2 回答

TA贡献1830条经验 获得超3个赞
TPL DataFlow API 的问题在于,一切都是内部/私有和/或密封的。这给您扩展 API 的可能性不大。
无论如何,对于您的问题,实现一个新的 SynchronizedJoinBlock 类可能是个好主意。实际的业务逻辑位于 GetMessagesRecursive 方法中:
public sealed class SynchronizedJoinBlock<T1, T2>
: IReceivableSourceBlock<Tuple<T1, T2>>
{
private readonly object _syncObject = new object();
private readonly Func<T1, T2, int> _compareFunction;
private readonly Queue<T1> _target1Messages;
private readonly Queue<T2> _target2Messages;
private readonly TransformManyBlock<T1, Tuple<T1, T2>> _target1;
private readonly TransformManyBlock<T2, Tuple<T1, T2>> _target2;
private readonly BatchedJoinBlock<Tuple<T1, T2>, Tuple<T1, T2>> _batchedJoinBlock;
private readonly TransformManyBlock<Tuple<IList<Tuple<T1, T2>>, IList<Tuple<T1, T2>>>, Tuple<T1, T2>> _transformManyBlock;
public ITargetBlock<T1> Target1 => _target1;
public ITargetBlock<T2> Target2 => _target2;
public Task Completion => _transformManyBlock.Completion;
public SynchronizedJoinBlock(Func<T1, T2, int> compareFunction)
{
_compareFunction = compareFunction
?? throw new ArgumentNullException(nameof(compareFunction));
_batchedJoinBlock = new BatchedJoinBlock<Tuple<T1, T2>, Tuple<T1, T2>>(1);
_target1Messages = new Queue<T1>();
_target2Messages = new Queue<T2>();
Func<ICollection<Tuple<T1, T2>>> getMessagesFunction = () =>
{
lock (_syncObject)
{
if (_target1Messages.Count > 0 && _target2Messages.Count > 0)
{
return GetMessagesRecursive(_target1Messages.Peek(), _target2Messages.Peek()).ToArray();
}
else
{
return new Tuple<T1, T2>[0];
}
}
};
_target1 = new TransformManyBlock<T1, Tuple<T1, T2>>((element) =>
{
_target1Messages.Enqueue(element);
return getMessagesFunction();
});
_target1.LinkTo(_batchedJoinBlock.Target1, new DataflowLinkOptions() { PropagateCompletion = true });
_target2 = new TransformManyBlock<T2, Tuple<T1, T2>>((element) =>
{
_target2Messages.Enqueue(element);
return getMessagesFunction();
});
_target2.LinkTo(_batchedJoinBlock.Target2, new DataflowLinkOptions() { PropagateCompletion = true });
_transformManyBlock = new TransformManyBlock<Tuple<IList<Tuple<T1, T2>>, IList<Tuple<T1, T2>>>, Tuple<T1, T2>>(
element => element.Item1.Concat(element.Item2)
);
_batchedJoinBlock.LinkTo(_transformManyBlock, new DataflowLinkOptions() { PropagateCompletion = true });
}
private IEnumerable<Tuple<T1, T2>> GetMessagesRecursive(T1 value1, T2 value2)
{
int result = _compareFunction(value1, value2);
if (result == 0)
{
yield return Tuple.Create(_target1Messages.Dequeue(), _target2Messages.Dequeue());
}
else if (result < 0)
{
yield return Tuple.Create(_target1Messages.Dequeue(), default(T2));
if (_target1Messages.Count > 0)
{
foreach (var item in GetMessagesRecursive(_target1Messages.Peek(), value2))
{
yield return item;
}
}
}
else
{
yield return Tuple.Create(default(T1), _target2Messages.Dequeue());
if (_target2Messages.Count > 0)
{
foreach (var item in GetMessagesRecursive(value1, _target2Messages.Peek()))
{
yield return item;
}
}
}
}
public void Complete()
{
_target1.Complete();
_target2.Complete();
}
Tuple<T1, T2> ISourceBlock<Tuple<T1, T2>>.ConsumeMessage(
DataflowMessageHeader messageHeader,
ITargetBlock<Tuple<T1, T2>> target, out bool messageConsumed)
{
return ((ISourceBlock<Tuple<T1, T2>>)_transformManyBlock)
.ConsumeMessage(messageHeader, target, out messageConsumed);
}
void IDataflowBlock.Fault(Exception exception)
{
((IDataflowBlock)_transformManyBlock).Fault(exception);
}
public IDisposable LinkTo(ITargetBlock<Tuple<T1, T2>> target,
DataflowLinkOptions linkOptions)
{
return _transformManyBlock.LinkTo(target, linkOptions);
}
void ISourceBlock<Tuple<T1, T2>>.ReleaseReservation(
DataflowMessageHeader messageHeader, ITargetBlock<Tuple<T1, T2>> target)
{
((ISourceBlock<Tuple<T1, T2>>)_transformManyBlock)
.ReleaseReservation(messageHeader, target);
}
bool ISourceBlock<Tuple<T1, T2>>.ReserveMessage(
DataflowMessageHeader messageHeader, ITargetBlock<Tuple<T1, T2>> target)
{
return ((ISourceBlock<Tuple<T1, T2>>)_transformManyBlock)
.ReserveMessage(messageHeader, target);
}
public bool TryReceive(Predicate<Tuple<T1, T2>> filter, out Tuple<T1, T2> item)
{
return _transformManyBlock.TryReceive(filter, out item);
}
public bool TryReceiveAll(out IList<Tuple<T1, T2>> items)
{
return _transformManyBlock.TryReceiveAll(out items);
}
}

TA贡献1776条经验 获得超12个赞
这是一个SynchronizedJoinBlock块的实现,类似于 Hardy Hobeck's answer中提供的那个。Target1这个负责处理一些次要的细节,例如取消、处理异常,以及在输入块Target2被标记为已完成时处理传播剩余项目。此外,合并逻辑不涉及递归,这应该使其性能更好(希望我没有测量它)并且不易受到堆栈溢出异常的影响。小偏差:输出是一个ValueTuple<T1, T2>而不是Tuple<T1, T2>(目的是减少分配)。
public sealed class SynchronizedJoinBlock<T1, T2> : IReceivableSourceBlock<(T1, T2)>
{
private readonly Func<T1, T2, int> _comparison;
private readonly Queue<T1> _queue1 = new Queue<T1>();
private readonly Queue<T2> _queue2 = new Queue<T2>();
private readonly ActionBlock<T1> _input1;
private readonly ActionBlock<T2> _input2;
private readonly BufferBlock<(T1, T2)> _output;
private readonly object _locker = new object();
public SynchronizedJoinBlock(Func<T1, T2, int> comparison,
CancellationToken cancellationToken = default)
{
_comparison = comparison ?? throw new ArgumentNullException(nameof(comparison));
// Create the three internal blocks
var options = new ExecutionDataflowBlockOptions()
{
CancellationToken = cancellationToken
};
_input1 = new ActionBlock<T1>(Add1, options);
_input2 = new ActionBlock<T2>(Add2, options);
_output = new BufferBlock<(T1, T2)>(options);
// Link the input blocks with the output block
var inputTasks = new Task[] { _input1.Completion, _input2.Completion };
Task.WhenAny(inputTasks).Unwrap().ContinueWith(t =>
{
// If ANY input block fails, then the whole block has failed
((IDataflowBlock)_output).Fault(t.Exception.InnerException);
if (!_input1.Completion.IsCompleted) _input1.Complete();
if (!_input2.Completion.IsCompleted) _input2.Complete();
ClearQueues();
}, default, TaskContinuationOptions.OnlyOnFaulted |
TaskContinuationOptions.RunContinuationsAsynchronously,
TaskScheduler.Default);
Task.WhenAll(inputTasks).ContinueWith(t =>
{
// If ALL input blocks succeeded, then the whole block has succeeded
try
{
if (!t.IsCanceled) PostRemaining(); // Post what's left
}
catch (Exception ex)
{
((IDataflowBlock)_output).Fault(ex);
}
_output.Complete();
ClearQueues();
}, default, TaskContinuationOptions.NotOnFaulted |
TaskContinuationOptions.RunContinuationsAsynchronously,
TaskScheduler.Default);
}
public ITargetBlock<T1> Target1 => _input1;
public ITargetBlock<T2> Target2 => _input2;
public Task Completion => _output.Completion;
private void Add1(T1 value1)
{
lock (_locker)
{
_queue1.Enqueue(value1);
FindAndPostMatched_Unsafe();
}
}
private void Add2(T2 value2)
{
lock (_locker)
{
_queue2.Enqueue(value2);
FindAndPostMatched_Unsafe();
}
}
private void FindAndPostMatched_Unsafe()
{
while (_queue1.Count > 0 && _queue2.Count > 0)
{
var result = _comparison(_queue1.Peek(), _queue2.Peek());
if (result < 0)
{
_output.Post((_queue1.Dequeue(), default));
}
else if (result > 0)
{
_output.Post((default, _queue2.Dequeue()));
}
else // result == 0
{
_output.Post((_queue1.Dequeue(), _queue2.Dequeue()));
}
}
}
private void PostRemaining()
{
lock (_locker)
{
while (_queue1.Count > 0)
{
_output.Post((_queue1.Dequeue(), default));
}
while (_queue2.Count > 0)
{
_output.Post((default, _queue2.Dequeue()));
}
}
}
private void ClearQueues()
{
lock (_locker)
{
_queue1.Clear();
_queue2.Clear();
}
}
public void Complete() => _output.Complete();
public void Fault(Exception exception)
=> ((IDataflowBlock)_output).Fault(exception);
public IDisposable LinkTo(ITargetBlock<(T1, T2)> target,
DataflowLinkOptions linkOptions)
=> _output.LinkTo(target, linkOptions);
public bool TryReceive(Predicate<(T1, T2)> filter, out (T1, T2) item)
=> _output.TryReceive(filter, out item);
public bool TryReceiveAll(out IList<(T1, T2)> items)
=> _output.TryReceiveAll(out items);
(T1, T2) ISourceBlock<(T1, T2)>.ConsumeMessage(
DataflowMessageHeader messageHeader, ITargetBlock<(T1, T2)> target,
out bool messageConsumed)
=> ((ISourceBlock<(T1, T2)>)_output).ConsumeMessage(
messageHeader, target, out messageConsumed);
void ISourceBlock<(T1, T2)>.ReleaseReservation(
DataflowMessageHeader messageHeader, ITargetBlock<(T1, T2)> target)
=> ((ISourceBlock<(T1, T2)>)_output).ReleaseReservation(
messageHeader, target);
bool ISourceBlock<(T1, T2)>.ReserveMessage(
DataflowMessageHeader messageHeader, ITargetBlock<(T1, T2)> target)
=> ((ISourceBlock<(T1, T2)>)_output).ReserveMessage(
messageHeader, target);
}
使用示例:
var joinBlock = new SynchronizedJoinBlock<(int, int), (int, int)>(
(x, y) => Comparer<int>.Default.Compare(x.Item1, y.Item1));
var source1 = new (int, int)[] {(17, 1700), (18, 1800), (19, 1900),
(20, 2000), (21, 2100), (22, 2200), (25, 2500), (26, 2600),
(27, 2700), (28, 2800), (29, 2900)};
var source2 = new (int, int)[] {(15, 1500), (16, 1600), (17, 1700),
(18, 1800), (19, 1900), (20, 2000), (21, 2100), (24, 2400),
(25, 2500), (26, 2600)};
Array.ForEach(source1, x => joinBlock.Target1.Post(x));
Array.ForEach(source2, x => joinBlock.Target2.Post(x));
joinBlock.Target1.Complete();
joinBlock.Target2.Complete();
while (joinBlock.OutputAvailableAsync().Result)
{
Console.WriteLine($"> Received: {joinBlock.Receive()}");
}
输出:
收到:((0, 0), (15, 1500))
收到:((0, 0), (16, 1600))
收到:((17, 1700), (17, 1700))
收到:((18 , 1800), (18, 1800))
收到: ((19, 1900), (19, 1900))
收到: ((20, 2000), (20, 2000))
收到: ((21, 2100), ( 21, 2100))
收到:((22, 2200), (0, 0))
收到:((0, 0), (24, 2400))
收到:((25, 2500), (25, 2500))
收到:((26, 2600), (26, 2600))
收到:((27, 2700), (0, 0))
收到:((28, 2800), (0, 0))
收到:((29 , 2900), (0, 0))
假定传入数据是有序的。
这个类与JoinDependencyBlock
我之前在一个有点相关的问题中发布的类具有相似的结构。
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