source: ThirdParty/CodePatterns/src/Observer/Observable.cpp

/*
 * Project: MoleCuilder
 * Description: creates and alters molecular systems
 * Copyright (C)  2010 University of Bonn. All rights reserved.
 * Please see the LICENSE file or "Copyright notice" in builder.cpp for details.
 */

/*
 * Observable.cpp
 *
 *  Created on: Dec 1, 2011
 *      Author: heber
 */

// include config.h
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

//#include "CodePatterns/MemDebug.hpp"

#include "CodePatterns/Observer/Observable.hpp"

#include "CodePatterns/Assert.hpp"
#include "CodePatterns/Observer/Channels.hpp"
#include "CodePatterns/Observer/defs.hpp"
#include "CodePatterns/Observer/Notification.hpp"

#include <algorithm>

#include <boost/thread/locks.hpp>
#include <boost/thread/recursive_mutex.hpp>

//!> This function does nothing with the given Observable
void NoOp_informer(const Observable *)
{}

Observable::graveyard_informer_t Observable::noop_informer(&NoOp_informer);

Observable::ChannelMap Observable::NotificationChannels;

/** Attaching Sub-observables to Observables.
 * Increases entry in Observable::(GlobalObservableInfo::getInstance().getdepth()) for this \a *publisher by one.
 *
 * The two functions \sa start_observer_internal() and \sa finish_observer_internal()
 * have to be used together at all time. Never use these functions directly
 * START_OBSERVER and FINISH_OBSERVER also construct a bogus while(0) loop
 * thus producing compiler-errors whenever only one is used.
 * \param *publisher reference of sub-observable
 */
void Observable::start_observer_internal(Observable *publisher)
{
  boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
  // increase the count for this observable by one
  // if no entry for this observable is found, an new one is created
  // by the STL and initialized to 0 (see STL documentation)
#ifdef LOG_OBSERVER
  observerLog().addMessage((GlobalObservableInfo::getInstance().getdepth())[publisher]) << ">> Locking " << observerLog().getName(publisher);
#endif
  (GlobalObservableInfo::getInstance().getdepth())[publisher]++;
}

/** Detaching Sub-observables from Observables.
 * Decreases entry in Observable::(GlobalObservableInfo::getInstance().getdepth()) for this \a *publisher by one. If zero, we
 * start notifying all our Observers.
 *
 * The two functions start_observer_internal() and finish_observer_internal()
 * have to be used together at all time. Never use these functions directly
 * START_OBSERVER and FINISH_OBSERVER also construct a bogus while(0) loop
 * thus producing compiler-errors whenever only one is used.
 * \param *publisher reference of sub-observable
 */
void Observable::finish_observer_internal(Observable *publisher)
{
  // decrease the count for this observable
  // if zero is reached all observed blocks are done and we can
  // start to notify our observers
  int depth_publisher = 0;
  {
    boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
    --(GlobalObservableInfo::getInstance().getdepth())[publisher];
#ifdef LOG_OBSERVER
    observerLog().addMessage((GlobalObservableInfo::getInstance().getdepth())[publisher]) << "<< Unlocking " << observerLog().getName(publisher);
#endif
    depth_publisher = (GlobalObservableInfo::getInstance().getdepth())[publisher];
  }
  if(depth_publisher){}
  else{
    publisher->notifyAll();
    // this item is done, so we don't have to keep the count with us
    // save some memory by erasing it
    {
      boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
      (GlobalObservableInfo::getInstance().getdepth()).erase(publisher);
    }
  }
}

void Observable::enque_notification_internal(Observable *publisher, Notification_ptr notification)
{
  boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
  (GlobalObservableInfo::getInstance().getnotifications())[publisher].insert(notification);
}

/** Constructor for Observable Protector.
 * Basically, calls start_observer_internal(). Hence use this class instead of
 * calling the function directly.
 *
 * \param *protege Observable to be protected.
 */
Observable::_Observable_protector::_Observable_protector(Observable *_protege) :
  protege(_protege)
{
  start_observer_internal(protege);
}

Observable::_Observable_protector::_Observable_protector(const _Observable_protector &dest) :
    protege(dest.protege)
{
  start_observer_internal(protege);
}

