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Cleaned up the leaf splitting condition

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Turns out if do the less-than condition first, we can simplify things. I
think this is due to how we bias the tree weights.
This commit is contained in:
Christopher Haster
2023-01-06 17:32:40 -06:00
parent 5c42e52324
commit 6a5aae98fc
1 changed files with 36 additions and 32 deletions
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lfs.c
+36 -32
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@@ -1529,7 +1529,7 @@ static int lfs_rbyd_append(lfs_t *lfs, lfs_rbyd_t *rbyd_,
lower_tag_ = tag & ~0x7fff;
upper_tag_ = lower_tag_ + 0x8000;
} else if (lfs_rtag_isrm(tag)) {
lower_tag_ = tag & ~0x7;
lower_tag_ = tag & ~0x1;
upper_tag_ = lower_tag_ + 0x8;
} else {
lower_tag_ = tag;
@@ -1756,13 +1756,12 @@ static int lfs_rbyd_append(lfs_t *lfs, lfs_rbyd_t *rbyd_,
}
stem:;
// TODO need this?
// unflip our bounds so lower_lower/upper_upper is correct
if (!diverged) {
upper_tag_ = lower_tag_;
upper_branch = lower_branch;
upper_lower = lower_lower;
upper_upper = lower_upper;
// unflip our bounds so lower_lower/upper_upper is correct
} else if (lower_tag_ > upper_tag_) {
lfs_swap(&lower_tag_, &upper_tag_);
lfs_swap(&lower_branch, &upper_branch);
@@ -1780,41 +1779,46 @@ stem:;
if (lfs_rtag_isrm(lower_tag_)) {
// no split needed, prune the removed tag
} else if (lfs_rtag_type1(tag) == LFS_TYPE1_CREATE
&& lfs_rtag_weight_(upper_tag_) >= lfs_rtag_weight_(tag & ~0x7fff)) {
// increase biased weight when creating
alt = LFS_MKRALT__(B, GT,
(upper_upper+0x8000) - (lfs_rtag_weight_(tag)+0x8));
jump = upper_branch;
} else if (lfs_rtag_type1(tag) == LFS_TYPE1_DELETE
&& lfs_rtag_weight_(upper_tag_) >= lfs_rtag_weight_(tag & ~0x7fff)+0x8000) {
// decrease biased weight when deleting
alt = LFS_MKRALT__(B, GT,
upper_upper-0x8000 - lower_lower);
jump = upper_branch;
} else if (lfs_rtag_type1(tag) != LFS_TYPE1_DELETE
&& lfs_rtag_isrm(tag)
&& lfs_rtag_weight_(upper_tag_) > lfs_rtag_weight_(tag)) {
// hide our tag during removes
alt = LFS_MKRALT__(B, GT,
upper_upper - lower_lower);
jump = upper_branch;
} else if (!lfs_rtag_isrm(tag)
&& lfs_rtag_weight_(upper_tag_) > lfs_rtag_weight_(tag)) {
// split greater than
alt = LFS_MKRALT__(B, GT,
upper_upper - (lfs_rtag_weight_(tag)+0x8));
jump = upper_branch;
} else if (lfs_rtag_weight_(lower_tag_) < lfs_rtag_weight_(tag)) {
// split less than, this is consistent for all appends and only happens
// when appending to the end of the tree
alt = LFS_MKRALT__(B, LT,
(lfs_rtag_weight_(lower_tag_)+0x8) - lower_lower);
jump = lower_branch;
} else if (lfs_rtag_type1(tag) == LFS_TYPE1_CREATE) {
if (lfs_rtag_weight_(upper_tag_)
>= lfs_rtag_weight_(tag & ~0x7fff)) {
// increase biased weight when creating
alt = LFS_MKRALT__(B, GT,
(upper_upper+0x8000) - (lfs_rtag_weight_(tag)+0x8));
jump = upper_branch;
}
} else if (lfs_rtag_type1(tag) == LFS_TYPE1_DELETE) {
if (lfs_rtag_weight_(upper_tag_)
>= lfs_rtag_weight_(tag & ~0x7fff)+0x8000) {
// decrease biased weight when deleting
alt = LFS_MKRALT__(B, GT,
upper_upper-0x8000 - lower_lower);
jump = upper_branch;
}
} else if (lfs_rtag_isrm(tag)) {
if (lfs_rtag_weight_(upper_tag_) > lfs_rtag_weight_(tag)) {
// hide our tag during removes
alt = LFS_MKRALT__(B, GT,
upper_upper - lower_lower);
jump = upper_branch;
}
} else {
if (lfs_rtag_weight_(upper_tag_) > lfs_rtag_weight_(tag)) {
// split greater than
alt = LFS_MKRALT__(B, GT,
upper_upper - (lfs_rtag_weight_(tag)+0x8));
jump = upper_branch;
}
}
if (alt) {