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state machine for move_to_rightmost

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This commit is contained in:
pedrocarlo
2025-07-30 15:20:44 -03:00
parent 966b96882e
commit 6bfba2518e
2 changed files with 41 additions and 25 deletions
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60
core/storage/btree.rs
View File

@@ -10,7 +10,7 @@ use crate::{
TableInteriorCell, TableLeafCell, CELL_PTR_SIZE_BYTES, INTERIOR_PAGE_HEADER_SIZE_BYTES,
LEAF_PAGE_HEADER_SIZE_BYTES, LEFT_CHILD_PTR_SIZE_BYTES,
},
state_machines::EmptyTableState,
state_machines::{EmptyTableState, MoveToRightState},
},
translate::plan::IterationDirection,
turso_assert,
@@ -571,7 +571,10 @@ pub struct BTreeCursor {
/// - Moving to a different record/row
/// - The underlying `ImmutableRecord` is modified
pub record_cursor: RefCell<RecordCursor>,
/// State machine for [BTreeCursor::is_empty_table]
is_empty_table_state: RefCell<EmptyTableState>,
/// State machine for [BTreeCursor::move_to_rightmost]
move_to_right_state: MoveToRightState,
}
/// We store the cell index and cell count for each page in the stack.
@@ -627,6 +630,7 @@ impl BTreeCursor {
parse_record_state: RefCell::new(ParseRecordState::Init),
record_cursor: RefCell::new(RecordCursor::with_capacity(num_columns)),
is_empty_table_state: RefCell::new(EmptyTableState::Start),
move_to_right_state: MoveToRightState::Start,
}
}
@@ -1342,33 +1346,39 @@ impl BTreeCursor {
/// Move the cursor to the rightmost record in the btree.
#[instrument(skip(self), level = Level::DEBUG)]
fn move_to_rightmost(&mut self) -> Result<IOResult<bool>> {
let c = self.move_to_root()?;
loop {
let mem_page = self.stack.top();
let page_idx = mem_page.get().get().id;
let (page, c) = self.read_page(page_idx)?;
return_if_locked_maybe_load!(self.pager, page);
let page = page.get();
let contents = page.get().contents.as_ref().unwrap();
if contents.is_leaf() {
if contents.cell_count() > 0 {
self.stack.set_cell_index(contents.cell_count() as i32 - 1);
return Ok(IOResult::Done(true));
}
return Ok(IOResult::Done(false));
match self.move_to_right_state {
MoveToRightState::Start => {
let c = self.move_to_root()?;
self.move_to_right_state = MoveToRightState::ProcessPage;
return Ok(IOResult::IO);
}
match contents.rightmost_pointer() {
Some(right_most_pointer) => {
self.stack.set_cell_index(contents.cell_count() as i32 + 1);
let (mem_page, c) = self.read_page(right_most_pointer as usize)?;
self.stack.push(mem_page);
continue;
MoveToRightState::ProcessPage => {
let mem_page = self.stack.top();
let page_idx = mem_page.get().get().id;
let (page, c) = self.read_page(page_idx)?;
return_if_locked_maybe_load!(self.pager, page);
let page = page.get();
let contents = page.get().contents.as_ref().unwrap();
if contents.is_leaf() {
self.move_to_right_state = MoveToRightState::Start;
if contents.cell_count() > 0 {
self.stack.set_cell_index(contents.cell_count() as i32 - 1);
return Ok(IOResult::Done(true));
}
return Ok(IOResult::Done(false));
}
None => {
unreachable!("interior page should have a rightmost pointer");
match contents.rightmost_pointer() {
Some(right_most_pointer) => {
self.stack.set_cell_index(contents.cell_count() as i32 + 1);
let (mem_page, c) = self.read_page(right_most_pointer as usize)?;
self.stack.push(mem_page);
return Ok(IOResult::IO);
}
None => {
unreachable!("interior page should have a rightmost pointer");
}
}
}
}

6
core/storage/state_machines.rs
View File

@@ -5,3 +5,9 @@ pub enum EmptyTableState {
Start,
ReadPage { page: PageRef },
}
#[derive(Debug, Clone, Copy)]
pub enum MoveToRightState {
Start,
ProcessPage,
}