Class BaseGenericObjectPool<T>

java.lang.Object
org.datanucleus.store.rdbms.datasource.dbcp2.pool2.BaseObject
org.datanucleus.store.rdbms.datasource.dbcp2.pool2.impl.BaseGenericObjectPool<T>
Type Parameters:
T - Type of element pooled in this pool. This class is intended to be thread-safe.
Direct Known Subclasses:
GenericKeyedObjectPool, GenericObjectPool

public abstract class BaseGenericObjectPool<T> extends BaseObject
Base class that provides common functionality for GenericObjectPool and GenericKeyedObjectPool. The primary reason this class exists is reduce code duplication between the two pool implementations.
Since:
2.0
  • Field Details

    • MEAN_TIMING_STATS_CACHE_SIZE

      public static final int MEAN_TIMING_STATS_CACHE_SIZE
      The size of the caches used to store historical data for some attributes so that rolling means may be calculated.
      See Also:
    • EVICTION_POLICY_TYPE_NAME

      private static final String EVICTION_POLICY_TYPE_NAME
    • maxTotal

      private volatile int maxTotal
    • blockWhenExhausted

      private volatile boolean blockWhenExhausted
    • maxWaitMillis

      private volatile long maxWaitMillis
    • lifo

      private volatile boolean lifo
    • fairness

      private final boolean fairness
    • testOnCreate

      private volatile boolean testOnCreate
    • testOnBorrow

      private volatile boolean testOnBorrow
    • testOnReturn

      private volatile boolean testOnReturn
    • testWhileIdle

      private volatile boolean testWhileIdle
    • timeBetweenEvictionRunsMillis

      private volatile long timeBetweenEvictionRunsMillis
    • numTestsPerEvictionRun

      private volatile int numTestsPerEvictionRun
    • minEvictableIdleTimeMillis

      private volatile long minEvictableIdleTimeMillis
    • softMinEvictableIdleTimeMillis

      private volatile long softMinEvictableIdleTimeMillis
    • evictionPolicy

      private volatile EvictionPolicy<T> evictionPolicy
    • evictorShutdownTimeoutMillis

      private volatile long evictorShutdownTimeoutMillis
    • closeLock

      final Object closeLock
    • closed

      volatile boolean closed
    • evictionLock

      final Object evictionLock
    • evictor

      private BaseGenericObjectPool<T>.Evictor evictor
    • evictionIterator

    • factoryClassLoader

      private final WeakReference<ClassLoader> factoryClassLoader
    • objectName

      private final ObjectName objectName
    • creationStackTrace

      private final String creationStackTrace
    • borrowedCount

      private final AtomicLong borrowedCount
    • returnedCount

      private final AtomicLong returnedCount
    • createdCount

      final AtomicLong createdCount
    • destroyedCount

      final AtomicLong destroyedCount
    • destroyedByEvictorCount

      final AtomicLong destroyedByEvictorCount
    • destroyedByBorrowValidationCount

      final AtomicLong destroyedByBorrowValidationCount
    • activeTimes

      private final BaseGenericObjectPool<T>.StatsStore activeTimes
    • idleTimes

      private final BaseGenericObjectPool<T>.StatsStore idleTimes
    • waitTimes

      private final BaseGenericObjectPool<T>.StatsStore waitTimes
    • maxBorrowWaitTimeMillis

      private final AtomicLong maxBorrowWaitTimeMillis
    • swallowedExceptionListener

      private volatile SwallowedExceptionListener swallowedExceptionListener
  • Constructor Details

    • BaseGenericObjectPool

      public BaseGenericObjectPool(BaseObjectPoolConfig<T> config, String jmxNameBase, String jmxNamePrefix)
      Handles JMX registration (if required) and the initialization required for monitoring.
      Parameters:
      config - Pool configuration
      jmxNameBase - The default base JMX name for the new pool unless overridden by the config
      jmxNamePrefix - Prefix to be used for JMX name for the new pool
  • Method Details

