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Reverted second resume-crystallization check

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Gah! I'm not sure why I thought this code was so useless... Without it
we risk immediate recrystallization if the crystal heuristic pushes
crystal_start such that it overlaps the crystallizing block.

We may not make progress on our buffer, but triggering recrystallization
isn't great.

Considering this really doesn't add _that_ much code, I think this is a
case where we are better safe than sorry:

           code          stack          ctx
  before: 37092           2304          636
  after:  37140 (+0.1%)   2304 (+0.0%)  636 (+0.0%)

This logic only gets hit after we decide to allocate a new block, so
there's no risk of losing erased-state to potential fragments.

---

In benchmarking it also looks like this recoups most of the extra disk
usage introduced by lazy rewrite crystallization. So that's a good
thing... I think...
This commit is contained in:
Christopher Haster
2025-05-23 13:25:47 -05:00
parent 1cce0dab5c
commit 09e3ad5eff
1 changed files with 33 additions and 0 deletions
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lfs.c
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@@ -12585,6 +12585,39 @@ static int lfsr_file_flush_(lfs_t *lfs, lfsr_file_t *file,
// exceeded crystallization threshold? we need to allocate a
// new block
// can we resume crystallizing with the fragments on disk?
block_start = file->leaf.pos
- lfsr_bptr_off(&file->leaf.bptr);
block_end = file->leaf.pos
+ lfsr_bptr_size(&file->leaf.bptr);
if (lfsr_bptr_isbptr(&file->leaf.bptr)
&& lfsr_bptr_iserased(&file->leaf.bptr)
&& crystal_start >= block_end
&& crystal_start < block_start + lfs->cfg->block_size) {
int err = lfsr_file_crystallize_(lfs, file,
file->leaf.pos - lfsr_bptr_off(&file->leaf.bptr),
crystal_end
- (file->leaf.pos - lfsr_bptr_off(&file->leaf.bptr)),
crystal_end
- (file->leaf.pos - lfsr_bptr_off(&file->leaf.bptr)),
pos, buffer, size);
if (err) {
return err;
}
// update buffer state, this may or may not make progress
lfs_soff_t d = lfs_max(
file->leaf.pos + lfsr_bptr_size(&file->leaf.bptr),
pos) - pos;
pos += d;
buffer += lfs_min(d, size);
size -= lfs_min(d, size);
// we should be aligned now
aligned = true;
continue;
}
// if we're mid-crystallization, finish crystallizing the block
// and graft it into our bshrub/btree
int err = lfsr_file_crystallize(lfs, file);