joaoh82 / rust_sqlite / 25626413047

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github

Committed by web-flow

Commit Message

feat(engine): Phase 11.1 multi-connection foundation (SQLR-22) (#122)

First slice of Phase 11 (concurrent writes via MVCC + BEGIN CONCURRENT).
Refactors Connection from owning Database by value to holding
Arc<Mutex<Database>>, so multiple Connection handles can address the
same engine state from inside one process.

Connection::connect() mints a sibling handle that shares the backing
Database. Connection is now Send + Sync and can be moved across
threads without an outer Mutex<Connection>. The pager's existing
process-level flock and per-database mutex still serialize commits;
true multi-writer throughput on disjoint rows lands with
BEGIN CONCURRENT in 11.4.

Connection::database() / database_mut() return MutexGuard<'_, Database>;
internal call sites in src/ask, sqlrite-mcp tools, and the
Python/Node/WASM SDK shims bind the guard to a local first.

Six new tests in src/connection.rs:
- connect_shares_underlying_database
- connect_shares_file_backed_database
- handle_count_reflects_live_handles
- threaded_writers_serialize_cleanly (8 threads × 25 INSERTs)
- prep_cache_is_per_handle
- connection_is_send_and_sync (compile-time Send+Sync check)

Docs sweep: roadmap gets a Phase 11 section linking to
concurrent-writes-plan.md (the plan-doc internally numbers
sub-phases as "Phase 10.x" — that's its working title from before
Phase 10 = benchmarks shipped). New design-decisions entry 12a.
embedding.md gains a "Sharing one database across threads" section.

No file-format change. 579/579 workspace tests pass. No new clippy
warnings. fmt clean.

Co-authored-by: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

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