/** Destructor for Observable Protector.
 * Basically, calls finish_observer_internal(). Hence use this class instead of
 * calling the function directly.
 *
 * \param *protege Observable to be protected.
 */
Observable::_Observable_protector::~_Observable_protector()
{
  finish_observer_internal(protege);
}

/************* Notification mechanism for observables **************/

/** Notify all Observers of changes.
 * Puts \a *this into Observable::(GlobalObservableInfo::getInstance().getbusyObservables()), calls Observer::update() for all in callee_t
 * and removes from busy list.
 */
void Observable::notifyAll() {
#ifdef LOG_OBSERVER
  observerLog().addMessage() << "--> " << observerLog().getName(this)
      << " is about to inform all its Observers.";
#endif
  // we are busy notifying others right now
  // add ourselves to the list of busy subjects to enable circle detection
  {
    boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
    (GlobalObservableInfo::getInstance().getbusyObservables()).insert(this);
  }
  // see if anyone has signed up for observation
  // and call all observers
  try {
    bool callTable_contains;
    {
      boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
      GlobalObservableInfo::calltable_t& callTable = GlobalObservableInfo::getInstance().getcallTable();
      callTable_contains = callTable.find(this) != callTable.end();
    }
    if (callTable_contains) {
      GlobalObservableInfo::callees_t callees;
      {
        boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
        GlobalObservableInfo::calltable_t& callTable = GlobalObservableInfo::getInstance().getcallTable();
        callees = callTable[this];
      }
      // elements are stored sorted by keys in the multimap
      // so iterating over it gives us a the callees sorted by
      // the priorities
      // copy such that signOff() within receiving update() does not affect iterating
      // this is because within the same thread and with the updateKilled() signOff() may be
      // called and when executed it modifies targets
      GlobalObservableInfo::callees_t::iterator iter;
      for(iter=callees.begin();iter!=callees.end();++iter){
#ifdef LOG_OBSERVER
        observerLog().addMessage() << "-> Sending update from " << observerLog().getName(this)
                                   << " to " << observerLog().getName((*iter).second)
                                   << " (priority=" << (*iter).first << ")";
#endif
        (*iter).second->update(this);
      }
    }
  }
  ASSERT_NOCATCH("Exception thrown from Observer Update");

  // send out all notifications that need to be done
  {
    GlobalObservableInfo::notificationSet currentNotifications;
    {
      boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
      currentNotifications = (GlobalObservableInfo::getInstance().getnotifications())[this];
    }
    for(GlobalObservableInfo::notificationSet::iterator it = currentNotifications.begin();
        it != currentNotifications.end();++it){
      (*it)->notifyAll(this);
    }
  }

  {
    boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
    (GlobalObservableInfo::getInstance().getnotifications()).erase(this);

     // done with notification, we can leave the set of busy subjects
    (GlobalObservableInfo::getInstance().getbusyObservables()).erase(this);
  }

#ifdef LOG_OBSERVER
  observerLog().addMessage() << "--> " << observerLog().getName(this)
      << " is done informing all its Observers.";
#endif
}


/** Handles passing on updates from sub-Observables.
 * Mimicks basically the Observer::update() function.
 *
 * \param *publisher The \a *this we observe.
 */
void Observable::update(Observable *publisher) {
  // circle detection
  bool presentCircle = false;
  {
    boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
    presentCircle = (GlobalObservableInfo::getInstance().getbusyObservables()).find(this)!=(GlobalObservableInfo::getInstance().getbusyObservables()).end();
  }
  if(presentCircle) {
    // somehow a circle was introduced... we were busy notifying our
    // observers, but still we are called by one of our sub-Observables
    // we cannot be sure observation will still work at this point
    ASSERT(0,"Circle detected in observation-graph.\n"
             "Observation-graph always needs to be a DAG to work correctly!\n"
             "Please check your observation code and fix this!\n");
    return;
  }
  else {
    bool depth_contains;
    {
      boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
      // see if we are in the process of changing ourselves
      // if we are changing ourselves at the same time our sub-observables change
      // we do not need to publish all the changes at each time we are called
      std::map<Observable*, int>& depth = GlobalObservableInfo::getInstance().getdepth();
      depth_contains = depth.find(this)==depth.end();
    }
    if(depth_contains) {
#ifdef LOG_OBSERVER
      observerLog().addMessage() << "-* Update from " << observerLog().getName(publisher)
                                 << " propagated by " << observerLog().getName(this);
#endif
      notifyAll();
    }
    else{
#ifdef LOG_OBSERVER
      observerLog().addMessage() << "-| Update from " <<  observerLog().getName(publisher)
                                 << " not propagated by " << observerLog().getName(this);
#endif
    }
  }
}

