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// Fraunhofer Institut fuer offene Kommunikationssysteme (FOKUS)
// Kompetenzzentrum fuer Satelitenkommunikation (SatCom)
// Stefan Bund <stefan.bund@fokus.fraunhofer.de>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// 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 General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the
// Free Software Foundation, Inc.,
// 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
/** \file
\brief Scheduler public header
#ifndef HH_Scheduler_
#define HH_Scheduler_ 1
// Custom includes
#include <signal.h>
#include <setjmp.h>
#include <boost/function.hpp>
#include <boost/utility.hpp>
#include <boost/call_traits.hpp>
#include "ClockService.hh"
#include "../Utils/Logger.hh"
//#include "scheduler.mpp"
///////////////////////////////hh.p////////////////////////////////////////
/** \brief SENF Project namespace */
The Scheduler singleton manages the central event loop. It manages and dispatches all types
of events managed by the scheduler library:
\li File descriptor notifications
\li Timeouts
\li UNIX Signals
The scheduler is entered by calling it's process() member. This call will continue to run as
long as there is something to do, or until one of the handlers calls terminate(). The
Scheduler has 'something to do' as long as there is any file descriptor or timeout active.
The Scheduler only provides low level primitive scheduling capability. Additional helpers
are defined on top of this functionality (e.g. ReadHelper or WriteHelper or the interval
timers of the PPI).
\section sched_handlers Specifying handlers
All handlers are passed as generic <a
href="http://www.boost.org/doc/html/function.html">Boost.Function</a> objects. This allows
to pass any callable as a handler. Depending on the type of handler, some additional
arguments may be passed to the handler by the scheduler.
If you need to pass additional information to your handler, use <a
href="http://www.boost.org/libs/bind/bind.html">Boost.Bind</a>:
\code
// Pass 'handle' as additional first argument to callback()
Scheduler::instance().add(handle, boost::bind(&callback, handle, _1))
// Call timeout() handler with argument 'n'
Scheduler::instance().timeout(boost::bind(&timeout, n))
\endcode
To use member-functions as callbacks, use either <a
href="http://www.boost.org/libs/bind/bind.html">Boost.Bind</a> or senf::membind()
\code
// e.g. in Foo::Foo() constructor:
Scheduler::instance().add(handle_, senf::membind(&Foo::callback, this))
\endcode
\section sched_fd Registering file descriptors
File descriptors are managed using add() or remove()
Scheduler::instance().add(handle, &callback);
Scheduler::instance().remove(handle);
The callback will be called with one additional argument. This argument is the event mask of
type EventId. This mask will tell, which of the registered events are signaled. The
additional flags EV_HUP or EV_ERR (on hangup or error condition) may be set additionally.
Only a single handler may be registered for any combination of file descriptor and event
(registering multiple callbacks for a single fd and event does not make sense).
The scheduler will accept any object as \a handle argument as long as retrieve_filehandle()
may be called on that object
\code
int fd = retrieve_filehandle(handle);
\endcode
to fetch the file handle given some abstract handle type. retrieve_filehandle() will be
found using ADL depending on the argument namespace. A default implementation is provided
for \c int arguments (file descriptors)
\section sched_timers Registering timers
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The Scheduler has very simple timer support. There is only one type of timer: A single-shot
deadline timer. More complex timers are built based on this. Timers are managed using
timeout() and cancelTimeout()
\code
int id = Scheduler::instance().timeout(Scheduler::instance().eventTime() + ClockService::milliseconds(100),
&callback);
Scheduler::instance().cancelTimeout(id);
\endcode
Timing is based on the ClockService, which provides a high resolution and strictly
monotonous time source. Registering a timeout will fire the callback when the target time is
reached. The timer may be canceled by passing the returned \a id to cancelTimeout().
