Cleanup, comments, renaming

[?]

Feb 14, 2021, 2:22 PM

CCNPHVQCIGINWTLXCHOASGVWUPBZXFOLM2F7HTKMEA2DMFTOX7TAC

Dependencies

[2] QYDGYIZR Split trait Representable into its mandatory part and an optional part
[3] H3FVSQIQ Unsized pages
[4] OFINGD26 implementing prev() on cursors (+ some cleanup)
[5] RV2L6CZW A few comments
[6] T73WR2BX Cleaner RC increments for keys and values containing references + more comments in `del`
[7] W26CFMAQ Improving safety of cursors
[8] G4JEQLLX Debugging synchronisation
[9] HN6Z5DU4 Cleanup
[10] 6DMPXOAT More debugging
[11] UUUVNC4D Debugging/cleanup around cursors
[12] NXMFNPZ7 Comments + debugging drop
[13] XEU2QVLC Debugging after plugging this into Pijul
[14] OP6SVMOD Resetting history
[15] OTWDDJE7 Trait/type cleanup
[16] WS4ZQM4R Debugging, tests, etc.
[17] QEUTVAZ4 Splitting btree::page
[18] ESUI5EUZ Making as_page() unsafe
[19] LSQ6V7M6 Cleanup + docs
[20] WAKPPBKO Fixing a double-free of roots after deletions (the root was freed both by handle_merge and by update_root)
[21] 6UVFCERM Formatting, debugging, etc.
[22] APPY2E7M Unsized deletions + custom sizes back
[23] KMT3MF5N Drop a database

Change contents

replacement in sanakirja-core/src/lib.rs at line 15

[3.632]→[3.632:720](∅→∅)

//! At the moment, only B trees are implemented, as well as three
//! important traits:

[3.632]

[3.720]

//! At the moment, only B trees are implemented, as well as the
//! following general traits:
edit in sanakirja-core/src/lib.rs at line 18

[3.724]→[3.724:826](∅→∅)

//! - [`Representable`] is the trait of types that can be written to
//! disk and read from the disk.
edit in sanakirja-core/src/lib.rs at line 26

[3.1317]

[3.134]

//!
//! Moreover, two other traits can be used to store things on pages:
//! [`Storable`] is a simple trait that all `Sized + Ord` types
//! without references can readily implement (the [`direct_repr!`]
//! macro does that). For types containing references to pages
//! allocated in the database, the comparison function can be
//! customised. Moreover, these types must supply an iterator over
//! these references, in order for reference-counting to work properly
//! when the datastructures referencing these types are forked.
//!
//! Dynamically-sized types, or types that need to be represented in a
//! dynamically-sized way, can use the [`UnsizedStorable`] format.
replacement in sanakirja-core/src/lib.rs at line 45

[3.119]→[3.265:303](∅→∅)

/// Types that can be stored on disk.

[3.119]

[2.0]

/// Types that can be stored on disk. This trait may be used in
/// conjunction with `Sized` in order to determine the on-disk size,
/// or with [`UnsizedStorable`] when special arrangements are needed.
replacement in sanakirja-core/src/lib.rs at line 57

[2.162]→[2.162:211](∅→∅)

fn page_offsets(&self) -> Self::PageOffsets;

[2.162]

[2.211]

fn page_references(&self) -> Self::PageReferences;
replacement in sanakirja-core/src/lib.rs at line 63

[3.1614]→[3.1614:1658](∅→∅)

type PageOffsets: Iterator<Item = u64>;

[3.1614]

[3.761]

type PageReferences: Iterator<Item = u64>;
replacement in sanakirja-core/src/lib.rs at line 66

[3.764]→[3.1318:1379](∅→∅)

/// A macro to implement [`Representable`] on "plain" types,

[3.764]

[3.1379]

/// A macro to implement [`Storable`] on "plain" types,
replacement in sanakirja-core/src/lib.rs at line 73

[2.244]→[3.851:964](∅→∅),[3.203]→[3.851:964](∅→∅),[3.851]→[3.851:964](∅→∅)

type PageOffsets = core::iter::Empty<u64>;
fn page_offsets(&self) -> Self::PageOffsets {

