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rbyd: Added LFS_ASSERTRBYDBALANCE for asserting rbyds are balanced

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This is _not_ free, so an opt-in define is needed.

This is also expected to fail right now due to balance issues with
diverging yellow nodes in range-removals, but it's the first step
towards trying to fix said balance issues.

I've been trying to avoid adding debug machinery to lfs.c itself, since
it tends to hurt readability, but I really don't know how you could
assert rbyd balance out-of-tree short of trying to fetch every block in
emubd somehow...

Oh well, finding and asserting rbyd balance in lfsr_rbyd_fetch at least
doesn't require that much code.

No code changes, thanks to const-propagation.
This commit is contained in:
Christopher Haster
2025-01-22 15:01:18 -06:00
parent 68f0534dd0
commit 94f493ec2e
2 changed files with 63 additions and 2 deletions
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lfs.c
+57 -2
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@@ -2717,6 +2717,12 @@ static int lfsr_rbyd_ckecksum(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
return (ecksum_ == ecksum->cksum) ? 0 : LFS_ERR_CORRUPT;
}
// needed in lfsr_rbyd_fetch_ if asserting rbyd balance
static int lfsr_rbyd_lookupnext_(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
lfsr_srid_t rid, lfsr_tag_t tag,
lfsr_srid_t *rid_, lfsr_tag_t *tag_, lfsr_rid_t *weight_,
lfsr_data_t *data_, lfs_size_t *height_);
// fetch an rbyd
static int lfsr_rbyd_fetch_(lfs_t *lfs,
lfsr_rbyd_t *rbyd, uint32_t *gcksumdelta,
@@ -2931,6 +2937,32 @@ static int lfsr_rbyd_fetch_(lfs_t *lfs,
rbyd->eoff = -1;
}
// asserting rbyd balance? check that all branches in the rbyd have
// the same height
#ifdef LFS_ASSERTRBYDBALANCE
lfsr_srid_t rid = -1;
lfsr_tag_t tag = 0;
lfs_ssize_t height = -1;
while (true) {
lfs_size_t height_;
int err = lfsr_rbyd_lookupnext_(lfs, rbyd,
rid, tag+1,
&rid, &tag, NULL, NULL, &height_);
if (err) {
if (err == LFS_ERR_NOENT) {
break;
}
return err;
}
// all branches should have the same height
if (height != -1) {
LFS_ASSERT(height_ == height);
}
height = height_;
}
#endif
return 0;
}
@@ -2973,10 +3005,10 @@ static int lfsr_rbyd_fetchck(lfs_t *lfs, lfsr_rbyd_t *rbyd,
}
static int lfsr_rbyd_lookupnext(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
static int lfsr_rbyd_lookupnext_(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
lfsr_srid_t rid, lfsr_tag_t tag,
lfsr_srid_t *rid_, lfsr_tag_t *tag_, lfsr_rid_t *weight_,
lfsr_data_t *data_) {
lfsr_data_t *data_, lfs_size_t *height_) {
// these bits should be clear at this point
LFS_ASSERT(lfsr_tag_mode(tag) == 0);
@@ -2989,6 +3021,11 @@ static int lfsr_rbyd_lookupnext(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
return LFS_ERR_NOENT;
}
// optionally find height for asserting rbyd balance
if (height_) {
*height_ = 0;
}
// keep track of bounds as we descend down the tree
lfs_size_t branch = lfsr_rbyd_trunk(rbyd);
lfsr_srid_t lower_rid = 0;
@@ -3011,6 +3048,16 @@ static int lfsr_rbyd_lookupnext(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
if (lfsr_tag_isalt(alt)) {
lfs_size_t branch_ = branch + d;
// only count black alts and followed alts towards height
if (height_
&& (lfsr_tag_isblack(alt)
|| lfsr_tag_follow(
alt, weight,
lower_rid, upper_rid,
rid, tag))) {
*height_ += 1;
}
// take alt?
if (lfsr_tag_follow(
alt, weight,
@@ -3061,6 +3108,14 @@ static int lfsr_rbyd_lookupnext(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
}
}
static int lfsr_rbyd_lookupnext(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
lfsr_srid_t rid, lfsr_tag_t tag,
lfsr_srid_t *rid_, lfsr_tag_t *tag_, lfsr_rid_t *weight_,
lfsr_data_t *data_) {
return lfsr_rbyd_lookupnext_(lfs, rbyd, rid, tag,
rid_, tag_, weight_, data_, NULL);
}
static int lfsr_rbyd_lookup(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
lfsr_srid_t rid, lfsr_tag_t tag,
lfsr_data_t *data_) {