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Stylet
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Fix suspected race condition in SingletonRegistration 

This could trigger if the first two requests for a singleton were on
different threads, and executed veyr close together
This commit is contained in:
Antony Male 2020-02-04 21:27:49 +00:00
parent 4fa7b9ca1a
commit 24ab49208f
2 changed files with 21 additions and 23 deletions
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17
Stylet/StyletIoC/Internal/Registrations/RegistrationBase.cs
View File

@ -12,8 +12,8 @@ namespace StyletIoC.Internal.Registrations
protected readonly ICreator Creator;
public RuntimeTypeHandle TypeHandle { get { return this.Creator.TypeHandle; } }
private readonly object generatorLock = new object();
private Func<IRegistrationContext, object> generator;
protected readonly object lockObject = new object();
protected Func<IRegistrationContext, object> generator;
protected RegistrationBase(ICreator creator)
{
@ -25,9 +25,10 @@ namespace StyletIoC.Internal.Registrations
if (this.generator != null)
return this.generator;
lock (this.generatorLock)
lock (this.lockObject)
{
this.generator = this.GetGeneratorInternal();
if (this.generator == null)
this.generator = this.GetGeneratorInternal();
return this.generator;
}
}
@ -38,14 +39,6 @@ namespace StyletIoC.Internal.Registrations
return Expression.Lambda<Func<IRegistrationContext, object>>(this.GetInstanceExpression(registrationContext), registrationContext).Compile();
}
protected void ClearGenerator()
{
lock (this.generatorLock)
{
this.generator = null;
}
}
public abstract Expression GetInstanceExpression(ParameterExpression registrationContext);
}
}

27
Stylet/StyletIoC/Internal/Registrations/SingletonRegistration.cs
View File

@ -11,7 +11,6 @@ namespace StyletIoC.Internal.Registrations
internal class SingletonRegistration : RegistrationBase
{
private readonly IRegistrationContext parentContext;
private Expression instanceExpression;
private object instance;
public SingletonRegistration(IRegistrationContext parentContext, ICreator creator)
@ -20,26 +19,32 @@ namespace StyletIoC.Internal.Registrations
this.parentContext = parentContext;
this.parentContext.Disposing += (o, e) =>
{
var disposable = this.instance as IDisposable;
IDisposable disposable;
lock (this.lockObject)
{
disposable = this.instance as IDisposable;
this.instance = null;
this.generator = null;
}
if (disposable != null)
disposable.Dispose();
this.instance = this.instanceExpression = null;
this.ClearGenerator();
};
}
public override Expression GetInstanceExpression(ParameterExpression registrationContext)
{
if (this.instanceExpression != null)
return this.instanceExpression;
this.instance = Expression.Lambda<Func<IRegistrationContext, object>>(this.Creator.GetInstanceExpression(registrationContext), registrationContext).Compile()(this.parentContext);
if (this.instance == null)
{
lock (this.lockObject)
{
if (this.instance == null)
this.instance = Expression.Lambda<Func<IRegistrationContext, object>>(this.Creator.GetInstanceExpression(registrationContext), registrationContext).Compile()(this.parentContext);
}
}
// This expression yields the actual type of instance, not 'object'
var instanceExpression = Expression.Constant(this.instance);
Interlocked.CompareExchange(ref this.instanceExpression, instanceExpression, null);
return this.instanceExpression;
return instanceExpression;
}
}
}