add simple parametric rc impl

Dependencies

• [2] FFERM7K5 add type alias with default rc impl
• [3] WS4ZQM4R Debugging, tests, etc.
• [4] E4MD6T3L Proofreading and commenting of this crate (massive bug fixes included)
• [5] EDTFMMZW add dummy RcEntry trait for rc tree key
• [6] DASFQGOR Debugging
• [7] YXKP4AIW New file locks, with multiple sets of free pages
• [8] NW4S4ZCC rename MutTxn to GenericMutTxn
• [9] S4V4QZ5C Debugging reference-counting for put
• [10] UUUVNC4D Debugging/cleanup around cursors
• [11] YWFYZNLZ Cleanup + inter-process concurrency
• [12] OP6SVMOD Resetting history
• [13] KMT3MF5N Drop a database
• [14] TSMS6W4D Fully commented implementation of Sized nodes + massive cleanup
• [15] OFINGD26 implementing prev() on cursors (+ some cleanup)
• [16] YATBB4O7 run cargo fmt
• [17] SYURNHHL Adding the `put_mut` and `set_left_child` methods
• [18] ONES3V46 reference counting works for put

Change contents

• replacement in "sanakirja/src/environment/muttxn.rs" at line 11
  [3.76]→[3.76:119](∅→∅)
  − pub trait RcEntry: PartialEq + Storable {}
  [3.76]

  [3.82]
  + pub trait RcEntry: PartialEq + Storable {

  + fn from_page_count(page: u64, count: u64) -> Self;

  + fn page(&self) -> u64;

  + fn count(&self) -> u64;

  + }
• replacement in "sanakirja/src/environment/muttxn.rs" at line 17
  [3.83]→[3.83:107](∅→∅)
  − impl RcEntry for u64 {}
  [3.83]

  [2.83]
  + impl RcEntry for u64 {

  + fn from_page_count(page: u64, count: u64) -> Self {

  + assert!(count <= 0xfff);

  + page | count

  + }
• replacement in "sanakirja/src/environment/muttxn.rs" at line 23
  [2.84]→[2.84:147](∅→∅)
  − pub type MutTxn<E: Borrow<Env>, T> = GenericMutTxn<E, T, u64>;
  [2.84]

  [3.37287]
  + fn page(&self) -> u64 {

  + *self & !0xfff

  + }

  +

  + fn count(&self) -> u64 {

  + *self & 0xfff

  + }

  + }

  +

  + /// A mutable transaction using 12 bits for the reference counting.

  + pub type MutTxn<E, T> = GenericMutTxn<E, T, u64>;
• replacement in "sanakirja/src/environment/muttxn.rs" at line 106
  [3.8146]→[3.300:405](∅→∅)
  − impl<'a, E: Borrow<Env>, T, R: RcEntry> Commit for GenericMutTxn<E, &'a mut GenericMutTxn<E, T, R>, R> {
  [3.8146]

  [3.37309]
  + impl<'a, E: Borrow<Env>, T, R: RcEntry> Commit

  + for GenericMutTxn<E, &'a mut GenericMutTxn<E, T, R>, R>

  + {
• replacement in "sanakirja/src/environment/muttxn.rs" at line 173
  [3.82078]→[3.406:512](∅→∅)
  − pub fn mut_txn_begin<E: Borrow<Self>, R: RcEntry>(env: E) -> Result<GenericMutTxn<E, (), R>, Error> {
  [3.82078]

  [3.82162]
  + pub fn mut_txn_begin<E: Borrow<Self>, R: RcEntry>(

  + env: E,

  + ) -> Result<GenericMutTxn<E, (), R>, Error> {
• replacement in "sanakirja/src/environment/muttxn.rs" at line 515
  [3.16374]→[3.19922:19963](∅→∅)
  − curs.set(self, &off, None)?;
  [3.16374]

  [3.19963]
  + curs.set(self, &R::from_page_count(off, 0), None)?;
• replacement in "sanakirja/src/environment/muttxn.rs" at line 517
  [3.19070]→[3.38483:38524](∅→∅),[3.20029]→[3.38483:38524](∅→∅),[3.38483]→[3.38483:38524](∅→∅),[3.38524]→[3.19071:19103](∅→∅)
  − if *rc & !0xfff == off {

  − *rc & 0xfff
  [3.20029]

  [3.38548]
  + if rc.page() == off {

  + rc.count()
• replacement in "sanakirja/src/environment/muttxn.rs" at line 529
  [3.2478]→[3.19176:19279](∅→∅),[3.2540]→[3.19176:19279](∅→∅),[3.20082]→[3.19176:19279](∅→∅),[3.89127]→[3.19176:19279](∅→∅)
  − assert!(rc + 1 <= 0xfff);

  − btree::put(self, &mut rc_, &(off | (rc + 1)), &())?;
  [3.2540]

  [3.19279]
  + btree::put(self, &mut rc_, &R::from_page_count(off, rc + 1), &())?;
• replacement in "sanakirja/src/environment/muttxn.rs" at line 534
  [3.19411]→[3.19411:19468](∅→∅)
  − btree::put(self, &mut rc, &(off | 2), &())?;
  [3.19411]

  [3.19468]
  + btree::put(self, &mut rc, &R::from_page_count(off, 2), &())?;
• replacement in "sanakirja/src/environment/muttxn.rs" at line 568
  [3.16443]→[3.42107:42148](∅→∅)
  − curs.set(self, &off, None)?;
  [3.16443]

  [3.20319]
  + curs.set(self, &R::from_page_count(off, 0), None)?;
• replacement in "sanakirja/src/environment/muttxn.rs" at line 573
  [3.38994]→[3.38994:39059](∅→∅)
  − if *rc & !0xfff == off {

  − *rc
  [3.38994]

  [3.39059]
  + if rc.page() == off {

  + rc.count()
• replacement in "sanakirja/src/environment/muttxn.rs" at line 586
  [3.1705]→[3.39211:39267](∅→∅),[3.2098]→[3.39211:39267](∅→∅),[3.20682]→[3.39211:39267](∅→∅),[3.39211]→[3.39211:39267](∅→∅),[3.1738]→[3.935:971](∅→∅),[3.39267]→[3.935:971](∅→∅),[3.971]→[3.971:1036](∅→∅)
  − btree::del(self, &mut rc_, &rc, None)?;

  − if rc & 0xfff > 2 {

  − btree::put(self, &mut rc_, &(rc - 1), &())?;
  [3.20682]

  [3.1036]
  + btree::del(self, &mut rc_, &R::from_page_count(off, rc), None)?;

  + if rc.count() > 2 {

  + btree::put(self, &mut rc_, &R::from_page_count(off, rc - 1), &())?;
• replacement in "sanakirja/src/environment/muttxn.rs" at line 596
  [3.1198]→[3.1739:1793](∅→∅)
  − return Ok((rc & 0xfff) as usize - 1);
  [3.1198]

  [3.2244]
  + return Ok(rc as usize - 1);
• replacement in "sanakirja/src/environment/muttxn.rs" at line 633
  [3.91142]→[3.2581:2653](∅→∅),[3.2653]→[3.91357:91440](∅→∅),[3.91357]→[3.91357:91440](∅→∅)
  − if let Some((rc, _)) = btree::get(self, rc, &page, None)? {

  − if *rc & !0xfff == page {

  − let r = *rc & 0xfff;
  [3.91142]

  [3.91440]
  + if let Some((rc, _)) = btree::get(self, rc, &R::from_page_count(page, 0), None)? {

  + if rc.page() == page {

  + let r = rc.count();