minor refresh of the Statistics API

- added getStart() returning an Instance
- removed a left-over @MXBean annotation
- refreshed some Javadoc
- fixed some warnings

hibernate-core/src/main/java/org/hibernate/stat/CacheRegionStatistics.java

@@ -9,7 +9,7 @@ package org.hibernate.stat;
 import java.io.Serializable;
 
 /**
- * Second level cache statistics of a specific region
+ * Second-level cache statistics of a specific region.
  *
  * @author Gavin King
  */
@@ -43,7 +43,7 @@ public interface CacheRegionStatistics extends Serializable {
 
 	/**
 	 * The number of elements currently in memory within the cache provider.
-	 *
+	 * <p>
 	 * This is an optional value contingent upon the underlying cache provider
 	 * providing extended stats support via
 	 * {@link org.hibernate.cache.spi.ExtendedStatisticsSupport}.  If the provider
@@ -54,7 +54,7 @@ public interface CacheRegionStatistics extends Serializable {
 
 	/**
 	 * The number of elements currently stored to disk within the cache provider.
-	 *
+	 * <p>
 	 * This is an optional value contingent upon the underlying cache provider
 	 * providing extended stats support via
 	 * {@link org.hibernate.cache.spi.ExtendedStatisticsSupport}.  If the provider
@@ -65,7 +65,7 @@ public interface CacheRegionStatistics extends Serializable {
 
 	/**
 	 * The size that the in-memory elements take up within the cache provider.
-	 *
+	 * <p>
 	 * This is an optional value contingent upon the underlying cache provider
 	 * providing extended stats support via
 	 * {@link org.hibernate.cache.spi.ExtendedStatisticsSupport}.  If the provider

hibernate-core/src/main/java/org/hibernate/stat/CollectionStatistics.java

@@ -9,7 +9,7 @@ package org.hibernate.stat;
 import java.io.Serializable;
 
 /**
- * Collection related statistics
+ * Collection-related statistics.
  *
  * @author Gavin King
  * @author Steve Ebersole

hibernate-core/src/main/java/org/hibernate/stat/EntityStatistics.java

@@ -9,7 +9,7 @@ package org.hibernate.stat;
 import java.io.Serializable;
 
 /**
- * Entity related statistics
+ * Entity-related statistics.
  *
  * @author Gavin King
  * @author Steve Ebersole

hibernate-core/src/main/java/org/hibernate/stat/NaturalIdStatistics.java

@@ -9,12 +9,13 @@ package org.hibernate.stat;
 import java.io.Serializable;
 
 /**
- * Statistics pertaining to the execution of the "natural id resolution" query.
+ * Statistics pertaining to the execution of queries which resolve a natural
+ * id lookup against the database.
  *
  * @apiNote The natural-id resolution data is allowed to be stored in the
- * second level cache, and if so stored will have available caching stats as
+ * second-level cache, and if so stored will have available caching stats as
- * well available via {@link Statistics#getDomainDataRegionStatistics} using the
+ * well available via {@link Statistics#getDomainDataRegionStatistics} using
- * configured region name
+ * the configured region name
  *
  * todo (6.0) : consider a means to get the cache Region statistics for:
  * 		1) an entity by name

hibernate-core/src/main/java/org/hibernate/stat/QueryStatistics.java

@@ -9,9 +9,11 @@ package org.hibernate.stat;
 import java.io.Serializable;
 
 /**
- * Query statistics (HQL and SQL)
+ * Statistics relating to a particular query written in HQL or SQL.
- * <p/>
+ * <p>
- * Note that for a cached query, the cache miss is equals to the db count
+ * Note that for a cached query, the number of cache missed is the
+ * same as the number of queries actually executed against the
+ * database.
  *
  * @author Gavin King
  * @author Steve Ebersole
@@ -23,7 +25,8 @@ public interface QueryStatistics extends Serializable {
 	long getExecutionCount();
 
 	/**
-	 * How many ResultSet rows have been processed for this query ?
+	 * How many {@link java.sql.ResultSet} rows have been processed
+	 * for this query
 	 */
 	long getExecutionRowCount();
 
@@ -43,7 +46,8 @@ public interface QueryStatistics extends Serializable {
 	long getExecutionMinTime();
 
 	/**
-	 * How long, cumulatively, have all executions of this query taken?
+	 * How long, cumulatively, have all executions of this query
+	 * taken?
 	 */
 	long getExecutionTotalTime();
 
