Module spsc 

Single-producer single-consumer byte ring buffer.

Design

┌─────────────────────────────────────────────────────────────────────────┐
│ Shared:                                                                 │
│   head: CachePadded<AtomicUsize>  ← Consumer writes, producer reads     │
│   buffer: *mut u8                                                       │
│   capacity: usize                 (power of 2)                          │
│   mask: usize                     (capacity - 1)                        │
└─────────────────────────────────────────────────────────────────────────┘

┌─────────────────────────────────┐   ┌─────────────────────────────────┐
│ Producer:                       │   │ Consumer:                       │
│   tail: usize        (local)    │   │   head: usize        (local)    │
│   cached_head: usize (local)    │   │                                 │
└─────────────────────────────────┘   └─────────────────────────────────┘

Record Layout

┌──────────────────────────────────────────────┐
│ len: u32                (4 bytes)            │ ← payload length / commit marker
├──────────────────────────────────────────────┤
│ payload: [u8; len]      (variable)           │ ← raw bytes
├──────────────────────────────────────────────┤
│ padding: [u8; ...]      (0-7 bytes)          │ ← align to 8-byte boundary
└──────────────────────────────────────────────┘

Records are packed contiguously. Total record size is align8(4 + len).

Len Field Encoding

• len == 0: Not committed, consumer waits
• len > 0, high bit clear: Committed record, payload is len bytes
• len high bit set: Skip marker, advance by len & 0x7FFF_FFFF bytes

Structs

Consumer

Consumer endpoint of the SPSC ring buffer.

Producer

Producer endpoint of the SPSC ring buffer.

ReadClaim

A claimed record for reading.

WriteClaim

A claimed region for writing a record.

Functions

new

Creates a bounded SPSC byte ring buffer.