From 83320efa31a4c3e7eaf2302d1322a1932a3102d7 Mon Sep 17 00:00:00 2001
From: Dany Laporte <dany_laporte@hotmail.com>
Date: Wed, 26 Feb 2020 04:40:31 -0500
Subject: [PATCH] Avoid error by `register()` on Windows (#103)

---
 actix-server/src/accept.rs | 46 ++++++++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 12 deletions(-)

diff --git a/actix-server/src/accept.rs b/actix-server/src/accept.rs
index 993ecab4..4dc218fd 100644
--- a/actix-server/src/accept.rs
+++ b/actix-server/src/accept.rs
@@ -298,12 +298,7 @@ impl Accept {
                     }
                     Command::Resume => {
                         for (token, info) in self.sockets.iter() {
-                            if let Err(err) = self.poll.register(
-                                &info.sock,
-                                mio::Token(token + DELTA),
-                                mio::Ready::readable(),
-                                mio::PollOpt::edge(),
-                            ) {
+                            if let Err(err) = self.register(token, info) {
                                 error!("Can not resume socket accept process: {}", err);
                             } else {
                                 info!(
@@ -338,17 +333,44 @@ impl Accept {
         true
     }
 
+    #[cfg(not(target_os = "windows"))]
+    fn register(&self, token: usize, info: &ServerSocketInfo) -> io::Result<()> {
+        self.poll.register(
+            &info.sock,
+            mio::Token(token + DELTA),
+            mio::Ready::readable(),
+            mio::PollOpt::edge(),
+        )
+    }
+
+    #[cfg(target_os = "windows")]
+    fn register(&self, token: usize, info: &ServerSocketInfo) -> io::Result<()> {
+        // On windows, calling register without deregister cause an error.
+        // See https://github.com/actix/actix-web/issues/905
+        // Calling reregister seems to fix the issue.
+        self.poll
+            .register(
+                &info.sock,
+                mio::Token(token + DELTA),
+                mio::Ready::readable(),
+                mio::PollOpt::edge(),
+            )
+            .or_else(|_| {
+                self.poll.reregister(
+                    &info.sock,
+                    mio::Token(token + DELTA),
+                    mio::Ready::readable(),
+                    mio::PollOpt::edge(),
+                )
+            })
+    }
+
     fn backpressure(&mut self, on: bool) {
         if self.backpressure {
             if !on {
                 self.backpressure = false;
                 for (token, info) in self.sockets.iter() {
-                    if let Err(err) = self.poll.register(
-                        &info.sock,
-                        mio::Token(token + DELTA),
-                        mio::Ready::readable(),
-                        mio::PollOpt::edge(),
-                    ) {
+                    if let Err(err) = self.register(token, info) {
                         error!("Can not resume socket accept process: {}", err);
                     } else {
                         info!("Accepting connections on {} has been resumed", info.addr);