cartel-sqlite 0.28.0

use crate::api::{batches, stmt, work};
use crate::retry;
use crate::runtime::slot::{Opening, lease::Lease};
use crate::runtime::{self, Error, heap};
use crate::{catalogs, config, sys};
use heap::scopes::Scope;
use o3::mem::lease::Open;
use std::{mem, ptr};

pub(crate) struct Local<I: catalogs::Catalog> {
    owned: Owned<I>,
    arena: runtime::raw::Span,
    work: work::Work,
    lookaside: runtime::raw::Span,
    lookaside_layout: crate::memory::Lookaside,
}

/// The pinned resource owner retains cleanup even when an installation is forgotten.
pub(super) struct Owned<I: catalogs::Catalog> {
    connection: Option<crate::sys::Connection>,
    statements: stmt::Storage<I>,
    scope: Option<Scope>,
}

impl<I: catalogs::Catalog> Local<I> {
    pub(crate) fn new(
        memory: runtime::raw::Memory,
        sqlite: heap::raw::Span,
        collect: runtime::raw::Span,
        stmts: runtime::raw::Span,
        aside: runtime::raw::Span,
        layout: crate::memory::Lookaside,
    ) -> Result<(Self, heap::raw::Local, heap::raw::Retained), Error> {
        let stmts = stmt::Storage::new(stmts)?;
        let (sqlite, retained) = heap::raw::Local::from_span(sqlite, memory);
        Ok((
            Self {
                owned: Owned {
                    connection: None,
                    statements: stmts,
                    scope: None,
                },
                arena: collect,
                work: work::Work::new(),
                lookaside: aside,
                lookaside_layout: layout,
            },
            sqlite,
            retained,
        ))
    }

    pub(crate) fn lease<'slot, 'd: 'slot>(
        &'slot mut self,
        heap: heap::raw::Local,
        retry: retry::raw::Loan<'slot, 'd>,
        report: &'slot mut crate::open::Completion,
    ) -> Result<Vacant<'slot, 'd, I>, crate::Error> {
        self.owned.scope = Some(Scope::enter(heap)?);
        let arena = &mut self.arena;
        let owned = ptr::NonNull::from(&mut self.owned);
        let lease = Lease::new(owned, retry, &self.work, report);
        Ok(Vacant {
            connection: &mut self.owned.connection,
            statements: &mut self.owned.statements,
            arena,
            lookaside: &mut self.lookaside,
            lookaside_layout: self.lookaside_layout,
            lease,
        })
    }
}

impl<I: catalogs::Catalog> Drop for Local<I> {
    fn drop(&mut self) {
        self.owned.retire(&self.work);
    }
}

impl<I: catalogs::Catalog> Owned<I> {
    /// Borrowed statement owners have already retired before their lease is returned.
    pub(super) fn finish(&mut self) {
        self.connection = None;
        if let Some(scope) = self.scope.take() {
            scope.finish();
        }
    }
    /// No borrower can execute after this pinned owner begins destruction.
    /// Forgotten owners leave initialized statement slots and callback contexts here.
    fn retire(&mut self, work: &work::Work) {
        if self.scope.is_some() {
            if let Some(db) = &self.connection {
                work.refresh(db);
            }
            self.statements.retire_all(work);
            self.finish();
        }
    }
}

pub(crate) struct Vacant<'slot, 'd, I: catalogs::Catalog> {
    connection: &'slot mut Option<crate::sys::Connection>,
    statements: &'slot mut stmt::Storage<I>,
    arena: batches::Arena<'slot>,
    lookaside: &'slot mut runtime::raw::Span,
    lookaside_layout: crate::memory::Lookaside,
    lease: Lease<'slot, 'd, I, Open>,
}

impl<'slot, 'd, I: catalogs::Catalog> Vacant<'slot, 'd, I> {
    pub(crate) fn open(self, db: sys::Connection) -> Result<Opening<'slot, 'd, I>, crate::Error> {
        let config = self.lease.config();
        let work = self.lease.work();
        let guard = work.begin(config.work.open.progress)?;
        work.progress(&db, config::Budget::PROGRESS_INTERVAL);
        Ok(Opening {
            guard,
            connection: self.connection.insert(db),
            statements: self.statements,
            arena: self.arena,
            lookaside: self.lookaside,
            lookaside_layout: self.lookaside_layout,
            lease: self.lease,
        })
    }
}

const _: () = {
    let word = mem::size_of::<usize>();
    assert!(mem::size_of::<Option<Scope>>() == word);
    let fields = mem::size_of::<Option<crate::sys::Connection>>()
        + mem::size_of::<stmt::Storage<catalogs::Empty>>()
        + 2 * mem::size_of::<runtime::raw::Span>()
        + mem::size_of::<work::Work>()
        + mem::size_of::<Option<Scope>>()
        + mem::size_of::<crate::memory::Lookaside>();
    let align = mem::align_of::<Local<catalogs::Empty>>();
    assert!(mem::size_of::<Local<catalogs::Empty>>() == fields.next_multiple_of(align));
};