/** Sign on an Observer to this Observable.
 * Puts \a *target into Observable::(GlobalObservableInfo::getInstance().getcallTable()) list.
 * \param *target Observer
 * \param priority number in [-20,20]
 */
void Observable::signOn(Observer *target, GlobalObservableInfo::PriorityLevel priority) const
{
#ifdef LOG_OBSERVER
  observerLog().addMessage() << "@@ Signing on " << observerLog().getName(target) << " to " << observerLog().getName(const_cast<Observable *>(this));
#endif
  bool res = false;
  boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
  GlobalObservableInfo::callees_t &callees = (GlobalObservableInfo::getInstance().getcallTable())[const_cast<Observable *>(this)];

  GlobalObservableInfo::callees_t::iterator iter;
  for(iter=callees.begin();iter!=callees.end();++iter){
    res |= ((*iter).second == target);
  }
  if(!res)
    callees.insert(std::pair<int,Observer*>(priority.level,target));
}

/** Sign off an Observer from this Observable.
 * Removes \a *target from Observable::(GlobalObservableInfo::getInstance().getcallTable()) list.
 * \param *target Observer
 */
void Observable::signOff(Observer *target) const
{
  {
    boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
    GlobalObservableInfo::calltable_t &callTable = GlobalObservableInfo::getInstance().getcallTable();
    ASSERT(callTable.count(const_cast<Observable *>(this)),
        "SignOff called for an Observable without Observers.");
#ifdef LOG_OBSERVER
    observerLog().addMessage() << "** Signing off " << observerLog().getName(target) << " from " << observerLog().getName(const_cast<Observable *>(this));
#endif
    GlobalObservableInfo::callees_t &callees = callTable[const_cast<Observable *>(this)];

    GlobalObservableInfo::callees_t::iterator iter;
    GlobalObservableInfo::callees_t::iterator deliter;
    for(iter=callees.begin();iter!=callees.end();) {
      if((*iter).second == target) {
        callees.erase(iter++);
      }
      else {
        ++iter;
      }
    }
    if(callees.empty()){
      callTable.erase(const_cast<Observable *>(this));
    }
  }
  (*graveyard_informer)(this);
}

void Observable::signOn(
    Observer *target,
    size_t channelno,
    GlobalObservableInfo::PriorityLevel priority) const
{
  Notification_ptr notification = getChannel(channelno);
#ifdef LOG_OBSERVER
  observerLog().addMessage() << "@@ Signing on " << observerLog().getName(target)
      << " to " << observerLog().getName(const_cast<Observable *>(this))
      << "'s channel no." << channelno << ".";
#endif
  notification->addObserver(target, priority.level);
}

void Observable::signOff(Observer *target, size_t channelno) const
{
  Notification_ptr notification = getChannel(channelno);
#ifdef LOG_OBSERVER
  observerLog().addMessage() << "** Signing off " << observerLog().getName(target)
      << " from " << observerLog().getName(const_cast<Observable *>(this))
      << "'s channel no." << channelno << ".";
#endif
  notification->removeObserver(target);
  (*graveyard_informer)(this);
}

bool Observable::isBlocked() const
{
  boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
  return (GlobalObservableInfo::getInstance().getdepth()).count(const_cast<Observable *>(this)) > 0;
}

Notification_ptr Observable::getChannel(size_t no) const
{
  return getNotificationChannel(this, no);
}

size_t Observable::getNumberOfObservers() const
{
  boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
  size_t ObserverCount = 0;
  {
    GlobalObservableInfo::calltable_t &callTable = GlobalObservableInfo::getInstance().getcallTable();
    GlobalObservableInfo::calltable_t::const_iterator callees_t_iter =
        callTable.find(const_cast<Observable *>(this));
    // if not present, then we have zero observers
    if (callees_t_iter != callTable.end())
      ObserverCount += callees_t_iter->second.size();
  }
  {
    boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
    const Channels *OurChannels = getNotificationChannels(this);
    if (OurChannels != NULL)
      for (Channels::NotificationTypetoRefMap::const_iterator channeliter = OurChannels->ChannelMap.begin();
          channeliter != OurChannels->ChannelMap.end();
          ++channeliter)
        ObserverCount += (channeliter->second)->getNumberOfObservers();
  }
  return ObserverCount;
}

