javapool.objects
Class ObjectPool

java.lang.Object
  |
  +--javapool.objects.ObjectPool

public abstract class ObjectPool

extends java.lang.Object

Class used to manage pools of objects. The specific object pools will extend this class

Field Summary

boolean	poolDead
boolean	poolStopped

Constructor Summary

ObjectPool(java.lang.String className, int poolSize, int maxPoolSize, int poolBuffer, int refreshFrequency, int objectLifeSpan, boolean doPing, int deadObjectPingCount, int reInstantiateObjectCount, int maxIssueTime)
Constructor in child classes should called this method using the super () call.

Method Summary

java.lang.String	getClassName() Returns the name of the class handled by this ObjectPool
java.lang.Object	getObject() Checks out and returns a free object.
void	printStats(java.io.BufferedWriter bw) Prints the stats for this object pool
void	returnObject(java.lang.Object obj) Restores an object back into the pool
void	shutdown() Shuts down the object pool
void	startup() Starts the object pool

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

poolDead

public boolean poolDead

poolStopped

public boolean poolStopped

Constructor Detail

ObjectPool

public ObjectPool(java.lang.String className,
                  int poolSize,
                  int maxPoolSize,
                  int poolBuffer,
                  int refreshFrequency,
                  int objectLifeSpan,
                  boolean doPing,
                  int deadObjectPingCount,
                  int reInstantiateObjectCount,
                  int maxIssueTime)

Constructor in child classes should called this method using the super () call. The constructor requires the following instantiation variables: value 0: String className -> The name of the class that this ObjectPool will be maintaining (ie. Customer, Address, Truck, etc.). The name of the specific object pool will be in the format className + "Pool.class" value 1: int poolSize -> Defines the size of this pool value 2: int maxPoolSize -> Defines the largest that this pool can grow value 3: int poolBuffer -> Defines when the pool should be resized. There are two situations in which a pool is resized. First is when the # of free objects is less than the buffer, at which time the poolSize is increased by the # specified by poolBuffer. The second occasion is when the number of free objects exceeds the poolSize, at which time the poolSize is decreased by the # specified by poolBuffer. value 4: int refreshFrequency -> Specifies the frequency in milliseconds for which the objects in this pool should be pinged. Object will not be pinged if this value is set to 0. If it is not, then the object should contain an implementation of the public boolean ping () method which returns true for a alive status and false for a dead status. value 5: int objectLifeSpan -> Specifies the lifespan of the ojects in milliseconds. Object will never die if set to 0. If not, then the object will be dereferenced and a new one instantiated to take it's place at the designated interval value 6: boolean doPing -> Specifies rather or not this object has a ping method implemented. If false then the values for pingPrior, refreshFrequency, deadObjectPingCount, and reInstantiateObjectCount will be insignificant. value 7: int deadObjectPingCount -> Number of times an object should be pinged before it is released and the system attempts to create a new one to take it's place value 8: int reInstantiateObjectCount -> Number of times that an object should be re-instantiated after reaching the deadObjectPingCount before this particular pool changes to a dead status (PoolDeadExceptions will be thrown in this status) value 9: int maxIssueTime -> Specifies the max issue time for the pool to have an object checked out. Once this max time is reached, the object should be released from the pool and another instantiated to take it's place. This value should always be specified as a safeguard

Method Detail

getClassName

public java.lang.String getClassName()

Returns the name of the class handled by this ObjectPool

getObject

public java.lang.Object getObject()
                           throws PoolBusyException,
                                  PoolDeadException,
                                  PoolStoppedException

Checks out and returns a free object. If no objects are free then a PoolBusyException is thrown

returnObject

public void returnObject(java.lang.Object obj)
                  throws ObjectNotInPoolException,
                         PoolDeadException,
                         PoolStoppedException

Restores an object back into the pool

shutdown

public void shutdown()

Shuts down the object pool

startup

public void startup()

Starts the object pool

printStats

public void printStats(java.io.BufferedWriter bw)

Prints the stats for this object pool