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fix: OnValueChanged not being triggered on collections when the collection changes back to the previous value #3539

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Merged
merged 5 commits into from
Jul 11, 2025
Merged

fix: OnValueChanged not being triggered on collections when the collection changes back to the previous value #3539

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3307aab
fix: collection authority OnValueChanged
EmandM Jul 9, 2025
578754b
Add non-collections test
EmandM Jul 9, 2025
6b54437
Update Changelog
EmandM Jul 9, 2025
d454cb6
rename m_InternalOriginalValue and add code doc
EmandM Jul 11, 2025
29a906b
Merge branch 'develop-2.0.0' of https://github.com/Unity-Technologies…
EmandM Jul 11, 2025
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1 change: 1 addition & 0 deletions com.unity.netcode.gameobjects/CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@ Additional documentation and release notes are available at [Multiplayer Documen

### Fixed

- Fixed ensuring OnValueChanged callback is still triggered on the authority when a collection changes and then reverts to the previous value in the same frame. (#3539)
- Fixed distributed authority related issue where enabling the `NetworkObject.DestroyWithScene` would cause errors when a destroying non-authority instances due to loading (single mode) or unloading scene events. (#3500)

### Changed
Expand Down
73 changes: 47 additions & 26 deletions com.unity.netcode.gameobjects/Runtime/NetworkVariable/NetworkVariable.cs
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Expand Up @@ -57,7 +57,7 @@ public override void OnInitialize()
base.OnInitialize();

m_HasPreviousValue = true;
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_InternalOriginalValue);
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_LastInternalValue);
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_PreviousValue);
}

Expand All @@ -73,7 +73,7 @@ public NetworkVariable(T value = default,
: base(readPerm, writePerm)
{
m_InternalValue = value;
m_InternalOriginalValue = default;
m_LastInternalValue = default;
// Since we start with IsDirty = true, this doesn't need to be duplicated
// right away. It won't get read until after ResetDirty() is called, and
// the duplicate will be made there. Avoiding calling
Expand All @@ -92,25 +92,45 @@ public void Reset(T value = default)
if (m_NetworkBehaviour == null || m_NetworkBehaviour != null && !m_NetworkBehaviour.NetworkObject.IsSpawned)
{
m_InternalValue = value;
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_InternalOriginalValue);
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_LastInternalValue);
m_PreviousValue = default;
}
}

/// <summary>
/// The internal value of the NetworkVariable
/// The current internal value of the NetworkVariable.
/// </summary>
/// <remarks>
/// When using collections, this InternalValue can be updated directly without going through the <see cref="NetworkVariable{T}.Value"/> setter.
/// </remarks>
[SerializeField]
private protected T m_InternalValue;

// The introduction of standard .NET collections caused an issue with permissions since there is no way to detect changes in the
// collection without doing a full comparison. While this approach does consume more memory per collection instance, it is the
// lowest risk approach to resolving the issue where a client with no write permissions could make changes to a collection locally
// which can cause a myriad of issues.
private protected T m_InternalOriginalValue;
/// <summary>
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/// The last valid/authorized value of the network variable.
/// </summary>
/// <remarks>
/// The introduction of standard .NET collections caused an issue with permissions since there is no way to detect changes in the
/// collection without doing a full comparison. While this approach does consume more memory per collection instance, it is the
/// lowest risk approach to resolving the issue where a client with no write permissions could make changes to a collection locally
/// which can cause a myriad of issues.
/// </remarks>
private protected T m_LastInternalValue;

/// <summary>
/// The most recent value that was synchronized over the network.
/// Synchronized over the network at the end of the frame in which the <see cref="NetworkVariable{T}"/> was marked dirty.
/// </summary>
/// <remarks>
/// Only contains the value synchronized over the network at the end of the last frame.
/// All in-between changes on the authority are tracked by <see cref="m_LastInternalValue"/>.
/// </remarks>
private protected T m_PreviousValue;

/// <summary>
/// Whether this network variable has had changes synchronized over the network.
/// Indicates whether <see cref="m_PreviousValue"/> is populated and valid.
/// </summary>
private bool m_HasPreviousValue;
private bool m_IsDisposed;

Expand Down Expand Up @@ -139,7 +159,7 @@ public virtual T Value
{
T previousValue = m_InternalValue;
m_InternalValue = value;
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_InternalOriginalValue);
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_LastInternalValue);
SetDirty(true);
m_IsDisposed = false;
OnValueChanged?.Invoke(previousValue, m_InternalValue);
Expand All @@ -165,20 +185,21 @@ public bool CheckDirtyState(bool forceCheck = false)
if (CannotWrite)
{
// If modifications are detected, then revert back to the last known current value
if (!NetworkVariableSerialization<T>.AreEqual(ref m_InternalValue, ref m_InternalOriginalValue))
if (!NetworkVariableSerialization<T>.AreEqual(ref m_InternalValue, ref m_LastInternalValue))
{
NetworkVariableSerialization<T>.Duplicate(m_InternalOriginalValue, ref m_InternalValue);
NetworkVariableSerialization<T>.Duplicate(m_LastInternalValue, ref m_InternalValue);
}
return false;
}

