shoney.arickathil
296efb52ed
- story 02: `status: done`, `review_pending` (forks 1–7 auto-approved for
autonomy); progress rows 6a ✅, 6b ➡ databasev2 5 Phase A, 7 `a310496`;
5c/5d rows cite the `dev` hashes (the pre-merge ones were unreachable);
task 6a's Given/When/Then met; Info records the seven forks (sentinel over
`:memory:`, its rules, the refusal contract, startup-only, the budget
leaves for 5, library-owned tables bind consumers, the v8 table bit);
History keeps the first cut that refused every class-bearing program
- database/src/CODE-LOGIC.md: "Startup refusal + WO_EPHEMERAL" — contract,
hatch, table bit, measured blast radius, deferred items, proof; the
dispatcher paragraph no longer says a failed commit un-applies the row
(fatal since databasev2 4 part A; WO_T_IO unreachable from a write path)
- residency spec + plan: task 6 items annotated with the 2026-09-09
decisions; the byte budget marked moved to databasev2 5
- README, seven example READMEs and four guides carry the one-line rule
(durable default refuses without WO_DATA; WO_EPHEMERAL=1; durable:
false); shop's RAM-only command sets the sentinel
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
(cherry picked from commit 2c3531998124042fe736388e8b926abda3841194)
63 lines
3.6 KiB
Markdown
63 lines
3.6 KiB
Markdown
# `db-actor` — the database reached from any shard
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> **Status: shipped — arc stage 3's acceptance gate.** Run it with
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> `just db-actor`. Landed 2026-08-21 with the shard-fiber arc
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> ([story 8](../../stories/language-runtime-database/08-shard-actor-runtime.md)
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> · [plan](../../superpowers/plans/2026-08-20-shard-fiber-arc.md)).
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The database lives on **one** shard — the owner, shard 0 — because RAM is
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authoritative and a single writer is what makes the WAL's ordering meaningful.
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That is a problem the moment actors are placed round-robin across cores: a
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`spawn`ed actor has no say in which shard it lands on, and before stage 3 a
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worker-shard `insert` trapped `WO_T_DB` with "database engine not initialized".
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Stage 3's answer is a **transparent DB actor**: statements issued off the owner
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shard marshal to it, execute there, and materialize their replies back. The
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program's source says nothing about any of it — the same `insert` and the same
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`from … select` work wherever the actor happens to run. This sample exists to
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prove exactly that, which is why its acceptance criterion is *placement
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independence* rather than any particular output.
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## What it does
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`Note` is a `@table` with a secondary index on `tag`. `Writer` is an actor: each
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one inserts a row, then scans the whole table and prints the sum it sees. `main`
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spawns two writers, waits, then scans once itself.
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With the default shard count, round-robin placement puts at least one writer off
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the owner shard — so one of those inserts and one of those scans travel the RPC
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path under test, and the other does not. Both must produce the same shape.
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```bash
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just db-actor # the gate
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woc docs/examples/db-actor/ # or build it by hand
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WO_SHARDS=1 ./docs/examples/db-actor/target/db-actor # force the local path
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```
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## What the gate proves
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`scripts/db-actor-accept.sh`, 8 checks:
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| Check | Why it is shaped that way |
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| --- | --- |
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| multi-shard, three rounds | The writer lines are asserted as a **set**, not a sequence — scheduling decides their order, and pinning it would be testing the scheduler, not the RPC. The `main` line is exact. |
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| both `WO_IO` backends forced | The reply park has to be plane-independent: io_uring and epoll must give the same answer, or the parking is leaking into semantics. |
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| single shard, byte-exact | The local path is untouched by stage 3. Any drift here means the RPC changed the non-RPC case. |
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| `WO_DATA` restart pair | A worker's insert must commit on the **owner's** WAL before its ack, so a restart replays it: 2 rows, then 2+2 after a second run. This is the durability claim the RPC could most easily break. A program with any durable table (the default) refuses to start without `WO_DATA`; `WO_EPHEMERAL=1` opts into a RAM-only run, `@table(durable: false)` opts a table out. |
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Run under `wovm_asan` and `wovm_tsan` as well — cross-shard message passing is
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exactly where a data race would hide, and TSan covering this demo is the one
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place it runs.
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## Read it for
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- **How little the source knows.** Compare `Writer.receive` here against the
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same statements in [`employee`](../employee/): identical. Transparency is the
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feature.
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- **Why `main` waits.** `main` is not an actor and has no mailbox, so it sleeps
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rather than awaiting — the gap iteration 31's `call` closes for actors and
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[iteration 24](../../stories/language-runtime-database/24-chat-websocket-workload.md)
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landed 2026-08-27.
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Reasoning under the engine side: [`database/src/CODE-LOGIC.md`](../../../database/src/CODE-LOGIC.md).
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Contract: [`plan/oop-vm/04-db-binding.md`](../../plan/oop-vm/04-db-binding.md).
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