[GitHub] [kafka] agavra commented on a change in pull request #11120: Add support for infinite endpoints for range queries

[GitBox <gi...@apache.org>]

agavra commented on a change in pull request #11120:
URL: https://github.com/apache/kafka/pull/11120#discussion_r676851943



##########
File path: streams/src/main/java/org/apache/kafka/streams/state/internals/NamedCache.java
##########
@@ -281,11 +280,27 @@ public boolean isEmpty() {
     }
 
     synchronized Iterator<Bytes> keyRange(final Bytes from, final Bytes to, final boolean toInclusive) {
-        return keySetIterator(cache.navigableKeySet().subSet(from, true, to, toInclusive), true);
+        final Set<Bytes> rangeSet = computeSubSet(from, to, toInclusive);
+        return keySetIterator(rangeSet, true);
     }
 
     synchronized Iterator<Bytes> reverseKeyRange(final Bytes from, final Bytes to) {
-        return keySetIterator(cache.navigableKeySet().subSet(from, true, to, true), false);
+        final Set<Bytes> rangeSet = computeSubSet(from, to, true);
+        return keySetIterator(rangeSet, false);
+    }
+
+    private Set<Bytes> computeSubSet(final Bytes from, final Bytes to, final boolean toInclusive) {
+        if (from == null && to == null) {
+            return cache.navigableKeySet();
+        } else if (from == null) {
+            return cache.headMap(to, toInclusive).keySet();
+        } else if (to == null) {
+            return cache.tailMap(from, true).keySet();
+        } else if (from.compareTo(to) > 0) {
+            return new TreeSet<>();

Review comment:
       instead of creating a new set, thoughts on just returning an empty collection? (`Collections.emptyNavigableSet()`)

##########
File path: streams/src/main/java/org/apache/kafka/streams/state/internals/RocksDBRangeIterator.java
##########
@@ -63,17 +65,20 @@
         final KeyValue<Bytes, byte[]> next = super.makeNext();
         if (next == null) {
             return allDone();
+        } else if (rawLastKey == null) {
+            return next;
+
         } else {
             if (forward) {
-                if (comparator.compare(next.key.get(), rawLastKey) < 0) {
+                if (rawLastKey != null && comparator.compare(next.key.get(), rawLastKey) < 0) {

Review comment:
       how can `rawLastKey` be null here (c.f. branch above)?




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