@@ -77,7 +81,8 @@ public interface QueryStatistics extends Serializable {
 	long getCachePutCount();
 
 	/**
-	 * The number of query plans successfully fetched from the cache.
+	 * The number of query plans successfully fetched from the
+	 * cache.
 	 */
 	default long getPlanCacheHitCount() {
 		//For backward compatibility
@@ -93,7 +98,8 @@ public interface QueryStatistics extends Serializable {
 	}
 
 	/**
-	 * The overall time spent to compile the plan for this particular query.
+	 * The overall time spent to compile the plan for this
+	 * particular query.
 	 */
 	default long getPlanCompilationTotalMicroseconds() {
 		//For backward compatibility

hibernate-core/src/main/java/org/hibernate/stat/SessionStatistics.java

@@ -9,28 +9,29 @@ package org.hibernate.stat;
 import java.util.Set;
 
 /**
- * Information about the first-level (session) cache
+ * Information about the first-level (session) cache for a particular
- * for a particular session instance
+ * instance of {@link org.hibernate.Session}.
+ *
  * @author Gavin King
  */
 public interface SessionStatistics {
 	/**
-	 * Get the number of entity instances associated with the session
+	 * The number of entity instances associated with the session.
 	 */
 	int getEntityCount();
 	/**
-	 * Get the number of collection instances associated with the session
+	 * The number of collection instances associated with the session.
 	 */
 	int getCollectionCount();
 
 	/**
-	 * Get the set of all {@code EntityKey}s
+	 * The set of all {@link org.hibernate.engine.spi.EntityKey}s
-	 * @see org.hibernate.engine.spi.EntityKey
+	 * currently held within the persistence context.
 	 */
 	Set<?> getEntityKeys();
 	/**
-	 * Get the set of all {@code CollectionKey}s
+	 * The set of all {@link org.hibernate.engine.spi.CollectionKey}s
-	 * @see org.hibernate.engine.spi.CollectionKey
+	 * currently held within the persistence context.
 	 */
 	Set<?> getCollectionKeys();
 	

hibernate-core/src/main/java/org/hibernate/stat/Statistics.java

@@ -6,373 +6,400 @@
  */
 package org.hibernate.stat;
 
-import javax.management.MXBean;
+import java.time.Instant;
 
 /**
- * Exposes statistics for a particular {@link org.hibernate.SessionFactory}.  Beware of milliseconds metrics, they
+ * Exposes statistics collected from all sessions belonging to a
- * are dependent of the JVM precision: you may then encounter a 10 ms approximation depending on you OS platform.
+ * particular {@link org.hibernate.SessionFactory}.
- * Please refer to the JVM documentation for more information.
+ * <p>
+ * Collection of statistics is enabled if the configuration property
+ * {@link org.hibernate.cfg.AvailableSettings#GENERATE_STATISTICS} is
+ * set to {@code true}. It may be dynamically enabled or disabled at
+ * runtime by calling {@link #setStatisticsEnabled(boolean)}.
  *
  * @author Emmanuel Bernard
  */
-@MXBean
 public interface Statistics {
 
+	/**
+	 * The default value of the configuration property
+	 * {@link org.hibernate.cfg.AvailableSettings#QUERY_STATISTICS_MAX_SIZE}.
+	 */
 	int DEFAULT_QUERY_STATISTICS_MAX_SIZE = 5000;
 
 	/**
-	 * Are statistics enabled
+	 * Is collection of statistics enabled?
 	 */
 	boolean isStatisticsEnabled();
 
 	/**
-	 * Enable statistics logs (this is a dynamic parameter)
+	 * Enable or disable statistics collection.
 	 */
-	void setStatisticsEnabled(boolean b);
+	void setStatisticsEnabled(boolean enabled);
+
 	/**
-	 * reset all statistics
+	 * Reset all statistics.
 	 */
 	void clear();
 
 	/**
-	 * log in info level the main statistics
+	 * Log the main statistics at level {@code INFO}.
 	 */
 	void logSummary();
 
 
     /**
-	 * find entity statistics per name
+	 * Obtain the statistics for the entity with the given name.
 	 *
-	 * @param entityName entity name
+	 * @param entityName the entity name
-	 * @return EntityStatistics object
 	 */
 	EntityStatistics getEntityStatistics(String entityName);
 
