arangodb/Dispatcher/DispatcherThread.cpp

////////////////////////////////////////////////////////////////////////////////
/// @brief dispatcher thread
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2010-2011 triagens GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
///     http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is triAGENS GmbH, Cologne, Germany
///
/// @author Dr. Frank Celler
/// @author Martin Schoenert
/// @author Copyright 2009-2011, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////

#include "DispatcherThread.h"

#include <Basics/Exceptions.h>
#include <Logger/Logger.h>
#include <Basics/StringUtils.h>

#include "Dispatcher/Dispatcher.h"
#include "Dispatcher/DispatcherQueue.h"
#include "Dispatcher/Job.h"

using namespace triagens::basics;
using namespace triagens::rest;

// -----------------------------------------------------------------------------
// --SECTION--                                            class DispatcherThread
// -----------------------------------------------------------------------------

// -----------------------------------------------------------------------------
// --SECTION--                                      constructors and destructors
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup Dispatcher
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief constructs a dispatcher thread
////////////////////////////////////////////////////////////////////////////////

DispatcherThread::DispatcherThread (DispatcherQueue* queue)
  : Thread("DispatcherThread"),
    queue(queue),
    jobType(Job::READ_JOB) {
  allowAsynchronousCancelation();
}

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                                 protected methods
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup Dispatcher
/// @{
////////////////////////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////////////////////////
/// @brief called to report the status of the thread
////////////////////////////////////////////////////////////////////////////////

void DispatcherThread::reportStatus () {
}

////////////////////////////////////////////////////////////////////////////////
/// @brief called in regular intervalls
////////////////////////////////////////////////////////////////////////////////

void DispatcherThread::tick (bool) {
}

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

// -----------------------------------------------------------------------------
// --SECTION--                                                    Thread methods
// -----------------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////////////
/// @addtogroup Dispatcher
/// @{
////////////////////////////////////////////////////////////////////////////////

void DispatcherThread::run () {
  queue->accessQueue.lock();

  queue->nrStarted--;
  queue->nrRunning++;

  queue->startedThreads.insert(this);

  // iterate until we are shutting down.
  while (jobType != Job::SPECIAL_JOB && queue->stopping == 0) {

    // delete old jobs
    for (list<DispatcherThread*>::iterator i = queue->stoppedThreads.begin();  i != queue->stoppedThreads.end();  ++i) {
      delete *i;
    }

    queue->stoppedThreads.clear();
    queue->nrStopped = 0;

    // a job is waiting to execute
    if (  ! queue->readyJobs.empty()
         && queue->monopolizer == 0
         && ! (queue->readyJobs.front()->type() == Job::WRITE_JOB && 1 < queue->nrRunning)) {

      // try next job
      Job* job = queue->readyJobs.front();
      queue->readyJobs.pop_front();

      // handle job type
      jobType = job->type();

      // start a new thread for special jobs
      if (jobType == Job::SPECIAL_JOB) {
        queue->nrRunning--;
        queue->nrSpecial++;
        queue->startQueueThread();
      }

      // monopolize queue
      else if (jobType == Job::WRITE_JOB) {
        queue->monopolizer = this;
      }

      // now release the queue lock (initialise is inside the lock, work outside)
      queue->accessQueue.unlock();

      // do the work (this might change the job type)
      Job::status_e status = Job::JOB_FAILED;

      try {

        // set current thread
        job->setDispatcherThread(this);

        // and do all the dirty work
        status = job->work();
      }
      catch (TriagensError const& ex) {
        try {
          job->handleError(ex);
        }
        catch (TriagensError const& ex) {
          LOGGER_WARNING << "caught error while handling error: " << DIAGNOSTIC_INFORMATION(ex);
        }
        catch (std::exception const& ex) {
          LOGGER_WARNING << "caught error while handling error: " << ex.what();
        }
        catch (...) {
          LOGGER_WARNING << "caught error while handling error!";
        }

        status = Job::JOB_FAILED;
      }
      catch (std::exception const& ex) {
        try {
          InternalError err(string("job failed with unknown in work: ") + ex.what());

          job->handleError(err);
        }
        catch (TriagensError const& ex) {
          LOGGER_WARNING << "caught error while handling error: " << DIAGNOSTIC_INFORMATION(ex);
        }
        catch (std::exception const& ex) {
          LOGGER_WARNING << "caught error while handling error: " << ex.what();
        }
        catch (...) {
          LOGGER_WARNING << "caught error while handling error!";
        }

        status = Job::JOB_FAILED;
      }
      catch (...) {
#ifdef TRI_HAVE_POSIX_THREADS
        if (queue->stopping != 0) {
          LOGGER_WARNING << "caught cancellation exception during work";
          throw;
        }
#endif

        try {
          InternalError err("job failed with unknown error in work");

          job->handleError(err);
        }
        catch (TriagensError const& ex) {
          LOGGER_WARNING << "caught error while handling error: " << DIAGNOSTIC_INFORMATION(ex);
        }
        catch (std::exception const& ex) {
          LOGGER_WARNING << "caught error while handling error: " << ex.what();
        }
        catch (...) {
          LOGGER_WARNING << "caught error while handling error!";
        }

        status = Job::JOB_FAILED;
      }

      // trigger GC
      tick(false);

      // require the lock
      queue->accessQueue.lock();
      
      // cleanup
      queue->monopolizer = 0;

      // finish jobs
      try {
        job->setDispatcherThread(0);
        
        if (status == Job::JOB_DONE) {
          job->cleanup();
        }
        else if (status == Job::JOB_REQUEUE) {
          queue->dispatcher->addJob(job);
        }
        else if (status == Job::JOB_FAILED) {
          job->cleanup();
        }
      }
      catch (...) {
#ifdef TRI_HAVE_POSIX_THREADS
        if (queue->stopping != 0) {
          LOGGER_WARNING << "caught cancellation exception during cleanup";
          throw;
        }
#endif
        
        LOGGER_WARNING << "caught error while cleaning up!";
      }

      if (0 < queue->nrWaiting && ! queue->readyJobs.empty()) {
        queue->accessQueue.broadcast();
      }
    }
    else {

      // cleanup without holding a lock
      queue->accessQueue.unlock();
      tick(true);
      queue->accessQueue.lock();

      // wait, if there are no jobs
      if (queue->readyJobs.empty()) {
        queue->nrRunning--;
        queue->nrWaiting++;

        queue->accessQueue.wait();

        queue->nrWaiting--;
        queue->nrRunning++;
      }
    }
  }

  queue->stoppedThreads.push_back(this);
  queue->startedThreads.erase(this);

  queue->nrRunning--;
  queue->nrStopped++;

  if (jobType == Job::SPECIAL_JOB) {
    queue->nrSpecial--;
  }

  queue->accessQueue.unlock();

  LOGGER_TRACE << "dispatcher thread has finished";
}

////////////////////////////////////////////////////////////////////////////////
/// @}
////////////////////////////////////////////////////////////////////////////////

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