Refactor the I/O driver, extracting slab to `tokio::util`. (#1792)

The I/O driver is made private and moved to `tokio::io::driver`. `Registration` is
moved to `tokio::io::Registration` and `PollEvented` is moved to `tokio::io::PollEvented`.

Additionally, the concurrent slab used by the I/O driver is cleaned up and extracted to
`tokio::util::slab`, allowing it to eventually be used by other types.

1 files changed, 11 insertions, 4 deletions

diff --git a/tokio/src/util/mod.rs b/tokio/src/util/mod.rs
index 44377fcf..a50b33ac 100644
--- a/tokio/src/util/mod.rs
+++ b/tokio/src/util/mod.rs
@@ -1,5 +1,12 @@
-mod pad;
-pub(crate) use self::pad::CachePadded;
+cfg_io_driver! {
+    pub(crate) mod bit;
+    pub(crate) mod slab;
+}
 
-mod rand;
-pub(crate) use self::rand::FastRand;
+cfg_rt_threaded! {
+    mod pad;
+    pub(crate) use pad::CachePadded;
+
+    mod rand;
+    pub(crate) use rand::FastRand;
+}