/** Handles sub-observables that just got killed
 *  when an sub-observerable dies we usually don't need to do anything
 *  \param *publisher Sub-Observable.
 */
void Observable::subjectKilled(Observable *publisher)
{
}

/** Constructor for class Observable.
 */
Observable::Observable(
    std::string name,
    const channels_t &_channels) :
  Observer(Observer::BaseConstructor()),
  graveyard_informer(&noop_informer)
{
#ifdef LOG_OBSERVER
  observerLog().addName(this,name);
  observerLog().addMessage() << "++ Creating Observable "
      << observerLog().getName(static_cast<Observable *>(this));
#endif

  if (!_channels.empty()) {
    Channels *OurChannel = new Channels;
    // add instance for each notification type
    for (channels_t::const_iterator iter = _channels.begin();
        iter != _channels.end(); ++iter)
      OurChannel->addChannel(*iter);
    insertNotificationChannel( std::make_pair(static_cast<Observable *>(this), OurChannel) );
  }
}

/** Destructor for class Observable.
 * When an observable is deleted, we let all our observers know. \sa Observable::subjectKilled().
 */
Observable::~Observable()
{
#ifdef LOG_OBSERVER
  observerLog().addMessage() << "-- Destroying Observable "
      << observerLog().getName(static_cast<Observable *>(this));
#endif
  bool CallTable_contains = false;
  {
    boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
    CallTable_contains = (GlobalObservableInfo::getInstance().getcallTable()).count(this);
  }
  if(CallTable_contains) {
    GlobalObservableInfo::callees_t callees;
    {
      // copy the list from the map
      boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
      // copy such that signOff() within receiving subjectKilled() does not affect iterating
      // this is because within the same thread and with the subjectKilled() signOff() may be
      // called and when executed it modifies targets
      callees = (GlobalObservableInfo::getInstance().getcallTable())[this];
    }
    // delete all entries for this observable
    GlobalObservableInfo::callees_t::iterator iter;
    for(iter=callees.begin();iter!=callees.end();++iter)
      (*iter).second->subjectKilled(this);
    // erase the list in the map
    {
      boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
      (GlobalObservableInfo::getInstance().getcallTable()).erase(this);
    }
  }

  // also kill instance in static Channels map if present
  eraseNotificationChannel(this);
}

Observable::channels_t Observable::getChannelList(const size_t max)
{
  channels_t channels(max);
  std::generate(channels.begin(), channels.end(), UniqueNumber());
  return channels;
}

void Observable::insertNotificationChannel(std::pair<Observable*, Channels *> _pair)
{
  boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
  NotificationChannels.insert(_pair);
}

void Observable::eraseNotificationChannel(Observable * const _target)
{
  boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
  ChannelMap::iterator iter = NotificationChannels.find(static_cast<Observable *>(_target));
  if (iter != NotificationChannels.end()) {
    iter->second->subjectKilled(static_cast<Observable *>(_target));
    delete iter->second;
    NotificationChannels.erase(iter);
  }
}

bool Observable::isNotificationChannelPresent(const Observable * const _target)
{
  boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
  ChannelMap::const_iterator iter =
      NotificationChannels.find(const_cast<Observable * const>(_target));
  return iter != NotificationChannels.end();
}


const Channels* Observable::getNotificationChannels(const Observable * const _target)
{
  boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
  ChannelMap::const_iterator iter =
      NotificationChannels.find(const_cast<Observable * const>(_target));
  if (iter != NotificationChannels.end())
    return iter->second;
  else
    return NULL;
}

Notification_ptr Observable::getNotificationChannel(const Observable * const _target, const size_t _no)
{
  boost::recursive_mutex::scoped_lock lock(GlobalObservableInfo::getInstance().getObservablesMapMutex());
  ChannelMap::const_iterator iter =
      NotificationChannels.find(const_cast<Observable * const>(_target));
  ASSERT(iter != NotificationChannels.end(),
      "Observable::getNotificationChannel() - could not find channel for target "
      +toString(_target)+".");
  return iter->second->getChannel(_no);
}