public void AddOrUpdate(TObject item)
{
if (_keySelector == null)
{
throw new KeySelectorException("A key selector must be specified");
}
var key = _keySelector.GetKey(item);
_cache.AddOrUpdate(item, key);
}
private IChangeSet <TDestination, TKey> ProcessUpdates(ChangeAwareCache <TDestination, TKey> cache, IEnumerable <TransformResult> transformedItems)
{
foreach (var result in transformedItems)
{
if (result.Success)
{
switch (result.Change.Reason)
{
case ChangeReason.Add:
case ChangeReason.Update:
cache.AddOrUpdate(result.Destination.ValueOrDefault(), result.Key);
break;
case ChangeReason.Remove:
cache.Remove(result.Key);
break;
case ChangeReason.Refresh:
cache.Refresh(result.Key);
break;
}
}
else
{
_exceptionCallback(new Error <TSource, TKey>(result.Error, result.Change.Current, result.Change.Key));
}
}
return(cache.CaptureChanges());
}
public static IChangeSet <TObject, TKey> RefreshFilteredFrom <TObject, TKey>(
this ChangeAwareCache <TObject, TKey> filtered,
Cache <TObject, TKey> allData,
Func <TObject, bool> predicate)
{
foreach (var kvp in allData.KeyValues)
{
var exisiting = filtered.Lookup(kvp.Key);
var matches = predicate(kvp.Value);
if (matches)
{
if (!exisiting.HasValue)
{
filtered.AddOrUpdate(kvp.Value, kvp.Key);
}
}
else
{
if (exisiting.HasValue)
{
filtered.Remove(kvp.Key);
}
}
}
return(filtered.CaptureChanges());
}
private void ProcessItem(ChangeAwareCache <TObject, TKey> target, MergeContainer[] sourceLists, TObject item, TKey key)
{
var cached = target.Lookup(key);
var shouldBeInResult = MatchesConstraint(sourceLists, key);
if (shouldBeInResult)
{
if (!cached.HasValue)
{
target.AddOrUpdate(item, key);
}
else if (!ReferenceEquals(item, cached.Value))
{
target.AddOrUpdate(item, key);
}
}
else
{
if (cached.HasValue)
{
target.Remove(key);
}
}
}
private IChangeSet <TDestination, TKey> ProcessUpdates(ChangeAwareCache <TransformedItemContainer, TKey> cache, TransformResult[] transformedItems)
{
//check for errors and callback if a handler has been specified
var errors = transformedItems.Where(t => !t.Success).ToArray();
if (errors.Any())
{
errors.ForEach(t => _exceptionCallback(new Error <TSource, TKey>(t.Error, t.Change.Current, t.Change.Key)));
}
foreach (var result in transformedItems.Where(t => t.Success))
{
var key = result.Key;
switch (result.Change.Reason)
{
case ChangeReason.Add:
case ChangeReason.Update:
cache.AddOrUpdate(result.Container.Value, key);
break;
case ChangeReason.Remove:
cache.Remove(key);
break;
case ChangeReason.Refresh:
cache.Refresh(key);
break;
}
}
var changes = cache.CaptureChanges();
var transformed = changes.Select(change => new Change <TDestination, TKey>(change.Reason,
change.Key,
change.Current.Destination,
change.Previous.Convert(x => x.Destination),
change.CurrentIndex,
change.PreviousIndex));
return(new ChangeSet <TDestination, TKey>(transformed));
}
public IObservable <IChangeSet <TObject, TKey> > Run()
{
return(Observable.Create <IChangeSet <TObject, TKey> >(observer =>
{
long orderItemWasAdded = -1;
var locker = new object();
if (_expireAfter == null && _limitSizeTo < 1)
{
return _source.Scan(new ChangeAwareCache <TObject, TKey>(), (state, latest) =>
{
latest.ForEach(t => state.AddOrUpdate(t, _keySelector(t)));
return state;
})
.Select(state => state.CaptureChanges())
.SubscribeSafe(observer);
}
var cache = new ChangeAwareCache <ExpirableItem <TObject, TKey>, TKey>();
