Rebalance: put can free pages without splitting (compaction)

Dependencies

• [2] L5CVF6UJ Debugging
• [3] Q7DRIBBR Debugging replace (which cannot be del+put)
• [4] QEUTVAZ4 Splitting btree::page
• [5] H3FVSQIQ Unsized pages
• [6] KX3WVNZW Testing/debugging "rebalance causes split of the root"

Change contents

• replacement in sanakirja-core/src/btree/page_unsized/rebalance.rs at line 58
  [2.1031]→[2.1031:1065](∅→∅)
  − assert_eq!(freed, 0);
  [2.1031]

  [2.1065]
  + if freed > 0 {

  + let b = if is_dirty { 1 } else { 0 };

  + freed_[0] = freed | b;

  + }
• replacement in sanakirja-core/src/btree/page_unsized/rebalance.rs at line 86
  [2.1565]→[2.1565:1599](∅→∅)
  − assert_eq!(freed, 0);
  [2.1565]

  [2.1599]
  + if freed > 0 {

  + let b = if is_dirty { 1 } else { 0 };

  + freed_[0] = freed | b;

  + }
• replacement in sanakirja-core/src/btree/page/rebalance.rs at line 56
  [2.5281]→[2.5281:5315](∅→∅)
  − assert_eq!(freed, 0);
  [2.5281]

  [2.5315]
  + if freed > 0 {

  + let b = if is_dirty { 1 } else { 0 };

  + // index 0 is ok here: if a page is freed, it means we

  + // just compacted a page, which implies that the call

  + // to `put` above didn't free.

  + freed_[0] = freed | b

  + }
• replacement in sanakirja-core/src/btree/page/rebalance.rs at line 87
  [2.5815]→[2.5815:5849](∅→∅)
  − assert_eq!(freed, 0);
  [2.5815]

  [2.5849]
  + if freed > 0 {

  + let b = if is_dirty { 1 } else { 0 };

  + // index 0 is ok here: if we freed a page in the call

  + // to `del` above, it is mutable and we can allocate

  + // on it. Else, we just compacted a page, but that

  + // also means `del` above didn't free.

  + freed_[0] = freed | b

  + }
• edit in sanakirja-core/src/btree/page/rebalance.rs at line 106
  [2.6227]→[2.6227:6286](∅→∅)
  − debug!("freed {:?} {:?}", line!(), freed);