetical order.
+	 * @throws IOException when a read/write error occurred
+	 */
+	@Test
+	public void testSaveMapSortedKeys() throws IOException {
+		final Map<String, String> props = new HashMap<>();
+		props.put("zeta", "1");
+		props.put("alpha", "2");
+		props.put("mu", "3");
+		props.put("beta", "4");
+		final File file = File.createTempFile("FileUtilsTest", ".conf");
+		try {
+			FileUtils.saveMap(file, props, "test");
+			final List<String> keys = new ArrayList<>();
+			for (final String line : Files.readAllLines(file.toPath(), StandardCharsets.UTF_8)) {
+				if (!line.startsWith("#")) {
+					keys.add(line.substring(0, line.indexOf('=')));
+				}
+			}
+			Assert.assertEquals(List.of("alpha", "beta", "mu", "zeta"), keys);
+			Assert.assertEquals(props, FileUtils.loadMap(file));
+		} finally {
+			file.delete();
+		}
+	}
 }