Re: [RFC] Remove pendingLimit from OSyncQueue

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> Hi,
>
> I would like to remove pendingLimit from OSyncQueue to fix the dead lock
> of ticket #1078. The pendingLimit of the OSyncQueue and the not fully
> independent messages can produced dead locks. Today the queue already
> causes deadlocks.
>
> What happens?
>
> The OSyncQueue stops dispatching if pendingLimit number of messages
> waiting for an answer. This is correct IPC behaviour if the messages are
> independent but this is not correct in case of OpenSync.
>
> Some protocols (e.g. SyncML) can only flush once for an object type
> (SyncML datastore). This means changes are collected and send if the
> maximum message size of the protocol is reached or all OpenSync messages
> are present. This means the only guaranteed send operation is done if
> the OpenSync message committed_all is handled.
>
> A first workaround was to commit all changes immediately and abort the
> complete synchronization if an error happens by signalling the error to
> the committed_all context. This does not work because the mapping (of
> SyncML) is potentially sent after the changes are received. OpenSync can
> handle mappings only for not committed changes.
>
> So the decision is simply to add a new mechanism for mapping IDs or to
> remove the pendingLimit which creates a dead lock between two originally
> independent queues.
>
> Best regards
>
> Michael
> - --
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>
> Michael Bell                        Humboldt-Universitaet zu Berlin
>
> Tel.: +49 (0)30-2093 2482           ZE Computer- und Medienservice
> Fax:  +49 (0)30-2093 2704           Unter den Linden 6
> michael.bell@...       D-10099 Berlin
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