[英]Is it a reasonable approach for lock-free design for this scenario
这是我在此之前提出的一个问题的跟进。 总之,在这种情况下,我想提出一种无锁设计,在这种情况下,我在取消任务后想调用第三方库的方法。 为了回答我的问题,一个有帮助的SO参与者建议使用CancellationToken.Register,但我不确定在这里和在哪里可以使用它。 下面是我想出的代码。 如果您发现此方法有任何问题,或者是否有更好的替代方法可以解决此问题,请告诉我。
class ProcessEmployees
{
private List<Employee> _Employees;
CancellationTokenSource cs = new CancellationTokenSource();
public ProcessEmployees()
{
_Employees = new List<Employee>()
{
new Employee() { ID = 1, FirstName = "John", LastName = "Doe" },
new Employee() { ID = 2, FirstName = "Peter", LastName = "Saul" },
new Employee() { ID = 3, FirstName = "Mike", LastName = "Sue" },
new Employee() { ID = 4, FirstName = "Catherina", LastName = "Desoza" },
new Employee() { ID = 5, FirstName = "Paul", LastName = "Smith" }
};
}
public void StartProcessing()
{
try
{
Task[] tasks = this._Employees.AsParallel().WithCancellation(cs.Token).Select(x => this.ProcessThisEmployee(x, cs.Token)).ToArray();
Task.WaitAll(tasks);
}
catch (AggregateException ae)
{
// error handling code
}
// other stuff
}
private async Task ProcessThisEmployee(Employee x, CancellationToken token)
{
ThirdPartyLibrary library = new ThirdPartyLibrary();
if (token.IsCancellationRequested)
token.ThrowIfCancellationRequested();
await Task.Factory.StartNew(() => library.SomeAPI(x) );
if (token.IsCancellationRequested)
{
library.Clean();
token.ThrowIfCancellationRequested();
}
}
}
您的过程代码可以简化为以下内容(这是注册的使用方式)
private void ProcessThisEmployee(Employee x, CancellationToken token)
{
ThirdPartyLibrary library = new ThirdPartyLibrary();
token.ThrowIfCancellationRequested();
using(token.Register(() => library.Clean())
{
library.SomeAPI(x);
}
token.ThrowIfCancellationRequested(); //Not sure why you cancel here in your original example.
}
如果令牌在using
语句范围内被取消,它将调用library.Clean()
如果之后被调用,则不调用该函数。 我也摆脱了您的Task.Run
,没有理由浪费多余的线程做您的工作。 最后,我摆脱了额外的if (token.IsCancellationRequested)
检查, ThrowIfCancellationRequested()
拥有如果在其内部进行检查,则无需事先检查。
另外,由于我的简化,您不再返回任务,因此StartProcessing代码变为
public void StartProcessing()
{
try
{
this._Employees.AsParallel().WithCancellation(cs.Token).ForAll(x => this.ProcessThisEmployee(x, cs.Token));
}
catch (AggregateException ae)
{
// error handling code
}
// other stuff
}
使用ForAll(
而不是Select(
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