unix,win: add uv_udp_try_send2

Add a version of uv_udp_try_send that can send multiple datagrams.

Uses sendmmsg(2) on platforms that support it (Linux, FreeBSD, macOS),
falls back to a regular sendmsg(2) loop elsewhere.

This work was sponsored by ISC, the Internet Systems Consortium.

4 files changed, 58 insertions, 0 deletions

diff --git a/src/unix/udp.c b/src/unix/udp.c
index 045e5fe8..67c01f7d 100644
--- a/src/unix/udp.c
+++ b/src/unix/udp.c
@@ -1401,3 +1401,18 @@ again:
 feed:
   uv__io_feed(handle->loop, &handle->io_watcher);
 }
+
+
+int uv__udp_try_send2(uv_udp_t* handle,
+                      unsigned int count,
+                      uv_buf_t* bufs[/*count*/],
+                      unsigned int nbufs[/*count*/],
+                      struct sockaddr* addrs[/*count*/]) {
+  int fd;
+
+  fd = handle->io_watcher.fd;
+  if (fd == -1)
+    return UV_EINVAL;
+
+  return uv__udp_sendmsgv(fd, count, bufs, nbufs, addrs);
+}
diff --git a/src/uv-common.c b/src/uv-common.c
index 327e142c..60ff56b9 100644
--- a/src/uv-common.c
+++ b/src/uv-common.c
@@ -514,6 +514,25 @@ int uv_udp_try_send(uv_udp_t* handle,
 }
 
 
+int uv_udp_try_send2(uv_udp_t* handle,
+                     unsigned int count,
+                     uv_buf_t* bufs[/*count*/],
+                     unsigned int nbufs[/*count*/],
+                     struct sockaddr* addrs[/*count*/],
+                     unsigned int flags) {
+  if (count < 1)
+    return UV_EINVAL;
+
+  if (flags != 0)
+    return UV_EINVAL;
+
+  if (handle->send_queue_count > 0)
+    return UV_EAGAIN;
+
+  return uv__udp_try_send2(handle, count, bufs, nbufs, addrs);
+}
+
+
 int uv_udp_recv_start(uv_udp_t* handle,
                       uv_alloc_cb alloc_cb,
                       uv_udp_recv_cb recv_cb) {
diff --git a/src/uv-common.h b/src/uv-common.h
index 10df1706..372f0c4b 100644
--- a/src/uv-common.h
+++ b/src/uv-common.h
@@ -191,6 +191,12 @@ int uv__udp_try_send(uv_udp_t* handle,
                      const struct sockaddr* addr,
                      unsigned int addrlen);
 
+int uv__udp_try_send2(uv_udp_t* handle,
+                      unsigned int count,
+                      uv_buf_t* bufs[/*count*/],
+                      unsigned int nbufs[/*count*/],
+                      struct sockaddr* addrs[/*count*/]);
+
 int uv__udp_recv_start(uv_udp_t* handle, uv_alloc_cb alloccb,
                        uv_udp_recv_cb recv_cb);
 
diff --git a/src/win/udp.c b/src/win/udp.c
index 557b4e60..e0873c2a 100644
--- a/src/win/udp.c
+++ b/src/win/udp.c
@@ -1142,3 +1142,21 @@ int uv__udp_try_send(uv_udp_t* handle,
 
   return bytes;
 }
+
+
+int uv__udp_try_send2(uv_udp_t* handle,
+                      unsigned int count,
+                      uv_buf_t* bufs[/*count*/],
+                      unsigned int nbufs[/*count*/],
+                      struct sockaddr* addrs[/*count*/]) {
+  unsigned int i;
+  int r;
+
+  for (i = 0; i < count; i++) {
+    r = uv_udp_try_send(handle, bufs[i], nbufs[i], addrs[i]);
+    if (r < 0)
+      return i > 0 ? i : r;  /* Error if first packet, else send count. */
+  }
+
+  return i;
+}