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Reduce CacheEntry size #45410

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merged 13 commits into from
Dec 2, 2020
Merged

Reduce CacheEntry size #45410

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f313e24
replace 3 boolean fields with one enum flag field
adamsitnik Dec 1, 2020
53259eb
use auto property for AbsoluteExpiration
adamsitnik Dec 1, 2020
681c2b2
simplify the code by using expression bodies
adamsitnik Dec 1, 2020
655091c
don't take a lock if _expirationTokenRegistrations is already set to …
adamsitnik Dec 1, 2020
f4f0ad9
don't use internal fields of CacheEntry, the public properties are en…
adamsitnik Dec 1, 2020
4b39c18
expose private methods of MemoryCache and replace the usage of delega…
adamsitnik Dec 1, 2020
f84b6cb
AbsoluteExpirationRelativeToNow can internally just use AbsoluteExpir…
adamsitnik Dec 1, 2020
850676e
more expressions, less code
adamsitnik Dec 1, 2020
359326b
so this is how nullable works with conditions...
adamsitnik Dec 1, 2020
cfd3ed6
address code review feedback: make Set a thread-safe method
adamsitnik Dec 1, 2020
628546a
address code review feedback
adamsitnik Dec 1, 2020
80eb6e0
Revert "AbsoluteExpirationRelativeToNow can internally just use Absol…
adamsitnik Dec 1, 2020
baf73b3
add comments
adamsitnik Dec 1, 2020
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165 changes: 62 additions & 103 deletions src/libraries/Microsoft.Extensions.Caching.Memory/src/CacheEntry.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -13,86 +13,44 @@ namespace Microsoft.Extensions.Caching.Memory
{
internal class CacheEntry : ICacheEntry
{
private bool _disposed;
private static readonly Action<object> ExpirationCallback = ExpirationTokensExpired;
private readonly Action<CacheEntry> _notifyCacheOfExpiration;
private readonly Action<CacheEntry> _notifyCacheEntryCommit;

private readonly object _lock = new object();
private readonly MemoryCache _cache;

private IList<IDisposable> _expirationTokenRegistrations;
private IList<PostEvictionCallbackRegistration> _postEvictionCallbacks;
private bool _isExpired;
private readonly ILogger _logger;

internal IList<IChangeToken> _expirationTokens;
internal DateTimeOffset? _absoluteExpiration;
internal TimeSpan? _absoluteExpirationRelativeToNow;
private IList<IChangeToken> _expirationTokens;
private TimeSpan? _absoluteExpirationRelativeToNow;
private TimeSpan? _slidingExpiration;
private long? _size;
private IDisposable _scope;
private object _value;
private bool _valueHasBeenSet;

internal readonly object _lock = new object();
private int _state; // actually a [Flag] enum called "State"
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internal CacheEntry(
object key,
Action<CacheEntry> notifyCacheEntryCommit,
Action<CacheEntry> notifyCacheOfExpiration,
ILogger logger)
internal CacheEntry(object key, MemoryCache memoryCache)
{
if (key == null)
{
throw new ArgumentNullException(nameof(key));
}

if (notifyCacheEntryCommit == null)
{
throw new ArgumentNullException(nameof(notifyCacheEntryCommit));
}

if (notifyCacheOfExpiration == null)
{
throw new ArgumentNullException(nameof(notifyCacheOfExpiration));
}

if (logger == null)
{
throw new ArgumentNullException(nameof(logger));
}

Key = key;
_notifyCacheEntryCommit = notifyCacheEntryCommit;
_notifyCacheOfExpiration = notifyCacheOfExpiration;

Key = key ?? throw new ArgumentNullException(nameof(key));
_cache = memoryCache ?? throw new ArgumentNullException(nameof(memoryCache));
_scope = CacheEntryHelper.EnterScope(this);
_logger = logger;
}

/// <summary>
/// Gets or sets an absolute expiration date for the cache entry.
/// </summary>
public DateTimeOffset? AbsoluteExpiration
{
get
{
return _absoluteExpiration;
}
set
{
_absoluteExpiration = value;
}
}
public DateTimeOffset? AbsoluteExpiration { get; set; }

/// <summary>
/// Gets or sets an absolute expiration time, relative to now.
/// </summary>
public TimeSpan? AbsoluteExpirationRelativeToNow
{
get
{
return _absoluteExpirationRelativeToNow;
}
get => _absoluteExpirationRelativeToNow;
set
{
// this method does not set AbsoluteExpiration as it would require calling Clock.UtcNow twice:
// once here and once in MemoryCache.SetEntry

if (value <= TimeSpan.Zero)
{
throw new ArgumentOutOfRangeException(
Expand All @@ -111,10 +69,7 @@ public TimeSpan? AbsoluteExpirationRelativeToNow
/// </summary>
public TimeSpan? SlidingExpiration
{
get
{
return _slidingExpiration;
}
get => _slidingExpiration;
set
{
if (value <= TimeSpan.Zero)
Expand All @@ -124,41 +79,20 @@ public TimeSpan? SlidingExpiration
value,
"The sliding expiration value must be positive.");
}

_slidingExpiration = value;
}
}

/// <summary>
/// Gets the <see cref="IChangeToken"/> instances which cause the cache entry to expire.
/// </summary>
public IList<IChangeToken> ExpirationTokens
{
get
{
if (_expirationTokens == null)
{
_expirationTokens = new List<IChangeToken>();
}

return _expirationTokens;
}
}
public IList<IChangeToken> ExpirationTokens => _expirationTokens ??= new List<IChangeToken>();

