LIBRARY read the whole catalogue back on every batch the scan wrote: `reload()`
is a `getAll` of the `photos` store, every row and every thumbnail in it, and on
a catalogue of 150,000 frames one read was measured at 2036ms, twenty of them at
315s with the worst at 58s, the heap behind them going from 44MB to 89MB — beside
a LibRaw open of a quarter of a gigabyte and four lanes of RAW bytes. On a folder
of RAW that is the crash, and on any long roll it is the strip taking the roll's
own time to move.
The read-back now runs on a clock: at most once every five seconds of a scan, and
once more when the reading ends, which is when the last of it is due. A batch
lands every second or so, and reading it back costs every frame in the catalogue
— so a scan that read it back each time spent the roll doing nothing else. The
strip still fills while the scan runs; it fills in steps.
The walk's own position went to the origin private file system. It is one path
per frame the walk has found and not read — about twenty-eight characters each,
measured over a folder of three thousand, which is the 85,626-character write —
and local storage on this origin takes 5,000,000 characters and then throws,
measured the same way. That is a hundred and seventy-five thousand frames: past
it the first write of a long roll fails, the position is nowhere, and the next
visit walks the whole roll from the top. That is the reading that goes back to
the start, and OPFS takes the same text as a file. It goes down at most once
every two seconds, for the same reason the catalogue is read back on a clock:
the string is a few megabytes of paths.
The folder is walked again for being raised no more than once every thirty
seconds. A hundred thousand frames is a hundred thousand stats on the disk, and
this screen is raised every time the reader comes back from the studio.
And the column no longer says there is no folder before it has looked. The note
waited on `folders` alone, which is empty for as long as the screen is coming up:
on the catalogue of 150,000 it said so for the whole of the load and showed the
folder after. It now waits on `loaded`, and says nothing until there is something
to say.
Checked on the running bundle: a 3000-frame scan reads the catalogue back 13
times where the code read it back once per batch, writes the position 21 times,
and leaves the peak heap at 116MB with no long tasks. A reading stopped at 483 of
4000 leaves `walk/ROLL.json` at 101,107 characters naming 3,550 unread frames,
with no local storage key beside it, and the visit after a reload carries on at
585 rather than at the top. LIBRARY on 150,000 frames shows no "No folder yet" at
any point and settles on "150000 photos". The wall, the strip, the grid, the deep
link and the phone's recipes all pass their checks.
3dtours
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