cmccabe commented on a change in pull request #11311:
URL: https://github.com/apache/kafka/pull/11311#discussion_r712471886
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File path: metadata/src/main/java/org/apache/kafka/image/TopicsImage.java
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@@ -92,6 +98,148 @@ public int hashCode() {
return Objects.hash(topicsById, topicsByName);
}
+ /**
+ * Expose a view of this TopicsImage as a map from topic names to IDs.
+ *
+ * Like TopicsImage itself, this map is immutable.
+ */
+ public Map<String, Uuid> topicNameToIdView() {
+ return new TopicNameToIdMap();
+ }
+
+ class TopicNameToIdMap extends AbstractMap<String, Uuid> {
+ private final TopicNameToIdMapEntrySet set = new
TopicNameToIdMapEntrySet();
+
+ @Override
+ public boolean containsKey(Object key) {
+ return topicsByName.containsKey(key);
+ }
+
+ @Override
+ public Uuid get(Object key) {
+ TopicImage image = topicsByName.get(key);
+ if (image == null) return null;
+ return image.id();
+ }
+
+ @Override
+ public Set<Entry<String, Uuid>> entrySet() {
+ return set;
+ }
+ }
+
+ class TopicNameToIdMapEntrySet extends AbstractSet<Entry<String, Uuid>> {
+ @Override
+ public Iterator<Entry<String, Uuid>> iterator() {
+ return new
TopicNameToIdMapEntrySetIterator(topicsByName.entrySet().iterator());
+ }
+
+ @SuppressWarnings("rawtypes")
+ @Override
+ public boolean contains(Object o) {
+ if (!(o instanceof Entry)) return false;
+ Entry other = (Entry) o;
+ TopicImage image = topicsByName.get(other.getKey());
+ if (image == null) return false;
+ return image.id().equals(other.getValue());
+ }
+
+ @Override
+ public int size() {
+ return topicsByName.size();
+ }
+ }
+
+ static class TopicNameToIdMapEntrySetIterator implements
Iterator<Entry<String, Uuid>> {
+ private final Iterator<Entry<String, TopicImage>> iterator;
+
+ TopicNameToIdMapEntrySetIterator(Iterator<Entry<String, TopicImage>>
iterator) {
+ this.iterator = iterator;
+ }
+
+ @Override
+ public boolean hasNext() {
+ return this.iterator.hasNext();
+ }
+
+ @Override
+ public Entry<String, Uuid> next() {
+ Entry<String, TopicImage> entry = iterator.next();
+ return new SimpleImmutableEntry<>(entry.getKey(),
entry.getValue().id());
+ }
+ }
+
+ /**
+ * Expose a view of this TopicsImage as a map from IDs to names.
+ *
+ * Like TopicsImage itself, this map is immutable.
+ */
+ public Map<Uuid, String> topicIdToNameView() {
+ return new TopicIdToNameMap();
+ }
+
+ class TopicIdToNameMap extends AbstractMap<Uuid, String> {
+ private final TopicIdToNameMapEntrySet set = new
TopicIdToNameMapEntrySet();
+
+ @Override
+ public boolean containsKey(Object key) {
+ return topicsById.containsKey(key);
+ }
+
+ @Override
+ public String get(Object key) {
+ TopicImage image = topicsById.get(key);
+ if (image == null) return null;
+ return image.name();
+ }
+
+ @Override
+ public Set<Entry<Uuid, String>> entrySet() {
+ return set;
+ }
+ }
+
+ class TopicIdToNameMapEntrySet extends AbstractSet<Entry<Uuid, String>> {
Review comment:
Yeah, I thought about that, but with only two cases, it didn't seem
worth it. If I have to add a third case, then I'll try to make something
generic, I guess.
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