var sizeLimited = _source.Synchronize(locker)
.Scan(cache, (state, latest) =>
{
latest.Select(t =>
{
var key = _keySelector(t);
return CreateExpirableItem(t, key, ref orderItemWasAdded);
}).ForEach(ei => cache.AddOrUpdate(ei, ei.Key));
if (_limitSizeTo > 0 && state.Count > _limitSizeTo)
{
var toRemove = state.Count - _limitSizeTo;
//remove oldest items
cache.KeyValues
.OrderBy(exp => exp.Value.Index)
.Take(toRemove)
.ForEach(ei => cache.Remove(ei.Key));
}
return state;
})
.Select(state => state.CaptureChanges())
.Publish();
var timeLimited = (_expireAfter == null ? Observable.Never <IChangeSet <ExpirableItem <TObject, TKey>, TKey> >() : sizeLimited)
.Filter(ei => ei.ExpireAt != DateTime.MaxValue)
.GroupWithImmutableState(ei => ei.ExpireAt)
.MergeMany(grouping =>
{
var expireAt = grouping.Key.Subtract(_scheduler.Now.DateTime);
return Observable.Timer(expireAt, _scheduler).Select(_ => grouping);
})
.Synchronize(locker)
.Select(grouping =>
{
cache.Remove(grouping.Keys);
return cache.CaptureChanges();
});
var publisher = sizeLimited
.Merge(timeLimited)
.Cast(ei => ei.Value)
.NotEmpty()
.SubscribeSafe(observer);
return new CompositeDisposable(publisher, sizeLimited.Connect());
}));
}
private IChangeSet <TObject, TKey> UpdateCombined(IChangeSet <TObject, TKey> updates)
{
//child caches have been updated before we reached this point.
foreach (var update in updates)
{
var key = update.Key;
switch (update.Reason)
{
case ChangeReason.Add:
case ChangeReason.Update:
{
// get the current key.
//check whether the item should belong to the cache
var cached = _combinedCache.Lookup(key);
var contained = cached.HasValue;
var match = MatchesConstraint(key);
if (match)
{
if (contained)
{
if (!ReferenceEquals(update.Current, cached.Value))
{
_combinedCache.AddOrUpdate(update.Current, key);
}
}
else
{
_combinedCache.AddOrUpdate(update.Current, key);
}
}
else
{
if (contained)
{
_combinedCache.Remove(key);
}
}
}
break;
case ChangeReason.Remove:
{
var cached = _combinedCache.Lookup(key);
var contained = cached.HasValue;
var shouldBeIncluded = MatchesConstraint(key);
if (shouldBeIncluded)
{
var firstOne = _sourceCaches.Select(s => s.Lookup(key))
.SelectValues()
.First();
if (!cached.HasValue)
{
_combinedCache.AddOrUpdate(firstOne, key);
}
else if (!ReferenceEquals(firstOne, cached.Value))
{
_combinedCache.AddOrUpdate(firstOne, key);
}
}
else
{
if (contained)
{
_combinedCache.Remove(key);
}
}
}
break;
case ChangeReason.Refresh:
{
_combinedCache.Refresh(key);
}
break;
}
}
return(_combinedCache.CaptureChanges());
}
public static void FilterChanges <TObject, TKey>(this ChangeAwareCache <TObject, TKey> cache,
IChangeSet <TObject, TKey> changes,
Func <TObject, bool> predicate)
{
foreach (var change in changes)
{
var key = change.Key;
switch (change.Reason)
{
case ChangeReason.Add:
{
if (predicate(change.Current))
{
cache.AddOrUpdate(change.Current, key);
}
}
break;
case ChangeReason.Update:
{
if (predicate(change.Current))
{
cache.AddOrUpdate(change.Current, key);
}
else
{
cache.Remove(key);
}
}
break;
case ChangeReason.Remove:
cache.Remove(key);
break;
case ChangeReason.Refresh:
{
var exisiting = cache.Lookup(key);
if (predicate(change.Current))
{
if (!exisiting.HasValue)
{
cache.AddOrUpdate(change.Current, key);
}
else
{
cache.Refresh(key);
}
}
else
{
if (exisiting.HasValue)
{
cache.Remove(key);
}
}
}
break;
}
}
}
