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Fix race condition in TransferHandle::WaitUntilFinished() deadlocking #511

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Fix race condition in TransferHandle::WaitUntilFinished() deadlocking #511

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a7f2442
Fix race condition in TransferHandle::WaitUntilFinished() deadlocking
Apr 24, 2017
215ba62
m_statusLock needs to be external to the conditional to avoid deadlock
May 11, 2017
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6 changes: 3 additions & 3 deletions aws-cpp-sdk-transfer/source/transfer/TransferHandle.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -229,6 +229,7 @@ namespace Aws

if(IsTransitionAllowed(currentStatus, value))
{
std::unique_lock<std::mutex> semaphoreLock(m_statusLock);
m_status.store(static_cast<long>(value));

if (IsFinishedStatus(value))
Expand All @@ -238,17 +239,16 @@ namespace Aws
CleanupDownloadStream();
}

std::unique_lock<std::mutex> semaphoreLock(m_statusLock);
m_waitUntilFinishedSignal.notify_all();
}
}
}

void TransferHandle::WaitUntilFinished() const
{
std::unique_lock<std::mutex> semaphoreLock(m_statusLock);
if (!IsFinishedStatus(static_cast<TransferStatus>(m_status.load())) || HasPendingParts())
{
std::unique_lock<std::mutex> semaphoreLock(m_statusLock);
m_waitUntilFinishedSignal.wait(semaphoreLock, [this]()
{ return IsFinishedStatus(static_cast<TransferStatus>(m_status.load())) && !HasPendingParts(); });
semaphoreLock.unlock();
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Is it necessary to unlock explicitly? Shouldn't the system unlock it when lock get destructed?

Expand Down Expand Up @@ -301,4 +301,4 @@ namespace Aws
}
}
}
}
}