tx: detect cycles in recursivelyCheckPageKeyOrderInternal#1195
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ivangsm wants to merge 1 commit intoetcd-io:mainfrom
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tx: detect cycles in recursivelyCheckPageKeyOrderInternal#1195ivangsm wants to merge 1 commit intoetcd-io:mainfrom
ivangsm wants to merge 1 commit intoetcd-io:mainfrom
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recursivelyCheckPageKeyOrderInternal walks branch children without tracking pages it has already entered, so a corrupted db whose branch references one of its own ancestors drives the goroutine stack to overflow even after forEachPageInternal (etcd-io#1194) stops looping. Thread a visited set through the recursion, emit a single "page cycle detected" error on revisit, and return so the outer Check continues to surface other diagnostics. Related to etcd-io#701 / etcd-io#581. Signed-off-by: Iván Salazar <ivangio.salazar@gmail.com>
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Summary
tx.Check()runs two recursive walkers fromcheckInvariantProperties:forEachPage(fixed by #1194) andrecursivelyCheckPageKeyOrder. Thesecond walker does not track visited pages, so a db with a branch page
that references one of its own ancestors still drives the goroutine stack
to overflow during a
Check, even with #1194 applied.This threads a
visited map[common.Pgid]struct{}through the recursion.On a revisit the function emits one
page cycle detected at pgId:%derror to the check channel and returns, so
Checkfinishes and surfacesany other diagnostics instead of crashing the process.
The accompanying whitebox test reproduces the corruption pattern from
#701 (copy a branch page over a leaf descendant to form a back-edge) and
asserts that the walker terminates with the expected error.
Partially addresses #581. Companion to #1194. Follows tjungblu's
follow-up ask in #701.
A third cycle-sensitive walker remains — the cursor-driven
b.ForEachBucketpath insiderecursivelyCheckBucket— and is beingtracked separately; it is not a mechanical patch and will get its own
issue/PR.
Test plan
go test -run TestTx_recursivelyCheckPageKeyOrder_CycleTerminatespasses with the fix and stack-overflows without it.TEST_FREELIST_TYPE=array BBOLT_VERIFY=all go test -short ./...passes.TEST_FREELIST_TYPE=hashmap BBOLT_VERIFY=all go test -short ./...passes.make fmtclean.