Don't spin in epoll_wait() / kevent() / port_getn() / etc. when we can't
accept() a new connection due to having reached the file descriptor limit.
Pass the error to the connection_cb and let the libuv user deal with it.
Some memory was leaked when the uv_udp_t handle was closed when there were
in-flight send requests with a heap allocated buffer list.
That doesn't happen much in practice. In the common case (writing < 5 buffers),
the buffer list is stored inside the uv_udp_send_t structure, not allocated on
the heap.
uv_async_send would always return 1 when non-gcc compilers were used.
When uv_async_send returns 1 no attempt is made to make port_getn
return, so in this situation uv_async_send didn't wake up the event
loop.
Set the non-blocking and close-on-exec flags with ioctl() instead of fcntl(),
it's about 10-25% faster.
Stick with fcntl() on Solaris. ioctl(FIONBIO) works but is twice as slow as
fcntl(O_NONBLOCK). ioctl(FIOCLEX) doesn't raise an error but doesn't actually
work either.
uv_update_time does not overwrite the high 32 bits of uv_loop_t.time.
It merely increments it by one when the low 32 bits have wrapped. That
means that `time` needs to be initialized to zero before
uv_update_time() is called for the first time.
Don't try the pipe2() or socketpair(O_CLOEXEC) syscalls when a previous call to
uv__make_pipe() or uv__make_socketpair() call established that the kernel
doesn't support it. Speeds up pipe and socketpair creation on older kernels.
Variables tagged with __read_mostly are put into a separate ELF section to
improve the cache locality of data that is read often but seldom written to.
kqueue(2) on osx doesn't work (emits EINVAL error) with specific fds
(i.e. /dev/tty, /dev/null, etc). When given such descriptors - start
select(2) watcher thread that will emit io events.
uv_fs_poll_t has an embedded uv_timer_t handle that got closed at a time when
the memory of the encapsulating handle might already have been deallocated.
Solve that by moving the poller's state into a structure that is allocated on
the heap and can be freed independently.
