rt: simplify coop implementation (#2498)

Simplifies coop implementation. Prunes unused code, create a `Budget`
type to track the current budget.

1 files changed, 20 insertions, 0 deletions

diff --git a/tokio/src/macros/cfg.rs b/tokio/src/macros/cfg.rs
index 618b8f66..288f58d2 100644
--- a/tokio/src/macros/cfg.rs
+++ b/tokio/src/macros/cfg.rs
@@ -363,3 +363,23 @@ macro_rules! cfg_unstable {
         )*
     }
 }
+
+macro_rules! cfg_coop {
+    ($($item:item)*) => {
+        $(
+            #[cfg(any(
+                    feature = "blocking",
+                    feature = "dns",
+                    feature = "fs",
+                    feature = "io-driver",
+                    feature = "io-std",
+                    feature = "process",
+                    feature = "rt-core",
+                    feature = "sync",
+                    feature = "stream",
+                    feature = "time"
+                    ))]
+            $item
+        )*
+    }
+}