This patch introduces `Timeout`. This new type allows setting a timeout
both using a duration and an instant. Given this overlap with
`Deadline`, `Deadline` is deprecated.
In addition to supporting future timeouts, the `Timeout` combinator is
able to provide timeout functionality to streams. It does this by
applying a duration based timeout to each item being yielded.
The main reason for introducing `Timeout` is that a deadline approach
does not work with streams. Since `Timeout` needed to be introduced
anyway, keeping `Deadline` around does not make sense.
* Remove `counted` field on `timer::Entry`.
It turns out that a better indicator of whether or not the number of
active timeouts should be decremented is if the `Entry` has been
associated with a timer. In other words, if `Entry::inner` can be
upgraded, then the count should be decremented on drop.
* timer: Tweak link between `Delay` and the driver
This tweaks the struct layout / details regarding how a `Delay` instance
is linked to a driver (timer instance). Instead of lazily allocating the
`Entry` (node shared between `Delay` and the timer), `Entry` is
allocated immediately when `Delay` is created. This allows using the
entry store data used by `Delay`.
This is in anticipation of further timer improvements that would
otherwise require the size of `Delay` to grow further. Since an
allocation is already made, the idea is to shrink the size of the
`Delay` struct.
This patch renames `Sleep` from tokio-timer and the tokio facade to
`Delay`. Given that the future does not actually put anything to sleep,
the `Delay` name feels more appropriate.
Fixes#263
Carl Lerche