render plot with a single dataseriew

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

@@ -1,23 +1,11 @@
 package org.lucares.performance.db;
 
 class Fields {
-	static final String TAG_PREFIX = "__tag_";
+	static final String PREFIX_INTERNAL_TAG = "__internal_";
 
-	static final String DATE_OFFSET = "__date_offset__";
+	static final String DATE_OFFSET = PREFIX_INTERNAL_TAG + "date_offset";
 
-	static String prefixedKey(final String key) {
-		return TAG_PREFIX + key;
+	static boolean isInternalField(final String key) {
+		return key.startsWith(PREFIX_INTERNAL_TAG);
 	}
-
-	static boolean isPrefixedKey(final String key) {
-		return key.startsWith(TAG_PREFIX);
-	}
-
-	static String stripPrefix(final String key) {
-		if (!isPrefixedKey(key)) {
-			throw new IllegalArgumentException(key + " is not prefixed by " + TAG_PREFIX);
-		}
-		return key.substring(TAG_PREFIX.length());
-	}
-
 }

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

@@ -31,6 +31,9 @@ public class PdbFileIterator implements Iterator<Entry>, AutoCloseable {
 			if (reader == null) {
 				nextFile();
 			}
+			if (reader == null) {
+				return null;
+			}
 			final Optional<Entry> optionalEntry = reader.readEntry(currentPdbFile.getTags());
 
 			return optionalEntry.orElseGet(() -> {

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

@@ -115,7 +115,22 @@ public class PerformanceDb implements AutoCloseable {
 	public Stream<Entry> get(final Tags tags) {
 
 		final List<PdbFile> pdbFiles = tagsToFile.getFilesMatchingTags(tags);
+		return toStream(pdbFiles);
+	}
 
+	/**
+	 * Return the entries as an unbound, ordered and non-parallel stream.
+	 *
+	 * @param query
+	 * @return {@link Stream} unbound, ordered and non-parallel
+	 */
+	public Stream<Entry> get(final String query) {
+
+		final List<PdbFile> pdbFiles = tagsToFile.getFilesForQuery(query);
+		return toStream(pdbFiles);
+	}
+
+	private Stream<Entry> toStream(final List<PdbFile> pdbFiles) {
 		final Iterator<Entry> iterator = new PdbFileIterator(pdbFiles);
 
 		final Spliterator<Entry> spliterator = Spliterators.spliteratorUnknownSize(iterator, Spliterator.ORDERED);

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

@@ -6,7 +6,7 @@ final class Query {
 
 		for (final String key : tags.getKeys()) {
 			tags.getValue(key).ifPresent(value -> {
-				result.append(Fields.prefixedKey(key));
+				result.append(key);
 				result.append("=");
 				result.append(value);
 				result.append(" ");

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

@@ -21,6 +21,15 @@ public class Tags {
 
 	private Tags(final Map<String, String> tags) {
 		this.tags.putAll(tags);
+		ensureNoInternalFields();
+	}
+
+	private void ensureNoInternalFields() {
+		tags.keySet().forEach(key -> {
+			if (Fields.isInternalField(key)) {
+				throw new IllegalArgumentException(key + " is an internal field. Choose another prefix.");
+			}
+		});
 	}
 
 	public static Tags create() {

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

@@ -48,8 +48,12 @@ public class TagsToFile implements AutoCloseable, CollectionUtils {
 	}
 
 	List<PdbFile> getFilesMatchingTags(final Tags tags) {
-		final List<PdbFile> result = new ArrayList<>();
 		final String query = Query.createQuery(tags);
+		return getFilesForQuery(query);
+	}
+
+	List<PdbFile> getFilesForQuery(final String query) {
+		final List<PdbFile> result = new ArrayList<>();
 		try {
 			final List<Document> searchResult = db.search(query);
 
@@ -81,9 +85,9 @@ public class TagsToFile implements AutoCloseable, CollectionUtils {
 
 		for (final String key : document.getProperties().keySet()) {
 
-			if (Fields.isPrefixedKey(key)) {
+			if (!Fields.isInternalField(key)) {
 				final String value = document.getPropertyString(key);
-				tagsOfFile = tagsOfFile.copyAdd(Fields.stripPrefix(key), value);
+				tagsOfFile = tagsOfFile.copyAdd(key, value);
 			}
 		}
 		return tagsOfFile;
@@ -130,7 +134,7 @@ public class TagsToFile implements AutoCloseable, CollectionUtils {
 		ensureFieldsExist(tags);
 
 		tags.forEach((key, value) -> {
-			db.setProperty(file, Fields.prefixedKey(key), value);
+			db.setProperty(file, key, value);
 		});
 
 		db.setProperty(file, Fields.DATE_OFFSET, day.serialize());
@@ -145,11 +149,9 @@ public class TagsToFile implements AutoCloseable, CollectionUtils {
 
 		tags.forEach((key, value) -> {
 
-			final String prefixedKey = Fields.prefixedKey(key);
-
-			final Field field = fieldsMap.get(prefixedKey);
+			final Field field = fieldsMap.get(key);
 			if (field == null) {
-				db.createField(prefixedKey, FieldType.STRING);
+				db.createField(key, FieldType.STRING);
 			}
 		});
 	}