private void IdleLoop(IdleState idle)
{
lock (idle.Client.SyncRoot) {
// Note: since the IMAP server will drop the connection after 30 minutes, we must loop sending IDLE commands that
// last ~29 minutes or until the user has requested that they do not want to IDLE anymore.
// For GMail, we use a 9 minute interval because they do not seem to keep the connection alive for more than ~10 minutes.
while (!idle.IsCancellationRequested)
{
using (var timeout = new CancellationTokenSource(TimeSpan.FromMinutes(_imapClientCanIdle ? 9 : 1))) {
try {
// We set the timeout source so that if the idle.DoneToken is cancelled, it can cancel the timeout
idle.SetTimeoutSource(timeout);
if (_imapClientCanIdle)
{
// The Idle() method will not return until the timeout has elapsed or idle.CancellationToken is cancelled
idle.Client.Idle(timeout.Token);
}
else
{
// The IMAP server does not support IDLE, so send a NOOP command instead
idle.Client.NoOp(idle.DoneToken);
// Wait for the timeout to elapse or the cancellation token to be cancelled
WaitHandle.WaitAny(new[] {
timeout.Token.WaitHandle, idle.DoneToken.WaitHandle
});
}
} finally {
// we will dispose timeout, dont throw an exeption because we are trying to cancel it
idle.SetTimeoutSource(null);
}
if (timeout.IsCancellationRequested)
{
_config.Tracer?.TraceVerbose($"Idle timed out, looping", $"{this}");
}
}
}
}
}
static void IdleLoop(object state)
{
IdleState idle = (IdleState)state;
lock (idle.Client.SyncRoot)
{
// Note: since the IMAP server will drop the connection after 30 minutes, we must loop sending IDLE commands that
// last ~29 minutes or until the user has requested that they do not want to IDLE anymore.
//
// For GMail, we use a 9 minute interval because they do not seem to keep the connection alive for more than ~10 minutes.
while (!idle.IsCancellationRequested)
{
using (var timeout = new CancellationTokenSource(new TimeSpan(0, 9, 0)))
{
try
{
// We set the timeout source so that if the idle.DoneToken is cancelled, it can cancel the timeout
idle.SetTimeoutSource(timeout);
if (idle.Client.Capabilities.HasFlag(ImapCapabilities.Idle))
{
// The Idle() method will not return until the timeout has elapsed or idle.CancellationToken is cancelled
idle.Client.Idle(timeout.Token, idle.CancellationToken);
}
else
{
// The IMAP server does not support IDLE, so send a NOOP command instead
idle.Client.NoOp(idle.CancellationToken);
// Wait for the timeout to elapse or the cancellation token to be cancelled
WaitHandle.WaitAny(new[] { timeout.Token.WaitHandle, idle.CancellationToken.WaitHandle });
}
}
catch (OperationCanceledException)
{
// This means that idle.CancellationToken was cancelled, not the DoneToken nor the timeout.
break;
}
catch (ImapProtocolException)
{
// The IMAP server sent garbage in a response and the ImapClient was unable to deal with it.
// This should never happen in practice, but it's probably still a good idea to handle it.
//
// Note: an ImapProtocolException almost always results in the ImapClient getting disconnected.
break;
}
catch (ImapCommandException)
{
// The IMAP server responded with "NO" or "BAD" to either the IDLE command or the NOOP command.
// This should never happen... but again, we're catching it for the sake of completeness.
break;
}
finally
{
// We're about to Dispose() the timeout source, so set it to null.
idle.SetTimeoutSource(null);
}
}
}
}
}