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/*
Aseba - an event-based framework for distributed robot control
Copyright (C) 2007--2016:
Stephane Magnenat <stephane at magnenat dot net>
(http://stephane.magnenat.net)
and other contributors, see authors.txt for details
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation, version 3 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "../utils/utils.h"
#include "../utils/FormatableString.h"
#include <dashel/dashel.h>
#include "zeroconf-thread.h"
#include "dns_sd.h"
#ifdef WIN32
#include <winsock2.h>
#endif
using namespace std;
namespace Aseba
{
using namespace Dashel;
//! Destructor, need to terminate the thread, clear all targets, and deallocate remaining service references
ThreadZeroconf::~ThreadZeroconf()
{
running = false;
threadWait.notify_one();
watcher.join(); // tell watcher to stop
// clear all targets
targets.clear();
// deallocate remaining service references
for (auto serviceRef: serviceRefs)
DNSServiceRefDeallocate(serviceRef);
for (auto serviceRef: pendingReleaseServiceRefs)
DNSServiceRefDeallocate(serviceRef);
}
//! Wait for the watcher thread to complete, rethrowing exceptions
void ThreadZeroconf::run()
{
watcher.join();
if (watcherException)
std::rethrow_exception(watcherException);
}
//! With the lock held, insert the provided service reference to serviceRefs
void ThreadZeroconf::processServiceRef(DNSServiceRef serviceRef)
{
assert(serviceRef);
{
std::lock_guard<std::recursive_mutex> locker(watcherLock);
serviceRefs.insert(serviceRef);
}
threadWait.notify_one();
}
//! With the lock held, move the provided service reference from serviceRefs to
//! pendingReleaseServiceRefs, so that it will be released after the current call to select has completed.
void ThreadZeroconf::releaseServiceRef(DNSServiceRef serviceRef)
{
if (!serviceRef)
return;
std::lock_guard<std::recursive_mutex> locker(watcherLock);
serviceRefs.erase(serviceRef);
pendingReleaseServiceRefs.insert(serviceRef);
}
//! When serviceRefs is not empty, for each service reference collect their associated
//! file descriptor and wait on them for activity using select.
void ThreadZeroconf::handleDnsServiceEvents()
{
struct timeval tv{1,0}; //!< maximum time to learn about a new service (1 sec)
while (true)
{
{// lock
std::unique_lock<std::recursive_mutex> locker(watcherLock);
// we use a condition variable to avoid infinite loops here
threadWait.wait(locker, [&] { return !serviceRefs.empty() || !running; });
}// unlock
if (!running)
break;
fd_set fds;
int max_fds(0);
FD_ZERO(&fds);
std::map<DNSServiceRef,int> serviceFd;
int fd_count(0);
{// lock
std::lock_guard<std::recursive_mutex> locker(watcherLock);
for (auto serviceRef: serviceRefs)
{
int fd = DNSServiceRefSockFD(serviceRef);
if (fd != -1)
{
max_fds = max_fds > fd ? max_fds : fd;
FD_SET(fd, &fds);
serviceFd[serviceRef] = fd;
fd_count++;
}
}
}// unlock
int result = select(max_fds+1, &fds, (fd_set*)nullptr, (fd_set*)nullptr, &tv);
try {
if (result >= 0)
{
// lock
std::lock_guard<std::recursive_mutex> locker(watcherLock);
// release old service refs
for (auto serviceRef: pendingReleaseServiceRefs)
DNSServiceRefDeallocate(serviceRef);
pendingReleaseServiceRefs.clear();
// check for activity
if (result > 0)
{
// no timeout
for (auto serviceRef: serviceRefs)
{
auto fdIt(serviceFd.find(serviceRef));
if (fdIt != serviceFd.end())
{
if (FD_ISSET(fdIt->second, &fds))
DNSServiceProcessResult(serviceRef);
}
}
}
else
; // timeout
// unlock
}
else
throw Zeroconf::Error(FormatableString("handleDnsServiceEvents: select returned %0 errno %1").arg(result).arg(errno));
}
catch (...) {
watcherException = std::current_exception();
break;
}
}
}
} // namespace Aseba
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