fix(ext/flash): reregister socket on partial read on Windows (#16076)

cli/tests/unit/flash_test.ts

@@ -2205,6 +2205,35 @@ Deno.test(
   },
 );
 
+// https://github.com/denoland/deno/issues/15549
+Deno.test(
+  { permissions: { net: true } },
+  async function testIssue15549() {
+    const ac = new AbortController();
+    const promise = deferred();
+    let count = 0;
+    const server = Deno.serve(() => {
+      count++;
+      return new Response(`hello world ${count}`);
+    }, {
+      async onListen() {
+        const res1 = await fetch("http://localhost:9000/");
+        assertEquals(await res1.text(), "hello world 1");
+
+        const res2 = await fetch("http://localhost:9000/");
+        assertEquals(await res2.text(), "hello world 2");
+
+        promise.resolve();
+        ac.abort();
+      },
+      signal: ac.signal,
+    });
+
+    await promise;
+    await server;
+  },
+);
+
 function chunkedBodyReader(h: Headers, r: BufReader): Deno.Reader {
   // Based on https://tools.ietf.org/html/rfc2616#section-19.4.6
   const tp = new TextProtoReader(r);

ext/flash/lib.rs

@@ -987,22 +987,48 @@ fn run_server(
                 // sockets.remove(&token);
                 continue 'events;
               }
-              Ok(read) => match req.parse(&buffer[..offset + read]) {
-                Ok(httparse::Status::Complete(n)) => {
-                  body_offset = n;
-                  body_len = offset + read;
-                  socket.parse_done = ParseStatus::None;
-                  break;
-                }
-                Ok(httparse::Status::Partial) => {
-                  socket.parse_done = ParseStatus::Ongoing(offset + read);
-                  continue;
-                }
-                Err(_) => {
-                  let _ = socket.write(b"HTTP/1.1 400 Bad Request\r\n\r\n");
-                  continue 'events;
+              Ok(read) => {
+                match req.parse(&buffer[..offset + read]) {
+                  Ok(httparse::Status::Complete(n)) => {
+                    body_offset = n;
+                    body_len = offset + read;
+                    socket.parse_done = ParseStatus::None;
+                    // On Windows, We must keep calling socket.read() until it fails with WouldBlock.
+                    //
+                    // Mio tries to emulate edge triggered events on Windows.
+                    // AFAICT it only rearms the event on WouldBlock, but it doesn't when a partial read happens.
+                    // https://github.com/denoland/deno/issues/15549
+                    #[cfg(target_os = "windows")]
+                    match &mut socket.inner {
+                      InnerStream::Tcp(ref mut socket) => {
+                        poll
+                          .registry()
+                          .reregister(socket, token, Interest::READABLE)
+                          .unwrap();
+                      }
+                      InnerStream::Tls(ref mut socket) => {
+                        poll
+                          .registry()
+                          .reregister(
+                            &mut socket.sock,
+                            token,
+                            Interest::READABLE,
+                          )
+                          .unwrap();
+                      }
+                    };
+                    break;
+                  }
+                  Ok(httparse::Status::Partial) => {
+                    socket.parse_done = ParseStatus::Ongoing(offset + read);
+                    continue;
+                  }
+                  Err(_) => {
+                    let _ = socket.write(b"HTTP/1.1 400 Bad Request\r\n\r\n");
+                    continue 'events;
+                  }
                 }
-              },
+              }
               Err(ref e) if e.kind() == std::io::ErrorKind::WouldBlock => {
                 break 'events
               }