// Compare the previous with the current if not dirty or forcing a check.
if ((!isDirty || forceCheck) && !NetworkVariableSerialization<T>.AreEqual(ref m_PreviousValue, ref m_InternalValue))
// Compare the last internal value with the current value if not dirty or forcing a check.
if ((!isDirty || forceCheck) && !NetworkVariableSerialization<T>.AreEqual(ref m_LastInternalValue, ref m_InternalValue))
{
SetDirty(true);
OnValueChanged?.Invoke(m_PreviousValue, m_InternalValue);
OnValueChanged?.Invoke(m_LastInternalValue, m_InternalValue);
m_IsDisposed = false;
isDirty = true;
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_LastInternalValue);
}
return isDirty;
}
Expand Down Expand Up @@ -212,11 +233,11 @@ public override void Dispose()
m_InternalValue = default;

// Dispose the internal original value
if (m_InternalOriginalValue is IDisposable internalOriginalValueDisposable)
if (m_LastInternalValue is IDisposable internalOriginalValueDisposable)
{
internalOriginalValueDisposable.Dispose();
}
m_InternalOriginalValue = default;
m_LastInternalValue = default;

// Dispose the previous value if there is one
if (m_HasPreviousValue && m_PreviousValue is IDisposable previousValueDisposable)
Expand Down Expand Up @@ -245,9 +266,9 @@ public override bool IsDirty()
{
// If the client does not have write permissions but the internal value is determined to be locally modified and we are applying updates, then we should revert
// to the original collection value prior to applying updates (primarily for collections).
if (!NetworkUpdaterCheck && CannotWrite && !NetworkVariableSerialization<T>.AreEqual(ref m_InternalValue, ref m_InternalOriginalValue))
if (!NetworkUpdaterCheck && CannotWrite && !NetworkVariableSerialization<T>.AreEqual(ref m_InternalValue, ref m_LastInternalValue))
{
NetworkVariableSerialization<T>.Duplicate(m_InternalOriginalValue, ref m_InternalValue);
NetworkVariableSerialization<T>.Duplicate(m_LastInternalValue, ref m_InternalValue);
return true;
}
// For most cases we can use the dirty flag.
Expand Down Expand Up @@ -284,7 +305,7 @@ public override void ResetDirty()
m_HasPreviousValue = true;
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_PreviousValue);
// Once updated, assure the original current value is updated for future comparison purposes
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_InternalOriginalValue);
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_LastInternalValue);
}
base.ResetDirty();
}
Expand All @@ -307,9 +328,9 @@ public override void ReadDelta(FastBufferReader reader, bool keepDirtyDelta)
{
// If the client does not have write permissions but the internal value is determined to be locally modified and we are applying updates, then we should revert
// to the original collection value prior to applying updates (primarily for collections).
if (CannotWrite && !NetworkVariableSerialization<T>.AreEqual(ref m_InternalOriginalValue, ref m_InternalValue))
if (CannotWrite && !NetworkVariableSerialization<T>.AreEqual(ref m_LastInternalValue, ref m_InternalValue))
{
NetworkVariableSerialization<T>.Duplicate(m_InternalOriginalValue, ref m_InternalValue);
NetworkVariableSerialization<T>.Duplicate(m_LastInternalValue, ref m_InternalValue);
}

NetworkVariableSerialization<T>.ReadDelta(reader, ref m_InternalValue);
Expand Down Expand Up @@ -341,17 +362,17 @@ internal override void PostDeltaRead()
m_HasPreviousValue = true;
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_PreviousValue);
// Once updated, assure the original current value is updated for future comparison purposes
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_InternalOriginalValue);
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_LastInternalValue);
}

/// <inheritdoc />
public override void ReadField(FastBufferReader reader)
{
// If the client does not have write permissions but the internal value is determined to be locally modified and we are applying updates, then we should revert
// to the original collection value prior to applying updates (primarily for collections).
if (CannotWrite && !NetworkVariableSerialization<T>.AreEqual(ref m_InternalOriginalValue, ref m_InternalValue))
if (CannotWrite && !NetworkVariableSerialization<T>.AreEqual(ref m_LastInternalValue, ref m_InternalValue))
{
NetworkVariableSerialization<T>.Duplicate(m_InternalOriginalValue, ref m_InternalValue);
NetworkVariableSerialization<T>.Duplicate(m_LastInternalValue, ref m_InternalValue);
}

NetworkVariableSerialization<T>.Read(reader, ref m_InternalValue);
Expand All @@ -363,7 +384,7 @@ public override void ReadField(FastBufferReader reader)
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_PreviousValue);

// Once updated, assure the original current value is updated for future comparison purposes
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_InternalOriginalValue);
NetworkVariableSerialization<T>.Duplicate(m_InternalValue, ref m_LastInternalValue);
}

/// <inheritdoc />
Expand Down
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