Improve RedisFieldValueCounterRepository

[artembilan]

From @sabbyanandan on May 6, 2016 17:8

From @ericbottard on December 18, 2015 11:21

Investigate possibility of directly serializing to a Map (instead of a Set<ZSetOperations.TypedTuple<String>>) in RedisFieldValueCounterRepository.getZSetData(String counterKey)

see https://github.com/spring-cloud/spring-cloud-stream-modules/blob/7004eedcf5a8df87eaf8f9a3a796c0dab26ed5c0/field-value-counter-sink/src/main/java/org/springframework/cloud/stream/module/metrics/RedisFieldValueCounterRepository.java#L105

Copied from original issue: spring-cloud/spring-cloud-stream-modules#138

Copied from original issue: spring-cloud/spring-cloud-stream-app-starters#67

Copied from original issue: spring-attic/field-value-counter#1

The old code says:

protected Map<String, Double> getZSetData(String counterKey) {
		// TODO directly serialize into a Map vs Set of TypedTuples to avoid extra copy
		Set<ZSetOperations.TypedTuple<String>> rangeWithScore = this.redisTemplate
.boundZSetOps(counterKey).rangeWithScores(0, -1);