Class Metrics

solr/core/src/java/org/apache/solr/blockcache/Metrics.java:30–162

A SolrInfoBean that provides metrics on block cache operations. @lucene.experimental

 * @lucene.experimental
 */
public class Metrics extends SolrCacheBase implements SolrInfoBean {

  public AtomicLong blockCacheSize = new AtomicLong(0);
  public AtomicLong blockCacheHit = new AtomicLong(0);
  public AtomicLong blockCacheMiss = new AtomicLong(0);
  public AtomicLong blockCacheEviction = new AtomicLong(0);
  public AtomicLong blockCacheStoreFail = new AtomicLong(0);

  // since the last call
  private AtomicLong blockCacheHit_last = new AtomicLong(0);
  private AtomicLong blockCacheMiss_last = new AtomicLong(0);
  private AtomicLong blockCacheEviction_last = new AtomicLong(0);
  public AtomicLong blockCacheStoreFail_last = new AtomicLong(0);

  // These are used by the BufferStore (just a generic cache of byte[]).
  // TODO: If this (the Store) is a good idea, we should make it more general and use it across more
  // places in Solr.
  public AtomicLong shardBuffercacheAllocate = new AtomicLong(0);
  public AtomicLong shardBuffercacheLost = new AtomicLong(0);

  private SolrMetricsContext solrMetricsContext;
  private long previous = System.nanoTime();

  @Override
  public void initializeMetrics(SolrMetricsContext parentContext, Attributes attributes) {
    solrMetricsContext = parentContext.getChildContext(this);
    var baseAttributes =
        attributes.toBuilder().put(CATEGORY_ATTR, getCategory().toString()).build();
    var blockcacheStats =
        solrMetricsContext.longGaugeMeasurement("solr_block_cache_stats", "Block cache stats");
    var hitRatio =
        solrMetricsContext.doubleGaugeMeasurement(
            "solr_block_cache_hit_ratio", "Block cache hit ratio");
    var perSecStats =
        solrMetricsContext.doubleGaugeMeasurement(
            "solr_block_cache_stats_per_second", "Block cache per second stats");
    var bufferCacheStats =
        solrMetricsContext.doubleGaugeMeasurement(
            "solr_buffer_cache_stats", "Buffer cache per second stats");

    solrMetricsContext.batchCallback(
        () -> {
          long now = System.nanoTime();
          long delta = Math.max(now - previous, 1);
          double seconds = delta / 1000000000.0;

          long hits_total = blockCacheHit.get();
          long hits_delta = hits_total - blockCacheHit_last.get();
          blockCacheHit_last.set(hits_total);

          long miss_total = blockCacheMiss.get();
          long miss_delta = miss_total - blockCacheMiss_last.get();
          blockCacheMiss_last.set(miss_total);

          long evict_total = blockCacheEviction.get();
          long evict_delta = evict_total - blockCacheEviction_last.get();
          blockCacheEviction_last.set(evict_total);