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Optimized memory usage of AttributesMap. 

Attributes are used rarely, so AttributesMap was creating a ConcurrentHashMap
that was never used.
In cases where AttributesMap is heavily used (for example CometD) this proved
to save a significant amount of memory footprint.
This commit is contained in:
Simone Bordet 2013-01-10 09:39:56 +01:00
parent a374ac0cc8
commit 34cc0e5d82
1 changed files with 57 additions and 79 deletions
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110
jetty-util/src/main/java/org/eclipse/jetty/util/AttributesMap.java
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@ -25,136 +25,115 @@ import java.util.List;
import java.util.Map; import java.util.Map;
import java.util.Set; import java.util.Set;
import java.util.concurrent.ConcurrentHashMap; import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.atomic.AtomicReference;
/* ------------------------------------------------------------ */
/** AttributesMap.
*
*
*/
public class AttributesMap implements Attributes public class AttributesMap implements Attributes
{ {
protected final Map<String,Object> _map; private final AtomicReference<ConcurrentMap<String, Object>> _map = new AtomicReference<>();
/* ------------------------------------------------------------ */
public AttributesMap() public AttributesMap()
{ {
_map=new ConcurrentHashMap<String,Object>();
} }
/* ------------------------------------------------------------ */ public AttributesMap(AttributesMap attributes)
public AttributesMap(Map<String,Object> map)
{ {
_map=map; ConcurrentMap<String, Object> map = attributes.map();
if (map != null)
_map.set(new ConcurrentHashMap<>(map));
} }
/* ------------------------------------------------------------ */ private ConcurrentMap<String, Object> map()
public AttributesMap(AttributesMap map)
{ {
_map=new ConcurrentHashMap<String,Object>(map._map); return _map.get();
}
private ConcurrentMap<String, Object> ensureMap()
{
while (true)
{
ConcurrentMap<String, Object> map = map();
if (map != null)
return map;
map = new ConcurrentHashMap<>();
if (_map.compareAndSet(null, map))
return map;
}
} }
/* ------------------------------------------------------------ */
/*
* @see org.eclipse.jetty.util.Attributes#removeAttribute(java.lang.String)
*/
@Override @Override
public void removeAttribute(String name) public void removeAttribute(String name)
{ {
_map.remove(name); Map<String, Object> map = map();
if (map != null)
map.remove(name);
} }
/* ------------------------------------------------------------ */
/*
* @see org.eclipse.jetty.util.Attributes#setAttribute(java.lang.String, java.lang.Object)
*/
@Override @Override
public void setAttribute(String name, Object attribute) public void setAttribute(String name, Object attribute)
{ {
if (attribute == null) if (attribute == null)
_map.remove(name); removeAttribute(name);
else else
_map.put(name, attribute); ensureMap().put(name, attribute);
} }
/* ------------------------------------------------------------ */
/*
* @see org.eclipse.jetty.util.Attributes#getAttribute(java.lang.String)
*/
@Override @Override
public Object getAttribute(String name) public Object getAttribute(String name)
{ {
return _map.get(name); Map<String, Object> map = map();
return map == null ? null : map.get(name);
} }
/* ------------------------------------------------------------ */
/*
* @see org.eclipse.jetty.util.Attributes#getAttributeNames()
*/
@Override @Override
public Enumeration<String> getAttributeNames() public Enumeration<String> getAttributeNames()
{ {
return Collections.enumeration(_map.keySet()); return Collections.enumeration(keySet());
} }
/* ------------------------------------------------------------ */
/*
* @see org.eclipse.jetty.util.Attributes#getAttributeNames()
*/
public Set<String> getAttributeNameSet()
{
return _map.keySet();
}
/* ------------------------------------------------------------ */
public Set<Map.Entry<String, Object>> getAttributeEntrySet() public Set<Map.Entry<String, Object>> getAttributeEntrySet()
{ {
return _map.entrySet(); Map<String, Object> map = map();
return map == null ? Collections.<Map.Entry<String, Object>>emptySet() : map.entrySet();
} }
/* ------------------------------------------------------------ */
/*
* @see org.eclipse.jetty.util.Attributes#getAttributeNames()
*/
public static Enumeration<String> getAttributeNamesCopy(Attributes attrs) public static Enumeration<String> getAttributeNamesCopy(Attributes attrs)
{ {
if (attrs instanceof AttributesMap) if (attrs instanceof AttributesMap)
return Collections.enumeration(((AttributesMap)attrs)._map.keySet()); return Collections.enumeration(((AttributesMap)attrs).keySet());
List<String> names = new ArrayList<String>(); List<String> names = new ArrayList<>();
names.addAll(Collections.list(attrs.getAttributeNames())); names.addAll(Collections.list(attrs.getAttributeNames()));
return Collections.enumeration(names); return Collections.enumeration(names);
} }
/* ------------------------------------------------------------ */
/*
* @see org.eclipse.jetty.util.Attributes#clear()
*/
@Override @Override
public void clearAttributes() public void clearAttributes()
{ {
_map.clear(); Map<String, Object> map = map();
if (map != null)
map.clear();
} }
/* ------------------------------------------------------------ */
public int size() public int size()
{ {
return _map.size(); Map<String, Object> map = map();
return map == null ? 0 : map.size();
} }
/* ------------------------------------------------------------ */
@Override @Override
public String toString() public String toString()
{ {
return _map.toString(); Map<String, Object> map = map();
return map == null ? "{}" : map.toString();
} }
/* ------------------------------------------------------------ */ private Set<String> keySet()
public Set<String> keySet()
{ {
return _map.keySet(); Map<String, Object> map = map();
return map == null ? Collections.<String>emptySet() : map.keySet();
} }
/* ------------------------------------------------------------ */
public void addAll(Attributes attributes) public void addAll(Attributes attributes)
{ {
Enumeration<String> e = attributes.getAttributeNames(); Enumeration<String> e = attributes.getAttributeNames();
@ -164,5 +143,4 @@ public class AttributesMap implements Attributes
setAttribute(name, attributes.getAttribute(name)); setAttribute(name, attributes.getAttribute(name));
} }
} }
} }