Avoid list copy on reverse iteration (#12297)

This reverts/modified parts of commit 115ee1cf39.

Co-authored-by: Simone Bordet <simone.bordet@gmail.com>

---------

Co-authored-by: Simone Bordet <simone.bordet@gmail.com>
This commit is contained in:
Greg Wilkins 2024-09-25 07:43:01 +10:00 committed by GitHub
parent 1d9f10871a
commit 18b9782550
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6 changed files with 45 additions and 29 deletions

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@ -653,11 +653,11 @@ public class ContextHandler extends Handler.Wrapper implements Attributes, Alias
*/
protected void notifyExitScope(Request request)
{
for (ContextScopeListener listener : TypeUtil.reverse(_contextListeners))
for (ListIterator<ContextScopeListener> i = TypeUtil.listIteratorAtEnd(_contextListeners); i.hasPrevious();)
{
try
{
listener.exitScope(_context, request);
i.previous().exitScope(_context, request);
}
catch (Throwable e)
{

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@ -34,6 +34,7 @@ import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Objects;
import java.util.Optional;
import java.util.ServiceConfigurationError;
@ -174,18 +175,29 @@ public class TypeUtil
}
/**
* <p>Returns a new list with the elements of the specified list in reverse order.</p>
* <p>The specified list is not modified, differently from {@link Collections#reverse(List)}.</p>
*
* @param list the list whose elements are to be reversed
* @return a new list with the elements in reverse order
* <p>Returns a {@link ListIterator} positioned at the last item in a list.</p>
* @param list the list
* @param <T> the element type
* @return A {@link ListIterator} positioned at the last item of the list.
*/
public static <T> List<T> reverse(List<T> list)
public static <T> ListIterator<T> listIteratorAtEnd(List<T> list)
{
List<T> result = new ArrayList<>(list);
Collections.reverse(result);
return result;
try
{
int size = list.size();
if (size == 0)
return Collections.emptyListIterator();
return list.listIterator(size);
}
catch (IndexOutOfBoundsException e)
{
// list was concurrently modified, so do this the hard way
ListIterator<T> i = list.listIterator();
while (i.hasNext())
i.next();
return i;
}
}
/**

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@ -31,6 +31,7 @@ import java.util.EventListener;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.ListIterator;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
@ -519,11 +520,11 @@ public class ServletContextHandler extends ContextHandler
//Call context listeners
Throwable multiException = null;
ServletContextEvent event = new ServletContextEvent(getServletContext());
for (ServletContextListener listener : TypeUtil.reverse(_destroyServletContextListeners))
for (ListIterator<ServletContextListener> i = TypeUtil.listIteratorAtEnd(_destroyServletContextListeners); i.hasPrevious();)
{
try
{
callContextDestroyed(listener, event);
callContextDestroyed(i.previous(), event);
}
catch (Exception x)
{
@ -574,17 +575,17 @@ public class ServletContextHandler extends ContextHandler
if (!_servletRequestListeners.isEmpty())
{
final ServletRequestEvent sre = new ServletRequestEvent(getServletContext(), request);
for (ServletRequestListener listener : TypeUtil.reverse(_servletRequestListeners))
for (ListIterator<ServletRequestListener> i = TypeUtil.listIteratorAtEnd(_servletRequestListeners); i.hasPrevious();)
{
listener.requestDestroyed(sre);
i.previous().requestDestroyed(sre);
}
}
if (!_servletRequestAttributeListeners.isEmpty())
{
for (ServletRequestAttributeListener listener : TypeUtil.reverse(_servletRequestAttributeListeners))
for (ListIterator<ServletRequestAttributeListener> i = TypeUtil.listIteratorAtEnd(_servletRequestAttributeListeners); i.hasPrevious();)
{
scopedRequest.removeEventListener(listener);
scopedRequest.removeEventListener(i.previous());
}
}
}
@ -1223,11 +1224,11 @@ public class ServletContextHandler extends ContextHandler
ServletContextRequest scopedRequest = Request.as(request, ServletContextRequest.class);
if (!_contextListeners.isEmpty())
{
for (ServletContextScopeListener listener : TypeUtil.reverse(_contextListeners))
for (ListIterator<ServletContextScopeListener> i = TypeUtil.listIteratorAtEnd(_contextListeners); i.hasPrevious(); )
{
try
{
listener.exitScope(getContext(), scopedRequest);
i.previous().exitScope(getContext(), scopedRequest);
}
catch (Throwable e)
{

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@ -19,6 +19,7 @@ import java.util.Enumeration;
import java.util.EventListener;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
@ -570,9 +571,9 @@ public class SessionHandler extends AbstractSessionManager implements Handler.Si
getSessionContext().run(() ->
{
HttpSessionEvent event = new HttpSessionEvent(session.getApi());
for (HttpSessionListener listener : TypeUtil.reverse(_sessionListeners))
for (ListIterator<HttpSessionListener> i = TypeUtil.listIteratorAtEnd(_sessionListeners); i.hasPrevious();)
{
listener.sessionDestroyed(event);
i.previous().sessionDestroyed(event);
}
});
}

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@ -29,6 +29,7 @@ import java.util.EventListener;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.ListIterator;
import java.util.Locale;
import java.util.Map;
import java.util.Objects;
@ -1000,17 +1001,17 @@ public class ContextHandler extends ScopedHandler implements Attributes, Supplie
if (!_servletRequestListeners.isEmpty())
{
final ServletRequestEvent sre = new ServletRequestEvent(_apiContext, request);
for (ServletRequestListener listener : TypeUtil.reverse(_servletRequestListeners))
for (ListIterator<ServletRequestListener> i = TypeUtil.listIteratorAtEnd(_servletRequestListeners); i.hasPrevious();)
{
listener.requestDestroyed(sre);
i.previous().requestDestroyed(sre);
}
}
if (!_servletRequestAttributeListeners.isEmpty())
{
for (ServletRequestAttributeListener listener : TypeUtil.reverse(_servletRequestAttributeListeners))
for (ListIterator<ServletRequestAttributeListener> i = TypeUtil.listIteratorAtEnd(_servletRequestAttributeListeners); i.hasPrevious();)
{
baseRequest.removeEventListener(listener);
baseRequest.removeEventListener(i.previous());
}
}
}
@ -1070,11 +1071,11 @@ public class ContextHandler extends ScopedHandler implements Attributes, Supplie
{
if (!_contextListeners.isEmpty())
{
for (ContextScopeListener listener : TypeUtil.reverse(_contextListeners))
for (ListIterator<ContextScopeListener> i = TypeUtil.listIteratorAtEnd(_contextListeners); i.hasPrevious();)
{
try
{
listener.exitScope(_apiContext, request);
i.previous().exitScope(_apiContext, request);
}
catch (Throwable e)
{

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@ -20,6 +20,7 @@ import java.util.EnumSet;
import java.util.Enumeration;
import java.util.EventListener;
import java.util.List;
import java.util.ListIterator;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.function.Function;
@ -835,9 +836,9 @@ public class SessionHandler extends ScopedHandler implements SessionConfig.Mutab
Runnable r = () ->
{
HttpSessionEvent event = new HttpSessionEvent(session.getApi());
for (HttpSessionListener listener : TypeUtil.reverse(_sessionListeners))
for (ListIterator<HttpSessionListener> i = TypeUtil.listIteratorAtEnd(_sessionListeners); i.hasPrevious();)
{
listener.sessionDestroyed(event);
i.previous().sessionDestroyed(event);
}
};
_contextHandler.getCoreContextHandler().getContext().run(r);