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Diffstat (limited to 'working/org-element-cache-persist-bug/README.org')
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diff --git a/working/org-element-cache-persist-bug/README.org b/working/org-element-cache-persist-bug/README.org new file mode 100644 index 00000000..2ad8b1bf --- /dev/null +++ b/working/org-element-cache-persist-bug/README.org @@ -0,0 +1,94 @@ +#+TITLE: org-element persistent-cache corruption — reproduction evidence +#+AUTHOR: Craig Jennings +#+DATE: 2026-07-28 + +* What this is + +Evidence for the org-element cache corruption I chased on 2026-07-28, kept +because the diagnosis outlived the fix. I shipped a fix as =d2103877=, put it +through four hostile reviews, and reverted it on their findings. These scripts +are what the reviews were arguing about. + +Run any of them with: + +: emacs --batch -q -l <script> + +Several of the failing ones never terminate once corruption sets in, because +=org-element--cache-self-verify= floods warnings (one run reached 26 million +lines). Use =timeout=. + +* The actual bug + +=org-element--cache-persist-before-write= (org-element.el:7694) resolves +=(get-file-buffer ...)= and destructively nils =:buffer= on the *live* cache. +The next edit to that buffer then signals =wrong-type-argument stringp nil= +from =org-element--cache-after-change=. + +It needs no second buffer and no dirvish. That is the finding that killed the +fix: I had diagnosed a *trigger* and written the fix against it. + +Which buffer gets corrupted is decided by =buffer-list= order, since +=get-file-buffer= returns the first buffer visiting the file. That is why the +symptom is intermittent, and why any future fix needs a test that controls the +order rather than accepting whatever the harness happens to produce. + +* The scripts + +| File | What it shows | +|----------------------------+-----------------------------------------------------------| +| =hostile-d-nopreview.el= | The root cause. One org buffer, no preview, no dirvish. | +| | =org-persist-write-all-buffer= alone strips =:buffer= | +| | from 6134 elements and the next insert signals. | +|----------------------------+-----------------------------------------------------------| +| =hostile-d-order.el= | Corruption depends on =buffer-list= order. Bury the real | +| | buffer and =get-file-buffer= returns the other one, and | +| | the run comes back clean. | +|----------------------------+-----------------------------------------------------------| +| =hostile-d-faithful.el= | A faithful replay of dirvish's preview, with the real | +| | =dirvish-preview-environment= bindings and buffer naming. | +| | Reproduces. My own replay below was looser. | +|----------------------------+-----------------------------------------------------------| +| =hostile-c-repro.el= | The regression the reverted fix introduced: with | +| | =org-element-cache-persistent= nil in a preview buffer, | +| | =org-element-cache-reset= unregisters the *real* file's | +| | persisted cache and removes it from disk. | +|----------------------------+-----------------------------------------------------------| +| =hostile-a-errorbranch.el= | dirvish.el:671-680 kills the preview buffer on a signal | +| | without ever running =dirvish-preview-setup-hook=, so a | +| | hook-based fix is skipped there. Needs =so-long= enabled | +| | to reach, which it is not here today. | +|----------------------------+-----------------------------------------------------------| +| =hostile-e-ffnoselect.el= | =dirvish--find-file-temporarily= returns the user's | +| | existing buffer, which dirvish later kills. Separate | +| | pre-existing bug, tracked as its own task. | +|----------------------------+-----------------------------------------------------------| +| =repro-preview-cache.el= | My original replay. Kept as the record of what I ran, | +| | not as good evidence: its control differs from it by | +| | three variables, so on its own it cannot attribute cause. | +|----------------------------+-----------------------------------------------------------| +| =control-no-preview.el= | That flawed control. | +|----------------------------+-----------------------------------------------------------| +| =variant-no-kill.el= | Preview created but not killed: clean. Supported the | +| | "the kill is required" framing, which turned out to be | +| | backwards. The persist *write* is causal; the kill only | +| | triggers it. | +|----------------------------+-----------------------------------------------------------| +| =variant-no-persist.el= | Same sequence with persistence off: clean. | +|----------------------------+-----------------------------------------------------------| +| =verify-shipped-fix.el= | The reverted fix suppressing the corruption on the | +| | dirvish path. It did work there. It was aimed one layer | +| | too low and carried a regression. | +|----------------------------+-----------------------------------------------------------| +| =d2103877-reverted.patch= | The reverted commit, kept so the approach is recoverable. | +|----------------------------+-----------------------------------------------------------| + +* What does not reproduce it + +Turning =org-element--cache-self-verify= on does *not* manufacture the error. +It reproduces at org's defaults; self-verify only makes it loud. I had worried +the instrumentation was creating the signal, and it is not. + +* Filed as + +See =todo.org=: the org-element persist task, and the separate dirvish +=find-file-noselect= buffer-kill task. |