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Refactor the implementation of check #651

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merged 1 commit into from
Dec 29, 2023
Merged

Refactor the implementation of check #651

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2 changes: 1 addition & 1 deletion db.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1206,7 +1206,7 @@ func (db *DB) freepages() []common.Pgid {
panic(fmt.Sprintf("freepages: failed to get all reachable pages (%v)", e))
}
}()
tx.checkBucket(&tx.root, reachable, nofreed, HexKVStringer(), ech)
tx.recursivelyCheckBucket(&tx.root, reachable, nofreed, HexKVStringer(), ech)
close(ech)

// TODO: If check bucket reported any corruptions (ech) we shouldn't proceed to freeing the pages.
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62 changes: 33 additions & 29 deletions tx_check.go
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Original file line number Diff line number Diff line change
Expand Up @@ -57,7 +57,7 @@ func (tx *Tx) check(kvStringer KVStringer, ch chan error) {
}

// Recursively check buckets.
tx.checkBucket(&tx.root, reachable, freed, kvStringer, ch)
tx.recursivelyCheckBucket(&tx.root, reachable, freed, kvStringer, ch)

// Ensure all pages below high water mark are either reachable or freed.
for i := common.Pgid(0); i < tx.meta.Pgid(); i++ {
Expand All @@ -71,7 +71,7 @@ func (tx *Tx) check(kvStringer KVStringer, ch chan error) {
close(ch)
}

func (tx *Tx) checkBucket(b *Bucket, reachable map[common.Pgid]*common.Page, freed map[common.Pgid]bool,
func (tx *Tx) recursivelyCheckBucket(b *Bucket, reachable map[common.Pgid]*common.Page, freed map[common.Pgid]bool,
kvStringer KVStringer, ch chan error) {
// Ignore inline buckets.
if b.RootPage() == 0 {
Expand All @@ -80,52 +80,56 @@ func (tx *Tx) checkBucket(b *Bucket, reachable map[common.Pgid]*common.Page, fre

// Check every page used by this bucket.
b.tx.forEachPage(b.RootPage(), func(p *common.Page, _ int, stack []common.Pgid) {
if p.Id() > tx.meta.Pgid() {
ch <- fmt.Errorf("page %d: out of bounds: %d (stack: %v)", int(p.Id()), int(b.tx.meta.Pgid()), stack)
}

// Ensure each page is only referenced once.
for i := common.Pgid(0); i <= common.Pgid(p.Overflow()); i++ {
var id = p.Id() + i
if _, ok := reachable[id]; ok {
ch <- fmt.Errorf("page %d: multiple references (stack: %v)", int(id), stack)
}
reachable[id] = p
}

// We should only encounter un-freed leaf and branch pages.
if freed[p.Id()] {
ch <- fmt.Errorf("page %d: reachable freed", int(p.Id()))
} else if !p.IsBranchPage() && !p.IsLeafPage() {
ch <- fmt.Errorf("page %d: invalid type: %s (stack: %v)", int(p.Id()), p.Typ(), stack)
}
verifyPageReachable(p, tx.meta.Pgid(), stack, reachable, freed, ch)
})

tx.recursivelyCheckPages(b.RootPage(), kvStringer.KeyToString, ch)
tx.recursivelyCheckPageKeyOrder(b.RootPage(), kvStringer.KeyToString, ch)

// Check each bucket within this bucket.
_ = b.ForEachBucket(func(k []byte) error {
if child := b.Bucket(k); child != nil {
tx.checkBucket(child, reachable, freed, kvStringer, ch)
tx.recursivelyCheckBucket(child, reachable, freed, kvStringer, ch)
}
return nil
})
}

// recursivelyCheckPages confirms database consistency with respect to b-tree
func verifyPageReachable(p *common.Page, hwm common.Pgid, stack []common.Pgid, reachable map[common.Pgid]*common.Page, freed map[common.Pgid]bool, ch chan error) {
if p.Id() > hwm {
ch <- fmt.Errorf("page %d: out of bounds: %d (stack: %v)", int(p.Id()), int(hwm), stack)
}

// Ensure each page is only referenced once.
for i := common.Pgid(0); i <= common.Pgid(p.Overflow()); i++ {
var id = p.Id() + i
if _, ok := reachable[id]; ok {
ch <- fmt.Errorf("page %d: multiple references (stack: %v)", int(id), stack)
}
reachable[id] = p
}

// We should only encounter un-freed leaf and branch pages.
if freed[p.Id()] {
ch <- fmt.Errorf("page %d: reachable freed", int(p.Id()))
} else if !p.IsBranchPage() && !p.IsLeafPage() {
ch <- fmt.Errorf("page %d: invalid type: %s (stack: %v)", int(p.Id()), p.Typ(), stack)
}
}

// recursivelyCheckPageKeyOrder verifies database consistency with respect to b-tree
// key order constraints:
// - keys on pages must be sorted
// - keys on children pages are between 2 consecutive keys on the parent's branch page).
func (tx *Tx) recursivelyCheckPages(pgId common.Pgid, keyToString func([]byte) string, ch chan error) {
tx.recursivelyCheckPagesInternal(pgId, nil, nil, nil, keyToString, ch)
func (tx *Tx) recursivelyCheckPageKeyOrder(pgId common.Pgid, keyToString func([]byte) string, ch chan error) {
tx.recursivelyCheckPageKeyOrderInternal(pgId, nil, nil, nil, keyToString, ch)
}

// recursivelyCheckPagesInternal verifies that all keys in the subtree rooted at `pgid` are:
// recursivelyCheckPageKeyOrderInternal verifies that all keys in the subtree rooted at `pgid` are:
// - >=`minKeyClosed` (can be nil)
// - <`maxKeyOpen` (can be nil)
// - Are in right ordering relationship to their parents.
// `pagesStack` is expected to contain IDs of pages from the tree root to `pgid` for the clean debugging message.
func (tx *Tx) recursivelyCheckPagesInternal(
func (tx *Tx) recursivelyCheckPageKeyOrderInternal(
pgId common.Pgid, minKeyClosed, maxKeyOpen []byte, pagesStack []common.Pgid,
keyToString func([]byte) string, ch chan error) (maxKeyInSubtree []byte) {

Expand All @@ -143,7 +147,7 @@ func (tx *Tx) recursivelyCheckPagesInternal(
if i < len(p.BranchPageElements())-1 {
maxKey = p.BranchPageElement(uint16(i + 1)).Key()
}
maxKeyInSubtree = tx.recursivelyCheckPagesInternal(elem.Pgid(), elem.Key(), maxKey, pagesStack, keyToString, ch)
maxKeyInSubtree = tx.recursivelyCheckPageKeyOrderInternal(elem.Pgid(), elem.Key(), maxKey, pagesStack, keyToString, ch)
runningMin = maxKeyInSubtree
}
return maxKeyInSubtree
Expand Down
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