Commit 253be348 authored by Committed by Olivier Crête
agent: Add support for vectored I/O for receives
Add two new public functions: • nice_agent_recv_messages() • nice_agent_recv_messages_nonblocking() which allow receiving multiple messages in a single call, and support vectors of buffers to receive the messages into. The existing nice_agent_recv[_nonblocking]() APIs have been left untouched. This tidies up a lot of the message handling code internally, and eliminates a couple of memcpy()s. There are still a few more memcpy()s on the critical path, which could be eliminated with further work. In the reliable agent case, every message is memcpy()ed twice: once into the pseudo-TCP receive buffer, and once out of it. The copy on input could be eliminated (in the case of in-order delivery of packets) by receiving directly into the receive buffer. The copy on output can’t be eliminated except in the I/O callback case (when nice_agent_attach_recv() has been used), in which case the callback could be invoked with a pointer directly into the pseudo-TCP receive buffer. In the non-reliable agent case, zero memcpy()s are used. A couple of the more complex socket implementations (TURN and HTTP) have slow paths during setup, and partially also during normal use. These could be optimised further, and FIXME comments have been added.
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