 	/**
-	 * Get collection statistics per role
+	 * Obtain the statistics for the collection with the given role.
 	 *
-	 * @param role collection role
+	 * @param role the collection role
-	 * @return CollectionStatistics
 	 */
 	CollectionStatistics getCollectionStatistics(String role);
 
 	/**
-	 * Natural id resolution query statistics for an entity type
+	 * Obtain the natural id resolution statistics for the entity
+	 * type with the given name.
 	 *
-	 * @param entityName The entity name that is the root of the hierarchy containing the
+	 * @param entityName The entity name that is the root of the
-	 * natural id
+	 *                   hierarchy containing the natural id
-	 * @return NaturalIdCacheStatistics
 	 */
 	NaturalIdStatistics getNaturalIdStatistics(String entityName);
 
 	/**
-	 * Query statistics from query string (HQL or SQL)
+	 * Obtain the query statistics for the given query string.
 	 *
-	 * @param queryString query string
+	 * @param queryString the query string, written in HQL or SQL
-	 * @return QueryStatistics
 	 */
 	QueryStatistics getQueryStatistics(String queryString);
 
 	/**
-	 * Second-level cache statistics per domain data (entity, collection, natural-id) region
+	 * Obtain the second-level cache statistics for the given cache
+	 * region.
 	 *
 	 * @param regionName The unqualified region name
 	 *
-	 * @return The stats for the named region, or {@code null} if the second level cache is
+	 * @return the statistics for the named region, or {@code null}
-	 * not enabled
+	 *         if the second-level cache is not enabled
 	 *
-	 * @throws IllegalArgumentException if the region name could not be resolved
+	 * @throws IllegalArgumentException if there is no region with the given name
 	 */
 	CacheRegionStatistics getDomainDataRegionStatistics(String regionName);
 
 	/**
-	 * Second-level cache statistics per query region
+	 * Obtain the second-level cache statistics for the given query
+	 * cache region.
 	 *
 	 * @param regionName The unqualified region name
 	 *
-	 * @return Stats for the named region, or {@code null} if (1) query result caching is
+	 * @return the statistics for the named region, or {@code null}
-	 * not enabled or (2) no query region exists with that name
+	 *         if either query result caching is not enabled, or no
+	 *         query cache region exists with the given name
 	 */
 	CacheRegionStatistics getQueryRegionStatistics(String regionName);
 
 	/**
-	 * Get statistics for either a domain-data or query-result region - this
+	 * Obtain the statistics for either a domain data or query result
-	 * method checks both, preferring domain data region if one.  Think of it
+	 * cache region.
-	 * as a cascading check to:<ol>
+	 * <p>
+	 * This method checks both, preferring the domain data region if
+	 * there is one. Think of it as a cascading check to:<ol>
 	 *     <li>{@link #getDomainDataRegionStatistics}</li>
 	 *     <li>{@link #getQueryRegionStatistics}</li>
 	 * </ol>
-	 * Note that returning null is preferred here over throwing an exception when
+	 * Note that null is returned instead of throwing an exception when
-	 * no region exists with that name.
+	 * no region exists with the given name.
 	 *
 	 * @param regionName The unqualified region name
 	 *
-	 * @return Stats for the named region, or {@code null} if no such region exists
+	 * @return the statistics for the named region, or {@code null} if
+	 *         there is no region with the given name
 	 */
 	CacheRegionStatistics getCacheRegionStatistics(String regionName);
 
     /**
-     * Get global number of entity deletes
+     * The global number of entity deletes.
-	 * @return entity deletion count
 	 */
 	long getEntityDeleteCount();
 
     /**
-     * Get global number of entity inserts
+     * The global number of entity inserts.
-	 * @return entity insertion count
 	 */
 	long getEntityInsertCount();
 
     /**
-     * Get global number of entity loads
+     * The global number of entity loads.
-	 * @return entity load (from DB)
 	 */
 	long getEntityLoadCount();
 
 	/**
-     * Get global number of entity fetches
+     * The global number of entity fetches.
-	 * @return entity fetch (from DB)
 	 */
 	long getEntityFetchCount();
 
 	/**
-     * Get global number of entity updates
+     * The global number of entity updates.
-	 * @return entity update
 	 */
 	long getEntityUpdateCount();
 
     /**
-     * Get global number of executed queries
+     * The global number of executed queries.
-	 * @return query execution count
 	 */
 	long getQueryExecutionCount();
 
