ringles commented on a change in pull request #7403:
URL: https://github.com/apache/geode/pull/7403#discussion_r839845893
##########
File path:
geode-for-redis/src/main/java/org/apache/geode/redis/internal/data/RedisList.java
##########
@@ -252,6 +253,56 @@ public void lset(Region<RedisKey, RedisData> region,
RedisKey key, int index, by
storeChanges(region, key, new ReplaceByteArrayAtOffset(index, value));
}
+ /**
+ * @param start the index of the first element to retain
+ * @param end the index of the last element to retain
+ * @param region the region this instance is stored in
+ * @param key the name of the list to pop from
+ */
+ public Void ltrim(int start, int end, Region<RedisKey, RedisData> region,
+ RedisKey key) {
+ int length = elementList.size();
+ int boundedStart = getBoundedStartIndex(start, length);
+ int boundedEnd = getBoundedEndIndex(end, length);
+
+ if (boundedStart > boundedEnd || boundedStart == length) {
+ // Remove everything
+ region.remove(key);
+ return null;
+ }
+
+ if (boundedStart == 0 && boundedEnd == length) {
+ // No-op, return without modifying the list
+ return null;
+ }
+
+ RetainElementsByIndexRange retainElementsByRange;
+ synchronized (this) {
+ elementsRetainByIndexRange(boundedStart, boundedEnd);
+
+ retainElementsByRange =
+ new RetainElementsByIndexRange(incrementAndGetVersion(),
boundedStart, boundedEnd);
+ }
+ storeChanges(region, key, retainElementsByRange);
+ return null;
+ }
+
+ private int getBoundedStartIndex(long index, int size) {
+ if (index >= 0L) {
+ return (int) Math.min(index, size);
+ } else {
+ return (int) Math.max(index + size, 0);
+ }
+ }
+
+ private int getBoundedEndIndex(long index, int size) {
Review comment:
Tweaked.
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