From cbb1bfdee2b37e98bd25f67190dbd22eb76f5cff Mon Sep 17 00:00:00 2001
From: Wassim Chegham <github@wassim.dev>
Date: Tue, 12 Dec 2023 16:57:38 +0100
Subject: [PATCH] chore: add SOCKET_UDP_CHECK_SEND

---
 packages/preview2-shim/lib/io/calls.js            |  1 +
 packages/preview2-shim/lib/io/worker-thread.js    | 10 ++++++++++
 .../lib/nodejs/sockets/udp-socket-impl.js         | 15 +++++++--------
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/packages/preview2-shim/lib/io/calls.js b/packages/preview2-shim/lib/io/calls.js
index 1ba6711cd..873131ff1 100644
--- a/packages/preview2-shim/lib/io/calls.js
+++ b/packages/preview2-shim/lib/io/calls.js
@@ -54,6 +54,7 @@ export const SOCKET_UDP_CREATE_HANDLE = ++call_id << 24;
 export const SOCKET_UDP_BIND = ++call_id << 24;
 export const SOCKET_UDP_CONNECT = ++call_id << 24;
 export const SOCKET_UDP_DISCONNECT = ++call_id << 24;
+export const SOCKET_UDP_CHECK_SEND = ++call_id << 24;
 export const SOCKET_UDP_SEND = ++call_id << 24;
 export const SOCKET_UDP_RECEIVE = ++call_id << 24;
 export const SOCKET_UDP_DISPOSE = ++call_id << 24;
diff --git a/packages/preview2-shim/lib/io/worker-thread.js b/packages/preview2-shim/lib/io/worker-thread.js
index 55487a205..da105c28a 100644
--- a/packages/preview2-shim/lib/io/worker-thread.js
+++ b/packages/preview2-shim/lib/io/worker-thread.js
@@ -45,6 +45,7 @@ import {
   SOCKET_RESOLVE_ADDRESS_DISPOSE_REQUEST,
   SOCKET_RESOLVE_ADDRESS_GET_AND_DISPOSE_REQUEST,
   SOCKET_UDP_BIND,
+  SOCKET_UDP_CHECK_SEND,
   SOCKET_UDP_CONNECT,
   SOCKET_UDP_CREATE_HANDLE,
   SOCKET_UDP_DISCONNECT,
@@ -316,6 +317,15 @@ function handle(call, id, payload) {
       });
     }
 
+    case SOCKET_UDP_CHECK_SEND: {
+      const socket = getSocketOrThrow(id);
+      try {
+        return socket.getSendBufferSize() - socket.getSendQueueSize();
+      } catch (err) {
+        return err.errno;
+      }
+    }
+
     case SOCKET_UDP_SEND: {
       let { remoteHost, remotePort, data } = payload;
       const socket = getSocketOrThrow(id);
diff --git a/packages/preview2-shim/lib/nodejs/sockets/udp-socket-impl.js b/packages/preview2-shim/lib/nodejs/sockets/udp-socket-impl.js
index 6c06896a6..6fb6db53d 100644
--- a/packages/preview2-shim/lib/nodejs/sockets/udp-socket-impl.js
+++ b/packages/preview2-shim/lib/nodejs/sockets/udp-socket-impl.js
@@ -10,6 +10,7 @@ import { isIP } from "node:net";
 import { assert } from "../../common/assert.js";
 import {
   SOCKET_UDP_BIND,
+  SOCKET_UDP_CHECK_SEND,
   SOCKET_UDP_CONNECT,
   SOCKET_UDP_CREATE_HANDLE,
   SOCKET_UDP_DISCONNECT,
@@ -129,14 +130,13 @@ export class OutgoingDatagramStream {
   /**
    *
    * @returns {bigint}
-   * @throws {invalid-state} The socket is not bound to any local address. (EINVAL)
    */
   checkSend() {
-    // TODO: implement the actual check
-    // socket.getSendBufferSize() - socket.getSendQueueSize() <= 0 --> throw
-    // attach an event listener to the socket to listen for the drain event
-    // untill the next sent completes
-    return 1024n;
+    const ret = ioCall(SOCKET_UDP_CHECK_SEND, this.#socketId);
+    // TODO: When this function returns ok(0), the `subscribe` pollable will
+    // become ready when this function will report at least ok(1), or an
+    // error.
+    return ret;
   }
 
   /**
@@ -179,8 +179,7 @@ export class OutgoingDatagramStream {
       );
       if (ret === 0) {
         datagramsSent++;
-      }
-      else {
+      } else {
         assert(ret === -65, "remote-unreachable");
       }
     }