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#include <poll.h>
CrossThreadChannel::CrossThreadChannel (bool non_blocking)
: receive_channel (0)
, receive_source (0)
{
fds[0] = -1;
fds[1] = -1;
if (pipe (fds)) {
error << "cannot create x-thread pipe for read (%2)" << ::strerror (errno) << endmsg;
return;
}
if (non_blocking) {
if (fcntl (fds[0], F_SETFL, O_NONBLOCK)) {
error << "cannot set non-blocking mode for x-thread pipe (read) (" << ::strerror (errno) << ')' << endmsg;
return;
}
if (fcntl (fds[1], F_SETFL, O_NONBLOCK)) {
error << "cannot set non-blocking mode for x-thread pipe (write) (%2)" << ::strerror (errno) << ')' << endmsg;
return;
}
}
receive_channel = g_io_channel_unix_new (fds[0]);
}
CrossThreadChannel::~CrossThreadChannel ()
{
if (receive_source) {
/* this disconnects it from any main context it was attached in
in ::attach(), this prevent its callback from being invoked
after the destructor has finished.
*/
g_source_destroy (receive_source);
}
if (receive_channel) {
g_io_channel_unref (receive_channel);
receive_channel = 0;
}
if (fds[0] >= 0) {
close (fds[0]);
fds[0] = -1;
}
if (fds[1] >= 0) {
close (fds[1]);
fds[1] = -1;
}
}
void
CrossThreadChannel::wakeup ()
{
char c = 0;
(void) ::write (fds[1], &c, 1);
}
void
CrossThreadChannel::drain ()
{
char buf[64];
while (::read (fds[0], buf, sizeof (buf)) > 0) {};
}
int
CrossThreadChannel::deliver (char msg)
{
return ::write (fds[1], &msg, 1);
}
bool
CrossThreadChannel::poll_for_request()
{
struct pollfd pfd[1];
pfd[0].fd = fds[0];
pfd[0].events = POLLIN|POLLERR|POLLHUP;
while(true) {
if (poll (pfd, 1, -1) < 0) {
if (errno == EINTR) {
continue;
}
break;
}
if (pfd[0].revents & ~POLLIN) {
break;
}
if (pfd[0].revents & POLLIN) {
return true;
}
}
return false;
}
int
CrossThreadChannel::receive (char& msg, bool wait)
{
if (wait) {
if (!poll_for_request ()) {
return -1;
}
}
return ::read (fds[0], &msg, 1);
}
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