objectpool

Object Pool Design Pattern

Object pool design pattern provides a way to reuse and manage objects which is costly to create.

Example

ObjectPool<T> holds the real logic. It has two sets - one for available objects and another for uses objects.

Acquire method will get the object, if available set is empty, then it created new one and reference of uses object save in uses set. Release method return object to available set for future use. Both methods are synchronised, so only one thread can access these method at a time.

DatabaseConnectonPool is the concrete pool which extends ObjectPool.

NB - this is very simple object pool method. In real life, pool may create object when it initialized or pool may have constants like maximum no of object creation etc.

Remarks

• Create abstract ObjectPool<T> class with private list of objects (here, set of availables and uses object)
• Create acquire and release methods in ObjectPool class
• Make an abstract create method.

Test

DatabaseConnection object = databaseConnectionPool.acquire();
Assertions.assertNotNull(object);

// or
DatabaseConnection object = databaseConnectionPool.acquire();
DatabaseConnection object2 = databaseConnectionPool.acquire();
Assertions.assertNotEquals(object, object2);

// or
DatabaseConnection object = databaseConnectionPool.acquire();
databaseConnectionPool.release(object);
DatabaseConnection object2 = databaseConnectionPool.acquire();
Assertions.assertEquals(object, object2);