Single-producer, multi-consumer ring buffer

Build RingBuffer(capacity), a FIFO queue stored in a list of exactly capacity slots allocated once, with a read index, a write index and a size (or another way to tell "full" from "empty", e.g. a size counter). Indexes wrap around modulo capacity.

• try_push(item) -> bool: append item at the back. If the buffer is full, leave it unchanged and return False (the overflow policy here is "reject the newest").
• try_pop(): remove and return the front item. Raise IndexError if the buffer is empty.
• __len__(), is_empty(), is_full(), and capacity as an attribute.

capacity >= 1. Items can be anything, including None. Every operation must be O(1): no list.pop(0), no insert(0, ...), no shifting.

rb = RingBuffer(2)
rb.try_push("a")   # True
rb.try_push("b")   # True
rb.try_push("c")   # False (full)
rb.try_pop()       # "a"
rb.try_push("c")   # True  (wraps around into slot 0)
[rb.try_pop(), rb.try_pop()]   # ["b", "c"]
rb.try_pop()       # IndexError