[systemd-devel] [PATCH v3] journalctl: Improve boot ID lookup

Jan Janssen medhefgo at web.de
Wed May 20 09:51:26 PDT 2015

Works fine. Don't forget to close the bug, though. :P

On 2015-05-19 00:37, Lennart Poettering wrote:
> On Fri, 01.05.15 15:15, Jan Janssen (medhefgo at web.de) wrote:
>> This method should greatly improve offset based lookup, by simply jumping
>> from one boot to the next boot. It starts at the journal head to get the
>> a boot ID, makes a _BOOT_ID match and then comes from the opposite
>> journal direction (tail) to get to the end that boot. After flushing the matches
>> and advancing the journal from that exact position, we arrive at the start
>> of next boot. Rinse and repeat.
>> This is faster than the old method of aggregating the full boot listing just
>> so we can jump to a specific boot, which can be a real pain on big journals
>> just for a mere "-b -1" case.
>> As an additional benefit --list-boots should improve slightly too, because
>> it does less seeking.
>> Note that there can be a change in boot order with this lookup method
>> because it will use the order of boots in the journal, not the realtime stamp
>> stored in them. That's arguably better, though.
>> Another deficiency is that it will get confused with boots interleaving in the
>> journal, therefore, it will refuse operation in --merge, --file and
>> --directory mode.
> I have now applied this. Afterwards I added a couple of (mostly
> unrelated) clean-ups to journalctl.
> Would be nice if you could verify that things still work as intended!
> Lennart

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