Package org.datanucleus.store.rdbms.datasource.dbcp2.pool2.impl

Class 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 Detail

      • 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:
        Constant Field Values

      • EVICTION_POLICY_TYPE_NAME

        private static final java.lang.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

      • evictorShutdownTimeoutMillis

        private volatile long evictorShutdownTimeoutMillis

      • closeLock

        final java.lang.Object closeLock

      • closed

        volatile boolean closed

      • evictionLock

        final java.lang.Object evictionLock

      • factoryClassLoader

        private final java.lang.ref.WeakReference<java.lang.ClassLoader> factoryClassLoader

      • objectName

        private final javax.management.ObjectName objectName

      • creationStackTrace

        private final java.lang.String creationStackTrace

      • borrowedCount

        private final java.util.concurrent.atomic.AtomicLong borrowedCount

      • returnedCount

        private final java.util.concurrent.atomic.AtomicLong returnedCount

      • createdCount

        final java.util.concurrent.atomic.AtomicLong createdCount

      • destroyedCount

        final java.util.concurrent.atomic.AtomicLong destroyedCount

      • destroyedByEvictorCount

        final java.util.concurrent.atomic.AtomicLong destroyedByEvictorCount

      • destroyedByBorrowValidationCount

        final java.util.concurrent.atomic.AtomicLong destroyedByBorrowValidationCount

      • maxBorrowWaitTimeMillis

        private final java.util.concurrent.atomic.AtomicLong maxBorrowWaitTimeMillis

    • Constructor Detail

      • BaseGenericObjectPool

        public BaseGenericObjectPool​(BaseObjectPoolConfig<T> config,
                             java.lang.String jmxNameBase,
                             java.lang.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 Detail

      • 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(int)

      • 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:
        getMaxTotal()

      • 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(boolean)

      • 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:
        getBlockWhenExhausted()

      • 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(long), setBlockWhenExhausted(boolean)

      • 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:
        getMaxWaitMillis(), setBlockWhenExhausted(boolean)

      • 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:
        setLifo(boolean)

      • 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:
        getLifo()

      • 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(boolean)

      • 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:
        getTestOnCreate()

      • 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(boolean)

      • 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:
        getTestOnBorrow()

      • 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(boolean)

      • 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:
        getTestOnReturn()

      • 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(boolean), setTimeBetweenEvictionRunsMillis(long)

      • 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:
        getTestWhileIdle(), setTimeBetweenEvictionRunsMillis(long)

      • 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(long)

      • 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:
        getTimeBetweenEvictionRunsMillis()

      • 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(int), setTimeBetweenEvictionRunsMillis(long)

      • 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:
        getNumTestsPerEvictionRun(), setTimeBetweenEvictionRunsMillis(long)

      • 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:
        getMinEvictableIdleTimeMillis(), setTimeBetweenEvictionRunsMillis(long)

      • 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​(java.lang.String evictionPolicyClassName,
                                             java.lang.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:
        getEvictionPolicyClassName()

      • setEvictionPolicy

        private void setEvictionPolicy​(java.lang.String className,
                               java.lang.ClassLoader classLoader)
                        throws java.lang.ClassNotFoundException,
                               java.lang.InstantiationException,
                               java.lang.IllegalAccessException,
                               java.lang.reflect.InvocationTargetException,
                               java.lang.NoSuchMethodException
        Sets the eviction policy.
        Parameters:
        className - Eviction policy class name.
        classLoader - Load the class from this class loader.
        Throws:
        java.lang.ClassNotFoundException
        java.lang.InstantiationException
        java.lang.IllegalAccessException
        java.lang.reflect.InvocationTargetException
        java.lang.NoSuchMethodException

      • setEvictionPolicyClassName

        public final void setEvictionPolicyClassName​(java.lang.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:
        getEvictionPolicyClassName()

      • 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 java.lang.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:
        java.lang.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 java.lang.IllegalStateException
        Verifies that the pool is open.
        Throws:
        java.lang.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 java.lang.Exception
        Tries to ensure that the configured minimum number of idle instances are available in the pool.
        Throws:
        java.lang.Exception - if an error occurs creating idle instances

      • getJmxName

        public final javax.management.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 java.lang.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​(java.lang.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 javax.management.ObjectName jmxRegister​(BaseObjectPoolConfig<T> config,
                                                java.lang.String jmxNameBase,
                                                java.lang.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 java.lang.String getStackTrace​(java.lang.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​(java.lang.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