peerplays-fc/src/thread/thread_d.hpp

#include <fc/thread/thread.hpp>
#include <fc/string.hpp>
#include <fc/time.hpp>
#include <boost/thread.hpp>
#include "context.hpp"
#include <boost/thread/condition_variable.hpp>
#include <boost/thread.hpp>
#include <boost/atomic.hpp>
#include <vector>
//#include <fc/logger.hpp>

namespace fc {
    struct sleep_priority_less {
        bool operator()( const context::ptr& a, const context::ptr& b ) {
            return a->resume_time > b->resume_time;
        }
    };
    class thread_d {

        public:
           thread_d(fc::thread& s)
            :self(s), boost_thread(0),
             task_in_queue(0),
             done(false),
             current(0),
             pt_head(0),
             ready_head(0),
             ready_tail(0),
             blocked(0),
             next_unused_task_storage_slot(0)
#ifndef NDEBUG
             ,non_preemptable_scope_count(0)
#endif
            { 
              static boost::atomic<int> cnt(0);
              name = fc::string("th_") + char('a'+cnt++); 
//              printf("thread=%p\n",this);
            }
            ~thread_d(){
              delete current;
              fc::context* temp;
              while (ready_head)
              {
                temp = ready_head->next;
                delete ready_head;
                ready_head = temp;
              }
              while (blocked)
              {
                temp = blocked->next;
                delete blocked;
                blocked = temp;
              }
              /*
              while (pt_head)
              {
                temp = pt_head->next;
                delete pt_head;
                pt_head = temp;
              }
              */
              //ilog("");
             if (boost_thread)
             {
               boost_thread->detach();
               delete boost_thread;
             }
            }
           fc::thread&             self;
           boost::thread* boost_thread;
           stack_allocator                  stack_alloc;
           boost::condition_variable        task_ready;
           boost::mutex                     task_ready_mutex;

           boost::atomic<task_base*>       task_in_queue;
           std::vector<task_base*>         task_pqueue;    // heap of tasks that have never started, ordered by proirity & scheduling time
           std::vector<task_base*>         task_sch_queue; // heap of tasks that have never started but are scheduled for a time in the future, ordered by the time they should be run
           std::vector<fc::context*>       sleep_pqueue;   // heap of running tasks that have sleeped, ordered by the time they should resume
           std::vector<fc::context*>       free_list;      // list of unused contexts that are ready for deletion

           bool                     done;
           fc::string               name;
           fc::context*             current;     // the currently-executing task in this thread

           fc::context*             pt_head;     // list of contexts that can be reused for new tasks

           fc::context*             ready_head;  // linked list (using 'next') of contexts that are ready to run
           fc::context*             ready_tail;

           fc::context*             blocked;     // linked list of contexts (using 'next_blocked') blocked on promises via wait()

           // values for thread specific data objects for this thread
           std::vector<detail::specific_data_info> thread_specific_data;
           // values for task_specific data for code executing on a thread that's
           // not a task launched by async (usually the default task on the main 
           // thread in a process)
           std::vector<detail::specific_data_info> non_task_specific_data;
           unsigned next_unused_task_storage_slot;

#ifndef NDEBUG
           unsigned                 non_preemptable_scope_count;
#endif

#if 0
           void debug( const fc::string& s ) {
          return;
              //boost::unique_lock<boost::mutex> lock(log_mutex());

              fc::cerr<<"--------------------- "<<s.c_str()<<" - "<<current;
              if( current && current->cur_task ) fc::cerr<<'('<<current->cur_task->get_desc()<<')';
              fc::cerr<<" ---------------------------\n";
              fc::cerr<<"  Ready\n";
              fc::context* c = ready_head;
              while( c ) {
                fc::cerr<<"    "<<c;
                if( c->cur_task ) fc::cerr<<'('<<c->cur_task->get_desc()<<')'; 
                fc::context* p = c->caller_context;
                while( p ) {
                  fc::cerr<<"  ->  "<<p;
                  p = p->caller_context;
                }
                fc::cerr<<"\n";
                c = c->next;
              }
              fc::cerr<<"  Blocked\n";
              c = blocked;
              while( c ) {
                fc::cerr<<"   ctx: "<< c; 
                if( c->cur_task ) fc::cerr<<'('<<c->cur_task->get_desc()<<')'; 
                fc::cerr << " blocked on prom: ";
                for( uint32_t i = 0; i < c->blocking_prom.size(); ++i ) {
                  fc::cerr<<c->blocking_prom[i].prom<<'('<<c->blocking_prom[i].prom->get_desc()<<')';
                  if( i + 1 < c->blocking_prom.size() ) { 
                    fc::cerr<<",";
                  }
                }