     /**
-     * Get the time in milliseconds of the slowest query.
+     * The time in milliseconds of the slowest query.
      */
 	long getQueryExecutionMaxTime();
 
 	/**
-	 * Get the query string for the slowest query.
+	 * The query string for the slowest query.
 	 */
 	String getQueryExecutionMaxTimeQueryString();
 
     /**
-     * Get the global number of cached queries successfully retrieved from cache
+     * The global number of cached queries successfully retrieved from
+	 * the cache.
      */
 	long getQueryCacheHitCount();
 
     /**
-     * Get the global number of cached queries *not* found in cache
+     * The global number of cached queries <em>not</em>not found in the
+	 * cache.
      */
 	long getQueryCacheMissCount();
 
     /**
-     * Get the global number of cacheable queries put in cache
+     * The global number of cacheable queries put in cache.
      */
 	long getQueryCachePutCount();
 
 	/**
-	 * Get the global number of natural id queries executed against the database
+	 * The global number of natural id queries executed against the
+	 * database.
 	 */
 	long getNaturalIdQueryExecutionCount();
 
 	/**
-	 * Get the global maximum query time for natural id queries executed against the database
+	 * The global maximum query time for natural id queries executed
+	 * against the database.
 	 */
 	long getNaturalIdQueryExecutionMaxTime();
 
 	/**
-	 * Get the region for the maximum natural id query time
+	 * The region for the maximum natural id query time.
 	 */
 	String getNaturalIdQueryExecutionMaxTimeRegion();
 
 	/**
-	 * Get the entity for the maximum natural id query time
+	 * The entity name for the maximum natural id query time.
 	 */
 	String getNaturalIdQueryExecutionMaxTimeEntity();
 
     /**
-     * Get the global number of cached natural id lookups successfully retrieved from cache
+     * The global number of cached natural id lookups successfully
+	 * retrieved from the cache.
      */
 	long getNaturalIdCacheHitCount();
 
     /**
-     * Get the global number of cached natural id lookups *not* found in cache
+     * The global number of cached natural id lookups <em>not</em> found
+	 * in the cache.
      */
 	long getNaturalIdCacheMissCount();
 
     /**
-     * Get the global number of cacheable natural id lookups put in cache
+     * The global number of cacheable natural id lookups put in cache.
      */
 	long getNaturalIdCachePutCount();
 
     /**
-     * Get the global number of timestamps successfully retrieved from cache
+     * The global number of timestamps successfully retrieved from cache.
      */
 	long getUpdateTimestampsCacheHitCount();
 
     /**
-     * Get the global number of timestamp requests that were not found in the cache
+     * The global number of timestamp requests that were not found in the
+	 * cache.
      */
 	long getUpdateTimestampsCacheMissCount();
 
     /**
-     * Get the global number of timestamps put in cache
+     * The global number of timestamps put in cache.
      */
 	long getUpdateTimestampsCachePutCount();
 
 	/**
-     * Get the global number of flush operations executed (either manual or automatic).
+     * The global number of flush operations executed, including automatic
+	 * (either manual or automatic).
      */
 	long getFlushCount();
 
 	/**
-	 * Get the global number of connections asked by the sessions
+	 * The global number of connections requested by sessions.
-     * (the actual number of connections used may be much smaller depending
+	 * <p>
-     * whether you use a connection pool or not)
+	 * The actual number of connections used may be much smaller, assuming
+	 * that a connection pool is in use.
 	 */
 	long getConnectCount();
 
 	/**
-     * Global number of cacheable entities/collections successfully retrieved from the cache
+     * The global number of cacheable entities and collections successfully
+	 * retrieved from the cache.
      */
 	long getSecondLevelCacheHitCount();
 
 	/**
-     * Global number of cacheable entities/collections not found in the cache and loaded from the database.
+     * The global number of cacheable entities collections not found in the
+	 * cache and loaded from the database.
      */
 	long getSecondLevelCacheMissCount();
 
 	/**
-	 * Global number of cacheable entities/collections put in the cache
+	 * The global number of cacheable entities and collections put in the
+	 * cache.
 	 */
 	long getSecondLevelCachePutCount();
 
 	/**
-	 * Global number of sessions closed
+	 * The global number of sessions closed.
 	 */
 	long getSessionCloseCount();
 
