Note that some of these changes affect the protocol in
backward-incompatible ways.
- Replace use of "initially-active" and "initially-inactive" with
"client" and "server" respectively for clarity.
- Fix a race condition involving Endpoint.Shutdown() by repeatedly
invoking FUTEX_WAKE until it is confirmed that no local thread is
blocked in FUTEX_WAIT.
- Drop flipcall.ControlMode.
PiperOrigin-RevId: 260981382
Flipcall is a (conceptually) simple local-only RPC mechanism. Compared
to unet, Flipcall does not support passing FDs (support for which will
be provided out of band by another package), requires users to establish
connections manually, and requires user management of concurrency since
each connected Endpoint pair supports only a single RPC at a time;
however, it improves performance by using shared memory for data
(reducing memory copies) and using futexes for control signaling (which
is much cheaper than sendto/recvfrom/sendmsg/recvmsg).
PiperOrigin-RevId: 254471986
Jamie Liu