                fc::context* p = c->caller_context;
                while( p ) {
                  fc::cerr<<"  ->  "<<p;
                  p = p->caller_context;
                }
                fc::cerr<<"\n";
                c = c->next_blocked;
              }
              fc::cerr<<"-------------------------------------------------\n";
           }
#endif
            // insert at from of blocked linked list
           inline void add_to_blocked( fc::context* c ) {
              c->next_blocked = blocked;
              blocked = c;
           }

           void pt_push_back(fc::context* c) {
              c->next = pt_head;
              pt_head = c;
              /* 
              fc::context* n = pt_head;
              int i = 0;
              while( n ) {
                ++i;
                n = n->next;
              }
              wlog( "idle context...%2%  %1%", c, i );
              */
           }
           fc::context::ptr ready_pop_front() {
                fc::context::ptr tmp = nullptr;
                if( ready_head ) {
                    tmp        = ready_head;
                    ready_head = tmp->next;
                    if( !ready_head )   
                        ready_tail = nullptr;
                    tmp->next = nullptr;
                }
                return tmp;
           }
           void ready_push_front( const fc::context::ptr& c ) {
                BOOST_ASSERT( c->next == nullptr );
                BOOST_ASSERT( c != current );
            //if( c == current ) wlog( "pushing current to ready??" );
                c->next = ready_head;
                ready_head = c;
                if( !ready_tail ) 
                    ready_tail = c;
           }
           void ready_push_back( const fc::context::ptr& c ) {
                BOOST_ASSERT( c->next == nullptr );
                BOOST_ASSERT( c != current );
            //if( c == current ) wlog( "pushing current to ready??" );
                c->next = 0;
                if( ready_tail ) { 
                    ready_tail->next = c;
                } else {
            assert( !ready_head );
                    ready_head = c;
                }
                ready_tail = c;
           }
           struct task_priority_less {
               bool operator()( task_base* a, task_base* b ) {
                   return a->_prio.value < b->_prio.value ? true :  (a->_prio.value > b->_prio.value ? false : a->_posted_num > b->_posted_num );
               }
           };
           struct task_when_less {
                bool operator()( task_base* a, task_base* b ) {
                    return a->_when > b->_when;
                }
           };

           void enqueue( task_base* t ) {
                time_point now = time_point::now();
                task_base* cur = t;
                while( cur ) {
                  if( cur->_when > now ) {
                    task_sch_queue.push_back(cur);
                    std::push_heap( task_sch_queue.begin(),
                                    task_sch_queue.end(), task_when_less()   );
                  } else {
                    task_pqueue.push_back(cur);
                    BOOST_ASSERT( this == thread::current().my );
                    std::push_heap( task_pqueue.begin(),
                                    task_pqueue.end(), task_priority_less()   );
                  }
                    cur = cur->_next;
                }
           }
           task_base* dequeue() {
                // get a new task
                BOOST_ASSERT( this == thread::current().my );
                
                task_base* pending = 0; 
                //DLN: changed from memory_order_consume for boost 1.55.
                //This appears to be safest replacement for now, maybe
                //can be changed to relaxed later, but needs analysis.
                pending = task_in_queue.exchange(0,boost::memory_order_seq_cst);
                if( pending ) { enqueue( pending ); }

