// Here a basic concept of how to add signal support to the scheduler:
//
-// Every signal to be reported by the scheduler will be asigned a
-// generic signal handler by the scheduler. This signal handler will
-// use longjmp (juck) to report this signal back to the scheduler
-// main-loop.
-//
-// To make this safe, the main-loop will look something like:
-//
-// int signal = setjmp(jmpBuffer_);
-// if (signal == 0) {
-// // unblock all signals which are registered with the
-// // scheduler
-// // call epoll
-// // block all relevant signals again
-// }
-//
-// // now handle the event
-//
-// The signal handler is then simply defined as
-//
-// static void Scheduler::sigHandler(int signal)
-// {
-// // make sure to restore the signal handler here if
-// // necessary
-// longjmp(Scheduler::instance().jmpBuffer_,signal);
-// }
-//
-// You should use sigaction to register the signal handlers and define
-// a sa_mask so all Scheduler-registered signals are automatically
-// *blocked* whenever one of the signals is called (including the
-// called signal!) (This also means, we will have to re-register all
-// signals if we change the registration of some signal since the
-// sa_mask changes). This ensures, that no two signals can be
-// delivered on top of each other. And of course any signal registered
-// with the scheduler must be blocked as soon as it is registered with
-// the scheduler.
+// ... no, I had overlooked one race condition. So back to the signal-pipe approach ...
#include "Scheduler.hh"
//#include "Scheduler.ih"
// Custom includes
#include <errno.h>
#include <sys/epoll.h>
+#include <unistd.h>
+#include <fcntl.h>
#include "../Utils/Exception.hh"
static const int EPollInitialSize = 16;
prefix_ senf::Scheduler::Scheduler()
: timerIdCounter_(0), epollFd_ (epoll_create(EPollInitialSize)), terminate_(false),
- eventTime_(0)
+ eventTime_(0), eventEarly_(ClockService::milliseconds(11)), eventAdjust_(0)
{
if (epollFd_<0)
throw SystemException(errno);
+
+ if (::pipe(sigpipe_) < 0)
+ throw SystemException(errno);
+
+ int flags (::fcntl(sigpipe_[1],F_GETFL));
+ if (flags < 0)
+ throw SystemException(errno);
+ flags |= O_NONBLOCK;
+ if (::fcntl(sigpipe_[1], F_SETFL, flags) < 0)
+ throw SystemException(errno);
+
+ ::epoll_event ev;
+ ::memset(&ev, 0, sizeof(ev));
+ ev.events = EV_READ;
+ ev.data.fd = sigpipe_[0];
+ if (::epoll_ctl(epollFd_, EPOLL_CTL_ADD, sigpipe_[0], &ev) < 0)
+ throw SystemException(errno);
+}
+
+prefix_ void senf::Scheduler::registerSignal(unsigned signal, SimpleCallback const & cb)
+{
+ ::sigset_t sig;
+ ::sigemptyset(&sig);
+ if (::sigaddset(&sig, signal) < 0)
+ throw InvalidSignalNumberException();
+ ::sigprocmask(SIG_BLOCK, &sig, 0);
+ ::sigaddset(&sigset_, signal);
+ if (sigHandlers_.size() <= signal)
+ sigHandlers_.resize(signal+1);
+ sigHandlers_[signal] = cb;
+
+ registerSigHandlers();
}
-prefix_ void senf::Scheduler::do_add(int fd, SimpleCallback const & cb, int eventMask)
+prefix_ void senf::Scheduler::unregisterSignal(unsigned signal)
+{
+ if (::sigdelset(&sigset_, signal) < 0)
+ throw InvalidSignalNumberException();
+ sigHandlers_[signal] = 0;
+ ::signal(signal, SIG_DFL);
+ registerSigHandlers();
+}
+
+prefix_ void senf::Scheduler::do_add(int fd, FdCallback const & cb, int eventMask)
{
FdTable::iterator i (fdTable_.find(fd));
int action (EPOLL_CTL_MOD);
throw SystemException(errno);
}
+prefix_ void senf::Scheduler::registerSigHandlers()
+{
+ for (unsigned signal; signal < sigHandlers_.size(); ++signal)
+ if (sigHandlers_[signal]) {
+ struct ::sigaction sa;
+ sa.sa_sigaction = & Scheduler::sigHandler;
+ sa.sa_mask = sigset_;
+ sa.sa_flags = SA_SIGINFO;
+ if (signal == SIGCHLD)
+ sa.sa_flags |= SA_NOCLDSTOP;
+ if (::sigaction(signal, &sa, 0) < 0)
+ throw SystemException(errno);
+ }
+}
+
+prefix_ void senf::Scheduler::sigHandler(int signal, ::siginfo_t * siginfo, void *)
+{
+ // This is a bit unsafe. Better write single bytes and place the siginfo into an explicit
+ // queue. Since signals are only unblocked during epoll_wait, we even wouldn't need to
+ // synchronize access to that queue any further.
