Crate firq_core 

Core scheduling primitives for Firq.

firq-core is runtime-agnostic and contains the scheduling engine used by the async and web integration crates.

It provides:

• Deficit Round Robin (DRR) fairness by tenant
• Global/per-tenant backpressure policies
• Deadline-aware dequeue semantics
• Queue-time metrics and saturation signals
• Prometheus text rendering helpers (metrics feature, enabled by default)
• Pending task cancellation and shutdown modes

Basic usage

use firq_core::{EnqueueResult, Priority, Scheduler, SchedulerConfig, Task, TenantKey};
use std::time::Instant;

let scheduler = Scheduler::new(SchedulerConfig::default());
let tenant = TenantKey::from(1);
let task = Task {
    payload: "work",
    enqueue_ts: Instant::now(),
    deadline: None,
    priority: Priority::Normal,
    cost: 1,
};

match scheduler.enqueue(tenant, task) {
    EnqueueResult::Enqueued => {}
    EnqueueResult::Rejected(_) => {}
    EnqueueResult::Closed => {}
}

Modules

prometheus

Structs

QueueTimeBucket

Single histogram bucket for queue time metrics.

Scheduler

Multi-tenant in-process scheduler with DRR fairness and explicit backpressure.

SchedulerConfig

Scheduler runtime configuration.

SchedulerStats

Snapshot of scheduler metrics.

Task

Enqueued unit of work.

TaskHandle

Opaque identifier for a pending task.

TenantCount

Tenant counter entry used in top-talker snapshots.

TenantKey

Stable fairness key used to assign work to shards and DRR queues.

Enums

BackpressurePolicy

Behavior when enqueue capacity limits are hit.

CancelResult

Result of task cancellation.

CloseMode

Scheduler shutdown mode.

DequeueResult

Result of a dequeue attempt.

EnqueueRejectReason

Reason for enqueue rejection.

EnqueueResult

Result of an enqueue operation.

EnqueueWithHandleResult

Result of enqueue_with_handle.

Priority

Scheduling priority for a task.