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udp: add UV_UDP_MMSG_FREE recv_cb flag

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Refs: https://github.com/libuv/libuv/issues/2822
PR-URL: https://github.com/libuv/libuv/pull/2836
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Jameson Nash <vtjnash@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
This commit is contained in:
Ryan Liptak 2020-05-06 15:56:57 -07:00 committed by cjihrig
parent fa8b4f27c0
commit ea17e1cffb
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4 changed files with 32 additions and 12 deletions
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12
docs/src/udp.rst
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@ -47,6 +47,12 @@ Data types
* must not be freed by the recv_cb callback. * must not be freed by the recv_cb callback.
*/ */
UV_UDP_MMSG_CHUNK = 8, UV_UDP_MMSG_CHUNK = 8,
/*
* Indicates that the buffer provided has been fully utilized by recvmmsg and
* that it should now be freed by the recv_cb callback. When this flag is set
* in uv_udp_recv_cb, nread will always be 0 and addr will always be NULL.
*/
UV_UDP_MMSG_FREE = 16,
/* /*
* Indicates that recvmmsg should be used, if available. * Indicates that recvmmsg should be used, if available.
*/ */
@ -80,8 +86,10 @@ Data types
When using :man:`recvmmsg(2)`, chunks will have the `UV_UDP_MMSG_CHUNK` flag set, 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, 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 `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 the `UV_UDP_MMSG_CHUNK` flag cleared and the `UV_UDP_MMSG_FREE` flag set.
free the provided buffer. The callee can now safely free the provided buffer.
.. versionchanged:: 1.39.0 added the `UV_UDP_MMSG_FREE` flag.
.. note:: .. note::
The receive callback will be called with `nread` == 0 and `addr` == NULL when there is The receive callback will be called with `nread` == 0 and `addr` == NULL when there is

6
include/uv.h
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@ -614,6 +614,12 @@ enum uv_udp_flags {
* must not be freed by the recv_cb callback. * must not be freed by the recv_cb callback.
*/ */
UV_UDP_MMSG_CHUNK = 8, UV_UDP_MMSG_CHUNK = 8,
/*
* Indicates that the buffer provided has been fully utilized by recvmmsg and
* that it should now be freed by the recv_cb callback. When this flag is set
* in uv_udp_recv_cb, nread will always be 0 and addr will always be NULL.
*/
UV_UDP_MMSG_FREE = 16,
/* /*
* Indicates that recvmmsg should be used, if available. * Indicates that recvmmsg should be used, if available.

2
src/unix/udp.c
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@ -238,7 +238,7 @@ static int uv__udp_recvmmsg(uv_udp_t* handle, uv_buf_t* buf) {
/* one last callback so the original buffer is freed */ /* one last callback so the original buffer is freed */
if (handle->recv_cb != NULL) if (handle->recv_cb != NULL)
handle->recv_cb(handle, 0, buf, NULL, 0); handle->recv_cb(handle, 0, buf, NULL, UV_UDP_MMSG_FREE);
} }
return nread; return nread;
} }

24
test/test-udp-mmsg.c
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@ -74,16 +74,22 @@ static void recv_cb(uv_udp_t* handle,
unsigned flags) { unsigned flags) {
ASSERT_GE(nread, 0); ASSERT_GE(nread, 0);
if (nread > 0) { /* free and return if this is a mmsg free-only callback invocation */
ASSERT_EQ(nread, 4); if (flags & UV_UDP_MMSG_FREE) {
ASSERT(addr != NULL); ASSERT_EQ(nread, 0);
ASSERT_MEM_EQ("PING", rcvbuf->base, nread); ASSERT(addr == NULL);
free(rcvbuf->base);
return;
}
recv_cb_called++; ASSERT_EQ(nread, 4);
if (recv_cb_called == NUM_SENDS) { ASSERT(addr != NULL);
uv_close((uv_handle_t*)handle, close_cb); ASSERT_MEM_EQ("PING", rcvbuf->base, nread);
uv_close((uv_handle_t*)&sender, close_cb);
} recv_cb_called++;
if (recv_cb_called == NUM_SENDS) {
uv_close((uv_handle_t*)handle, close_cb);
uv_close((uv_handle_t*)&sender, close_cb);
} }
/* Don't free if the buffer could be reused via mmsg */ /* Don't free if the buffer could be reused via mmsg */