[2.244]

[3.964]

type PageReferences = core::iter::Empty<u64>;
fn page_references(&self) -> Self::PageReferences {
replacement in sanakirja-core/src/lib.rs at line 139

[2.1715]→[3.392:489](∅→∅),[3.392]→[3.392:489](∅→∅)

type PageOffsets = core::iter::Empty<u64>;
fn page_offsets(&self) -> Self::PageOffsets {

[2.1715]

[3.489]

type PageReferences = core::iter::Empty<u64>;
fn page_references(&self) -> Self::PageReferences {
replacement in sanakirja-core/src/lib.rs at line 201

[3.2399]→[3.1706:1754](∅→∅)

/// Representation of a mutable or shared page.

[3.2399]

[3.1754]

/// Representation of a mutable or shared page. This is an owned page
/// (like `Vec` in Rust's std), but we do not know whether we can
/// mutate it or not.
///
/// The least-significant bit of the first byte of each page is 1 if
/// and only if the page was allocated by the current transaction (and
/// hence isn't visible to any other transaction, meaning we can write
/// on it).
edit in sanakirja-core/src/lib.rs at line 216

[3.2494]

[3.2494]

/// Representation of a borrowed, or immutable page, like a slice in
/// Rust.
edit in sanakirja-core/src/lib.rs at line 226

[3.412]

[3.1795]

/// Borrows the page.
edit in sanakirja-core/src/lib.rs at line 231

[3.1627]→[3.1627:1637](∅→∅),[3.1637]→[3.0:116](∅→∅),[3.495]→[3.0:116](∅→∅)

}
}
pub fn null() -> Self {
CowPage {
data: core::ptr::null_mut(),
offset: 0,
replacement in sanakirja-core/src/lib.rs at line 235

[3.2555]→[3.281:362](∅→∅)

/// The layout of pages is as follows: the LSB of the first byte is
/// "dirty".

[3.2555]

[3.504]

/// An owned page on which we can write. This is just a wrapper around
/// `CowPage` to avoid checking the "dirty" bit at running time.
edit in sanakirja-core/src/lib.rs at line 247

[3.1662]

[3.1662]

/// Checks the dirty bit of a page.
replacement in sanakirja-core/src/lib.rs at line 253

[3.2732]→[3.2732:2836](∅→∅)

/// Trait for loading a page and a root. Base trait to implement
/// "storage engines" under Sanakirja.

[3.2732]

[3.2836]

/// Trait for loading a page.
replacement in sanakirja-core/src/lib.rs at line 258

[3.623]→[3.2961:3028](∅→∅),[3.2961]→[3.2961:3028](∅→∅)

/// RC
fn rc(&self, off: u64) -> Result<u64, Self::Error>;

[3.623]

[3.3028]

/// Reference-counting. Since reference-counts are designed to be
/// storable into B trees by external allocators, pages referenced
/// once aren't stored, and hence are indistinguishable from pages
/// that are never referenced. The default implementation returns
/// 0.
///
/// This has the extra benefit of requiring less disk space, and
/// isn't more unsafe than storing the reference count, since we
/// aren't supposed to hold a reference to a page with "logical
/// RC" 0, so storing "1" for that page would be redundant anyway.
fn rc(&self, _off: u64) -> Result<u64, Self::Error> {
Ok(0)
}
replacement in sanakirja-core/src/lib.rs at line 274

[3.3031]→[3.3031:3135](∅→∅)

/// Trait for loading a page and a root. Base trait to implement
/// "storage engines" under Sanakirja.

[3.3031]

[3.3135]

/// Trait for allocating and freeing pages.
edit in sanakirja-core/src/lib.rs at line 276

[3.3167]

[3.3167]

/// Allocate a new page.
replacement in sanakirja-core/src/lib.rs at line 278

[3.3229]→[3.0:27](∅→∅)

// Returns the new RC.

[3.3229]

[3.27]

/// Increment the page's reference count.
replacement in sanakirja-core/src/lib.rs at line 280

[3.94]→[3.94:134](∅→∅)

// Returns the new RC (0 if freed).

