adixitconfluent commented on code in PR #19148:
URL: https://github.com/apache/kafka/pull/19148#discussion_r1990559413
##########
server/src/main/java/org/apache/kafka/server/share/fetch/PartitionRotateStrategy.java:
##########
@@ -80,20 +81,8 @@ static LinkedHashMap<TopicIdPartition, Integer>
rotateRoundRobin(
return topicIdPartitions;
}
- // TODO: Once the partition max bytes is removed then the partition
will be a linked list and rotation
- // will be a simple operation. Else consider using
ImplicitLinkedHashCollection.
- LinkedHashMap<TopicIdPartition, Integer> suffixPartitions = new
LinkedHashMap<>(rotateAt);
- LinkedHashMap<TopicIdPartition, Integer> rotatedPartitions = new
LinkedHashMap<>(topicIdPartitions.size());
- int i = 0;
- for (Map.Entry<TopicIdPartition, Integer> entry :
topicIdPartitions.entrySet()) {
- if (i < rotateAt) {
- suffixPartitions.put(entry.getKey(), entry.getValue());
- } else {
- rotatedPartitions.put(entry.getKey(), entry.getValue());
- }
- i++;
- }
- rotatedPartitions.putAll(suffixPartitions);
+ List<TopicIdPartition> rotatedPartitions = new
ArrayList<>(topicIdPartitions);
+ Collections.rotate(rotatedPartitions, -1 * rotateAt);
Review Comment:
I have added the comment `We want the elements from the end of the list to
move left by the distance provided i.e. if the original list is [1,2,3], and we
want to rotate it by 1, we want the output as [2,3,1] and not [3,1,2]. Hence,
we need negation of distance here` in the code. Regarding why I multiplied -1
to `rotateAt` instead of -`rotateAt`, its because `-1 * rotateAt` looks cleaner
to me.
##########
server/src/main/java/org/apache/kafka/server/share/fetch/PartitionRotateStrategy.java:
##########
@@ -80,20 +81,8 @@ static LinkedHashMap<TopicIdPartition, Integer>
rotateRoundRobin(
return topicIdPartitions;
}
- // TODO: Once the partition max bytes is removed then the partition
will be a linked list and rotation
- // will be a simple operation. Else consider using
ImplicitLinkedHashCollection.
- LinkedHashMap<TopicIdPartition, Integer> suffixPartitions = new
LinkedHashMap<>(rotateAt);
- LinkedHashMap<TopicIdPartition, Integer> rotatedPartitions = new
LinkedHashMap<>(topicIdPartitions.size());
- int i = 0;
- for (Map.Entry<TopicIdPartition, Integer> entry :
topicIdPartitions.entrySet()) {
- if (i < rotateAt) {
- suffixPartitions.put(entry.getKey(), entry.getValue());
- } else {
- rotatedPartitions.put(entry.getKey(), entry.getValue());
- }
- i++;
- }
- rotatedPartitions.putAll(suffixPartitions);
+ List<TopicIdPartition> rotatedPartitions = new
ArrayList<>(topicIdPartitions);
+ Collections.rotate(rotatedPartitions, -1 * rotateAt);
Review Comment:
I have added the comment `We want the elements from the end of the list to
move left by the distance provided i.e. if the original list is [1,2,3], and we
want to rotate it by 1, we want the output as [2,3,1] and not [3,1,2]. Hence,
we need negation of distance here` in the code. Regarding why I multiplied -1
to `rotateAt` instead of -`rotateAt`, its because `-1 * rotateAt` looks cleaner
code to me.
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