 	/**
-	 * Global number of sessions opened
+	 * The global number of sessions opened.
 	 */
 	long getSessionOpenCount();
 
 	/**
-	 * Global number of collections loaded
+	 * The global number of collections loaded.
 	 */
 	long getCollectionLoadCount();
 
 	/**
-	 * Global number of collections fetched
+	 * The global number of collections fetched.
 	 */
 	long getCollectionFetchCount();
 
 	/**
-	 * Global number of collections updated
+	 * The global number of collections updated.
 	 */
 	long getCollectionUpdateCount();
 
 	/**
-	 * Global number of collections removed
+	 * The global number of collections removed.
 	 */
     //even on inverse="true"
 	long getCollectionRemoveCount();
 
 	/**
-	 * Global number of collections recreated
+	 * The global number of collections recreated
 	 */
 	long getCollectionRecreateCount();
 
 	/**
-	 * The milliseconds (JVM standard {@link System#currentTimeMillis()})
+	 * The {@link Instant} at which this instance of {@code Statistics}
-	 * since the initial creation of this Statistics
+	 * was created, or since the last time {@link #clear()} was called.
-	 * instance or the last time {@link #clear()} was called.
-	 *
-	 * @apiNote This time(stamp) is
 	 */
+	Instant getStart();
+
+	/**
+	 * The {@linkplain Instant#toEpochMilli()}  milliseconds}) since the
+	 * initial creation of this instance, or since the last time
+	 * {@link #clear()} was called.
+	 *
+	 * @deprecated use {@link #getStart()}
+	 */
+	@Deprecated(since = "6.0")
 	long getStartTime();
 
 	/**
-	 * Get all executed query strings.
+	 * All executed query strings.
-	 *
+	 * <p>
-	 * The maximum number of queries tracked by the Hibernate statistics is given by the {@code hibernate.statistics.query_max_size} property.
+	 * The maximum number of queries tracked by the Hibernate statistics
+	 * is determined by the configuration property
+	 * {@link org.hibernate.cfg.AvailableSettings#QUERY_STATISTICS_MAX_SIZE}.
 	 */
 	String[] getQueries();
 
 	/**
-	 * Get the names of all entities
+	 * The names of all entities.
 	 */
 	String[] getEntityNames();
 
 	/**
-	 * Get the names of all collection roles
+	 * The names of all collection roles.
 	 */
 	String[] getCollectionRoleNames();
 
 	/**
-	 * Get all second-level cache region names.  Note: for backwards
+	 * All second-level cache region names. For backwards compatibility,
-	 * compatibility this method returns just the names of regions
+	 * this method returns just the names of regions storing domain data,
-	 * storing domain data, not query result regions
+	 * not query result cache regions.
 	 */
 	String[] getSecondLevelCacheRegionNames();
 
 	/**
-	 * The number of transactions we know to have been successful
+	 * The number of transactions we know to have been successful.
 	 */
 	long getSuccessfulTransactionCount();
 
 	/**
-	 * The number of transactions we know to have completed
+	 * The number of transactions we know to have completed.
 	 */
 	long getTransactionCount();
 
 	/**
-	 * The number of prepared statements that were acquired
+	 * The number of prepared statements that were acquired.
 	 */
 	long getPrepareStatementCount();
 
 	/**
-	 * The number of prepared statements that were released
+	 * The number of prepared statements that were released.
 	 */
 	long getCloseStatementCount();
 
 	/**
-	 * The number of Hibernate {@code StaleObjectStateException}s or JPA {@code OptimisticLockException}s
+	 * The number of Hibernate {@code StaleObjectStateException}s or JPA
-	 * that occurred.
+	 * {@code OptimisticLockException}s that have occurred.
 	 */
 	long getOptimisticFailureCount();
 
 
 	/**
-	 * Second-level cache statistics per region
+	 * Second-level cache statistics per region.
 	 *
 	 * @param regionName qualified region name
 	 *
-	 * @return SecondLevelCacheStatistics or {@code null} if the second level cache is not enabled
+	 * @return the statistics object, or {@code null} if the second-level
+	 *         cache is not enabled
 	 *
-	 * @throws IllegalArgumentException if the region name could not be resolved
+	 * @throws IllegalArgumentException if there is no region with the given name
 	 *
-	 * @deprecated (since 5.3) Use {@link #getDomainDataRegionStatistics} instead
+	 * @deprecated Use {@link #getDomainDataRegionStatistics}
 	 */
-	@Deprecated
+	@Deprecated(since = "5.3")
 	SecondLevelCacheStatistics getSecondLevelCacheStatistics(String regionName);
 
