This implementation does not use locking or condition variables
internally; it's purely based on atomics and futexes.
Notably, concurrent sem_wait() and sem_post() calls can run *completely
in parallel* without slowing each other down, as long as there are empty
slots for them all to succeed without blocking.
Additionally, sem_wait() never executes an atomic operation with release
ordering, and sem_post() never executes an atomic operation with acquire
ordering (unless you count the syscall). This means the compiler and the
hardware are free to reorder code *into* the critical section.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
