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安正超
62 lines
2.3 KiB
Markdown
62 lines
2.3 KiB
Markdown
# Workload Admission Contracts
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This document records the `rustfs/backlog#660` PR-05 and PR-07 scheduler
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preservation and runtime workload-class contract slice.
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## Preservation Coverage
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The `rustfs-concurrency` tests pin the current reusable scheduler and
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admission-facing behavior before later snapshot extraction:
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- Worker slot over-release remains clamped by the configured worker limit.
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- Scheduler default buffer and priority thresholds remain unchanged.
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- Scheduler priority boundaries remain high below the high threshold, normal at
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both thresholds, and low above the low threshold.
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- Backpressure pipe metadata reads preserve buffer capacity and state without
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mutating the manager state.
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- `GetObjectQueueSnapshot` preserves saturated, over-available, and zero-total
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permit semantics.
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## Workload Class Contract
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`WorkloadClass` defines the required future admission categories:
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- Foreground read.
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- Foreground write.
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- Metadata.
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- Scanner.
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- Repair.
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- Replication.
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`AdmissionState`, `WorkloadAdmissionSnapshot`, and
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`WorkloadAdmissionRegistrySnapshot` define read-only status shapes for later
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runtime owners. They do not replace the current scheduler, request guard,
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scanner, heal, replication, or ECStore placement behavior.
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## Boundary Rules
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- `rustfs-concurrency` owns this reusable contract surface.
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- The contract does not depend on `rustfs-ecstore` or RustFS binary runtime
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state.
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- No scheduler decision logic, queue capacity, Tokio runtime default, scanner
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admission, heal admission, replication admission, placement, membership, or
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NUMA behavior changes are part of this slice.
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## Set-Local Snapshot Extraction
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The RustFS storage `ConcurrencyManager` now implements
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`WorkloadAdmissionSnapshotProvider` for local foreground-read admission:
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- `ForegroundRead` reports local disk-read permit usage through
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`GetObjectQueueSnapshot`.
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- `active` is the number of disk-read permits currently in use.
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- `limit` is the configured maximum concurrent disk reads.
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- `queued` remains `None` because the current semaphore does not expose waiter
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counts.
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- Scanner, repair, replication, foreground write, and metadata entries remain
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`Unknown` until their owning runtime components expose read-only status.
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This is an observation surface only. Permit acquisition, priority assignment,
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buffer sizing, storage media detection, request guards, and queue behavior are
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unchanged.
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