There are two parameters which adjust the exact: \a timeoutEarly and \a timeoutAdjust. \a
timeoutEarly is the time, a callback may be called before the deadline time is
reached. Setting this value below the scheduling granularity of the kernel will have the
scheduler go into a <em>busy wait</em> (that is, an endless loop consuming 100% of CPU
recources) until the deadline time is reached! This is seldom desired. The default setting
of 11ms is adequate in most cases (it's slightly above the lowest linux scheduling
granularity).
The other timeout scheduling parameter is \a timeoutAdjust. This value will be added to the
timeout value before calculating the next delay value thereby compensating for \a
timeoutEarly. By default, this value is set to 0 but may be changed if needed.
\section sched_signals Registering POSIX/UNIX signals
The Scheduler also incorporates standard POSIX/UNIX signals. Signals registered with the
scheduler will be handled \e synchronously within the event loop.
\code
Scheduler::instance().registerSignal(SIGUSR1, &callback);
Scheduler::instance().unregisterSignal(SIGUSR1);
\endcode
When registering a signal with the scheduler, that signal will automatically be blocked so
it can be handled within the scheduler.
A registered signal does \e not count as 'something to do'. It is therefore not possible to
wait for signals \e only.
\todo Fix EventId parameter (probably to int) to allow |-ing without casting ...
\todo Fix the file support to use threads (?) fork (?) and a pipe so it works reliably even
over e.g. NFS.
*/
class Scheduler
: boost::noncopyable
{
public:
SENF_LOG_CLASS_AREA();
///////////////////////////////////////////////////////////////////////////
// Types
EV_READ=1, EV_PRIO=2, EV_WRITE=4,
EV_ALL=7,
EV_HUP=8, EV_ERR=16 };
/** \brief Template typedef for Callback type
This is a template typedef (which does not exist in C++) that is, a template class whose
sole member is a typedef symbol defining the callback type given the handle type.
The Callback is any callable object taking a \c Handle and an \c EventId as argument.
\code
template <class Handle>
struct GenericCallback {
typedef boost::function<void (typename boost::call_traits<Handle>::param_type,
EventId) > Callback;
};
\endcode
*/
typedef boost::function<void (EventId)> FdCallback;
/** \brief Callback type for timer events */
typedef boost::function<void ()> SimpleCallback;
///////////////////////////////////////////////////////////////////////////
///\name Structors and default members
///@{
// private default constructor
// no copy constructor
// no copy assignment
// default destructor
// no conversion constructors
/** \brief Return Scheduler instance
This static member is used to access the singleton instance. This member is save to
return a correctly initialized Scheduler instance even if called at global construction
time
\implementation This static member just defines the Scheduler as a static method
variable. The C++ standard then provides above guarantee. The instance will be
initialized the first time, the code flow passes the variable declaration found in
the instance() body.
*/
static Scheduler & instance();
///@}
///////////////////////////////////////////////////////////////////////////
///\name File Descriptors
///\{
template <class Handle>
void add(Handle const & handle, FdCallback const & cb,
int eventMask = EV_ALL); ///< Add file handle event callback
/**< add() will add a callback to the Scheduler. The
callback will be called for the given type of event on
the given arbitrary file-descriptor or
handle-like object. If there already is a Callback
handler will replace the old one.
\param[in] handle file descriptor or handle providing
the Handle interface defined above.
\param[in] cb callback
\param[in] eventMask arbitrary combination via '|'
operator of EventId designators. */
template <class Handle>
void remove(Handle const & handle, int eventMask = EV_ALL); ///< Remove event callback
/**< remove() will remove any callback registered for any of
the given events on the given file descriptor or handle
like object.
\param[in] handle file descriptor or handle providing
the Handle interface defined above.
