Re: [Vala] disable free at block end



Le jeudi 10 mars 2016 à 23:34 +0530, MohanR a écrit :
Hi,

May be a i'm wrong, but here is my issue,

namespace test {
      struct Remote {
              uint16 id;
              uint32 ip;
      }
      class SocketReader: Object {
              Socket socket;
              Array<Remote*> remotes;
              public SocketReader(Socket socket) {
                      this.socket = socket;
                      this.remotes = new Array<Remote*>();
              }
              public read() {
                      int8[] buffer = new int8[sizeof(Remote)];
                      while(socket.receive(buffer,
                              sizeof(Remote)) > 0) {
                              Remote* remote = Memory.dup(buffer,
                              sizeof(Remote));
                              this.remotes.append_val(remote);
                      }
              }
      }
}

when read() goes out-of-scope, "buffer" gets freed, So I have to  
 make a dup of that memory to store it in "remotes" array. But If I
have some way to tell vala not to free buffer, I dont need to dup the
buffer.

Am I doing this right? or any better way? All I need is to get the
data
coming from the socket and use it as "Remote" struct. Need your
suggestions.

Thanks,
Mohan R

You should read directly in the memory allocated for the 'Remote'
struct instead of using a temporary buffer. I think it's correct to
cast it to uint8[].

socket.receive ((uint8[]) remote);
remotes.append_val (remote);

However, your code is likely incorrect, because 'Socket.receive' states
that it will read up to 'buffer.length', so you may end with a partial
read.

You need to loop with an offset, something like:

    size_t offset = 0;
    while (offset < sizeof (Remote)
        offset += socket.receive ((uint8[] remote) [offset:sizeof
(Remote) - offset]);

Unless you are doing something very specific, use SocketService, it has
a much simpler interface:

http://valadoc.org/#!api=gio-2.0/GLib.SocketService

The SocketConnection is an IOStream, so you have access to
input_stream.read_all, which will perform a complete read for the
requested buffer size.

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