nidas  v1.2-1520
Public Types | Public Member Functions | Static Public Member Functions | Protected Member Functions | Private Member Functions | Private Attributes | List of all members
nidas::dynld::UDPSampleOutput::ConnectionMonitor Class Reference

Thread that waits for connections to die. More...

Inheritance diagram for nidas::dynld::UDPSampleOutput::ConnectionMonitor:
Inheritance graph
[legend]

Public Types

enum  runStatus { RUN_CANCELED = -1, RUN_OK = 0, NOT_RUNNING = 1, RUN_EXCEPTION = 2 }
 Values that can be returned by run method. More...
 
enum  SchedPolicy { NU_THREAD_OTHER =SCHED_OTHER, NU_THREAD_FIFO =SCHED_FIFO, NU_THREAD_RR =SCHED_RR }
 

Public Member Functions

 ConnectionMonitor (nidas::core::MultipleUDPSockets *msock)
 
 ~ConnectionMonitor ()
 
int run () throw (nidas::util::Exception)
 The method which will run in its own thread. More...
 
void addConnection (nidas::util::Socket *, unsigned short udpport)
 A TCP connection has been made. More...
 
void removeConnection (nidas::util::Socket *, unsigned short udpport)
 
void addDestination (const nidas::core::ConnectionInfo &, unsigned short udpport)
 A UDP request packet has arrived. More...
 
virtual void start () throw (Exception)
 Start the thread running, meaning execute the run method in a separate thread. More...
 
virtual int join () throw (Exception)
 The calling thread joins this thread, waiting until the thread finishes, which means either that the run() method returned, the thread called pthread_exit() or the thread was cancelled. More...
 
virtual void kill (int sig) throw (Exception)
 Send a signal to this thread. More...
 
virtual void cancel () throw (Exception)
 Cancel this thread. More...
 
virtual void interrupt ()
 Interrupt this thread. More...
 
virtual bool isInterrupted () const
 Return true when this thread has been interrupted. More...
 
virtual bool isRunning () const
 Is this thread running? More...
 
virtual bool isJoined () const
 Has this thread been joined? More...
 
virtual bool isDetached () const
 Is this a detached thread. More...
 
bool isCancelEnabled () const
 Return true if the cancel state of this thread is PTHREAD_CANCEL_ENABLE. More...
 
bool isCancelDeferred () const
 Return true if the cancel type of this thread is PTHREAD_CANCEL_DEFERRED. More...
 
const std::string & getName () const throw ()
 Return the name of this thread. More...
 
const std::string & getFullName () throw ()
 Return a name with a bunch of descriptive fields, specifying whether it is detached, the real-time priority, etc. More...
 
bool setRealTimeRoundRobinPriority (int val) throw (Exception)
 
bool setRealTimeFIFOPriority (int val) throw (Exception)
 
bool setNonRealTimePriority () throw (Exception)
 
void setThreadScheduler (enum SchedPolicy policy, int priority) throw (Exception)
 
void blockSignal (int)
 Block a signal in this thread. More...
 
void unblockSignal (int)
 Install a signal handler and unblock the signal. More...
 

Static Public Member Functions

static ThreadcurrentThread ()
 Return the thread object for the current thread. More...
 
static pthread_t currentThreadId ()
 
static ThreadlookupThread (pthread_t id)
 
static const std::string & currentName ()
 Convenience routine to return the name for the current thread, or a string indicating that the name of the thread is unknown. More...
 
static std::string getPolicyString (int policy)
 Convenience function to return a string for the given scheduler policy: "Non-RT", "RT:FIFO", "RT:RR" or "RT:Unknown". More...
 
static int test (int argc, char **argv)
 a test method. More...
 

Protected Member Functions

void setCancelEnabled (bool val)
 Set the cancel state for this thread - false means cancel requests are ignored. More...
 
void setCancelDeferred (bool val)
 Set the cancel type for this thread. More...
 
pthread_t getId () const
 
void testCancel () const
 Check if we have been cancelled. More...
 
virtual bool amInterrupted () const
 Call testCancel, and return true when this thread has been interrupted. More...
 

Private Member Functions

void updatePollfds ()
 
 ConnectionMonitor (const ConnectionMonitor &)
 No copying. More...
 
