https://bugs.freedesktop.org/show_bug.cgi?id=86335
--- Comment #3 from Patrick Ohly <[email protected]> --- The unexpectedly high traffic is caused by a "is the collection empty" check. This is relevant for slow sync prevention, because a slow sync is allowed to run when there is no data. The 1.5 release does the check whereas 1.4 (unintentionally) skipped it. This was fixed for 1.4.99.4 in: commit dec741ea501add6d9e173821b99af85ee0262034 Author: Patrick Ohly <[email protected]> Date: Wed Aug 20 16:23:15 2014 +0200 VirtualSyncSource, MapSyncSource: implement m_isEmpty This is relevant for isUsable() and not so much (not at all?) for slow sync prevention. The comment explain why the change was made. It *is* relevant for slow sync prevention, it just wasn't the primary reason for changing the code. The underlying problem is that the "is empty" check is currently done using code which downloads the entire calendar. This is necessary to work around bugs in (ironically) servers like Radical 0.7 which did (do?) not implement a less costly operation reliably: when asked to report only about VEVENTs, VTODO or VJOURNAL are also included in the response and vice versa. The underlying problem is that a collection may contain a mixture of those, but SyncEvolution only syncs one kind and thus needs to determine the content type of each item. There is no good support for that in CalDAV. There are three possible solutions: 1. restore the 1.4 behavior of always assuming that there is data (basically disabling the more intelligent slow-sync prevention) 2. implement a simpler "is empty" check with potentially false "is not empty" results when there are some items of unknown content (for example, we sync VEVENTs and the collection contains only VJOURNAL, but we don't know that because we avoid downloading the data and thus incorrectly assume that there might be VEVENTs) 3. implement logic which determines whether a collection really can contain a mixture of items and only do the more costly check in that case Option 3 can be combined with 2. I think I'll start with 2. -- You are receiving this mail because: You are on the CC list for the bug.
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