core/src/main/java/com/orientechnologies/orient/core/storage/impl/local/statistic/OSessionStoragePerformanceStatistic.java
public void stopWriteCacheFlushTimer(int pagesFlushed) {
    // lazy initialization to prevent memory consumption
    if (writCacheCountersHolder == null)
      writCacheCountersHolder = new WritCacheCountersHolder();

    final long endTs = nanoTimer.getNano();
    final long timeDiff = (endTs - timeStamps.pop());

    writCacheCountersHolder.flushOperationsCount++;

    writCacheCountersHolder.amountOfPagesFlushed += pagesFlushed;
    writCacheCountersHolder.flushOperationsTime += timeDiff;

    makeSnapshotIfNeeded(endTs);
  }
public void stopWriteCacheFlushTimer(int pagesFlushed) {
    // lazy initialization to prevent memory consumption
    if (writCacheCountersHolder == null)
      writCacheCountersHolder = new WritCacheCountersHolder();

    final long endTs = nanoTimer.getNano();
    final long timeDiff = (endTs - timeStamps.pop());

    writCacheCountersHolder.flushOperationsCount++;

    writCacheCountersHolder.amountOfPagesFlushed += pagesFlushed;
    writCacheCountersHolder.flushOperationsTime += timeDiff;

    makeSnapshotIfNeeded(endTs);
  }
Stops and records results of timer which counts how much time was spent on operation of flush pages in write cache.

@param pagesFlushed Amount of pages were flushed during this operation.