public async Task CompleteSwitchingBrokerAsync(CancellationToken cancellationToken)
{
if (_lockToken == null)
{
throw new InvalidOperationException($"{nameof(AcquireLockAsync)} must be called before {nameof(CompleteSwitchingBrokerAsync)}");
}
_session._disposeToken.ThrowIfDisposed();
if (_session._startupInfo == null)
{
// Session never started. No need to restart it.
// Reset _initializationLock so that next awaiter can proceed.
_lockToken.Reset();
return;
}
var brokerClient = _session.BrokerClient;
var startupInfo = _session._startupInfo;
var host = _session._host;
var hostRunTask = _session._hostRunTask;
// host may be null if previous attempts to start it have failed
if (host != null)
{
// Detach RHost from RSession
host.DetachCallback();
// Cancel all current requests
await _session.CancelAllAsync(cancellationToken);
}
// Start new RHost
await _session.StartHostAsyncBackground(_hostToSwitch, _lockToken, cancellationToken);
// Shut down the old host, gracefully if possible, and wait for old hostRunTask to exit;
if (hostRunTask != null)
{
await StopHostAsync(brokerClient, startupInfo?.Name, host, hostRunTask);
}
host?.Dispose();
if (hostRunTask != null && hostRunTask.Status == TaskStatus.Running)
{
await hostRunTask;
}
_hostToSwitch = null;
}
private async Task StartHostAsyncBackground(RHostStartupInfo startupInfo, IRSessionCallback callback, IBinaryAsyncLockToken lockToken, int timeout)
{
await TaskUtilities.SwitchToBackgroundThread();
_callback = callback;
_startupInfo = startupInfo;
RHost host;
try {
host = await BrokerClient.ConnectAsync(startupInfo.Name, this, startupInfo.RHostCommandLineArguments, timeout);
} catch (OperationCanceledException ex) {
_initializationTcs.TrySetCanceled(ex);
lockToken.Reset();
throw;
} catch (Exception ex) {
_initializationTcs.TrySetException(ex);
lockToken.Reset();
throw;
}
await StartHostAsyncBackground(host, lockToken);
}
private async Task RunHost(IBinaryAsyncLockToken lockToken, CancellationToken initializationCt)
{
try {
ScheduleAfterHostStarted(_startupInfo);
await _host.Run(initializationCt);
} catch (OperationCanceledException oce) {
_initializationTcs.TrySetCanceled(oce);
} catch (MessageTransportException mte) {
_initializationTcs.TrySetCanceled(new RHostDisconnectedException(string.Empty, mte));
} catch (Exception ex) {
_initializationTcs.TrySetException(ex);
} finally {
lockToken.Reset();
}
}
private bool VerifyTransactionState(string methodName)
{
if (_lockToken == null)
{
throw new InvalidOperationException($"{nameof(AcquireLockAsync)} must be called before {methodName}");
}
if (_session._startupInfo == null)
{
// Session never started. No need to restart it or connect to the host.
_lockToken.Reset();
return(false);
}
return(true);
}
public void Dispose()
{
_lockToken?.Reset();
_hostToSwitch?.Dispose();
}