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Fixed that .Edit() operations would not defer notifications for new subscriptions occurring during the edit. #1133

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Fixed that .Edit() operations would not defer notifications for new subscriptions occurring during the edit. #1133

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53 changes: 52 additions & 1 deletion src/DynamicData.Tests/Cache/SourceCacheFixture.cs
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Original file line number Diff line number Diff line change
@@ -1,12 +1,13 @@
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reactive.Disposables;
using System.Reactive.Linq;
using System.Threading;
using System.Threading.Tasks;

using DynamicData.Tests.Domain;

using DynamicData.Tests.Utilities;
using FluentAssertions;

using Xunit;
Expand Down Expand Up @@ -354,5 +355,55 @@ public void ConnectDuringDeliveryDoesNotDuplicate()
addCounts.GetValueOrDefault("k2").Should().Be(1, "k2 should appear once, not duplicated from snapshot + queued delivery");
}

// Covers https://github.com/reactivemarbles/DynamicData/issues/1129
[Fact]
public void ConnectDuringEditDoesNotDuplicate()
{
using var items = new SourceCache<int, int>(static item => item);

using var subscriptions = new CompositeDisposable();

// An initial subscription is required to initiate internal buffering of changes, during the upcoming .Edit().
// That is, we want there to be changes buffered, internally, when the mid-edit subscription comes in, to
// ensure that they don't get duplicated. This is the scenario that came in up #1129.
subscriptions.Add(items
.Connect()
.Subscribe());

CacheItemRecordingObserver<int, int>? results = null;

items.Edit(inner =>
{
inner.AddOrUpdate(1);

subscriptions.Add(items
.Connect()
.ValidateChangeSets(static item => item)
.RecordCacheItems(out results));

results.Error.Should().BeNull("no errors should have occurred");
results.RecordedChangeSets.Should().BeEmpty("no changes should be published in the middle of an edit");

inner.AddOrUpdate(2);

results.Error.Should().BeNull("no errors should have occurred");
results.RecordedChangeSets.Should().BeEmpty("no changes should be published in the middle of an edit");
});

results.Should().NotBeNull("the edit delegate should have been invoked");
results.Error.Should().BeNull("no errors should have occurred");
results.RecordedChangeSets.Should().ContainSingle("subscribers should only receive a single initial changeset");
results.RecordedItemsByKey.Should().BeEquivalentTo(
new Dictionary<int, int>()
{
[1] = 1,
[2] = 2
},
options => options.WithoutStrictOrdering(),
"all items in the source should have propagated downstream");

results.HasCompleted.Should().BeFalse("the source has not yet completed");
}

private sealed record TestItem(string Key, string Value);
}
50 changes: 50 additions & 0 deletions src/DynamicData.Tests/List/SourceListFixture.cs
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Original file line number Diff line number Diff line change
@@ -1,13 +1,63 @@
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reactive.Disposables;

using FluentAssertions;
using Xunit;

using DynamicData.Tests.Utilities;

namespace DynamicData.Tests.List;

public class SourceListFixture
{
// Covers https://github.com/reactivemarbles/DynamicData/issues/1129
[Fact]
public void ConnectDuringEditDoesNotDuplicate()
{
using var items = new SourceList<int>();

using var subscriptions = new CompositeDisposable();

// An initial subscription is required to initiate internal buffering of changes, during the upcoming .Edit().
// That is, we want there to be changes buffered, internally, when the mid-edit subscription comes in, to
// ensure that they don't get duplicated. This is the scenario that came in up #1129.
subscriptions.Add(items
.Connect()
.Subscribe());