                task_base* p(0);
                if( task_sch_queue.size() ) {
                    if( task_sch_queue.front()->_when <= time_point::now() ) {
                        p = task_sch_queue.front();
                        std::pop_heap(task_sch_queue.begin(), task_sch_queue.end(), task_when_less() );
                        task_sch_queue.pop_back();
                        return p;
                    }
                }
                if( task_pqueue.size() ) {
                    p = task_pqueue.front();
                    std::pop_heap(task_pqueue.begin(), task_pqueue.end(), task_priority_less() );
                    task_pqueue.pop_back();
                }
                return p;
           }

           bool process_canceled_tasks()
           {
              bool canceled_task = false;
              for( auto task_itr = task_sch_queue.begin();
                   task_itr != task_sch_queue.end();
                   )
              {
                 if( (*task_itr)->canceled() )
                 {
                    (*task_itr)->run();
                    (*task_itr)->release();
                    task_itr = task_sch_queue.erase(task_itr);
                    canceled_task = true;
                    continue;
                 }
                 ++task_itr;
              }

              if( canceled_task )  
                 std::make_heap( task_sch_queue.begin(), task_sch_queue.end(), task_when_less() );

              return canceled_task;
           }
           
           /**
            * This should be before or after a context switch to
            * detect quit/cancel operations and throw an exception.
            */
           void check_fiber_exceptions() {
              if( current && current->canceled ) {
#ifdef NDEBUG
                FC_THROW_EXCEPTION( canceled_exception, "" );
#else
                FC_THROW_EXCEPTION( canceled_exception, "cancellation reason: ${reason}", ("reason", current->cancellation_reason ? current->cancellation_reason : "[none given]"));
#endif
              } else if( done )  {
                ilog( "throwing canceled exception" );
                FC_THROW_EXCEPTION( canceled_exception, "cancellation reason: thread quitting" ); 
             //   BOOST_THROW_EXCEPTION( thread_quit() );
              }
           }
           
           /**
            *   Find the next available context and switch to it.
            *   If none are available then create a new context and
            *   have it wait for something to do.
            */
           bool start_next_fiber( bool reschedule = false ) {
              assert(non_preemptable_scope_count == 0);
              check_for_timeouts();
              if( !current ) current = new fc::context( &fc::thread::current() );

              // check to see if any other contexts are ready
              if( ready_head ) { 
                fc::context* next = ready_pop_front();
                if( next == current ) {
                  // elog( "next == current... something went wrong" );
                  assert(next != current);
                   return false;
                }
                BOOST_ASSERT( next != current ); 

                // jump to next context, saving current context
                fc::context* prev = current;
                current = next;
                if( reschedule ) ready_push_back(prev);
          //         slog( "jump to %p from %p", next, prev );
          //          fc_dlog( logger::get("fc_context"), "from ${from} to ${to}", ( "from", int64_t(prev) )( "to", int64_t(next) ) ); 
#if BOOST_VERSION >= 105600
                   bc::jump_fcontext( &prev->my_context, next->my_context, 0 );
#elif BOOST_VERSION >= 105300
                   bc::jump_fcontext( prev->my_context, next->my_context, 0 );
#else
                   bc::jump_fcontext( &prev->my_context, &next->my_context, 0 );
#endif
                   BOOST_ASSERT( current );
                   BOOST_ASSERT( current == prev );
                //current = prev;
              } else { // all contexts are blocked, create a new context 
                       // that will process posted tasks...
                fc::context* prev = current;

                fc::context* next = nullptr;
                if( pt_head ) { // grab cached context
                  next = pt_head;
                  pt_head = pt_head->next;
                  next->next = 0;
                  next->reinitialize();
                } else { // create new context.
                  next = new fc::context( &thread_d::start_process_tasks, stack_alloc,
                                                                      &fc::thread::current() );
                }

                current = next;
                if( reschedule )  ready_push_back(prev);

