bruns added inline comments.
INLINE COMMENTS
> databasesanitizer.cpp:159
> + // Create a hash to sum-up indexed items
> QMultiHash<quint32, FileInfo> usedDevices;
> + for (const auto& info : infos) {
I can not come up with a reason to use a MultiHash here in the first place -
all that is needed is the deviceId and the file count per device.
You can use a QMap<DeviceId, Count> here, and use
usedDevices[info.deviceId] += 1;
(operator[] default-constructs the ValueType, which for e.g. `int` is guranteed
by Qt to be 0).
This reduces the effort for counting the items per device from //(D + 3) * F//
to //F//.
(D: number of devices, F: number of files).
Currently you walk the infos list once to create the MultiHash, and then walk
the Multihash once for `uniqueKeys()`, and once for each device when calling
`usedDevices.value()`. Cumulated effort for `.count()` is //F//.
In your case, this would reduce the time for counting by a factor of 14. You
also save the memory for creating a temporary MultiHash with ~20000 items.
> michaelh wrote in fsutils.cpp:111
> Sure? We would have to add Solid as a dependency for `libKF5BalooEngine.so`.
> `databasesanitizer` currently is experimental not exported by default (You
> cannot see this because I haven't rebase yet.).
> I did not use Solid, because I don't know it well and it seemed easier to
> copy and adapt `FSUtils::getDirectoryFileSystem`. I'm not objecting to use
> Solid though.
>
> The true reason for 'fsutils`'s existence is to disable CoW on btrfs. Can
> Solid do that? If so we can drop `fsutils`.
The question is if this really belongs in the library then.
IMHO the whole `printDevices()` function should be moved into baloodb.cpp, The
DatabaseSanitizer should export either `createList` or a function returning
`QVector<DeviceId, Count>`. Going from the DeviceId to the DeviceInfo should
happen in baloodb.
REPOSITORY
R293 Baloo
REVISION DETAIL
https://phabricator.kde.org/D11452
To: michaelh, #baloo, #frameworks
Cc: bruns, smithjd, ashaposhnikov, michaelh, astippich, spoorun, ngraham,
alexeymin