ListItemRecordingObserver<int>? results = null;

items.Edit(inner =>
{
inner.Add(1);

subscriptions.Add(items
.Connect()
.ValidateChangeSets()
.RecordListItems(out results));

results.Error.Should().BeNull("no errors should have occurred");
results.RecordedChangeSets.Should().BeEmpty("no changes should be published in the middle of an edit");

inner.Add(2);

results.Error.Should().BeNull("no errors should have occurred");
results.RecordedChangeSets.Should().BeEmpty("no changes should be published in the middle of an edit");
});

results.Should().NotBeNull("the edit delegate should have been invoked");
results.Error.Should().BeNull("no errors should have occurred");
results.RecordedChangeSets.Should().ContainSingle("subscribers should only receive a single initial changeset");
results.RecordedItems.Should().BeEquivalentTo(
new[] { 1, 2, },
options => options.WithStrictOrdering(),
"all items in the source should have propagated downstream");

results.HasCompleted.Should().BeFalse("the source has not yet completed");
}

[Fact]
public void InitialChangeIsRange()
{
Expand Down
44 changes: 36 additions & 8 deletions src/DynamicData/Cache/ObservableCache.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,9 +6,8 @@
using System.Reactive.Disposables;
using System.Reactive.Linq;
using System.Reactive.Subjects;
using System.Threading;

using DynamicData.Binding;
using DynamicData.Cache;
using DynamicData.Cache.Internal;

// ReSharper disable once CheckNamespace
Expand Down Expand Up @@ -42,6 +41,9 @@ internal sealed class ObservableCache<TObject, TKey> : IObservableCache<TObject,
[System.Diagnostics.CodeAnalysis.SuppressMessage("Usage", "CA2213:Disposable fields should be disposed", Justification = "Terminated via NotifyCompleted in _cleanUp")]
private readonly DeliveryQueue<CacheUpdate> _notifications;

[System.Diagnostics.CodeAnalysis.SuppressMessage("Usage", "CA2213:Disposable fields should be disposed", Justification = "Disposed with _cleanUp")]
private readonly BehaviorSubject<bool> _isEditInProgress;

private int _editLevel; // The level of recursion in editing.

private long _currentVersion; // Monotonic counter incremented under lock for each enqueued change notification.
Expand All @@ -53,6 +55,7 @@ public ObservableCache(IObservable<IChangeSet<TObject, TKey>> source)
_readerWriter = new ReaderWriter<TObject, TKey>();
_notifications = new DeliveryQueue<CacheUpdate>(_locker, new CacheUpdateObserver(this));
_suspensionTracker = new(() => new SuspensionTracker());
_isEditInProgress = new(false);

var loader = source.Subscribe(
changeSet =>
Expand Down Expand Up @@ -83,6 +86,7 @@ public ObservableCache(Func<TObject, TKey>? keySelector = null)
_readerWriter = new ReaderWriter<TObject, TKey>(keySelector);
_notifications = new DeliveryQueue<CacheUpdate>(_locker, new CacheUpdateObserver(this));
_suspensionTracker = new(() => new SuspensionTracker());
_isEditInProgress = new(false);

_cleanUp = Disposable.Create(NotifyCompleted);
}
Expand Down Expand Up @@ -115,14 +119,22 @@ public IObservable<IChangeSet<TObject, TKey>> Connect(Func<TObject, bool>? predi
{
lock (_locker)
{
var observable = (!_suspensionTracker.IsValueCreated || !_suspensionTracker.Value.AreNotificationsSuspended)
var observable = ((!_suspensionTracker.IsValueCreated || !_suspensionTracker.Value.AreNotificationsSuspended)
&& (!_isEditInProgress.Value))

// Create the Connection Observable
? CreateConnectObservable(predicate, suppressEmptyChangeSets)