[3.94]

[3.134]

/// Decrement the page's reference count, assuming the page was
/// first allocated by another transaction. If the RC reaches 0,
/// free the page. Must return the new RC (0 if freed).
replacement in sanakirja-core/src/lib.rs at line 284

[3.201]→[3.201:241](∅→∅)

// Returns the new RC (0 if freed).

[3.201]

[3.241]

/// Same as [`decr_rc`], but for pages allocated by the current
/// transaction. This is an important distinction, as pages
/// allocated by the current transaction can be reused immediately
/// after being freed.
replacement in sanakirja-core/src/btree/put.rs at line 221

[3.3297]→[3.8397:8461](∅→∅),[3.1200]→[3.8397:8461](∅→∅),[3.264]→[3.8397:8461](∅→∅),[3.1215]→[3.8397:8461](∅→∅),[3.8397]→[3.8397:8461](∅→∅)

for o in k.page_offsets().chain(v.page_offsets()) {

[3.3297]

[3.8461]

for o in k.page_references().chain(v.page_references()) {
replacement in sanakirja-core/src/btree/mod.rs at line 443

[3.13429]→[3.2319:2387](∅→∅),[3.6934]→[3.2319:2387](∅→∅),[3.2319]→[3.2319:2387](∅→∅)

for o in k.page_offsets().chain(v.page_offsets()) {

[3.13429]

[3.2387]

for o in k.page_references().chain(v.page_references()) {
replacement in sanakirja-core/src/btree/del.rs at line 58

[3.1194]→[3.1194:1260](∅→∅)

for o in delk.page_offsets().chain(delv.page_offsets()) {

[3.1194]

[3.450]

for o in delk.page_references().chain(delv.page_references()) {
replacement in sanakirja-core/src/btree/del.rs at line 173

[3.1825]→[3.1913:1977](∅→∅)

for o in k.page_offsets().chain(v.page_offsets()) {

[3.1825]

[3.1897]

for o in k.page_references().chain(v.page_references()) {
replacement in sanakirja-core/src/btree/del.rs at line 351

[3.5226]→[3.5226:5294](∅→∅)

for o in k.page_offsets().chain(v.page_offsets()) {

[3.5226]

[3.5294]

for o in k.page_references().chain(v.page_references()) {
replacement in sanakirja-core/src/btree/del.rs at line 421

[3.2310]→[3.37710:37796](∅→∅),[3.16957]→[3.37710:37796](∅→∅),[3.10492]→[3.37710:37796](∅→∅),[3.37710]→[3.37710:37796](∅→∅)

for o in split_key.page_offsets().chain(split_value.page_offsets()) {

[3.16957]

[3.37796]

for o in split_key
.page_references()
.chain(split_value.page_references())
{
replacement in sanakirja-core/src/btree/del.rs at line 457

[3.17243]→[3.9970:10030](∅→∅),[3.8090]→[3.9970:10030](∅→∅),[3.9970]→[3.9970:10030](∅→∅)

for o in k.page_offsets().chain(v.page_offsets()) {

[3.17243]

[3.10030]

for o in k.page_references().chain(v.page_references()) {
replacement in sanakirja-core/src/btree/del.rs at line 482

[3.17315]→[3.10710:10770](∅→∅),[3.8173]→[3.10710:10770](∅→∅),[3.10710]→[3.10710:10770](∅→∅)

for o in k.page_offsets().chain(v.page_offsets()) {

[3.17315]

[3.10770]

for o in k.page_references().chain(v.page_references()) {
replacement in sanakirja-core/src/btree/del.rs at line 491

[3.17390]→[3.11016:11076](∅→∅),[3.8259]→[3.11016:11076](∅→∅),[3.11016]→[3.11016:11076](∅→∅)

for o in k.page_offsets().chain(v.page_offsets()) {

[3.17390]

[3.11076]

for o in k.page_references().chain(v.page_references()) {
replacement in sanakirja-core/src/btree/del.rs at line 581

[3.24321]→[3.7767:7835](∅→∅)

for o in k.page_offsets().chain(v.page_offsets()) {

[3.24321]

[3.39482]

for o in k.page_references().chain(v.page_references()) {