ExtendedS3Storage class does not publish any storage related metrics

[sachin-j-joshi]

Problem description
ExtendedS3Storage class does not publish any storage related metrics.

Problem location
ExtendedS3Storage implementation.

Suggestions for an improvement

Implement following metrics.

// Storage stats
    public static final String STORAGE_READ_LATENCY = PREFIX + "segmentstore.storage.read_latency_ms";   // Histogram
    public static final String STORAGE_WRITE_LATENCY = PREFIX + "segmentstore.storage.write_latency_ms"; // Histogram
    public static final String STORAGE_READ_BYTES = PREFIX + "segmentstore.storage.read_bytes";          // Counter
    public static final String STORAGE_WRITE_BYTES = PREFIX + "segmentstore.storage.write_bytes";        // Counter
    public static final String STORAGE_CREATE_COUNT = PREFIX + "segmentstore.storage.create_count";      // Counter

Define metrics for ECS in following class and use it in ExtendedS3Storage.java at appropriate places

final class ExtendedS3Metrics {
    private static final StatsLogger ECS_LOGGER = MetricsProvider.createStatsLogger("ecs");
    static final OpStatsLogger READ_LATENCY = ECS_LOGGER.createStats(MetricsNames.STORAGE_READ_LATENCY);
    static final OpStatsLogger WRITE_LATENCY = ECS_LOGGER.createStats(MetricsNames.STORAGE_WRITE_LATENCY);
    static final Counter READ_BYTES = ECS_LOGGER.createCounter(MetricsNames.STORAGE_READ_BYTES);
    static final Counter WRITE_BYTES = ECS_LOGGER.createCounter(MetricsNames.STORAGE_WRITE_BYTES);
    static final Counter CREATE_COUNT = ECS_LOGGER.createCounter(MetricsNames.STORAGE_CREATE_COUNT);
}