 	/**
-	 * Natural id cache statistics per region
+	 * Natural id cache statistics per region.
 	 *
 	 * @param regionName region name
 	 * @return NaturalIdCacheStatistics
 	 *
-	 * @deprecated (since 5.3) Use {@link #getNaturalIdStatistics} or
+	 * @deprecated Use {@link #getNaturalIdStatistics} or
-	 * {@link #getDomainDataRegionStatistics} instead depending on need
+	 *             {@link #getDomainDataRegionStatistics}
 	 */
-	@Deprecated
+	@Deprecated(since = "5.3")
 	NaturalIdCacheStatistics getNaturalIdCacheStatistics(String regionName);
 
 	/**
-	 * Get the global number of query plans successfully retrieved from cache
+	 * The global number of query plans successfully retrieved from cache.
 	 */
 	default long getQueryPlanCacheHitCount() {
 		//For backward compatibility
@@ -380,7 +407,7 @@ public interface Statistics {
 	}
 
 	/**
-	 * Get the global number of query plans lookups *not* found in cache
+	 * The global number of query plans lookups <em>not</em> found in cache.
 	 */
 	default long getQueryPlanCacheMissCount() {
 		//For backward compatibility

hibernate-core/src/main/java/org/hibernate/stat/internal/StatisticsImpl.java

@@ -6,6 +6,7 @@
  */
 package org.hibernate.stat.internal;
 
+import java.time.Instant;
 import java.util.Objects;
 import java.util.concurrent.atomic.AtomicLong;
 import java.util.concurrent.atomic.LongAdder;
@@ -32,7 +33,6 @@ import static org.hibernate.internal.CoreLogging.messageLogger;
  * @author Alex Snaps
  * @author Sanne Grinovero
  */
-@SuppressWarnings({ "unchecked" })
 public class StatisticsImpl implements StatisticsImplementor, Service {
 
 	private static final CoreMessageLogger LOG = messageLogger( StatisticsImpl.class );
@@ -44,7 +44,7 @@ public class StatisticsImpl implements StatisticsImplementor, Service {
 	private final boolean queryCacheEnabled;
 
 	private volatile boolean isStatisticsEnabled;
-	private volatile long startTime;
+	private volatile Instant startTime;
 
 	private final LongAdder sessionOpenCount = new LongAdder();
 	private final LongAdder sessionCloseCount = new LongAdder();
@@ -96,9 +96,9 @@ public class StatisticsImpl implements StatisticsImplementor, Service {
 
 	private final LongAdder optimisticFailureCount = new LongAdder();
 
-	private final StatsNamedContainer<EntityStatisticsImpl> entityStatsMap = new StatsNamedContainer();
+	private final StatsNamedContainer<EntityStatisticsImpl> entityStatsMap = new StatsNamedContainer<>();
-	private final StatsNamedContainer<NaturalIdStatisticsImpl> naturalIdQueryStatsMap = new StatsNamedContainer();
+	private final StatsNamedContainer<NaturalIdStatisticsImpl> naturalIdQueryStatsMap = new StatsNamedContainer<>();
-	private final StatsNamedContainer<CollectionStatisticsImpl> collectionStatsMap = new StatsNamedContainer();
+	private final StatsNamedContainer<CollectionStatisticsImpl> collectionStatsMap = new StatsNamedContainer<>();
 
 	/**
 	 * Keyed by query string
@@ -110,18 +110,19 @@ public class StatisticsImpl implements StatisticsImplementor, Service {
 	 */
 	private final StatsNamedContainer<CacheRegionStatisticsImpl> l2CacheStatsMap = new StatsNamedContainer<>();
 