    • getMaxTotal

      public final int getMaxTotal()
      Returns the maximum number of objects that can be allocated by the pool (checked out to clients, or idle awaiting checkout) at a given time. When negative, there is no limit to the number of objects that can be managed by the pool at one time.
      Returns:
      the cap on the total number of object instances managed by the pool.
      See Also:
    • setMaxTotal

      public final void setMaxTotal(int maxTotal)
      Sets the cap on the number of objects that can be allocated by the pool (checked out to clients, or idle awaiting checkout) at a given time. Use a negative value for no limit.
      Parameters:
      maxTotal - The cap on the total number of object instances managed by the pool. Negative values mean that there is no limit to the number of objects allocated by the pool.
      See Also:
    • getBlockWhenExhausted

      public final boolean getBlockWhenExhausted()
      Returns whether to block when the borrowObject() method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).
      Returns:
      true if borrowObject() should block when the pool is exhausted
      See Also:
    • setBlockWhenExhausted

      public final void setBlockWhenExhausted(boolean blockWhenExhausted)
      Sets whether to block when the borrowObject() method is invoked when the pool is exhausted (the maximum number of "active" objects has been reached).
      Parameters:
      blockWhenExhausted - true if borrowObject() should block when the pool is exhausted
      See Also:
    • setConfig

      protected void setConfig(BaseObjectPoolConfig<T> config)
      Initializes the receiver with the given configuration.
      Parameters:
      config - Initialization source.
    • getMaxWaitMillis

      public final long getMaxWaitMillis()
      Returns the maximum amount of time (in milliseconds) the borrowObject() method should block before throwing an exception when the pool is exhausted and getBlockWhenExhausted() is true. When less than 0, the borrowObject() method may block indefinitely.
      Returns:
      the maximum number of milliseconds borrowObject() will block.
      See Also:
    • setMaxWaitMillis

      public final void setMaxWaitMillis(long maxWaitMillis)
      Sets the maximum amount of time (in milliseconds) the borrowObject() method should block before throwing an exception when the pool is exhausted and getBlockWhenExhausted() is true. When less than 0, the borrowObject() method may block indefinitely.
      Parameters:
      maxWaitMillis - the maximum number of milliseconds borrowObject() will block or negative for indefinitely.
      See Also:
    • getLifo

      public final boolean getLifo()
      Returns whether the pool has LIFO (last in, first out) behaviour with respect to idle objects - always returning the most recently used object from the pool, or as a FIFO (first in, first out) queue, where the pool always returns the oldest object in the idle object pool.
      Returns:
      true if the pool is configured with LIFO behaviour or false if the pool is configured with FIFO behaviour
      See Also:
    • getFairness

      public final boolean getFairness()
      Returns whether or not the pool serves threads waiting to borrow objects fairly. True means that waiting threads are served as if waiting in a FIFO queue.
      Returns:
      true if waiting threads are to be served by the pool in arrival order
    • setLifo

      public final void setLifo(boolean lifo)
      Sets whether the pool has LIFO (last in, first out) behaviour with respect to idle objects - always returning the most recently used object from the pool, or as a FIFO (first in, first out) queue, where the pool always returns the oldest object in the idle object pool.
      Parameters:
      lifo - true if the pool is to be configured with LIFO behaviour or false if the pool is to be configured with FIFO behaviour
      See Also:
    • getTestOnCreate

      public final boolean getTestOnCreate()
      Returns whether objects created for the pool will be validated before being returned from the borrowObject() method. Validation is performed by the validateObject() method of the factory associated with the pool. If the object fails to validate, then borrowObject() will fail.
      Returns:
      true if newly created objects are validated before being returned from the borrowObject() method
      Since:
      2.2
      See Also:
    • setTestOnCreate

      public final void setTestOnCreate(boolean testOnCreate)
      Sets whether objects created for the pool will be validated before being returned from the borrowObject() method. Validation is performed by the validateObject() method of the factory associated with the pool. If the object fails to validate, then borrowObject() will fail.
      Parameters:
      testOnCreate - true if newly created objects should be validated before being returned from the borrowObject() method
      Since:
      2.2
      See Also:
    • getTestOnBorrow