ConnectionMonitoroperator= (const ConnectionMonitor &)
 No assignment. More...
 

Private Attributes

nidas::core::MultipleUDPSockets_msock
 
std::list< std::pair
< nidas::util::Socket
*, unsigned short > > 
_pendingSockets
 
std::list< std::pair
< nidas::util::Socket
*, unsigned short > > 
_pendingRemoveSockets
 
std::vector< std::pair
< nidas::util::Socket
*, unsigned short > > 
_sockets
 
std::map
< nidas::util::Inet4SocketAddress,
nidas::core::ConnectionInfo
_destinations
 
bool _changed
 
nidas::util::Mutex _sockLock
 
struct pollfd * _fds
 
int _nfds
 

Detailed Description

Thread that waits for connections to die.

Member Enumeration Documentation

Values that can be returned by run method.

User can define other values greater than RUN_EXCEPTION. These values are then returned by int join(). Note that PTHREAD_CANCELLED is -1

Enumerator
RUN_CANCELED 
RUN_OK 
NOT_RUNNING 
RUN_EXCEPTION 
Enumerator
NU_THREAD_OTHER 
NU_THREAD_FIFO 
NU_THREAD_RR 

Constructor & Destructor Documentation

UDPSampleOutput::ConnectionMonitor::ConnectionMonitor ( nidas::core::MultipleUDPSockets msock)
UDPSampleOutput::ConnectionMonitor::~ConnectionMonitor ( )
nidas::dynld::UDPSampleOutput::ConnectionMonitor::ConnectionMonitor ( const ConnectionMonitor )
private

No copying.

Member Function Documentation

void UDPSampleOutput::ConnectionMonitor::addConnection ( nidas::util::Socket sock,
unsigned short  udpport 
)
void UDPSampleOutput::ConnectionMonitor::addDestination ( const nidas::core::ConnectionInfo info,
unsigned short  udpport 
)
bool Runnable::amInterrupted ( ) const
protectedvirtualinherited

Call testCancel, and return true when this thread has been interrupted.

This is protected because it should only called within the run method of the thread.

Referenced by nidas::core::SampleOutputRequestThread::run(), nidas::core::Looper::run(), nidas::dynld::isff::GOESOutput::run(), nidas::core::DSMServerStat::run(), and nidas::util::Thread::test().

void Thread::blockSignal ( int  sig)
inherited
void Thread::cancel ( )
throw (Exception
)
virtualinherited
static const std::string& nidas::util::Thread::currentName ( )
inlinestaticinherited

Convenience routine to return the name for the current thread, or a string indicating that the name of the thread is unknown.

References nidas::util::Thread::currentThread(), nidas::util::Thread::getName(), and nidas::util::Thread::unknownName.

Referenced by nidas::util::Logger::msg_locked().

Thread * Thread::currentThread ( )
staticinherited

Return the thread object for the current thread.

Returns null if not found.

Referenced by nidas::util::Thread::blockSignal(), nidas::util::Thread::currentName(), and nidas::util::Thread::unblockSignal().

pthread_t Thread::currentThreadId ( )
staticinherited
const std::string & Thread::getFullName ( )
throw (
)
inherited

Return a name with a bunch of descriptive fields, specifying whether it is detached, the real-time priority, etc.

References nidas::util::Thread::_fullname.

Referenced by nidas::util::Thread::pRun(), nidas::util::Thread::test(), nidas::util::Thread::thr_cleanup(), and nidas::util::Thread::thr_cleanup_delete().

pthread_t nidas::util::Thread::getId ( ) const
inlineprotectedinherited
const std::string & Thread::getName ( ) const
throw (
)
inherited
string Thread::getPolicyString ( int  policy)
staticinherited

Convenience function to return a string for the given scheduler policy: "Non-RT", "RT:FIFO", "RT:RR" or "RT:Unknown".

References nidas::util::Thread::NU_THREAD_FIFO, nidas::util::Thread::NU_THREAD_OTHER, and nidas::util::Thread::NU_THREAD_RR.

Referenced by nidas::core::DSMSensor::getLooper(), and nidas::util::Thread::makeFullName().

void Thread::interrupt ( )
virtualinherited

Interrupt this thread.

This sets a boolean which can be tested with isInterrupted(). It is up to the run() implementation to return when interrupted. This is a "soft" request to terminate the thread.