-	private final StatsNamedContainer<DeprecatedNaturalIdCacheStatisticsImpl> deprecatedNaturalIdStatsMap = new StatsNamedContainer();
+	private final StatsNamedContainer<DeprecatedNaturalIdCacheStatisticsImpl> deprecatedNaturalIdStatsMap
+			= new StatsNamedContainer<>();
 
 	public StatisticsImpl(SessionFactoryImplementor sessionFactory) {
 		Objects.requireNonNull( sessionFactory );
 		SessionFactoryOptions sessionFactoryOptions = sessionFactory.getSessionFactoryOptions();
-		this.queryStatsMap = new StatsNamedContainer(
+		this.queryStatsMap = new StatsNamedContainer<>(
 				sessionFactory != null ?
 					sessionFactoryOptions.getQueryStatisticsMaxSize() :
 					Statistics.DEFAULT_QUERY_STATISTICS_MAX_SIZE,
 				20
 		);
-		resetStartTime();
+		resetStart();
 		metamodel = sessionFactory.getMetamodel();
 		cache = sessionFactory.getCache();
 		cacheRegionPrefix = sessionFactoryOptions.getCacheRegionPrefix();
@@ -191,16 +192,21 @@ public class StatisticsImpl implements StatisticsImplementor, Service {
 		queryPlanCacheHitCount.reset();
 		queryPlanCacheMissCount.reset();
 
-		resetStartTime();
+		resetStart();
 	}
 
-	private void resetStartTime() {
+	private void resetStart() {
-		startTime = System.currentTimeMillis();
+		startTime = Instant.now();
+	}
+
+	@Override
+	public Instant getStart() {
+		return startTime;
 	}
 
 	@Override
 	public long getStartTime() {
-		return startTime;
+		return startTime.toEpochMilli();
 	}
 
 	@Override
@@ -209,8 +215,8 @@ public class StatisticsImpl implements StatisticsImplementor, Service {
 	}
 
 	@Override
-	public void setStatisticsEnabled(boolean b) {
+	public void setStatisticsEnabled(boolean enabled) {
-		isStatisticsEnabled = b;
+		isStatisticsEnabled = enabled;
 	}
 
 
@@ -875,7 +881,7 @@ public class StatisticsImpl implements StatisticsImplementor, Service {
 	@Override
 	public void logSummary() {
 		LOG.loggingStatistics();
-		LOG.startTime( startTime );
+		LOG.startTime( startTime.toEpochMilli() );
 		LOG.sessionsOpened( sessionOpenCount.sum() );
 		LOG.sessionsClosed( sessionCloseCount.sum() );
 		LOG.transactions( transactionCount.sum() );
@@ -917,48 +923,46 @@ public class StatisticsImpl implements StatisticsImplementor, Service {
 
