| Filename | Latest commit message | Latest commit date |
|---|---|---|
f7548e4535
Two review findings from the operator, both about the builder being more
reachable than the design said.
**The builder must not leave the crate.** The module doc claimed "an
insertion API, not a spec factory — a builder is only ever handed to a
closure by the queue's insertion entry point", and then `new()` and
`insert_into` were public, so a caller could build one, carry it around
and insert it later. That is a spec factory with a builder's name on it.
`insert_job(root_parent, |b| …)` is now the whole API: the builder is
created inside the call, handed to the closure, and consumed there.
`new` / `insert_into` / `insert_with` are crate-private.
**A handle names the job that issued it.** `NodeGuid` was a per-builder
counter, so two jobs' first handles compared equal. `NodeRef` converts
into a bare `NodeGuid` — dropping the borrow that ties it to its
builder — so a handle carried into a second job (an inner closure
capturing an outer handle) would silently resolve to whatever that job's
first node happened to be. It is now `{ job, seq }` with a random `job`
half, so a foreign handle is a miss and the insert fails naming it. The
randomness comes from `RandomState`, which is collision-avoidance rather
than cryptography and needs no new dependency.
Tests moved onto the closure API rather than keeping their in-crate
access to the private constructor — a test that only passes because it
lives inside the crate is not testing the API a caller has. The two
forward-reference tests stopped asserting literal guid values (a random
half cannot be written down) and compare against the handles instead,
and a new test carries a handle between two jobs to pin the behaviour
that motivated the change.
|
||
| .. | ||
| src | ||
| Cargo.toml | ||
| README.md | ||
hive-jobq
A persistent job-DAG scheduler, extracted from hive-c0re's in-tree job_queue
as a domain-agnostic library. It schedules a single persistent graph of
nodes over named resources; it knows nothing about containers, rebuilds, or any
hyperhive type — the node payload N and resource name R are both generic, so
the caller supplies its own domain.
When to use it
Reach for this crate whenever you need to run a DAG of interdependent work items under bounded, named concurrency — the hive-c0re rebuild/lifecycle queue is the first consumer, but nothing here is specific to it. The caller defines the node kinds, wires deps, and supplies a runner; the scheduler decides what can start.
Model
One persistent graph for the whole system, not a DAG per job. Enqueuing inserts a self-contained sub-DAG and returns the new node ids; the scheduler runs a continuous loop, starting every node whose deps are satisfied:
- Resource deps are named counting semaphores over a caller-chosen type
R— e.g.build-slot(capacity N),agent/<name>(capacity 1), or any unconfigured name (capacity 1, created on use). A node acquires all its resource deps atomically at start (all-or-nothing) — no hold-and-wait, so no deadlock. - Node deps wait on another node per
DepWhen:AfterOkneeds success (a failed dep cancels the dependent),AfterAnyonly needs terminal.
A node carries two independent axes: its Deps (ordering + resource needs) and
its parent (structural grouping). The parent chain, not the node edges, is
what the scheduler consults for resource re-entrancy: a resource unit is held
for the acquiring node plus its whole parent subtree, and a descendant needing
a resource an ancestor already holds re-uses that grant (a re-entrant borrow,
one branch at a time) rather than taking a fresh unit.
A NodeId is opaque, stable, and monotonic (safe to persist). The scheduler is
single-threaded — it owns the resource table and mutates it directly.
Shape
Graph<N, R>— the persistent node store.insertmints ids and validates dep/parent references;set_stateis the single state-transition choke point (and where each node's lifecycle timestamps —started_at/finished_at,DateTime<Utc>— are stamped).Node<N, R>—{ id, parent, payload, deps, state, started_at, finished_at, error }. All fields public; derives serde for persistence + the wire.Scheduler<N, R>— drives the graph:settle()starts every ready node (acquiring resources atomically),complete(id, outcome)reports a finished node's result and rolls terminality up the parent chain, releasing grants once a subtree is done.Outcome::{Done, Failed(String)}— the failure reason ridesFailedonto the node'serror.ResourceTable<R>— per-name capacities; unconfigured names default to capacity 1.
See the crate-root and scheduler module //! docs for the full borrow/release
model.