\param[in] eventMask arbitrary combination via '|'
operator of EventId designators. */
///\}
///\name Timeouts
///\{
unsigned timeout(ClockService::clock_type timeout, SimpleCallback const & cb);
///< Add timeout event
\param[in] cb callback to call after \a timeout
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void cancelTimeout(unsigned id); ///< Cancel timeout \a id
ClockService::clock_type timeoutEarly() const;
///< Fetch the \a timeoutEarly parameter
void timeoutEarly(ClockService::clock_type v);
///< Set the \a timeoutEarly parameter
ClockService::clock_type timeoutAdjust() const;\
///< Fetch the \a timeoutAdjust parameter
void timeoutAdjust(ClockService::clock_type v);
///< Set the \a timeoutAdjust parameter
///\}
///\name Signal handlers
///\{
void registerSignal(unsigned signal, SimpleCallback const & cb);
///< Add signal handler
/**< \param[in] signal signal number to register handler for
\param[in] cb callback to call whenever \a signal is
delivered. */
void unregisterSignal(unsigned signal);
///< Remove signal handler for \a signal
/// The signal number passed to registerSignal or unregisterSignal is invalid
struct InvalidSignalNumberException : public std::exception
{ virtual char const * what() const throw()
{ return "senf::Scheduler::InvalidSignalNumberException"; } };
///\}
void process(); ///< Event handler main loop
/**< This member must be called at some time to enter the
event handler main loop. Only while this function is
running any events are handled. The call will return
only, if any callback calls terminate(). */
void terminate(); ///< Called by callbacks to terminate the main loop
/**< This member may be called by any callback to tell the
main loop to terminate. The main loop will return to
it's caller after the currently running callback
returns. */
ClockService::clock_type eventTime() const; ///< Return date/time of last event
void do_add(int fd, FdCallback const & cb, int eventMask = EV_ALL);
void registerSigHandlers();
static void sigHandler(int signal, ::siginfo_t * siginfo, void *);
# ifndef DOXYGEN
/** \brief Descriptor event specification
\internal */
struct EventSpec
FdCallback cb_read;
FdCallback cb_prio;
FdCallback cb_write;
EventSpec() : file(false) {}
bool file;
/** \brief Timer event specification
\internal */
struct TimerSpec
{
TimerSpec() : timeout(), cb() {}
TimerSpec(ClockService::clock_type timeout_, SimpleCallback cb_, unsigned id_)
: timeout(timeout_), cb(cb_), id(id_), canceled(false) {}
bool operator< (TimerSpec const & other) const
{ return timeout > other.timeout; }
ClockService::clock_type timeout;
unsigned id;
bool canceled;
typedef std::map<unsigned,TimerSpec> TimerMap; // sorted by id
typedef std::vector<unsigned> FdEraseList;
struct TimerSpecCompare
{
typedef TimerMap::iterator first_argument_type;
typedef TimerMap::iterator second_argument_type;
typedef bool result_type;
result_type operator()(first_argument_type a, second_argument_type b);
};
typedef std::priority_queue<TimerMap::iterator, std::vector<TimerMap::iterator>,
TimerSpecCompare> TimerQueue; // sorted by time
typedef std::vector<SimpleCallback> SigHandlers;
FdEraseList fdErase_;
unsigned files_;
SigHandlers sigHandlers_;
::sigset_t sigset_;
int sigpipe_[2];
ClockService::clock_type eventEarly_;
ClockService::clock_type eventAdjust_;
/** \brief Default file descriptor accessor
retrieve_filehandle() provides the Scheduler with support for explicit file descriptors as
file handle argument.
\relates Scheduler
int retrieve_filehandle(int fd);
/** \brief Scheduler specific time source for Utils/Logger framework
This time source may be used to provide timing information for log messages within the
Utils/Logger framework. This time source will use Scheduler::eventTime() to provide timing
information.
*/
struct SchedulerLogTimeSource : public senf::log::TimeSource
{
boost::posix_time::ptime operator()() const;
};
///////////////////////////////hh.e////////////////////////////////////////
#include "Scheduler.cti"
#endif
// Local Variables:
// mode: c++
// c-file-style: "senf"
// indent-tabs-mode: nil
// ispell-local-dictionary: "american"
// compile-command: "scons -u test"