 	@Override
 	public String toString() {
-		return new StringBuilder()
+		return "Statistics[" +
-				.append( "Statistics[" )
+				"start time=" + startTime +
-				.append( "start time=" ).append( startTime )
+				",sessions opened=" + sessionOpenCount +
-				.append( ",sessions opened=" ).append( sessionOpenCount )
+				",sessions closed=" + sessionCloseCount +
-				.append( ",sessions closed=" ).append( sessionCloseCount )
+				",transactions=" + transactionCount +
-				.append( ",transactions=" ).append( transactionCount )
+				",successful transactions=" + committedTransactionCount +
-				.append( ",successful transactions=" ).append( committedTransactionCount )
+				",optimistic lock failures=" + optimisticFailureCount +
-				.append( ",optimistic lock failures=" ).append( optimisticFailureCount )
+				",flushes=" + flushCount +
-				.append( ",flushes=" ).append( flushCount )
+				",connections obtained=" + connectCount +
-				.append( ",connections obtained=" ).append( connectCount )
+				",statements prepared=" + prepareStatementCount +
-				.append( ",statements prepared=" ).append( prepareStatementCount )
+				",statements closed=" + closeStatementCount +
-				.append( ",statements closed=" ).append( closeStatementCount )
+				",second level cache puts=" + secondLevelCachePutCount +
-				.append( ",second level cache puts=" ).append( secondLevelCachePutCount )
+				",second level cache hits=" + secondLevelCacheHitCount +
-				.append( ",second level cache hits=" ).append( secondLevelCacheHitCount )
+				",second level cache misses=" + secondLevelCacheMissCount +
-				.append( ",second level cache misses=" ).append( secondLevelCacheMissCount )
+				",entities loaded=" + entityLoadCount +
-				.append( ",entities loaded=" ).append( entityLoadCount )
+				",entities updated=" + entityUpdateCount +
-				.append( ",entities updated=" ).append( entityUpdateCount )
+				",entities inserted=" + entityInsertCount +
-				.append( ",entities inserted=" ).append( entityInsertCount )
+				",entities deleted=" + entityDeleteCount +
-				.append( ",entities deleted=" ).append( entityDeleteCount )
+				",entities fetched=" + entityFetchCount +
-				.append( ",entities fetched=" ).append( entityFetchCount )
+				",collections loaded=" + collectionLoadCount +
-				.append( ",collections loaded=" ).append( collectionLoadCount )
+				",collections updated=" + collectionUpdateCount +
-				.append( ",collections updated=" ).append( collectionUpdateCount )
+				",collections removed=" + collectionRemoveCount +
-				.append( ",collections removed=" ).append( collectionRemoveCount )
+				",collections recreated=" + collectionRecreateCount +
-				.append( ",collections recreated=" ).append( collectionRecreateCount )
+				",collections fetched=" + collectionFetchCount +
-				.append( ",collections fetched=" ).append( collectionFetchCount )
+				",naturalId queries executed to database=" + naturalIdQueryExecutionCount +
-				.append( ",naturalId queries executed to database=" ).append( naturalIdQueryExecutionCount )
+				",naturalId cache puts=" + naturalIdCachePutCount +
-				.append( ",naturalId cache puts=" ).append( naturalIdCachePutCount )
+				",naturalId cache hits=" + naturalIdCacheHitCount +
-				.append( ",naturalId cache hits=" ).append( naturalIdCacheHitCount )
+				",naturalId cache misses=" + naturalIdCacheMissCount +
-				.append( ",naturalId cache misses=" ).append( naturalIdCacheMissCount )
+				",naturalId max query time=" + naturalIdQueryExecutionMaxTime +
-				.append( ",naturalId max query time=" ).append( naturalIdQueryExecutionMaxTime )
+				",queries executed to database=" + queryExecutionCount +
-				.append( ",queries executed to database=" ).append( queryExecutionCount )
+				",query cache puts=" + queryCachePutCount +
-				.append( ",query cache puts=" ).append( queryCachePutCount )
+				",query cache hits=" + queryCacheHitCount +
-				.append( ",query cache hits=" ).append( queryCacheHitCount )
+				",query cache misses=" + queryCacheMissCount +
-				.append( ",query cache misses=" ).append( queryCacheMissCount )
+				",update timestamps cache puts=" + updateTimestampsCachePutCount +
-				.append(",update timestamps cache puts=").append(updateTimestampsCachePutCount)
+				",update timestamps cache hits=" + updateTimestampsCacheHitCount +
-				.append(",update timestamps cache hits=").append(updateTimestampsCacheHitCount)
+				",update timestamps cache misses=" + updateTimestampsCacheMissCount +
-				.append(",update timestamps cache misses=").append(updateTimestampsCacheMissCount)
+				",max query time=" + queryExecutionMaxTime +
-				.append( ",max query time=" ).append( queryExecutionMaxTime )
+				",query plan cache hits=" + queryPlanCacheHitCount +
-				.append( ",query plan cache hits=" ).append( queryPlanCacheHitCount )
+				",query plan cache misses=" + queryPlanCacheMissCount +
-				.append( ",query plan cache misses=" ).append( queryPlanCacheMissCount )
+				']';
-				.append( ']' )
-				.toString();
 	}
 
 	private EntityStatisticsImpl instantiateEntityStatistics(final String entityName) {

hibernate-core/src/main/java/org/hibernate/stat/internal/StatsNamedContainer.java

@@ -32,7 +32,7 @@ public final class StatsNamedContainer<V> {
 	 * Creates a bounded container - based on BoundedConcurrentHashMap
 	 */
 	public StatsNamedContainer(int capacity, int concurrencyLevel) {
-		this.map = new BoundedConcurrentHashMap( capacity, concurrencyLevel, BoundedConcurrentHashMap.Eviction.LRU );
+		this.map = new BoundedConcurrentHashMap<>( capacity, concurrencyLevel, BoundedConcurrentHashMap.Eviction.LRU );
 	}
 
 	/**
@@ -63,6 +63,7 @@ public final class StatsNamedContainer<V> {
 	 * Most notably, the ConcurrentHashMap implementation might block other accesses for the sake of making
 	 * sure the function is invoked at most once: we don't need this guarantee, and prefer to reduce risk of blocking.
 	 */
+	@SuppressWarnings("unchecked")
 	public V getOrCompute(final String key, final Function<String, V> function) {
 		final Object v1 = map.get( key );
 		if ( v1 != null ) {