         //       slog( "jump to %p from %p", next, prev );
        //        fc_dlog( logger::get("fc_context"), "from ${from} to ${to}", ( "from", int64_t(prev) )( "to", int64_t(next) ) );
#if BOOST_VERSION >= 105600
                bc::jump_fcontext( &prev->my_context, next->my_context, (intptr_t)this );
#elif BOOST_VERSION >= 105300
                bc::jump_fcontext( prev->my_context, next->my_context, (intptr_t)this );
#else
                bc::jump_fcontext( &prev->my_context, &next->my_context, (intptr_t)this );
#endif
                BOOST_ASSERT( current );
                BOOST_ASSERT( current == prev );
                //current = prev;
              }

              if( current->canceled ) {
                //current->canceled = false;
#ifdef NDEBUG
                FC_THROW_EXCEPTION( canceled_exception, "" );
#else
                FC_THROW_EXCEPTION( canceled_exception, "cancellation reason: ${reason}", ("reason", current->cancellation_reason ? current->cancellation_reason : "[none given]"));
#endif
              }

              return true;
           }

           static void start_process_tasks( intptr_t my ) {
              thread_d* self = (thread_d*)my;
              try {
                self->process_tasks();
              } catch ( canceled_exception& ) {
                 // allowed exception...
              } catch ( ... ) {
                 elog( "fiber ${name} exited with uncaught exception: ${e}", ("e",fc::except_str())("name", self->name) );
     //            assert( !"fiber exited with uncaught exception" );
     //TODO replace errror           fc::cerr<<"fiber exited with uncaught exception:\n "<< 
     //                 boost::current_exception_diagnostic_information() <<std::endl;
              }
              self->free_list.push_back(self->current);
              self->start_next_fiber( false );
           }

           bool run_next_task() {
                check_for_timeouts();
                task_base* next = dequeue();

                if( next ) {
                    next->_set_active_context( current );
                    current->cur_task = next;
                    next->run();
                    current->cur_task = 0;
                    next->_set_active_context(0);
                    next->release();
                    current->reinitialize();
                    return true;
                }
                return false;
           }
           bool has_next_task() {
             if( task_pqueue.size() ||
                 (task_sch_queue.size() && task_sch_queue.front()->_when <= time_point::now()) ||
                 task_in_queue.load( boost::memory_order_relaxed ) )
                  return true;
             return false;
           }
           void clear_free_list() {
              for( uint32_t i = 0; i < free_list.size(); ++i ) {
                delete free_list[i];
              }
              free_list.clear();
           }
           void process_tasks() {
              while( !done || blocked ) {
                if( run_next_task() ) continue;

                // if I have something else to do other than
                // process tasks... do it.
                if( ready_head ) { 
                   pt_push_back( current ); 
                   start_next_fiber(false);  
                   continue;
                }

                if( process_canceled_tasks() ) continue;

                clear_free_list();

                { // lock scope
                  boost::unique_lock<boost::mutex> lock(task_ready_mutex);
                  if( has_next_task() ) continue;
                  time_point timeout_time = check_for_timeouts();
                  
                  if( done ) return;
                  if( timeout_time == time_point::maximum() ) {
                    task_ready.wait( lock );
                  } else if( timeout_time != time_point::min() ) {
                     // there may be tasks that have been canceled we should filter them out now
                     // rather than waiting... 


                    /* This bit is kind of sloppy -- this wait was originally implemented as a wait
                     * with respect to boost::chrono::system_clock.  This behaved rather comically
                     * if you were to do a:
                     *   fc::usleep(fc::seconds(60));
                     * and then set your system's clock back a month, it would sleep for a month
                     * plus a minute before waking back up (this happened on Linux, it seems 
                     * Windows' behavior in this case was less unexpected).
                     *
                     * Boost Chrono's steady_clock will always increase monotonically so it will 
                     * avoid this behavior.
                     *
                     * Right now we don't really have a way to distinguish when a timeout_time is coming
                     * from a function that takes a relative time like fc::usleep() vs something
                     * that takes an absolute time like fc::promise::wait_until(), so we can't always
                     * do the right thing here.
                     */ 
                    task_ready.wait_until( lock, boost::chrono::steady_clock::now() + 
                                                 boost::chrono::microseconds(timeout_time.time_since_epoch().count() - time_point::now().time_since_epoch().count()) );
                  }
                }
              }
           }
    /**
     *    Return system_clock::time_point::min() if tasks have timed out
     *    Retunn system_clock::time_point::max() if there are no scheduled tasks
     *    Return the time the next task needs to be run if there is anything scheduled.
     */
    time_point check_for_timeouts() {
        if( !sleep_pqueue.size() && !task_sch_queue.size() ) {
            //ilog( "no timeouts ready" );
            return time_point::maximum();
        }