      public final boolean getTestOnBorrow()
      Returns whether objects borrowed from the pool will be validated before being returned from the borrowObject() method. Validation is performed by the validateObject() method of the factory associated with the pool. If the object fails to validate, it will be removed from the pool and destroyed, and a new attempt will be made to borrow an object from the pool.
      Returns:
      true if objects are validated before being returned from the borrowObject() method
      See Also:
    • setTestOnBorrow

      public final void setTestOnBorrow(boolean testOnBorrow)
      Sets whether objects borrowed from the pool will be validated before being returned from the borrowObject() method. Validation is performed by the validateObject() method of the factory associated with the pool. If the object fails to validate, it will be removed from the pool and destroyed, and a new attempt will be made to borrow an object from the pool.
      Parameters:
      testOnBorrow - true if objects should be validated before being returned from the borrowObject() method
      See Also:
    • getTestOnReturn

      public final boolean getTestOnReturn()
      Returns whether objects borrowed from the pool will be validated when they are returned to the pool via the returnObject() method. Validation is performed by the validateObject() method of the factory associated with the pool. Returning objects that fail validation are destroyed rather then being returned the pool.
      Returns:
      true if objects are validated on return to the pool via the returnObject() method
      See Also:
    • setTestOnReturn

      public final void setTestOnReturn(boolean testOnReturn)
      Sets whether objects borrowed from the pool will be validated when they are returned to the pool via the returnObject() method. Validation is performed by the validateObject() method of the factory associated with the pool. Returning objects that fail validation are destroyed rather then being returned the pool.
      Parameters:
      testOnReturn - true if objects are validated on return to the pool via the returnObject() method
      See Also:
    • getTestWhileIdle

      public final boolean getTestWhileIdle()
      Returns whether objects sitting idle in the pool will be validated by the idle object evictor (if any - see setTimeBetweenEvictionRunsMillis(long)). Validation is performed by the validateObject() method of the factory associated with the pool. If the object fails to validate, it will be removed from the pool and destroyed.
      Returns:
      true if objects will be validated by the evictor
      See Also:
    • setTestWhileIdle

      public final void setTestWhileIdle(boolean testWhileIdle)
      Returns whether objects sitting idle in the pool will be validated by the idle object evictor (if any - see setTimeBetweenEvictionRunsMillis(long)). Validation is performed by the validateObject() method of the factory associated with the pool. If the object fails to validate, it will be removed from the pool and destroyed. Note that setting this property has no effect unless the idle object evictor is enabled by setting timeBetweenEvictionRunsMillis to a positive value.
      Parameters:
      testWhileIdle - true so objects will be validated by the evictor
      See Also:
    • getTimeBetweenEvictionRunsMillis

      public final long getTimeBetweenEvictionRunsMillis()
      Returns the number of milliseconds to sleep between runs of the idle object evictor thread. When non-positive, no idle object evictor thread will be run.
      Returns:
      number of milliseconds to sleep between evictor runs
      See Also:
    • setTimeBetweenEvictionRunsMillis

      public final void setTimeBetweenEvictionRunsMillis(long timeBetweenEvictionRunsMillis)
      Sets the number of milliseconds to sleep between runs of the idle object evictor thread.
      • When positive, the idle object evictor thread starts.
      • When non-positive, no idle object evictor thread runs.
      Parameters:
      timeBetweenEvictionRunsMillis - number of milliseconds to sleep between evictor runs
      See Also:
    • getNumTestsPerEvictionRun

      public final int getNumTestsPerEvictionRun()
      Returns the maximum number of objects to examine during each run (if any) of the idle object evictor thread. When positive, the number of tests performed for a run will be the minimum of the configured value and the number of idle instances in the pool. When negative, the number of tests performed will be ceil(getNumIdle()/ abs(getNumTestsPerEvictionRun())) which means that when the value is -n roughly one nth of the idle objects will be tested per run.
      Returns:
      max number of objects to examine during each evictor run
      See Also:
    • setNumTestsPerEvictionRun