/// <summary>
/// Gets or sets the callbacks will be fired after the cache entry is evicted from the cache.
/// </summary>
public IList<PostEvictionCallbackRegistration> PostEvictionCallbacks
{
get
{
if (_postEvictionCallbacks == null)
{
_postEvictionCallbacks = new List<PostEvictionCallbackRegistration>();
}

return _postEvictionCallbacks;
}
}
public IList<PostEvictionCallbackRegistration> PostEvictionCallbacks => _postEvictionCallbacks ??= new List<PostEvictionCallbackRegistration>();

/// <summary>
/// Gets or sets the priority for keeping the cache entry in the cache during a
Expand Down Expand Up @@ -191,19 +125,25 @@ public object Value
set
{
_value = value;
_valueHasBeenSet = true;
IsValueSet = true;
}
}

internal DateTimeOffset LastAccessed { get; set; }

internal EvictionReason EvictionReason { get; private set; }

private bool IsDisposed { get => ((State)_state).HasFlag(State.IsDisposed); set => Set(State.IsDisposed, value); }

private bool IsExpired { get => ((State)_state).HasFlag(State.IsExpired); set => Set(State.IsExpired, value); }

private bool IsValueSet { get => ((State)_state).HasFlag(State.IsValueSet); set => Set(State.IsValueSet, value); }

public void Dispose()
{
if (!_disposed)
if (!IsDisposed)
{
_disposed = true;
IsDisposed = true;

// Ensure the _scope reference is cleared because it can reference other CacheEntry instances.
// This CacheEntry is going to be put into a MemoryCache, and we don't want to root unnecessary objects.
Expand All @@ -213,9 +153,9 @@ public void Dispose()
// Don't commit or propagate options if the CacheEntry Value was never set.
// We assume an exception occurred causing the caller to not set the Value successfully,
// so don't use this entry.
if (_valueHasBeenSet)
if (IsValueSet)
{
_notifyCacheEntryCommit(this);
_cache.SetEntry(this);

if (CanPropagateOptions())
{
Expand All @@ -226,24 +166,21 @@ public void Dispose()
}

[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal bool CheckExpired(in DateTimeOffset now)
{
return _isExpired || CheckForExpiredTime(now) || CheckForExpiredTokens();
}
internal bool CheckExpired(in DateTimeOffset now) => IsExpired || CheckForExpiredTime(now) || CheckForExpiredTokens();

internal void SetExpired(EvictionReason reason)
{
if (EvictionReason == EvictionReason.None)
{
EvictionReason = reason;
}
_isExpired = true;
IsExpired = true;
DetachTokens();
}

private bool CheckForExpiredTime(in DateTimeOffset now)
{
if (!_absoluteExpiration.HasValue && !_slidingExpiration.HasValue)
if (!AbsoluteExpiration.HasValue && !_slidingExpiration.HasValue)
{
return false;
}
Expand All @@ -252,7 +189,7 @@ private bool CheckForExpiredTime(in DateTimeOffset now)

bool FullCheck(in DateTimeOffset offset)
{
if (_absoluteExpiration.HasValue && _absoluteExpiration.Value <= offset)
if (AbsoluteExpiration.HasValue && AbsoluteExpiration.Value <= offset)
{
SetExpired(EvictionReason.Expired);
return true;
Expand Down Expand Up @@ -323,12 +260,13 @@ private static void ExpirationTokensExpired(object obj)
{
var entry = (CacheEntry)state;
entry.SetExpired(EvictionReason.TokenExpired);
entry._notifyCacheOfExpiration(entry);
entry._cache.EntryExpired(entry);
}, obj, CancellationToken.None, TaskCreationOptions.DenyChildAttach, TaskScheduler.Default);
}

private void DetachTokens()
{
// _expirationTokenRegistrations is not checked for null, because AttachTokens might initialize it under lock
lock (_lock)
{
IList<IDisposable> registrations = _expirationTokenRegistrations;
Expand Down Expand Up @@ -373,12 +311,13 @@ private static void InvokeCallbacks(CacheEntry entry)
catch (Exception e)
{
// This will be invoked on a background thread, don't let it throw.
entry._logger.LogError(e, "EvictionCallback invoked failed");
entry._cache._logger.LogError(e, "EvictionCallback invoked failed");
}
}
}

internal bool CanPropagateOptions() => _expirationTokens != null || _absoluteExpiration.HasValue;
// this simple check very often allows us to avoid expensive call to PropagateOptions(CacheEntryHelper.Current)
internal bool CanPropagateOptions() => _expirationTokens != null || AbsoluteExpiration.HasValue;

internal void PropagateOptions(CacheEntry parent)
{
Expand All @@ -403,13 +342,33 @@ internal void PropagateOptions(CacheEntry parent)
}
}

if (_absoluteExpiration.HasValue)
if (AbsoluteExpiration.HasValue)
{
if (!parent._absoluteExpiration.HasValue || _absoluteExpiration < parent._absoluteExpiration)
if (!parent.AbsoluteExpiration.HasValue || AbsoluteExpiration < parent.AbsoluteExpiration)
{
parent._absoluteExpiration = _absoluteExpiration;
parent.AbsoluteExpiration = AbsoluteExpiration;
}
}
}

private void Set(State option, bool value)
{
int before, after;

do
{
before = _state;
after = value ? (_state | (int)option) : (_state & ~(int)option);
} while (Interlocked.CompareExchange(ref _state, after, before) != before);
}

[Flags]
private enum State
{
Default = 0,
IsValueSet = 1 << 0,
IsExpired = 1 << 1,
IsDisposed = 1 << 2,
}
}
}
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