| Filename | Latest commit message | Latest commit date |
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f035b63b9a
Three findings from the operator's review, all correct. 1. Two insert_job's. Graph::insert_job had no caller outside hive-jobq's own tests -- production only ever went through Scheduler::insert_job. It existed because the graph-level one got written first. Deleted; the tests moved onto a Scheduler, which is where insertion belongs anyway. 2. insert_job was not atomic, and the previous commit made that worse: a forward edge or forward parent surfaced mid-loop, leaving the nodes before it in the graph, and resolve_wanted ran after every insert, so an unknown handle failed once the whole job was already committed. The module documented this under "Partial insertion" instead of fixing it -- prose describing a hole is not a design. All three are decidable from what the builder holds, so check_declaration_order now runs before the first insert and the loop indexes ids directly. A malformed job leaves the graph untouched. What remains mid-insert is the graph's own rejection (out-of-group dep, empty DepWhen); closing that needs a dry-run validate on Graph, which is a separate change. 3. DagSpec no longer boxes its recipe: it is generic over the closure, which travels from the template that built it straight into submit. The box bought type inference, and paying for it costs annotations -- `|b: &Job|` at each declaration site (the field needs an HRTB, and an unannotated closure binds one lifetime) and `+ use<>` on each returning signature (or the opaque type captures the caller's borrows). Erasure is still needed where several recipe shapes share one type: the boxed Declare stays for the executor's append_subgraph, and a test table uses an erase() helper. |
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| .. | ||
| 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 ids of the nodes the job asked for, in the order it named them; 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.