/// <summary>
/// Remove dead entries from the data for the given source. Returns true if
/// some entries were actually removed.
/// </summary>
protected virtual bool Purge(object source, object data, bool purgeAll)
{
bool foundDirt = false;
bool removeList = purgeAll || source == null;
// remove dead entries from the list
if (!removeList)
{
ListenerList list = (ListenerList)data;
if (ListenerList.PrepareForWriting(ref list) && source != null)
{
Table[this, source] = list;
}
if (list.Purge())
{
foundDirt = true;
}
removeList = list.IsEmpty;
}
// if the list is no longer needed, stop listening to the event
if (removeList)
{
if (source != null) // source may have been GC'd
{
StopListening(source);
// remove the list completely (in the purgeAll case, we'll do it later)
if (!purgeAll)
{
Table.Remove(this, source);
foundDirt = true;
}
}
}
return(foundDirt);
}
/// <summary>
/// Remove dead entries from the data for the given source. Returns true if
/// some entries were actually removed.
/// </summary>
protected override bool Purge(object source, object data, bool purgeAll)
{
bool foundDirt = false;
if (!purgeAll)
{
HybridDictionary dict = (HybridDictionary)data;
int ignoredKeys = 0;
if (!BaseAppContextSwitches.EnableWeakEventMemoryImprovements)
{
// copy the keys into a separate array, so that later on
// we can change the dictionary while iterating over the keys
ICollection ic = dict.Keys;
String[] keys = new String[ic.Count];
ic.CopyTo(keys, 0);
for (int i = keys.Length - 1; i >= 0; --i)
{
if (keys[i] == AllListenersKey)
{
++ignoredKeys;
continue; // ignore the special entry for now
}
// for each key, remove dead entries in its list
bool removeList = purgeAll || source == null;
if (!removeList)
{
ListenerList list = (ListenerList)dict[keys[i]];
if (ListenerList.PrepareForWriting(ref list))
{
dict[keys[i]] = list;
}
if (list.Purge())
{
foundDirt = true;
}
removeList = (list.IsEmpty);
}
// if there are no more entries, remove the key
if (removeList)
{
dict.Remove(keys[i]);
}
}
#if WeakEventTelemetry
LogAllocation(ic.GetType(), 1, 12); // dict.Keys - Hashtable+KeyCollection
LogAllocation(typeof(String[]), 1, 12 + ic.Count * 4); // keys
#endif
}
else
{
Debug.Assert(_toRemove.Count == 0, "to-remove list should be empty");
// If an "in-use" list is changed, we will re-install its clone
// back into the dictionary. Doing this inside the loop
// causes an exception "collection was modified after the enumerator
// was instantiated" (DDVSO 812614), so instead just record
// what to do and do the actual work after the loop.
// This is a rare case - it only arises if a PropertyChanged event
// handler calls (indirectly) into the cleanup code - so allocate
// the temporary memory lazily on the stack.
// [In the bug, the indirect call comes about because the app's
// event handler calls ShowDialog(), which pushes a dispatcher
// frame to run a nested message pump. Then a pending cleanup task
// reaches the front of the dispatcher queue before the dialog
// is dismissed, effectively calling this method while the
// PropertyChanged event delivery is in progress.]
HybridDictionary toInstall = null;
// enumerate the dictionary using IDE explicitly rather than
// foreach, to avoid allocating temporary DictionaryEntry objects
IDictionaryEnumerator ide = dict.GetEnumerator() as IDictionaryEnumerator;
while (ide.MoveNext())
{
String key = (String)ide.Key;
if (key == AllListenersKey)
{
++ignoredKeys;
continue; // ignore the special entry for now
}
// for each key, remove dead entries in its list
bool removeList = purgeAll || source == null;
if (!removeList)
{
ListenerList list = (ListenerList)ide.Value;
bool inUse = ListenerList.PrepareForWriting(ref list);
bool isChanged = false;
if (list.Purge())
{
isChanged = true;
foundDirt = true;
}
removeList = (list.IsEmpty);
// if a cloned list changed, remember the details
// so that the clone can be installed back into the
// dictionary outside the iteration (DDVSO 812614)
if (!removeList && inUse && isChanged)
{
if (toInstall == null)
{
// lazy allocation
toInstall = new HybridDictionary();
}
toInstall[key] = list;
}
}
// if there are no more entries, remove the key
if (removeList)
{
_toRemove.Add(key);
}
}
// do the actual removal (outside the dictionary iteration)
if (_toRemove.Count > 0)
{
foreach (String key in _toRemove)
{
dict.Remove(key);
}
_toRemove.Clear();
_toRemove.TrimExcess();
}
// do the actual re-install of "in-use" lists that changed
if (toInstall != null)
{
IDictionaryEnumerator installDE = toInstall.GetEnumerator() as IDictionaryEnumerator;
while (installDE.MoveNext())
{
String key = (String)installDE.Key;
ListenerList list = (ListenerList)installDE.Value;
dict[key] = list;
}
}
#if WeakEventTelemetry
Type enumeratorType = ide.GetType();
if (enumeratorType.Name.IndexOf("NodeEnumerator") >= 0)
{
LogAllocation(enumeratorType, 1, 24); // ListDictionary+NodeEnumerator
}
else
{
LogAllocation(enumeratorType, 1, 36); // Hashtable+HashtableEnumerator
}
#endif
}
if (dict.Count == ignoredKeys)
{
// if there are no more listeners at all, remove the entry from
// the main table, and prepare to stop listening
purgeAll = true;
if (source != null) // source may have been GC'd
{
this.Remove(source);
}
}
else if (foundDirt)
{
// if any entries were purged, invalidate the special entry
dict.Remove(AllListenersKey);
_proposedAllListenersList = null;
}
}
if (purgeAll)
{
// stop listening. List cleanup is handled by Purge()
if (source != null) // source may have been GC'd
{
StopListening(source);
}
foundDirt = true;
}
return(foundDirt);
}
/// <summary>
/// Remove dead entries from the data for the given source. Returns true if
/// some entries were actually removed.
