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rbyd: Made LFS_DEBUGRBYDBALANCE output a bit more interesting

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Now with both height (alt-height) and bheight (black-height):

  lfs.c:2970:debug: rbyd 0x9.c05: height 6-11, bheight 6-6

It's interesting to note this highlighted a minor mistake in our assumed
rbyd bounds.

Originally, our rbyd algorithm generated trees with height bounded by
2*bheight+1, but now that we have range removals, our height can get up
to 2*bheight+2 due to how diverged paths are stitched together.
This commit is contained in:
Christopher Haster
2025-01-28 00:15:44 -06:00
parent 558911693b
commit 98ecb5420d
1 changed files with 43 additions and 18 deletions
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lfs.c
+43 -18
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@@ -2717,11 +2717,12 @@ static int lfsr_rbyd_ckecksum(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
return (ecksum_ == ecksum->cksum) ? 0 : LFS_ERR_CORRUPT; return (ecksum_ == ecksum->cksum) ? 0 : LFS_ERR_CORRUPT;
} }
// needed in lfsr_rbyd_fetch_ if asserting rbyd balance // needed in lfsr_rbyd_fetch_ if debugging rbyd balance
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_srid_t *rid_, lfsr_tag_t *tag_, lfsr_rid_t *weight_, lfsr_srid_t *rid_, lfsr_tag_t *tag_, lfsr_rid_t *weight_,
lfsr_data_t *data_, lfs_size_t *height_); lfsr_data_t *data_,
lfs_size_t *height_, lfs_size_t *bheight_);
// fetch an rbyd // fetch an rbyd
static int lfsr_rbyd_fetch_(lfs_t *lfs, static int lfsr_rbyd_fetch_(lfs_t *lfs,
@@ -2937,17 +2938,22 @@ static int lfsr_rbyd_fetch_(lfs_t *lfs,
rbyd->eoff = -1; rbyd->eoff = -1;
} }
// asserting rbyd balance? check that all branches in the rbyd have // debugging rbyd balance? check that all branches in the rbyd have
// the same height // the same height
#ifdef LFS_DEBUGRBYDBALANCE #ifdef LFS_DEBUGRBYDBALANCE
lfsr_srid_t rid = -1; lfsr_srid_t rid = -1;
lfsr_tag_t tag = 0; lfsr_tag_t tag = 0;
lfs_ssize_t height = -1; lfs_size_t min_height = 0;
lfs_size_t max_height = 0;
lfs_size_t min_bheight = 0;
lfs_size_t max_bheight = 0;
while (true) { while (true) {
lfs_size_t height_; lfs_size_t height;
lfs_size_t bheight;
int err = lfsr_rbyd_lookupnext_(lfs, rbyd, int err = lfsr_rbyd_lookupnext_(lfs, rbyd,
rid, tag+1, rid, tag+1,
&rid, &tag, NULL, NULL, &height_); &rid, &tag, NULL, NULL,
&height, &bheight);
if (err) { if (err) {
if (err == LFS_ERR_NOENT) { if (err == LFS_ERR_NOENT) {
break; break;
@@ -2955,13 +2961,23 @@ static int lfsr_rbyd_fetch_(lfs_t *lfs,
return err; return err;
} }
// all branches should have the same height // find the min/max height and bheight
LFS_DEBUG("%d 0x%04x: height %d", rid, tag, height_); min_height = (min_height) ? lfs_min(min_height, height) : height;
if (height != -1) { max_height = (max_height) ? lfs_max(max_height, height) : height;
LFS_ASSERT(height_ == height); min_bheight = (min_bheight) ? lfs_min(min_bheight, bheight) : bheight;
} max_bheight = (max_bheight) ? lfs_max(max_bheight, bheight) : bheight;
height = height_;
} }
LFS_DEBUG("rbyd 0x%"PRIx32".%"PRIx32": "
"height %"PRId32"-%"PRId32", "
"bheight %"PRId32"-%"PRId32,
rbyd->blocks[0], lfsr_rbyd_trunk(rbyd),
min_height, max_height,
min_bheight, max_bheight);
// all branches in the rbyd should have the same bheight
LFS_ASSERT(max_bheight == min_bheight);
// this limits alt height to no worse than 2*bheight+2 (2*bheight+1
// for normal appends, 2*bheight+2 with range removals)
LFS_ASSERT(max_height <= 2*min_height+2);
#endif #endif
return 0; return 0;
@@ -3009,7 +3025,8 @@ 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_srid_t *rid_, lfsr_tag_t *tag_, lfsr_rid_t *weight_, lfsr_srid_t *rid_, lfsr_tag_t *tag_, lfsr_rid_t *weight_,
lfsr_data_t *data_, lfs_size_t *height_) { lfsr_data_t *data_,
lfs_size_t *height_, lfs_size_t *bheight_) {
// these bits should be clear at this point // these bits should be clear at this point
LFS_ASSERT(lfsr_tag_mode(tag) == 0); LFS_ASSERT(lfsr_tag_mode(tag) == 0);
@@ -3022,10 +3039,13 @@ static int lfsr_rbyd_lookupnext_(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
return LFS_ERR_NOENT; return LFS_ERR_NOENT;
} }
// optionally find height for asserting rbyd balance // optionally find height/bheight for debugging rbyd balance
if (height_) { if (height_) {
*height_ = 0; *height_ = 0;
} }
if (bheight_) {
*bheight_ = 0;
}
// keep track of bounds as we descend down the tree // keep track of bounds as we descend down the tree
lfs_size_t branch = lfsr_rbyd_trunk(rbyd); lfs_size_t branch = lfsr_rbyd_trunk(rbyd);
@@ -3049,14 +3069,18 @@ static int lfsr_rbyd_lookupnext_(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
if (lfsr_tag_isalt(alt)) { if (lfsr_tag_isalt(alt)) {
lfs_size_t branch_ = branch + d; lfs_size_t branch_ = branch + d;
// only count black alts and followed alts towards height // keep track of height for debugging
if (height_ if (height_) {
*height_ += 1;
}
if (bheight_
// only count black+followed alts towards bheight
&& (lfsr_tag_isblack(alt) && (lfsr_tag_isblack(alt)
|| lfsr_tag_follow( || lfsr_tag_follow(
alt, weight, alt, weight,
lower_rid, upper_rid, lower_rid, upper_rid,
rid, tag))) { rid, tag))) {
*height_ += 1; *bheight_ += 1;
} }
// take alt? // take alt?
@@ -3114,7 +3138,8 @@ static int lfsr_rbyd_lookupnext(lfs_t *lfs, const lfsr_rbyd_t *rbyd,
lfsr_srid_t *rid_, lfsr_tag_t *tag_, lfsr_rid_t *weight_, lfsr_srid_t *rid_, lfsr_tag_t *tag_, lfsr_rid_t *weight_,
lfsr_data_t *data_) { lfsr_data_t *data_) {
return lfsr_rbyd_lookupnext_(lfs, rbyd, rid, tag, return lfsr_rbyd_lookupnext_(lfs, rbyd, rid, tag,
rid_, tag_, weight_, data_, NULL); rid_, tag_, weight_, data_,
NULL, NULL);
} }
static int lfsr_rbyd_lookup(lfs_t *lfs, const lfsr_rbyd_t *rbyd, static int lfsr_rbyd_lookup(lfs_t *lfs, const lfsr_rbyd_t *rbyd,