What follows is a discussion of when to use cancel(), kill(), or interrupt() to terminate a thread.

If you can consistently check the state of isInterrupted() in the run method, and return if it is true, at a time interval which is an acceptable amount of time to wait for the thread to terminate, then using interrupt() should work well.

If the run method does I/O, then things are usually a bit more complicated.

If all I/O is guaranteed to finish quickly, which is a rare situation, or is done with a timeout, such as using select/poll with a timeout before every read/write, then one could still use interrupt() as above, and the thread will terminate within the timeout period.

If the thread does blocking I/O operations, and the I/O might block for a period of time longer than you're willing to wait for the thread to terminate, then you need to use kill(sig) or cancel().

If a signal is sent to the thread with kill(sig) while the thread is blocking on an I/O operation, the I/O will immediately return with an errno of EINTR, and one could then return from the run method, after any necessary cleanup.

However there is a possibility that the signal could be missed. In order to make sure you receive a signal, you must block it, so that any received signals are held as pending, and then atomically unblock it with pselect/ppoll/epoll_pwait before performing the I/O operation.

If you do not use I/O timeouts, or kill(sig) with pselect/ppoll/epoll_pwait, or other tricks such as writing to a pipe that is watched with select/poll in the run method, then using cancel() is the only way to guarantee that your thread will terminate in an acceptable amount of time.

All NIDAS Threads support deferred cancelation. Immediate asynchronous cancellation is not fully supported (and is very hard to get right). Deferred cancelation means that cancellation is delayed until the thread next calls a system function that is a cancellation point. At that point the thread run method will simply terminate without any return value from the system function, and then execute any cleanup methods that may have been registered with pthread_cleanup_push.

A list of cancellation points is provided in the pthreads(7) man page. Cancellation points are typically I/O operations, waits or sleeps.

This immediate thread termination can be a problem if there is a possibility that your objects could be left in a bad state, such as with a mutex locked, though it isn't generally a good practice to hold mutexes during a time-consuming I/O operation, wait or sleep.

One should check the run method to see if the state of the objects is OK if execution stops at any of the cancellation points. Note that logging a message, or writing to cerr is a cancellation point. Typically there is error/exception handling associated with an I/O operation. Ensuring the state is OK upon a cancellation is similar to preparation for a fatal I/O error that requires a return of the run method. One can use setCancelEnabled() to defer cancellation.

One can use pthread_cleanup_push and pthread_cleanup_pop to register cleanup routines that are called when a thread is cancelled if special handling is required.

Implements nidas::util::Runnable.

Reimplemented in nidas::util::McSocketMulticaster< SocketTT >, nidas::util::ThreadRunnable, nidas::util::McSocketListener, nidas::core::ServerSocket::ConnectionThread, nidas::core::Socket::ConnectionThread, nidas::dynld::RawSampleService::Worker, nidas::dynld::UDPSampleOutput::XMLSocketListener, nidas::core::SensorHandler, nidas::core::SampleSorter, nidas::core::SampleBuffer, nidas::dynld::UDPSampleOutput::VariableListWorker, nidas::dynld::raf::SyncServer, nidas::core::DerivedDataReader, nidas::core::SensorOpener, nidas::dynld::XMLConfigService::Worker, nidas::core::SampleOutputRequestThread, and nidas::core::XmlRpcThread.

References nidas::util::Thread::_interrupted, and nidas::util::Thread::_mutex.

Referenced by nidas::dynld::UDPSampleOutput::close(), nidas::util::McSocket< SocketT >::close(), nidas::core::SampleOutputRequestThread::interrupt(), nidas::core::SensorOpener::interrupt(), nidas::dynld::raf::SyncServer::interrupt(), nidas::core::DSMService::interrupt(), nidas::core::SampleSorter::interrupt(), nidas::core::SamplePipeline::interrupt(), nidas::core::DSMEngine::interrupt(), nidas::util::McSocketListener::interrupt(), nidas::core::SamplePipeline::join(), nidas::core::Looper::removeClient(), and nidas::dynld::UDPSampleOutput::~UDPSampleOutput().

bool Thread::isCancelDeferred ( ) const
inherited

Return true if the cancel type of this thread is PTHREAD_CANCEL_DEFERRED.