/// </summary>
protected override bool Purge(object source, object data, bool purgeAll)
{
bool foundDirt = false;
if (!purgeAll)
{
HybridDictionary dict = (HybridDictionary)data;
// copy the keys into a separate array, so that later on
// we can change the dictionary while iterating over the keys
ICollection ic = dict.Keys;
String[] keys = new String[ic.Count];
ic.CopyTo(keys, 0);
for (int i = keys.Length - 1; i >= 0; --i)
{
if (keys[i] == AllListenersKey)
{
continue; // ignore the special entry for now
}
// for each key, remove dead entries in its list
bool removeList = purgeAll || source == null;
if (!removeList)
{
ListenerList list = (ListenerList)dict[keys[i]];
if (ListenerList.PrepareForWriting(ref list))
{
dict[keys[i]] = list;
}
if (list.Purge())
{
foundDirt = true;
}
removeList = (list.IsEmpty);
}
// if there are no more entries, remove the key
if (removeList)
{
dict.Remove(keys[i]);
}
}
if (dict.Count == 0)
{
// if there are no more listeners at all, remove the entry from
// the main table, and prepare to stop listening
purgeAll = true;
if (source != null) // source may have been GC'd
{
this.Remove(source);
}
}
else if (foundDirt)
{
// if any entries were purged, invalidate the special entry
dict.Remove(AllListenersKey);
_proposedAllListenersList = null;
}
}
if (purgeAll)
{
// stop listening. List cleanup is handled by Purge()
if (source != null) // source may have been GC'd
{
StopListening(source);
}
foundDirt = true;
}
return(foundDirt);
}
internal bool Purge()
{
ListenerList.PrepareForWriting(ref _listeners);
return(_listeners.Purge());
}
/// <summary>
/// Remove dead entries from the data for the given source. Returns true if
/// some entries were actually removed.
/// </summary>
protected override bool Purge(object source, object data, bool purgeAll)
{
bool foundDirt = false;
if (!purgeAll)
{
HybridDictionary dict = (HybridDictionary)data;
int ignoredKeys = 0;
if (!BaseAppContextSwitches.EnableWeakEventMemoryImprovements)
{
// copy the keys into a separate array, so that later on
// we can change the dictionary while iterating over the keys
ICollection ic = dict.Keys;
String[] keys = new String[ic.Count];
ic.CopyTo(keys, 0);
for (int i = keys.Length - 1; i >= 0; --i)
{
if (keys[i] == AllListenersKey)
{
++ignoredKeys;
continue; // ignore the special entry for now
}
// for each key, remove dead entries in its list
bool removeList = purgeAll || source == null;
if (!removeList)
{
ListenerList list = (ListenerList)dict[keys[i]];
if (ListenerList.PrepareForWriting(ref list))
{
dict[keys[i]] = list;
}
if (list.Purge())
{
foundDirt = true;
}
removeList = (list.IsEmpty);
}
// if there are no more entries, remove the key
if (removeList)
{
dict.Remove(keys[i]);
}
}
#if WeakEventTelemetry
LogAllocation(ic.GetType(), 1, 12); // dict.Keys - Hashtable+KeyCollection
LogAllocation(typeof(String[]), 1, 12 + ic.Count * 4); // keys
#endif
}
else
{
Debug.Assert(_toRemove.Count == 0, "to-remove list should be empty");
// enumerate the dictionary using IDE explicitly rather than
// foreach, to avoid allocating temporary DictionaryEntry objects
IDictionaryEnumerator ide = dict.GetEnumerator() as IDictionaryEnumerator;
while (ide.MoveNext())
{
String key = (String)ide.Key;
if (key == AllListenersKey)
{
++ignoredKeys;
continue; // ignore the special entry for now
}
// for each key, remove dead entries in its list
bool removeList = purgeAll || source == null;
if (!removeList)
{
ListenerList list = (ListenerList)ide.Value;
if (ListenerList.PrepareForWriting(ref list))
{
dict[key] = list;
}
if (list.Purge())
{
foundDirt = true;
}
removeList = (list.IsEmpty);
}
// if there are no more entries, remove the key
if (removeList)
{
_toRemove.Add(key);
}
}
// do the actual removal (outside the dictionary iteration)
if (_toRemove.Count > 0)
{
foreach (String key in _toRemove)
{
dict.Remove(key);
}
_toRemove.Clear();
_toRemove.TrimExcess();
}
#if WeakEventTelemetry
Type enumeratorType = ide.GetType();
if (enumeratorType.Name.IndexOf("NodeEnumerator") >= 0)
{
LogAllocation(enumeratorType, 1, 24); // ListDictionary+NodeEnumerator
}
else
{
LogAllocation(enumeratorType, 1, 36); // Hashtable+HashtableEnumerator
}
#endif
}
if (dict.Count == ignoredKeys)
{
// if there are no more listeners at all, remove the entry from
// the main table, and prepare to stop listening
purgeAll = true;
if (source != null) // source may have been GC'd
{
this.Remove(source);
}
}
else if (foundDirt)
{
// if any entries were purged, invalidate the special entry
dict.Remove(AllListenersKey);
_proposedAllListenersList = null;
}
}
if (purgeAll)
{
// stop listening. List cleanup is handled by Purge()
if (source != null) // source may have been GC'd
{
StopListening(source);
}
foundDirt = true;
}
return(foundDirt);
}
