Module buffered 

RAM-buffered wrapper for QueueStorage.

NOR flash writes are slow and erases are very slow. If a producer emits data faster than the flash interface can commit it, BufferedQueue accepts items into a fixed-size RAM ring buffer via the synchronous enqueue call (no flash I/O) and asynchronously drains them to flash via drain_one or drain_all.

Overflow policy

When the RAM ring is full, enqueue behaviour is controlled by OverflowPolicy: either return Err(()) or silently evict the oldest buffered item.

Ordering

FIFO ordering is preserved: flash items are always older than RAM items. pop and peek read from flash first, falling back to the oldest RAM item if flash is empty.

Power-fail note

Items that are in the RAM ring and have not yet been drained to flash will be lost on power loss. Items that have been drained follow the power-fail safety guarantees of sequential-storage.

Embassy / ISR-safe use

Enable the shared-ram-ring feature for [SharedRamRing], which wraps the ring in a critical-section mutex so it can be enqueued to from an interrupt handler, and signals a drain task the moment data arrives.

Structs

BufferedQueue

A write-buffered queue that accepts items into a RAM ring and drains them to NOR flash.

Enums

OverflowPolicy

Controls what happens when enqueue is called on a full RAM ring.