stripes

nimony/lib/std/stripes.nim

• type FifoStripe = object
    lock: SysLock
    head: int64
    tail: int64
    count: int64
    data: seq[T]

• proc init(s: var FifoStripe[T]; capacity: int64)
• proc tryEnqueue(s: var FifoStripe[T]; item: T): bool
• proc tryBulkEnqueue(s: var FifoStripe[T]; items: openArray[T]): int64

  Enqueue as many leading items of items (in order) as fit under one lock acquisition; returns how many were taken.

• proc tryBulkDequeue(s: var FifoStripe[T]; bulkSize: int64; buf: var openArray[T]): int64
• proc grow(s: var FifoStripe[T]; newCapacity: int64)
• proc tryEnqueue(s: var FifoStripe[T]; item: T; maxCapacity: int64): bool

  Like tryEnqueue, but a full stripe first doubles its capacity, up to maxCapacity, so that a stripe can start small and still absorb a burst.

• type LocalRing = object
    head: int64
    count: int64
    data: seq[T]
    mask: int64

• proc tryEnqueue(r: var LocalRing[T]; item: T; capacity: int64): bool

  Push item; false when the ring is full. Capacity is fixed at the first push (the ring starts empty, so no allocation is paid by a lane that never submits an op) and never changes: a full ring is backpressure for the caller, and reallocating would mean moving the elements of a ring that is being filled.

• proc tryBulkDequeue(r: var LocalRing[T]; bulkSize: int64; buf: var openArray[T]): int64

  Take up to bulkSize items in FIFO order; 0 when the ring is empty.