This patch updates `poll_read_ready` to take a `mask` argument, enabling
the caller to specify the desired readiness. `need_read` is renamed to
`clear_read_ready` and also takes a mask.
This enables a caller to listen for HUP events without requiring reading
from the I/O resource.
Mio will be requiring `deregister` to be called explicitly in order to
guarantee that Poll releases any state associated with the I/O resource.
See carllerche/mio#753.
This patch adds an explicit `deregister` function to `Registration` and
updates `PollEvented` to call this function on drop.
`Registration::deregister` is also called on `PollEvented::into_inner`.
Closes#168
This allows libraries that require access to reactor related types to
depend on this crate without having to depend on the entirety of Tokio.
For example, libraries that implement their custom I/O resource will
need to access `Registration` or `PollEvented`.
Carl Lerche