References nidas::util::Thread::_cancel_deferred.

bool Thread::isCancelEnabled ( ) const
inherited

Return true if the cancel state of this thread is PTHREAD_CANCEL_ENABLE.

References nidas::util::Thread::_cancel_enabled.

virtual bool nidas::util::Thread::isDetached ( ) const
inlinevirtualinherited

Is this a detached thread.

References nidas::util::Thread::_detached.

virtual bool nidas::util::Thread::isInterrupted ( ) const
inlinevirtualinherited
virtual bool nidas::util::Thread::isJoined ( ) const
inlinevirtualinherited
virtual bool nidas::util::Thread::isRunning ( ) const
inlinevirtualinherited
int Thread::join ( )
throw (Exception
)
virtualinherited

The calling thread joins this thread, waiting until the thread finishes, which means either that the run() method returned, the thread called pthread_exit() or the thread was cancelled.

The return value is the int return value of the run method, or PTHREAD_CANCELED (-1). If the run method threw an Exception, it will be caught and then re-thrown by join.

Reimplemented in nidas::core::SensorHandler.

References nidas::util::Thread::_exception, nidas::util::Thread::_id, nidas::util::Thread::_mutex, nidas::util::Exception::errnoToString(), nidas::util::Thread::getId(), nidas::util::Thread::getName(), nidas::util::Thread::RUN_EXCEPTION, and nidas::util::Thread::RUN_OK.

Referenced by nidas::core::DSMService::checkSubThreads(), nidas::dynld::UDPSampleOutput::XMLSocketListener::checkWorkers(), nidas::dynld::UDPSampleOutput::close(), nidas::util::McSocketListener::close(), nidas::core::DerivedDataReader::deleteInstance(), nidas::dynld::UDPSampleOutput::XMLSocketListener::fireWorkers(), nidas::core::DSMService::join(), nidas::core::SensorHandler::join(), nidas::core::SamplePipeline::join(), nidas::core::DSMEngine::joinDataThreads(), nidas::dynld::isff::GOESOutput::joinThread(), nidas::core::DSMServerApp::killStatusThread(), nidas::core::DSMServerApp::killXmlRpcThread(), nidas::core::DSMEngine::killXmlRpcThread(), main(), nidas::core::Looper::removeClient(), nidas::util::ThreadJoiner::run(), nidas::core::SampleBuffer::~SampleBuffer(), nidas::core::SampleSorter::~SampleSorter(), nidas::core::ServerSocket::~ServerSocket(), and nidas::dynld::UDPSampleOutput::~UDPSampleOutput().

void Thread::kill ( int  sig)
throw (Exception
)
virtualinherited
Thread * Thread::lookupThread ( pthread_t  id)
staticinherited
ConnectionMonitor& nidas::dynld::UDPSampleOutput::ConnectionMonitor::operator= ( const ConnectionMonitor )
private

No assignment.

void UDPSampleOutput::ConnectionMonitor::removeConnection ( nidas::util::Socket sock,
unsigned short  udpport 
)
int UDPSampleOutput::ConnectionMonitor::run ( )
throw (nidas::util::Exception
)
virtual

The method which will run in its own thread.

This method must be supplied by the Runnable or Thread subclass.

Implements nidas::util::Runnable.

References nidas::util::Socket::getRemoteSocketAddress(), ILOG, MSECS_PER_SEC, and nidas::util::SocketAddress::toAddressString().

void Thread::setCancelDeferred ( bool  val)
protectedinherited

Set the cancel type for this thread.

true means cancel requests are deferred until the next cancellation point. false means they occur instantly. This is protected, it should be called only from a thread's own run method. See the pthreads(7) man page for a list of the cancellation points.

Note: non-deferred canceling is difficult to get right. It has not been tested with this class, and is not recommended.

References nidas::util::Thread::_cancel_deferred.

void Thread::setCancelEnabled ( bool  val)
protectedinherited

Set the cancel state for this thread - false means cancel requests are ignored.

See pthread_setcancelstate. This is protected, it should be called only from a thread's own run method.

