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| author | Saúl Ibarra Corretgé <s@saghul.net> | 2020-03-12 20:27:35 +0100 |
|---|---|---|
| committer | Saúl Ibarra Corretgé <s@saghul.net> | 2020-03-24 08:27:00 +0100 |
| commit | d9cd7d437d6bcea56355b6e0ef215aa64687d7a1 (patch) | |
| tree | 0feb1889e98936dc94e904b920d56d3b7cea3cb2 /docs/src | |
| parent | 055e89f637fcd767096a3b258243c08fc5c93ddf (diff) | |
| download | libuv-d9cd7d437d6bcea56355b6e0ef215aa64687d7a1.tar.gz libuv-d9cd7d437d6bcea56355b6e0ef215aa64687d7a1.zip | |
udp: return recvmmsg-ed datagrams in order
When recvmmsg support was added it returned the datagrams in reverse
received order, which may impact some applications.
To restore the previous behavior, we call recv_cb one last time with
nread == 0 and addr == NULL so applications can free the buffer.
PR-URL: https://github.com/libuv/libuv/pull/2736
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Diffstat (limited to 'docs/src')
| -rw-r--r-- | docs/src/udp.rst | 17 |
1 files changed, 12 insertions, 5 deletions
diff --git a/docs/src/udp.rst b/docs/src/udp.rst index 2ca0736b..786a28b0 100644 --- a/docs/src/udp.rst +++ b/docs/src/udp.rst @@ -43,8 +43,7 @@ Data types */ UV_UDP_REUSEADDR = 4 /* - * Indicates that the message was received by recvmmsg and that it's not at - * the beginning of the buffer allocated by alloc_cb - so the buffer provided + * Indicates that the message was received by recvmmsg, so the buffer provided * must not be freed by the recv_cb callback. */ UV_UDP_MMSG_CHUNK = 8 @@ -72,9 +71,13 @@ Data types The callee is responsible for freeing the buffer, libuv does not reuse it. The buffer may be a null buffer (where `buf->base` == NULL and `buf->len` == 0) - on error. Don't free the buffer when the UV_UDP_MMSG_CHUNK flag is set. - The final callback receives the whole buffer (containing the first chunk) - with the UV_UDP_MMSG_CHUNK flag cleared. + on error. + + When using :man:`recvmmsg(2)`, chunks will have the `UV_UDP_MMSG_CHUNK` flag set, + those must not be freed. There will be a final callback with `nread` set to 0, + `addr` set to NULL and the buffer pointing at the initially allocated data with + the `UV_UDP_MMSG_CHUNK` flag cleared. This is a good chance for the callee to + free the provided buffer. .. note:: The receive callback will be called with `nread` == 0 and `addr` == NULL when there is @@ -373,6 +376,10 @@ API :returns: 0 on success, or an error code < 0 on failure. + .. versionchanged:: 1.35.0 added support for :man:`recvmmsg(2)` on supported platforms). + The use of this feature requires a buffer larger than + 2 * 64KB to be passed to `alloc_cb`. + .. c:function:: int uv_udp_recv_stop(uv_udp_t* handle) Stop listening for incoming datagrams. |