[nanomsg] Re: When is it safe to use NN_MSG?
- From: stefan@xxxxxxxxx
- To: nanomsg@xxxxxxxxxxxxx
- Date: Wed, 11 Dec 2013 03:54:49 +0100
"Jason E. Aten" <j.e.aten@xxxxxxxxx> schreef:
>sample code using nn_recv with NN_MSG:
>
>https://github.com/glycerine/rust-nanomsg/blob/master/samples/clinano.c
Your suggestion is unrelated to the question...
Stefan
>
>
>
>On Tue, Dec 10, 2013 at 6:27 PM, Stefan de Konink <stefan@xxxxxxxxx>
>wrote:
>
>> I'm currently using a construction where an iov contains a uint32_t
>and a
>> struct. It make sense that I have to manually set iov_len with the
>> appropriate sizes of these objects.
>>
>> When receiving the object back, I should receive a string-like object
>> (instead of the struct). I was expecting I could use a lazy method
>let
>> nanomsg do my allocation like in the test.
>>
>> https://github.com/nanomsg/nanomsg/blob/master/tests/msg.c#L81
>>
>> For some reason I cannot get the following to work, either response
>side
>> remains 0x0 or it plainly hangs.
>>
>> Sender>>
>> void *msg = nn_allocmsg(result_length, 0);
>> strncpy(msg, result_buf, result_length);
>> iov[0].iov_base = &sd;
>> iov[0].iov_len = sizeof(uint32_t);
>> iov[1].iov_base = &msg;
>> iov[1].iov_len = NN_MSG;
>> bzero (&hdr, sizeof (hdr));
>> hdr.msg_iov = iov;
>> hdr.msg_iovlen = 2;
>> nn_sendmsg(sock, &hdr, 0);
>>
>> <<Receiver
>> char *response = NULL;
>> uint32_t sd;
>> struct nn_msghdr hdr;
>> struct nn_iovec iov [2];
>> iov [0]iov_base = &sd;
>> iov [0].iov_len = sizeof(uint32_t);
>> iov [1].iov_base = &response;
>> iov [1].iov_len = NN_MSG;
>> bzero(&hdr, sizeof (hdr));
>> hdr.msg_iov = iov;
>> hdr.msg_iovlen = 2;
>> nn_recvmsg (broker_socket, &hdr, 0);
>>
>>
>> When I change the iov[1] parts on both sides to preallocated buffers,
>with
>> a fixed size, I do get messages around. Could someone give a hint?
>>
>> Stefan
>
>
>!DSPAM:1,52a7d1ab190671589787207!
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