Hello!
The Synthesis engine has the feature that its backends are allowed to
use IDs of arbitrary length. The engine will translate into IDs shorter
than the maximum ID size supported by the peer.
TLocalEngineDS::adjustLocalIDforSize() creates these temporary IDs,
using:
fTempGUIDMap.size() + 1
// as list only grows, we have unique tempuids for sure
I'm currently (involuntarily ;-) stress-testing this code by running
SyncEvolution<->SyncEvolution syncs with lots of iCalendar 2.0 items,
which happen to have very long IDs.
I see failures where the server assigns the same temporary ID to
different items in the same sync.
I've added debug logging. It shows that the following happens:
1. fTempGUIDMap is restored from the map file such that it has 105
entries, *but* these are non-contiguous (from #1 to #124).
2. fTempGUIDMap.size() + 1 is #106, which already exists in
fTempGUIDMap.
3. Overwriting that entry does not increase fTempGUIDMap.size().
4. A second item is assigned the same #106 temp ID.
I don't know exactly how I arrived at this state. Is the on-disk dump of
fTempGUIDMap really meant to preserve all temporary IDs in perpetuity? I
don't think so, because that would fill up the disk and there is a
"delete map item" operation.
Unless there is some additional constraint, then the assumption that
"the list only grows" is wrong. I have added a workaround which checks
for ID collisions in TLocalEngineDS::adjustLocalIDforSize(). Is that the
right solution or do I need to search for the reason why the mapping has
gaps?
Also note that I end up with a temporary ID which must have been used
before in an older sync session. Could that be a problem?
--
Best Regards, Patrick Ohly
The content of this message is my personal opinion only and although
I am an employee of Intel, the statements I make here in no way
represent Intel's position on the issue, nor am I authorized to speak
on behalf of Intel on this matter.
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