+
+ ::write(instance().sigpipe_[1], siginfo, sizeof(siginfo));
+
+ // We ignore errors. The file handle is set to non-blocking IO. If any failure occurs (pipe
+ // full), the signal will be dropped. That's like kernel signal handling which may also drop
+ // signals.
+}
prefix_ int senf::Scheduler::EventSpec::epollMask()
const
}
else {
ClockService::clock_type delta (
- (timerQueue_.top()->second.timeout - eventTime_)/1000000UL);
+ (timerQueue_.top()->second.timeout - eventTime_ + eventAdjust_)/1000000UL);
timeout = delta < 0 ? 0 : delta;
}
///\todo Handle more than one epoll_event per call
struct epoll_event ev;
- int events = epoll_wait(epollFd_, &ev, 1, timeout);
+
+ ::sigprocmask(SIG_UNBLOCK, &sigset_, 0);
+ int events (epoll_wait(epollFd_, &ev, 1, timeout));
+ ::sigprocmask(SIG_BLOCK, &sigset_, 0);
+
if (events<0)
if (errno != EINTR)
throw SystemException(errno);
eventTime_ = ClockService::now();
- // We always run event handlers. This is important, even if a file-descriptor is signaled
+ // We always run timeout handlers. This is important, even if a file-descriptor is signaled
// since some descriptors (e.g. real files) will *always* be ready and we still may want to
- // handle timers.
- // Time handlers are run before file events to not delay them unnecessarily.
+ // handle timers. Time handlers are run before file events to not delay them unnecessarily.
while (! timerQueue_.empty()) {
TimerMap::iterator i (timerQueue_.top());
if (i->second.canceled)
;
- else if (i->second.timeout <= eventTime_)
+ else if (i->second.timeout <= eventTime_ + eventEarly_)
i->second.cb();
else
break;
- timerMap_.erase(i);
timerQueue_.pop();
+ timerMap_.erase(i);
}
if (events <= 0)
continue;
+ // Check the signal queue
+ if (ev.data.fd == sigpipe_[0]) {
+ ::siginfo_t siginfo;
+ if (::read(sigpipe_[0], &siginfo, sizeof(siginfo)) < int(sizeof(siginfo)))
+ // We ignore truncated records which may only occur if the signal
+ // queue became filled up
+ continue;
+ if (siginfo.si_signo < int(sigHandlers_.size()) && sigHandlers_[siginfo.si_signo])
+ sigHandlers_[siginfo.si_signo]();
+ continue;
+ }
+
FdTable::iterator i = fdTable_.find(ev.data.fd);
BOOST_ASSERT (i != fdTable_.end() );
EventSpec spec (i->second);
}
}
+///////////////////////////////////////////////////////////////////////////
+// senf::SchedulerLogTimeSource
+
+prefix_ boost::posix_time::ptime senf::SchedulerLogTimeSource::operator()()
+ const
+{
+ return ClockService::abstime(Scheduler::instance().eventTime());
+}
+
///////////////////////////////cc.e////////////////////////////////////////
#undef prefix_
projects / senf.git / blobdiff