// Defer until notifications are no longer suspended
: _suspensionTracker.Value.NotificationsSuspendedObservable.Do(static _ => { }, observer.OnCompleted)
.Where(static b => !b).Take(1).Select(_ => CreateConnectObservable(predicate, suppressEmptyChangeSets)).Switch();
: Observable.CombineLatest(
_suspensionTracker.Value.NotificationsSuspendedObservable,
_isEditInProgress,
static (areNotificationsSuspended, isEditInProgress) => areNotificationsSuspended || isEditInProgress)
.Do(static _ => { }, observer.OnCompleted)
.Where(static shouldConnectionBeDeferred => !shouldConnectionBeDeferred)
.Take(1)
.Select(_ => CreateConnectObservable(predicate, suppressEmptyChangeSets))
.Switch();

return observable.SubscribeSafe(observer);
}
Expand All @@ -139,14 +151,22 @@ public IObservable<Change<TObject, TKey>> Watch(TKey key) =>
{
lock (_locker)
{
var observable = (!_suspensionTracker.IsValueCreated || !_suspensionTracker.Value.AreNotificationsSuspended)
var observable = ((!_suspensionTracker.IsValueCreated || !_suspensionTracker.Value.AreNotificationsSuspended)
&& (!_isEditInProgress.Value))

// Create the Watch Observable
? CreateWatchObservable(key)

// Defer until notifications are no longer suspended
: _suspensionTracker.Value.NotificationsSuspendedObservable.Do(static _ => { }, observer.OnCompleted)
.Where(static b => !b).Take(1).Select(_ => CreateWatchObservable(key)).Switch();
: Observable.CombineLatest(
_suspensionTracker.Value.NotificationsSuspendedObservable,
_isEditInProgress,
static (areNotificationsSuspended, isEditInProgress) => areNotificationsSuspended || isEditInProgress)
.Do(static _ => { }, observer.OnCompleted)
.Where(static shouldConnectionBeDeferred => !shouldConnectionBeDeferred)
.Take(1)
.Select(_ => CreateWatchObservable(key))
.Switch();

return observable.SubscribeSafe(observer);
}
Expand Down Expand Up @@ -181,6 +201,7 @@ internal void UpdateFromIntermediate(Action<ICacheUpdater<TObject, TKey>> update
ChangeSet<TObject, TKey>? changes = null;

_editLevel++;
_isEditInProgress.OnNext(_editLevel is not 0);
if (_editLevel == 1)
{
var previewHandler = _changesPreview.HasObservers ? (Action<ChangeSet<TObject, TKey>>)InvokePreview : null;
Expand All @@ -197,6 +218,8 @@ internal void UpdateFromIntermediate(Action<ICacheUpdater<TObject, TKey>> update
{
notifications.EnqueueNext(new CacheUpdate(changes, _readerWriter.Count, ++_currentVersion));
}

_isEditInProgress.OnNext(_editLevel is not 0);
}

internal void UpdateFromSource(Action<ISourceUpdater<TObject, TKey>> updateAction)
Expand All @@ -208,6 +231,7 @@ internal void UpdateFromSource(Action<ISourceUpdater<TObject, TKey>> updateActio
ChangeSet<TObject, TKey>? changes = null;

_editLevel++;
_isEditInProgress.OnNext(_editLevel is not 0);
if (_editLevel == 1)
{
var previewHandler = _changesPreview.HasObservers ? (Action<ChangeSet<TObject, TKey>>)InvokePreview : null;
Expand All @@ -224,6 +248,8 @@ internal void UpdateFromSource(Action<ISourceUpdater<TObject, TKey>> updateActio
{
notifications.EnqueueNext(new CacheUpdate(changes, _readerWriter.Count, ++_currentVersion));
}

_isEditInProgress.OnNext(_editLevel is not 0);
}

private IObservable<IChangeSet<TObject, TKey>> CreateConnectObservable(Func<TObject, bool>? predicate, bool suppressEmptyChangeSets) =>
Expand Down Expand Up @@ -386,6 +412,7 @@ public void OnError(Exception error)
{
cache._changesPreview.OnError(error);
cache._changes.OnError(error);
cache._isEditInProgress.OnError(error);

if (cache._countChanged.IsValueCreated)
{
Expand All @@ -402,6 +429,7 @@ public void OnCompleted()
{
cache._changes.OnCompleted();
cache._changesPreview.OnCompleted();
cache._isEditInProgress.OnCompleted();

if (cache._countChanged.IsValueCreated)
{
Expand Down
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