      public final void setNumTestsPerEvictionRun(int numTestsPerEvictionRun)
      Sets the maximum number of objects to examine during each run (if any) of the idle object evictor thread. When positive, the number of tests performed for a run will be the minimum of the configured value and the number of idle instances in the pool. When negative, the number of tests performed will be ceil(getNumIdle()/ abs(getNumTestsPerEvictionRun())) which means that when the value is -n roughly one nth of the idle objects will be tested per run.
      Parameters:
      numTestsPerEvictionRun - max number of objects to examine during each evictor run
      See Also:
    • getMinEvictableIdleTimeMillis

      public final long getMinEvictableIdleTimeMillis()
      Returns the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any - see setTimeBetweenEvictionRunsMillis(long)). When non-positive, no objects will be evicted from the pool due to idle time alone.
      Returns:
      minimum amount of time an object may sit idle in the pool before it is eligible for eviction
      See Also:
    • setMinEvictableIdleTimeMillis

      public final void setMinEvictableIdleTimeMillis(long minEvictableIdleTimeMillis)
      Sets the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any - see setTimeBetweenEvictionRunsMillis(long)). When non-positive, no objects will be evicted from the pool due to idle time alone.
      Parameters:
      minEvictableIdleTimeMillis - minimum amount of time an object may sit idle in the pool before it is eligible for eviction
      See Also:
    • getSoftMinEvictableIdleTimeMillis

      public final long getSoftMinEvictableIdleTimeMillis()
      Returns the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any - see setTimeBetweenEvictionRunsMillis(long)), with the extra condition that at least minIdle object instances remain in the pool. This setting is overridden by getMinEvictableIdleTimeMillis() (that is, if getMinEvictableIdleTimeMillis() is positive, then getSoftMinEvictableIdleTimeMillis() is ignored).
      Returns:
      minimum amount of time an object may sit idle in the pool before it is eligible for eviction if minIdle instances are available
      See Also:
    • setSoftMinEvictableIdleTimeMillis

      public final void setSoftMinEvictableIdleTimeMillis(long softMinEvictableIdleTimeMillis)
      Sets the minimum amount of time an object may sit idle in the pool before it is eligible for eviction by the idle object evictor (if any - see setTimeBetweenEvictionRunsMillis(long)), with the extra condition that at least minIdle object instances remain in the pool. This setting is overridden by getMinEvictableIdleTimeMillis() (that is, if getMinEvictableIdleTimeMillis() is positive, then getSoftMinEvictableIdleTimeMillis() is ignored).
      Parameters:
      softMinEvictableIdleTimeMillis - minimum amount of time an object may sit idle in the pool before it is eligible for eviction if minIdle instances are available
      See Also:
    • getEvictionPolicyClassName

      public final String getEvictionPolicyClassName()
      Returns the name of the EvictionPolicy implementation that is used by this pool.
      Returns:
      The fully qualified class name of the EvictionPolicy
      See Also:
    • setEvictionPolicy

      public void setEvictionPolicy(EvictionPolicy<T> evictionPolicy)
      Sets the eviction policy for this pool.
      Parameters:
      evictionPolicy - the eviction policy for this pool.
      Since:
      2.6.0
    • setEvictionPolicyClassName

      public final void setEvictionPolicyClassName(String evictionPolicyClassName, ClassLoader classLoader)
      Sets the name of the EvictionPolicy implementation that is used by this pool. The Pool will attempt to load the class using the given class loader. If that fails, use the class loader for the EvictionPolicy interface.
      Parameters:
      evictionPolicyClassName - the fully qualified class name of the new eviction policy
      classLoader - the class loader to load the given evictionPolicyClassName.
      Since:
      2.6.0 If loading the class using the given class loader fails, use the class loader for the EvictionPolicy interface.
      See Also:
    • setEvictionPolicy