References nidas::util::Thread::_cancel_enabled.

bool Thread::setNonRealTimePriority ( )
throw (Exception
)
inherited
bool Thread::setRealTimeFIFOPriority ( int  val)
throw (Exception
)
inherited
bool Thread::setRealTimeRoundRobinPriority ( int  val)
throw (Exception
)
inherited
void Thread::setThreadScheduler ( enum SchedPolicy  policy,
int  priority 
)
throw (Exception
)
inherited
void Thread::start ( )
throw (Exception
)
virtualinherited
int Thread::test ( int  argc,
char **  argv 
)
staticinherited
void nidas::util::Runnable::testCancel ( ) const
inlineprotectedinherited

Check if we have been cancelled.

Calls pthread_testcancel. This is protected since it only checks the current thread - i.e. it must be called within the run method. Since it just calls pthread_testcancel, it is a cancellation point.

void Thread::unblockSignal ( int  sig)
inherited

Install a signal handler and unblock the signal.

The signal handler will log a message about the receipt of the signal at severity LOG_INFO using the nidas::util::Logger. Then, if the signal handler is being invoked from a registered Thread, the virtual method signalHandler() for that Thread will be called.

The signal handler is installed with the sigaction() system call, and will be the action for the given signal in all threads, including the main() thread. If other threads do not wish to take action on a given signal, they should call blockSignal(sig). Or they can define their own signalHandler() method.

After installing the signal handler, the signal is added to those that are unblocked for the thread, or if the Thread is not yet running, the signal will be unblocked in the thread once it runs.

As with blockSignal(), this method is typically called on this Thread before it has started. If this Thread has started, then the signal will only be unblocked if the method is called from this Thread, i.e. from its own run() method.

To install a signal handler, and then block the signal so that it is held as pending until it is later unblocked, typically with pselect(), or sigwaitinfo(), do:

void Thread::run()
{
// get the existing signal mask
sigset_t sigmask;
pthread_sigmask(SIG_BLOCK,NULL,&sigmask);
// remove SIGUSR1 from the mask passed to pselect
sigdelset(&sigmask,SIGUSR1);
for (;;) {
pselect(nfd,&readfds,0,0,0,&sigmask);
...
}
}
...
thread.unblockSignal(SIGUSR1);
thread.blockSignal(SIGUSR1);
thread.start();
...
try {
if (thread.isRunning()) {
thread.kill(SIGUSR1);
thread.join()
}
}

References nidas::util::Thread::_blockedSignals, nidas::util::Thread::_unblockedSignals, nidas::util::Thread::currentThread(), nidas::util::Thread::isRunning(), and nidas::util::Thread::thr_add_sig().

Referenced by nidas::core::DerivedDataReader::DerivedDataReader(), nidas::core::FsMountWorkerThread::FsMountWorkerThread(), nidas::core::StatusListener::StatusListener(), nidas::core::StatusThread::StatusThread(), nidas::dynld::XMLConfigService::Worker::Worker(), nidas::core::XmlRpcThread::XmlRpcThread(), and nidas::dynld::UDPSampleOutput::XMLSocketListener::XMLSocketListener().

void UDPSampleOutput::ConnectionMonitor::updatePollfds ( )
private

Member Data Documentation

bool nidas::dynld::UDPSampleOutput::ConnectionMonitor::_changed
private
std::map<nidas::util::Inet4SocketAddress,nidas::core::ConnectionInfo> nidas::dynld::UDPSampleOutput::ConnectionMonitor::_destinations
private
struct pollfd* nidas::dynld::UDPSampleOutput::ConnectionMonitor::_fds
private
nidas::core::MultipleUDPSockets* nidas::dynld::UDPSampleOutput::ConnectionMonitor::_msock
private
int nidas::dynld::UDPSampleOutput::ConnectionMonitor::_nfds
private
std::list<std::pair<nidas::util::Socket*,unsigned short> > nidas::dynld::UDPSampleOutput::ConnectionMonitor::_pendingRemoveSockets
private
std::list<std::pair<nidas::util::Socket*,unsigned short> > nidas::dynld::UDPSampleOutput::ConnectionMonitor::_pendingSockets
private
std::vector<std::pair<nidas::util::Socket*,unsigned short> > nidas::dynld::UDPSampleOutput::ConnectionMonitor::_sockets
private
nidas::util::Mutex nidas::dynld::UDPSampleOutput::ConnectionMonitor::_sockLock
private

The documentation for this class was generated from the following files: