CancellationContext.cpp

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/*
 * SPDX-License-Identifier: GPL-2.0-or-later
 * SPDX-FileName: CancellationContext.cpp
 * SPDX-FileContributor: Dmitry Vedenko
 */
 
#include "CancellationContext.h"
 
#include <algorithm>
 
#include "ICancellable.h"
 
namespace audacity::concurrency
{
CancellationContext::CancellationContext(Tag)
{
}
 
std::shared_ptr<CancellationContext> CancellationContext::Create()
{
   return std::make_shared<CancellationContext>(Tag {});
}
 
void CancellationContext::Cancel()
{
   if (mCancelled.exchange(true))
      return;
 
   std::vector<CancellableWPtr> cancellableObjects;
 
   {
      auto lock = std::lock_guard { mCancellableObjectsMutex };
      std::swap(cancellableObjects, mCancellableObjects);
   }
 
   std::for_each(
      cancellableObjects.begin(), cancellableObjects.end(),
      [](auto& wptr)
      {
         if (auto lock = wptr.lock())
            lock->Cancel();
      });
}
 
void CancellationContext::OnCancelled(CancellableWPtr cancellable)
{
   auto locked = cancellable.lock();
   if (!locked)
      return;
 
   if (mCancelled.load(std::memory_order_acquire))
   {
      locked->Cancel();
      return;
   }
 
   auto lock = std::lock_guard { mCancellableObjectsMutex };
   mCancellableObjects.erase(
      std::remove_if(
         mCancellableObjects.begin(), mCancellableObjects.end(),
         [](auto& wptr) { return wptr.expired(); }),
      mCancellableObjects.end());
 
   mCancellableObjects.push_back(std::move(cancellable));
}
} // namespace audacity::concurrency