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Delay initialization of Task related properties which are rarely used #45127

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merged 4 commits into from
Nov 24, 2020
Merged

Delay initialization of Task related properties which are rarely used #45127

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Delay initialization of Task related properties which are rarely used
marek-safar Nov 23, 2020
fe618c5
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marek-safar Nov 24, 2020
f19c05a
fix up previous commit
marek-safar Nov 24, 2020
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Update src/libraries/System.Private.CoreLib/src/System/Threading/Exec…
marek-safar Nov 24, 2020
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6 changes: 4 additions & 2 deletions src/libraries/System.Private.CoreLib/src/System/Threading/ExecutionContext.cs
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Expand Up @@ -25,7 +25,7 @@ namespace System.Threading
public sealed class ExecutionContext : IDisposable, ISerializable
{
internal static readonly ExecutionContext Default = new ExecutionContext(isDefault: true);
internal static readonly ExecutionContext DefaultFlowSuppressed = new ExecutionContext(AsyncLocalValueMap.Empty, Array.Empty<IAsyncLocal>(), isFlowSuppressed: true);
private static volatile ExecutionContext? s_defaultFlowSuppressed;

private readonly IAsyncLocalValueMap? m_localValues;
private readonly IAsyncLocal[]? m_localChangeNotifications;
Expand Down Expand Up @@ -88,9 +88,11 @@ public void GetObjectData(SerializationInfo info, StreamingContext context)

if (m_localValues == null || AsyncLocalValueMap.IsEmpty(m_localValues))
{
#pragma warning disable CA1825 // Avoid unnecessary zero-length array allocations
return isFlowSuppressed ?
DefaultFlowSuppressed :
(s_defaultFlowSuppressed ??= new ExecutionContext(AsyncLocalValueMap.Empty, new IAsyncLocal[0], isFlowSuppressed: true)) :
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null; // implies the default context
#pragma warning restore
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}

return new ExecutionContext(m_localValues, m_localChangeNotifications, isFlowSuppressed);
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7 changes: 5 additions & 2 deletions src/libraries/System.Private.CoreLib/src/System/Threading/Tasks/Future.cs
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Expand Up @@ -61,7 +61,7 @@ public class Task<TResult> : Task
/// <summary>A cached task for default(TResult).</summary>
internal static readonly Task<TResult> s_defaultResultTask = TaskCache.CreateCacheableTask<TResult>(default);

private static readonly TaskFactory<TResult> s_Factory = new TaskFactory<TResult>();
private static TaskFactory<TResult>? s_Factory;

// The value itself, if set.
internal TResult? m_result;
Expand Down Expand Up @@ -486,7 +486,10 @@ internal TResult GetResultCore(bool waitCompletionNotification)
/// of <see cref="System.Threading.Tasks.TaskFactory{TResult}"/>, as would result from using
/// the default constructor on the factory type.
/// </remarks>
public static new TaskFactory<TResult> Factory => s_Factory;
public static new TaskFactory<TResult> Factory =>
Volatile.Read(ref s_Factory) ??
Interlocked.CompareExchange(ref s_Factory, new TaskFactory<TResult>(), null) ??
s_Factory;

/// <summary>
/// Evaluates the value selector of the Task which is passed in as an object and stores the result.
Expand Down