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state machine for insert

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This commit is contained in:
pedrocarlo
2025-08-11 15:15:33 -03:00
parent 78a89f0fd3
commit 4010dc8f32
2 changed files with 93 additions and 54 deletions
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139
core/storage/btree.rs
View File

@@ -10,8 +10,8 @@ use crate::{
LEAF_PAGE_HEADER_SIZE_BYTES, LEFT_CHILD_PTR_SIZE_BYTES,
},
state_machines::{
AdvanceState, CountState, EmptyTableState, MoveToRightState, RewindState, SeekEndState,
SeekToLastState,
AdvanceState, CountState, EmptyTableState, InsertState, MoveToRightState, RewindState,
SeekEndState, SeekToLastState,
},
},
translate::plan::IterationDirection,
@@ -558,6 +558,8 @@ pub struct BTreeCursor {
count_state: CountState,
/// State machine for [BTreeCursor::seek_end]
seek_end_state: SeekEndState,
/// State machine for [BTreeCursor::insert]
insert_state: InsertState,
}
/// We store the cell index and cell count for each page in the stack.
@@ -624,6 +626,7 @@ impl BTreeCursor {
advance_state: AdvanceState::Start,
count_state: CountState::Start,
seek_end_state: SeekEndState::Start,
insert_state: InsertState::Start,
}
}
@@ -4444,61 +4447,89 @@ impl BTreeCursor {
None => todo!("Support mvcc inserts with index btrees"),
},
None => {
match (&self.valid_state, self.is_write_in_progress()) {
(CursorValidState::Valid, _) => {
// consider the current position valid unless the caller explicitly asks us to seek.
}
(CursorValidState::RequireSeek, false) => {
// we must seek.
moved_before = false;
}
(CursorValidState::RequireSeek, true) => {
// illegal to seek during a write no matter what CursorValidState or caller says -- we might e.g. move to the wrong page during balancing
moved_before = true;
}
(CursorValidState::RequireAdvance(direction), _) => {
// FIXME: this is a hack to support the case where we need to advance the cursor after a seek.
// We should have a proper state machine for this.
return_if_io!(match direction {
IterationDirection::Forwards => self.next(),
IterationDirection::Backwards => self.prev(),
});
self.valid_state = CursorValidState::Valid;
self.seek_state = CursorSeekState::Start;
moved_before = true;
}
};
if !moved_before {
let seek_result = match key {
BTreeKey::IndexKey(_) => {
return_if_io!(self.seek(
SeekKey::IndexKey(key.get_record().unwrap()),
SeekOp::GE { eq_only: true }
))
loop {
let state = self.insert_state;
match state {
InsertState::Start => {
match (&self.valid_state, self.is_write_in_progress()) {
(CursorValidState::Valid, _) => {
// consider the current position valid unless the caller explicitly asks us to seek.
}
(CursorValidState::RequireSeek, false) => {
// we must seek.
moved_before = false;
}
(CursorValidState::RequireSeek, true) => {
// illegal to seek during a write no matter what CursorValidState or caller says -- we might e.g. move to the wrong page during balancing
moved_before = true;
}
(CursorValidState::RequireAdvance(direction), _) => {
// FIXME: this is a hack to support the case where we need to advance the cursor after a seek.
// We should have a proper state machine for this.
return_if_io!(match direction {
IterationDirection::Forwards => self.next(),
IterationDirection::Backwards => self.prev(),
});
self.valid_state = CursorValidState::Valid;
self.seek_state = CursorSeekState::Start;
moved_before = true;
}
};
if !moved_before {
self.insert_state = InsertState::Seek;
} else {
self.insert_state = InsertState::InsertIntoPage;
}
}
BTreeKey::TableRowId(_) => {
return_if_io!(self.seek(
SeekKey::TableRowId(key.to_rowid()),
SeekOp::GE { eq_only: true }
))
InsertState::Seek => {
let seek_result = match key {
BTreeKey::IndexKey(_) => {
return_if_io!(self.seek(
SeekKey::IndexKey(key.get_record().unwrap()),
SeekOp::GE { eq_only: true }
))
}
BTreeKey::TableRowId(_) => {
return_if_io!(self.seek(
SeekKey::TableRowId(key.to_rowid()),
SeekOp::GE { eq_only: true }
))
}
};
if SeekResult::TryAdvance == seek_result {
self.valid_state =
CursorValidState::RequireAdvance(IterationDirection::Forwards);
self.insert_state = InsertState::Advance;
}
self.context.take(); // we know where we wanted to move so if there was any saved context, discard it.
self.valid_state = CursorValidState::Valid;
self.seek_state = CursorSeekState::Start;
tracing::debug!(
"seeked to the right place, page is now {:?}",
self.stack.top().get().get().id
);
self.insert_state = InsertState::InsertIntoPage;
}
InsertState::Advance => {
return_if_io!(self.next());
self.context.take(); // we know where we wanted to move so if there was any saved context, discard it.
self.valid_state = CursorValidState::Valid;
self.seek_state = CursorSeekState::Start;
tracing::debug!(
"seeked to the right place, page is now {:?}",
self.stack.top().get().get().id
);
self.insert_state = InsertState::InsertIntoPage;
}
InsertState::InsertIntoPage => {
return_if_io!(self.insert_into_page(key));
if key.maybe_rowid().is_some() {
self.has_record.replace(true);
}
self.insert_state = InsertState::Start;
break;
}
};
if SeekResult::TryAdvance == seek_result {
self.valid_state =
CursorValidState::RequireAdvance(IterationDirection::Forwards);
return_if_io!(self.next());
}
self.context.take(); // we know where we wanted to move so if there was any saved context, discard it.
self.valid_state = CursorValidState::Valid;
self.seek_state = CursorSeekState::Start;
tracing::debug!(
"seeked to the right place, page is now {:?}",
self.stack.top().get().get().id
);
}
return_if_io!(self.insert_into_page(key));
if key.maybe_rowid().is_some() {
self.has_record.replace(true);
}
}
};

8
core/storage/state_machines.rs
View File

@@ -42,3 +42,11 @@ pub enum SeekEndState {
Start,
ProcessPage,
}
#[derive(Debug, Clone, Copy)]
pub enum InsertState {
Start,
Seek,
Advance,
InsertIntoPage,
}