`read`

std::size_t read(void *destination, std::size_t capacity) noexcept

Parameters

Name	Type
`destination`	`void *`
`capacity`	`std::size_t`

std::size_t

The record's size, or 0 when the ring is empty or capacity is smaller than the oldest record; the ring is left unchanged then.

Copies the oldest record into destination and removes it.

Precondition

Called only from the consumer thread.