Package io.agroal.pool.util

Class AutoCloseableElement

java.lang.Object

io.agroal.pool.util.AutoCloseableElement

All Implemented Interfaces:

AutoCloseable

Direct Known Subclasses:

ConnectionWrapper, ResultSetWrapper, StatementWrapper, XAConnectionWrapper, XAResourceWrapper

public abstract class AutoCloseableElement
extends Object
implements AutoCloseable

Abstract class to track auto-closeable resources by having them forming a collection between themselves. This class is designed to prevent leaks of Agroal JDBC wrapper objects. Once a new wrapper is created it tries to insert itself between the head and the first element of the list (if it exists). There is the invariant that at any given point in time the list can be traversed from the head and all inserted elements are reachable. As an implementation detail, the collection formed is actually a stack (FILO behaviour) and is thread-safe.

The resources do not remove themselves on close. It's assumed that the implementations of this interface are wrappers and the contents are dropped at that moment. Also, allowing removal of elements would introduce an undesirable amount of complexity to this class.

Author:

Luis Barreiro

Constructor Summary

Constructors

Modifier	Constructor	Description
protected	AutoCloseableElement(AutoCloseableElement head)

Method Summary

Modifier and Type	Method	Description
int	closeAllAutocloseableElements()	Returns the number of resources that were not properly closed.
abstract boolean	isClosed()
static AutoCloseableElement	newHead()	Create a special marker element to be used as head of a collection.

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.lang.AutoCloseable

close

Constructor Details

AutoCloseableElement

protected AutoCloseableElement(AutoCloseableElement head)

Method Details

isClosed

public abstract boolean isClosed()
                          throws Exception

Throws:

Exception

closeAllAutocloseableElements

public int closeAllAutocloseableElements()

Returns the number of resources that were not properly closed. The resources are closed in the process and the collection is cleared. This method should be invoked on the collection head only, otherwise it may not traverse the whole collection.

newHead

public static AutoCloseableElement newHead()

Create a special marker element to be used as head of a collection.