Hello Everyone,
I only have a few days experience with libuv, but done a lot of reading of
uv.h, the libuv-dox, and other resources, and I've gotten both a udp client
and udp echo server running with just libuv. I understand all the memory
management is on the user, which is an area I'm pretty green in. I'm using
the current version of the master branch.
Both programs are fairly simple: the client opens a socket for sending and
recieving, and while loops calls to uv_udp_send hundreds of char * packets
("packet 1," "packet 2," etc.), individually malloc'd, to the server. The
server opens a socket for receiving, has a receive callback that prints the
message, copies that into a newly allocated buffer, sends it back to the
same addr it got it from, and frees() the received buf->base. The client
receives the echoed message, prints it, and frees the received buffer. So
far that's the strategy I've seen in all the examples.
In both cases, that leaves the send buffers to be freed. I realized I
couldn't free them immediately after calling uv_udp_send, since that just
points to the buffer and doesn't send it right away. So I went to free it
in the send callback, but unlike the receive and read cbs, you can't just
free(buf->base). I tried free(req->bufs[0].base) similar to the write
examples, but it appears to have already been freed and set to null in
uv__udp_run_completed, before the callback is called. So that segfaults,
but free(req->bufsml[0].base) works and gives no valgrind errors or leaks.
I tried iterating over all non-null array entries in bufsml [ int i=0;
while (req->bufsml[i].base) free(req->bufsml[i].base); ++i; ] but that
gives me one valgrind error per packet ("Conditional jump or move depends
on uninitialised value(s)").
Am I doing this right?
I haven't been able to find any samples or examples of udp echo servers
using libuv that even free memory in the send_cb other than free(req), but
as far as I can tell, they all have memory leaks. The tcp server example in
libuv-dox uses free(wr->buf.base) in its write_cb, but valgrind reports it
has a huge memory leak (maybe it didn't 8 or 9 months ago with the version
it was made for, but it does now). I don't know what the difference between
bufs and bufsml is, and don't know if I should be concerned that I can't
seem to check all members of the bufsml array to see if I should free them,
only blindly free the first. It seems like this is harder than it should be.
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