Support wasm32-wasi target

Signed-off-by: Richard Zak <richard@profian.com>

Cargo.toml

@@ -72,6 +72,7 @@ rustdoc-args = ["--cfg", "docsrs"]
 targets = [
   "aarch64-apple-ios",
   "aarch64-linux-android",
+  "wasm32-wasi",
   "x86_64-apple-darwin",
   "x86_64-pc-windows-msvc",
   "x86_64-unknown-dragonfly",

src/poll.rs

@@ -2,6 +2,7 @@ use crate::{event, sys, Events, Interest, Token};
 use log::trace;
 #[cfg(unix)]
 use std::os::unix::io::{AsRawFd, RawFd};
+use std::sync::Arc;
 use std::time::Duration;
 use std::{fmt, io};
 
@@ -230,7 +231,7 @@ pub struct Poll {
 
 /// Registers I/O resources.
 pub struct Registry {
-    selector: sys::Selector,
+    selector: Arc<sys::Selector>,
 }
 
 impl Poll {
@@ -270,13 +271,12 @@ impl Poll {
         /// ```
         pub fn new() -> io::Result<Poll> {
             sys::Selector::new().map(|selector| Poll {
-                registry: Registry { selector },
+                registry: Registry { selector: Arc::new(selector) },
             })
         }
     }
 
-    /// Create a separate `Registry` which can be used to register
-    /// `event::Source`s.
+    /// Get access to the `Registry`, which can be used to register `event::Source`s.
     pub fn registry(&self) -> &Registry {
         &self.registry
     }
@@ -637,9 +637,9 @@ impl Registry {
     /// the original `Registry` and `Poll` instance.
     #[cfg(not(target_os = "wasi"))]
     pub fn try_clone(&self) -> io::Result<Registry> {
-        self.selector
-            .try_clone()
-            .map(|selector| Registry { selector })
+        self.selector.try_clone().map(|selector| Registry {
+            selector: Arc::new(selector),
+        })
     }
 
     /// Internal check to ensure only a single `Waker` is active per [`Poll`]
@@ -659,6 +659,18 @@ impl Registry {
     }
 }
 
+impl Clone for Registry {
+    /// Creates a new independently owned `Registry`.
+    ///
+    /// Event sources registered with this `Registry` will be registered with
+    /// the original `Registry` and `Poll` instance.
+    fn clone(&self) -> Self {
+        Registry {
+            selector: self.selector.clone(),
+        }
+    }
+}
+
 impl fmt::Debug for Registry {
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt.debug_struct("Registry").finish()