        time_point next = time_point::maximum();
        if( sleep_pqueue.size() && next > sleep_pqueue.front()->resume_time )
          next = sleep_pqueue.front()->resume_time;
        if( task_sch_queue.size() && next > task_sch_queue.front()->_when )
          next = task_sch_queue.front()->_when;

        time_point now = time_point::now();
        if( now < next ) { return next; }

        // move all expired sleeping tasks to the ready queue
        while( sleep_pqueue.size() && sleep_pqueue.front()->resume_time < now ) 
        {
            fc::context::ptr c = sleep_pqueue.front();
            std::pop_heap(sleep_pqueue.begin(), sleep_pqueue.end(), sleep_priority_less() );
            //ilog( "sleep pop back..." );
            sleep_pqueue.pop_back();

            if( c->blocking_prom.size() ) 
            {
             //   ilog( "timeotu blocking prom" );
                c->timeout_blocking_promises();
            }
            else 
            { 
                //ilog( "..." );
                //ilog( "ready_push_front" );
                if (c != current)
                  ready_push_front( c ); 
            }
        }
        return time_point::min();
    }

         void unblock( fc::context* c ) {
             if(  fc::thread::current().my != this ) {
               self.async( [=](){ unblock(c); }, "thread_d::unblock" );
               return;
             }
               if( c != current ) ready_push_front(c); 
         }

        void yield_until( const time_point& tp, bool reschedule ) {
          check_fiber_exceptions();

          if( tp <= (time_point::now()+fc::microseconds(10000)) ) 
          {
            return;
          }

          if( !current )  {
            current = new fc::context(&fc::thread::current());
          }

          current->resume_time = tp;
          current->clear_blocking_promises();

          sleep_pqueue.push_back(current);
          std::push_heap( sleep_pqueue.begin(),
                          sleep_pqueue.end(), sleep_priority_less()   );
          
          start_next_fiber(reschedule);

          // clear current context from sleep queue...
          for( uint32_t i = 0; i < sleep_pqueue.size(); ++i ) {
            if( sleep_pqueue[i] == current ) {
              sleep_pqueue[i] = sleep_pqueue.back();
              sleep_pqueue.pop_back();
              std::make_heap( sleep_pqueue.begin(),
                              sleep_pqueue.end(), sleep_priority_less() );
              break;
            }
          }

          current->resume_time = time_point::maximum();
          check_fiber_exceptions();
        }

        void wait( const promise_base::ptr& p, const time_point& timeout ) {
          if( p->ready() ) return;
          if( timeout < time_point::now() ) 
                FC_THROW_EXCEPTION( timeout_exception, "" );
          
          if( !current ) { 
            current = new fc::context(&fc::thread::current()); 
          }
          
          //slog( "                                 %1% blocking on %2%", current, p.get() );
          current->add_blocking_promise(p.get(),true);

          // if not max timeout, added to sleep pqueue
          if( timeout != time_point::maximum() ) {
              current->resume_time = timeout;
              sleep_pqueue.push_back(current);
              std::push_heap( sleep_pqueue.begin(),
                              sleep_pqueue.end(), 
                              sleep_priority_less()   );
          }

        //  elog( "blocking %1%", current );
          add_to_blocked( current );
       //   debug("swtiching fibers..." );


          start_next_fiber();
         // slog( "resuming %1%", current );

          //slog( "                                 %1% unblocking blocking on %2%", current, p.get() );
          current->remove_blocking_promise(p.get());

          check_fiber_exceptions();
        }

        void cleanup_thread_specific_data()
        {
          for (auto iter = non_task_specific_data.begin(); iter != non_task_specific_data.end(); ++iter)
            if (iter->cleanup)
              iter->cleanup(iter->value);

          for (auto iter = thread_specific_data.begin(); iter != thread_specific_data.end(); ++iter)
            if (iter->cleanup)
              iter->cleanup(iter->value);
        }

    };
} // namespace fc