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state machine for seek_end

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This commit is contained in:
pedrocarlo
2025-08-11 12:05:51 -03:00
parent fc05518192
commit fe0e4bcbb7
2 changed files with 36 additions and 21 deletions
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51
core/storage/btree.rs
View File

@@ -10,7 +10,7 @@ use crate::{
LEAF_PAGE_HEADER_SIZE_BYTES, LEFT_CHILD_PTR_SIZE_BYTES,
},
state_machines::{
AdvanceState, CountState, EmptyTableState, MoveToRightState, RewindState,
AdvanceState, CountState, EmptyTableState, MoveToRightState, RewindState, SeekEndState,
SeekToLastState,
},
},
@@ -556,6 +556,8 @@ pub struct BTreeCursor {
advance_state: AdvanceState,
/// State machine for [BTreeCursor::count]
count_state: CountState,
/// State machine for [BTreeCursor::seek_end]
seek_end_state: SeekEndState,
}
/// We store the cell index and cell count for each page in the stack.
@@ -621,6 +623,7 @@ impl BTreeCursor {
rewind_state: RewindState::Start,
advance_state: AdvanceState::Start,
count_state: CountState::Start,
seek_end_state: SeekEndState::Start,
}
}
@@ -4135,28 +4138,34 @@ impl BTreeCursor {
pub fn seek_end(&mut self) -> Result<IOResult<()>> {
assert!(self.mv_cursor.is_none()); // unsure about this -_-
let _c = self.move_to_root()?;
loop {
let mem_page = self.stack.top();
let page_id = mem_page.get().get().id;
let (page, _c) = self.read_page(page_id)?;
return_if_locked_maybe_load!(self.pager, page);
let page = page.get();
let contents = page.get().contents.as_ref().unwrap();
if contents.is_leaf() {
// set cursor just past the last cell to append
self.stack.set_cell_index(contents.cell_count() as i32);
return Ok(IOResult::Done(()));
match self.seek_end_state {
SeekEndState::Start => {
let _c = self.move_to_root()?;
self.seek_end_state = SeekEndState::ProcessPage;
Ok(IOResult::IO)
}
match contents.rightmost_pointer() {
Some(right_most_pointer) => {
self.stack.set_cell_index(contents.cell_count() as i32 + 1); // invalid on interior
let (child, _c) = self.read_page(right_most_pointer as usize)?;
self.stack.push(child);
SeekEndState::ProcessPage => {
let mem_page = self.stack.top();
let page = mem_page.get();
// TODO: remove this with IO Completion tracking
return_if_locked!(page);
let contents = page.get().contents.as_ref().unwrap();
if contents.is_leaf() {
// set cursor just past the last cell to append
self.stack.set_cell_index(contents.cell_count() as i32);
self.seek_end_state = SeekEndState::Start;
return Ok(IOResult::Done(()));
}
match contents.rightmost_pointer() {
Some(right_most_pointer) => {
self.stack.set_cell_index(contents.cell_count() as i32 + 1); // invalid on interior
let (child, _c) = self.read_page(right_most_pointer as usize)?;
self.stack.push(child);
Ok(IOResult::IO)
}
None => unreachable!("interior page must have rightmost pointer"),
}
None => unreachable!("interior page must have rightmost pointer"),
}
}
}

6
core/storage/state_machines.rs
View File

@@ -36,3 +36,9 @@ pub enum CountState {
Loop,
Finish,
}
#[derive(Debug, Clone, Copy)]
pub enum SeekEndState {
Start,
ProcessPage,
}