      Sets the eviction policy.
      Parameters:
      className - Eviction policy class name.
      classLoader - Load the class from this class loader.
      Throws:
      ClassNotFoundException
      InstantiationException
      IllegalAccessException
      InvocationTargetException
      NoSuchMethodException
    • setEvictionPolicyClassName

      public final void setEvictionPolicyClassName(String evictionPolicyClassName)
      Sets the name of the EvictionPolicy implementation that is used by this pool. The Pool will attempt to load the class using the thread context class loader. If that fails, the use the class loader for the EvictionPolicy interface.
      Parameters:
      evictionPolicyClassName - the fully qualified class name of the new eviction policy
      Since:
      2.6.0 If loading the class using the thread context class loader fails, use the class loader for the EvictionPolicy interface.
      See Also:
    • getEvictorShutdownTimeoutMillis

      public final long getEvictorShutdownTimeoutMillis()
      Gets the timeout that will be used when waiting for the Evictor to shutdown if this pool is closed and it is the only pool still using the the value for the Evictor.
      Returns:
      The timeout in milliseconds that will be used while waiting for the Evictor to shut down.
    • setEvictorShutdownTimeoutMillis

      public final void setEvictorShutdownTimeoutMillis(long evictorShutdownTimeoutMillis)
      Sets the timeout that will be used when waiting for the Evictor to shutdown if this pool is closed and it is the only pool still using the the value for the Evictor.
      Parameters:
      evictorShutdownTimeoutMillis - the timeout in milliseconds that will be used while waiting for the Evictor to shut down.
    • close

      public abstract void close()
      Closes the pool, destroys the remaining idle objects and, if registered in JMX, deregisters it.
    • isClosed

      public final boolean isClosed()
      Has this pool instance been closed.
      Returns:
      true when this pool has been closed.
    • evict

      public abstract void evict() throws Exception

      Perform numTests idle object eviction tests, evicting examined objects that meet the criteria for eviction. If testWhileIdle is true, examined objects are validated when visited (and removed if invalid); otherwise only objects that have been idle for more than minEvicableIdleTimeMillis are removed.

      Throws:
      Exception - when there is a problem evicting idle objects.
    • getEvictionPolicy

      public EvictionPolicy<T> getEvictionPolicy()
      Returns the EvictionPolicy defined for this pool.
      Returns:
      the eviction policy
      Since:
      2.4, 2.6.0 Changed access from protected to public.
    • assertOpen

      final void assertOpen() throws IllegalStateException
      Verifies that the pool is open.
      Throws:
      IllegalStateException - if the pool is closed.
    • startEvictor

      final void startEvictor(long delay)

      Starts the evictor with the given delay. If there is an evictor running when this method is called, it is stopped and replaced with a new evictor with the specified delay.

      This method needs to be final, since it is called from a constructor. See POOL-195.

      Parameters:
      delay - time in milliseconds before start and between eviction runs
    • stopEvictor

      void stopEvictor()
      Stops the evictor.
    • ensureMinIdle

      abstract void ensureMinIdle() throws Exception
      Tries to ensure that the configured minimum number of idle instances are available in the pool.
      Throws:
      Exception - if an error occurs creating idle instances
    • getJmxName

      public final ObjectName getJmxName()
      Provides the name under which the pool has been registered with the platform MBean server or null if the pool has not been registered.
      Returns:
      the JMX name
    • getCreationStackTrace

      public final String getCreationStackTrace()
      Provides the stack trace for the call that created this pool. JMX registration may trigger a memory leak so it is important that pools are deregistered when no longer used by calling the close() method. This method is provided to assist with identifying code that creates but does not close it thereby creating a memory leak.
      Returns:
      pool creation stack trace
    • getBorrowedCount

      public final long getBorrowedCount()
      The total number of objects successfully borrowed from this pool over the lifetime of the pool.
      Returns:
      the borrowed object count
    • getReturnedCount

      public final long getReturnedCount()
      The total number of objects returned to this pool over the lifetime of the pool. This excludes attempts to return the same object multiple times.
      Returns:
      the returned object count
    • getCreatedCount

      public final long getCreatedCount()
      The total number of objects created for this pool over the lifetime of the pool.
      Returns:
      the created object count
    • getDestroyedCount

      public final long getDestroyedCount()
      The total number of objects destroyed by this pool over the lifetime of the pool.
      Returns:
      the destroyed object count
    • getDestroyedByEvictorCount

      public final long getDestroyedByEvictorCount()
      The total number of objects destroyed by the evictor associated with this pool over the lifetime of the pool.
      Returns:
      the evictor destroyed object count
    • getDestroyedByBorrowValidationCount

