//find a match in the already received fifo
other_action = SIMIX_fifo_get_comm(rdv->done_comm_fifo, SIMIX_COMM_SEND, match_fun, data, this_action);
//if not found, assume the receiver came first, register it to the mailbox in the classical way
if (!other_action) {
//find a match in the already received fifo
other_action = SIMIX_fifo_get_comm(rdv->done_comm_fifo, SIMIX_COMM_SEND, match_fun, data, this_action);
//if not found, assume the receiver came first, register it to the mailbox in the classical way
if (!other_action) {