Fix s3 transfer dead lock (#96)

* Fix race condition in TransferHandle::WaitUntilFinished() deadlocking
#511 #520

Author: singku

aws-cpp-sdk-transfer/source/transfer/TransferHandle.cpp

@@ -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))
@@ -238,20 +239,18 @@ 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();
             }
         }
 
@@ -301,4 +300,4 @@ namespace Aws
             }
         }
     }
-}
+}

aws-cpp-sdk-transfer/source/transfer/TransferManager.cpp

@@ -501,9 +501,9 @@ namespace Aws
             }
             else
             {
-                transferContext->handle->UpdateStatus(DetermineIfFailedOrCanceled(*transferContext->handle));
                 transferContext->handle->ChangePartToFailed(transferContext->partState);
                 transferContext->handle->SetError(outcome.GetError());
+                transferContext->handle->UpdateStatus(DetermineIfFailedOrCanceled(*transferContext->handle));
                 TriggerErrorCallback(*transferContext->handle, outcome.GetError());
             }