change directory structure

- the tags come first, then the date, 
  e.g. "mykey=myvalue_<uuid>/2016/01/01/<uuid>"
- We do this, so that we don't have to tag each file, 
  but only the root folder. This should speed up searches

performanceDb/src/main/java/org/lucares/performance/db/StorageUtils.java

@@ -1,11 +1,16 @@
 package org.lucares.performance.db;
 
-import java.io.File;
 import java.nio.file.Path;
+import java.util.UUID;
 
 public class StorageUtils {
 
-	static File createStorageFile(final Path parent, final Day day, final String name) {
+	public static Path createStorageFile(final Path parent, final String tagBaseDir, final Day day) {
-		return new File(parent.toFile(), day.format(File.separator) + File.separator + name);
+
+		final Path tagSpecificFolder = parent.resolve(tagBaseDir);
+		final Path dateSpecificFolder = tagSpecificFolder.resolve(day.format("/"));
+		final Path storageFile = dateSpecificFolder.resolve(UUID.randomUUID().toString());
+
+		return storageFile;
 	}
 }

performanceDb/src/main/java/org/lucares/performance/db/TagsToFile.java

@@ -145,16 +145,16 @@ public class TagsToFile implements CollectionUtils {
 
 	private File createNewFile(final OffsetDateTime date, final Tags tags) {
 		final Day day = new Day(date);
-		final String name = tags.abbreviatedRepresentation() + UUID.randomUUID().toString();
+		final String tagBaseDir = tags.abbreviatedRepresentation() + UUID.randomUUID().toString();
 
-		final File result = StorageUtils.createStorageFile(dataDirectory, day, name);
+		final Path result = StorageUtils.createStorageFile(dataDirectory, tagBaseDir, day);
 		try {
-			Files.createDirectories(result.getParentFile().toPath());
+			Files.createDirectories(result.getParent());
-			Files.createFile(result.toPath());
+			Files.createFile(result);
 		} catch (final IOException e) {
 			throw new IllegalStateException(e); // very unlikely
 		}
 
-		return result;
+		return result.toFile();
 	}
 }

performanceDb/src/test/java/org/lucares/performance/db/PerformanceDbTest.java

@@ -5,11 +5,11 @@ import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.time.OffsetDateTime;
-import java.time.ZoneOffset;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.concurrent.ThreadLocalRandom;
+import java.util.stream.Collectors;
 
 import org.apache.commons.collections4.CollectionUtils;
 import org.lucares.pdb.api.Entry;
@@ -92,7 +92,11 @@ public class PerformanceDbTest {
 
 		try (PerformanceDb db = new PerformanceDb(dataDirectory)) {
 
-			final TimeRange timeRange = TimeRange.ofDay(OffsetDateTime.now(ZoneOffset.UTC));
+			final int year = 2016;
+			final int month = 1;
+			final int day = 2;
+
+			final TimeRange timeRange = TimeRange.ofDay(DateUtils.getDate(year, month, day, 1, 1, 1));
 			final long numberOfEntries = 2;
 
 			final Tags tags = Tags.create("myKey", "one");
@@ -107,10 +111,14 @@ public class PerformanceDbTest {
 			final List<Entry> actualEntries = db.get(Query.createQuery(tags)).singleGroup().asList();
 			Assert.assertEquals(actualEntries, entries);
 
-			final File storageFileForToday = StorageUtils.createStorageFile(dataDirectory, new Day(timeRange.getFrom()),
+			final List<Path> foldersInStorage = Files.list(dataDirectory).filter(Files::isDirectory)
-					"name doesn't matter");
+					.collect(Collectors.toList());
-			final File storageFolderForToday = storageFileForToday.getParentFile();
+			Assert.assertEquals(foldersInStorage.size(), 1);
-			final File[] filesInStorage = storageFolderForToday.listFiles();
+
+			final Path dateSpecificFolder = foldersInStorage.get(0)
+					.resolve(new Day(timeRange.getFrom()).format(File.separator));
+
+			final File[] filesInStorage = dateSpecificFolder.toFile().listFiles();
 			Assert.assertEquals(filesInStorage.length, 1,
 					"one file in storage, but was: " + Arrays.asList(filesInStorage));
 		}