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state machine for 'next' and prev

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This commit is contained in:
pedrocarlo
2025-08-02 01:22:00 -03:00
parent f1df9a909e
commit 1585d5cbee
2 changed files with 42 additions and 11 deletions
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47
core/storage/btree.rs
View File

@@ -10,7 +10,9 @@ 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, MoveToRightState, RewindState, SeekToLastState},
state_machines::{
AdvanceState, EmptyTableState, MoveToRightState, RewindState, SeekToLastState,
},
},
translate::plan::IterationDirection,
turso_assert,
@@ -580,6 +582,8 @@ pub struct BTreeCursor {
seek_to_last_state: SeekToLastState,
/// State machine for [BTreeCursor::rewind]
rewind_state: RewindState,
/// State machine for [BTreeCursor::next] and [BTreeCursor::prev]
advance_state: AdvanceState,
}
/// We store the cell index and cell count for each page in the stack.
@@ -638,6 +642,7 @@ impl BTreeCursor {
move_to_right_state: (MoveToRightState::Start, None),
seek_to_last_state: SeekToLastState::Start,
rewind_state: RewindState::Start,
advance_state: AdvanceState::Start,
}
}
@@ -4279,11 +4284,21 @@ impl BTreeCursor {
#[instrument(skip_all, level = Level::DEBUG)]
pub fn next(&mut self) -> Result<IOResult<bool>> {
return_if_io!(self.restore_context());
let cursor_has_record = return_if_io!(self.get_next_record());
self.has_record.replace(cursor_has_record);
self.invalidate_record();
Ok(IOResult::Done(cursor_has_record))
loop {
match self.advance_state {
AdvanceState::Start => {
return_if_io!(self.restore_context());
self.advance_state = AdvanceState::Advance;
}
AdvanceState::Advance => {
let cursor_has_record = return_if_io!(self.get_next_record());
self.has_record.replace(cursor_has_record);
self.invalidate_record();
self.advance_state = AdvanceState::Start;
return Ok(IOResult::Done(cursor_has_record));
}
}
}
}
fn invalidate_record(&mut self) {
@@ -4297,11 +4312,21 @@ impl BTreeCursor {
#[instrument(skip_all, level = Level::DEBUG)]
pub fn prev(&mut self) -> Result<IOResult<bool>> {
assert!(self.mv_cursor.is_none());
return_if_io!(self.restore_context());
let cursor_has_record = return_if_io!(self.get_prev_record());
self.has_record.replace(cursor_has_record);
self.invalidate_record();
Ok(IOResult::Done(cursor_has_record))
loop {
match self.advance_state {
AdvanceState::Start => {
return_if_io!(self.restore_context());
self.advance_state = AdvanceState::Advance;
}
AdvanceState::Advance => {
let cursor_has_record = return_if_io!(self.get_prev_record());
self.has_record.replace(cursor_has_record);
self.invalidate_record();
self.advance_state = AdvanceState::Start;
return Ok(IOResult::Done(cursor_has_record));
}
}
}
}
#[instrument(skip(self), level = Level::DEBUG)]

6
core/storage/state_machines.rs
View File

@@ -23,3 +23,9 @@ pub enum RewindState {
Start,
NextRecord,
}
#[derive(Debug, Clone, Copy)]
pub enum AdvanceState {
Start,
Advance,
}