public IObservable <IChangeSet <TObject, TKey> > Run()
{
return(Observable.Create <IChangeSet <TObject, TKey> >(observer =>
{
long orderItemWasAdded = -1;
var locker = new object();
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());
}));
}
public void Remove(TObject item)
{
if (_keySelector == null)
{
throw new KeySelectorException("A key selector must be specified");
}
var key = _keySelector.GetKey(item);
_cache.Remove(key);
}
public IChangeSet<TObject, TKey> Change(IChangeSet<ExpirableItem<TObject, TKey>, TKey> updates)
{
_cache.Clone(updates);
var itemstoexpire = _cache.KeyValues
.OrderByDescending(exp => exp.Value.ExpireAt)
.Skip(_sizeLimit)
.Select(exp => new Change<TObject, TKey>(ChangeReason.Remove, exp.Key, exp.Value.Value))
.ToList();
if (itemstoexpire.Count > 0)
{
_cache.Remove(itemstoexpire.Select(exp => exp.Key));
}
var notifications = _cache.CaptureChanges();
var changed = notifications.Select(update => new Change<TObject, TKey>
(
update.Reason,
update.Key,
update.Current.Value,
update.Previous.HasValue ? update.Previous.Value.Value : Optional<TObject>.None
));
return new ChangeSet<TObject, TKey>(changed);
}
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.Length > 0)
{
errors.ForEach(t => _exceptionCallback?.Invoke(new Error <TSource, TKey>(t.Error, t.Change.Current, t.Change.Key)));
}
foreach (var result in transformedItems.Where(t => t.Success))
{
TKey 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 static IChangeSet <TObject, TKey> RefreshFilteredFrom <TObject, TKey>(this ChangeAwareCache <TObject, TKey> filtered, Cache <TObject, TKey> allData, Func <TObject, bool> predicate)
where TKey : notnull
{
if (allData.Count == 0)
{
return(ChangeSet <TObject, TKey> .Empty);
}
foreach (var kvp in allData.KeyValues)
{
var existing = filtered.Lookup(kvp.Key);
var matches = predicate(kvp.Value);
if (matches)
{
if (!existing.HasValue)
{
filtered.Add(kvp.Value, kvp.Key);
}
}
else
{
if (existing.HasValue)
{
filtered.Remove(kvp.Key);
}
}
}
return(filtered.CaptureChanges());
}
private void ProcessItem(ChangeAwareCache <TObject, TKey> target, MergeContainer[] sourceLists, TObject item, TKey key)
{
//TODO: Check whether individual items should be updated
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 <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.Value, 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());
}
private IChangeSet <TDestination, TKey> ProcessUpdates(ChangeAwareCache <TransformedItemContainer, 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.Container.Value, 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));
}
}
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));
}
private IChangeSet <TObject, TKey> UpdateCombined(IChangeSet <TObject, TKey> updates)
{
//child caches have been updated before we reached this point.
foreach (var update in updates)
{
TKey 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;
bool 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 IObservable <IChangeSet <TObject, TKey> > Run()
{
return(Observable.Create <IChangeSet <TObject, TKey> >(
observer =>
{
long orderItemWasAdded = -1;
var locker = new object();
if (_expireAfter is null && _limitSizeTo < 1)
{
return _source.Scan(
new ChangeAwareCache <TObject, TKey>(),
(state, latest) =>
{
if (latest is IList <TObject> list)
{
// zero allocation enumerator
var enumerableList = EnumerableIList.Create(list);
if (!_singleValueSource)
{
state.Remove(state.Keys.Except(enumerableList.Select(_keySelector)).ToList());
}
foreach (var item in enumerableList)
{
state.AddOrUpdate(item, _keySelector(item));
}
}
else
{
var enumerable = latest.ToList();
if (!_singleValueSource)
{
state.Remove(state.Keys.Except(enumerable.Select(_keySelector)).ToList());
}
foreach (var item in enumerable)
{
state.AddOrUpdate(item, _keySelector(item));
}
}
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 is null ? Observable.Never <IChangeSet <ExpirableItem <TObject, TKey>, TKey> >() : sizeLimited).Filter(ei => ei.ExpireAt != DateTime.MaxValue).MergeMany(
grouping =>
{
var expireAt = grouping.ExpireAt.Subtract(_scheduler.Now.DateTime);
return Observable.Timer(expireAt, _scheduler).Select(_ => grouping);
}).Synchronize(locker).Select(
item =>
{
cache.Remove(item.Key);
return cache.CaptureChanges();
});
var publisher = sizeLimited.Merge(timeLimited).Cast(ei => ei.Value).NotEmpty().SubscribeSafe(observer);
return new CompositeDisposable(publisher, sizeLimited.Connect());
}));
}
public static void FilterChanges <TObject, TKey>(this ChangeAwareCache <TObject, TKey> cache, IChangeSet <TObject, TKey> changes, Func <TObject, bool> predicate)
where TKey : notnull
{
foreach (var change in changes.ToConcreteType())
{
var key = change.Key;
switch (change.Reason)
{
case ChangeReason.Add:
{
var current = change.Current;
if (predicate(current))
{
cache.AddOrUpdate(current, key);
}
}
break;
case ChangeReason.Update:
{
var current = change.Current;
if (predicate(current))
{
cache.AddOrUpdate(current, key);
}
else
{
cache.Remove(key);
}
}
break;
case ChangeReason.Remove:
cache.Remove(key);
break;
case ChangeReason.Refresh:
{
var existing = cache.Lookup(key);
if (predicate(change.Current))
{
if (!existing.HasValue)
{
cache.AddOrUpdate(change.Current, key);
}
else
{
cache.Refresh(key);
}
}
else
{
if (existing.HasValue)
{
cache.Remove(key);
}
}
}
break;
}
}
}