      public final long getDestroyedByBorrowValidationCount()
      The total number of objects destroyed by this pool as a result of failing validation during borrowObject() over the lifetime of the pool.
      Returns:
      validation destroyed object count
    • getMeanActiveTimeMillis

      public final long getMeanActiveTimeMillis()
      The mean time objects are active for based on the last MEAN_TIMING_STATS_CACHE_SIZE objects returned to the pool.
      Returns:
      mean time an object has been checked out from the pool among recently returned objects
    • getMeanIdleTimeMillis

      public final long getMeanIdleTimeMillis()
      The mean time objects are idle for based on the last MEAN_TIMING_STATS_CACHE_SIZE objects borrowed from the pool.
      Returns:
      mean time an object has been idle in the pool among recently borrowed objects
    • getMeanBorrowWaitTimeMillis

      public final long getMeanBorrowWaitTimeMillis()
      The mean time threads wait to borrow an object based on the last MEAN_TIMING_STATS_CACHE_SIZE objects borrowed from the pool.
      Returns:
      mean time in milliseconds that a recently served thread has had to wait to borrow an object from the pool
    • getMaxBorrowWaitTimeMillis

      public final long getMaxBorrowWaitTimeMillis()
      The maximum time a thread has waited to borrow objects from the pool.
      Returns:
      maximum wait time in milliseconds since the pool was created
    • getNumIdle

      public abstract int getNumIdle()
      The number of instances currently idle in this pool.
      Returns:
      count of instances available for checkout from the pool
    • getSwallowedExceptionListener

      public final SwallowedExceptionListener getSwallowedExceptionListener()
      The listener used (if any) to receive notifications of exceptions unavoidably swallowed by the pool.
      Returns:
      The listener or null for no listener
    • setSwallowedExceptionListener

      public final void setSwallowedExceptionListener(SwallowedExceptionListener swallowedExceptionListener)
      The listener used (if any) to receive notifications of exceptions unavoidably swallowed by the pool.
      Parameters:
      swallowedExceptionListener - The listener or null for no listener
    • swallowException

      final void swallowException(Exception swallowException)
      Swallows an exception and notifies the configured listener for swallowed exceptions queue.
      Parameters:
      swallowException - exception to be swallowed
    • updateStatsBorrow

      final void updateStatsBorrow(PooledObject<T> p, long waitTime)
      Updates statistics after an object is borrowed from the pool.
      Parameters:
      p - object borrowed from the pool
      waitTime - time (in milliseconds) that the borrowing thread had to wait
    • updateStatsReturn

      final void updateStatsReturn(long activeTime)
      Updates statistics after an object is returned to the pool.
      Parameters:
      activeTime - the amount of time (in milliseconds) that the returning object was checked out
    • markReturningState

      protected void markReturningState(PooledObject<T> pooledObject)
      Marks the object as returning to the pool.
      Parameters:
      pooledObject - instance to return to the keyed pool
    • jmxUnregister

      final void jmxUnregister()
      Unregisters this pool's MBean.
    • jmxRegister

      private ObjectName jmxRegister(BaseObjectPoolConfig<T> config, String jmxNameBase, String jmxNamePrefix)
      Registers the pool with the platform MBean server. The registered name will be jmxNameBase + jmxNamePrefix + i where i is the least integer greater than or equal to 1 such that the name is not already registered. Swallows MBeanRegistrationException, NotCompliantMBeanException returning null.
      Parameters:
      config - Pool configuration
      jmxNameBase - default base JMX name for this pool
      jmxNamePrefix - name prefix
      Returns:
      registered ObjectName, null if registration fails
    • getStackTrace

      private String getStackTrace(Exception e)
      Gets the stack trace of an exception as a string.
      Parameters:
      e - exception to trace
      Returns:
      exception stack trace as a string
    • toStringAppendFields

      protected void toStringAppendFields(StringBuilder builder)
      Description copied from class: BaseObject
      Used by sub-classes to include the fields defined by the sub-class in the BaseObject.toString() output.
      Overrides:
      toStringAppendFields in class BaseObject
      Parameters:
      builder - Field names and values are appended to this object