/*
 * Project: MoleCuilder
 * Description: creates and alters molecular systems
 * Copyright (C)  2011 University of Bonn. All rights reserved.
 * Please see the LICENSE file or "Copyright notice" in builder.cpp for details.
 */

/*
 * WorkerPool.cpp
 *
 *  Created on: 22.02.2012
 *      Author: heber
 */

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

// boost asio needs specific operator new
#include <boost/asio.hpp>

#include "CodePatterns/MemDebug.hpp"

#include "WorkerPool.hpp"

#include "CodePatterns/Assert.hpp"
#include "CodePatterns/Info.hpp"
#include "CodePatterns/Log.hpp"
#include "Connection.hpp"

WorkerPool::priority_t WorkerPool::default_priority = 0;
WorkerAddress WorkerPool::emptyAddress("empty", "empty");

/** Constructor for class WorkerPool.
 *
 */
WorkerPool::WorkerPool()
{}

/** Destructor for class WorkerPool.
 *
 */
WorkerPool::~WorkerPool()
{}

/** Helper function to check whether an address is already in the pool.
 *
 * @param address worker address to check
 * @return true - address is present, false - else
 */
bool WorkerPool::presentInPool(const WorkerAddress &address) const
{
  return pool.find(address) != pool.end();
}

/** Get address of next idle worker.
 *
 * Note that worker is automatically marked as busy, \sa WorkerPool::markWorkerBusy()
 *
 * @return address of idle worker
 */
WorkerAddress WorkerPool::getNextIdleWorker()
{
  // get first idle worker
  ASSERT( presentIdleWorkers(),
      "WorkerPool::getNextIdleWorker() - there is no idle worker.");
  if (!presentIdleWorkers())
    return emptyAddress;
  Idle_Queue_t::iterator iter = idle_queue.begin();
  const WorkerAddress returnaddress = iter->second;

  // enter in busy queue
  markWorkerBusy( iter );

  // return address
  return returnaddress;
}

WorkerPool::Idle_Queue_t::iterator WorkerPool::getIdleWorker(const WorkerAddress &address)
{
  Idle_Queue_t::iterator idleiter = idle_queue.begin();
  while (idleiter != idle_queue.end()) {
    if (idleiter->second == address) {
      break;
    }
    ++idleiter;
  }
  return idleiter;
}

/** Checks whether a worker is busy or not.
 *
 * @param address address of worker to check
 */
bool WorkerPool::isWorkerBusy(const WorkerAddress &address) const
{
  Busy_Queue_t::const_iterator iter = busy_queue.find(address);
  if (iter != busy_queue.end())
    return true;
#ifndef NDEBUG
  else {
    Idle_Queue_t::const_iterator iter = idle_queue.begin();
    for(;iter != idle_queue.end(); ++iter)
      if (iter->second == address)
        break;
    ASSERT( iter != idle_queue.end(),
        "WorkerPool::isWorkerBusy() - worker "+toString(address)
        +" is neither busy nor idle.");

  }
#endif
  return false;
}

/** Adds another worker to the pool by noting down its address.
 *
 * @param address host and service address of the listening worker
 * @return true - added successfully, false - not added
 */
bool WorkerPool::addWorker(const WorkerAddress& address)
{
  std::pair<Pool_t::iterator, bool> inserter =
      pool.insert( address );
  if (inserter.second) { // if new also add to queue
    LOG(1, "INFO: Successfully added "+toString(address)+" to pool.");
    idle_queue.insert( make_pair( default_priority, address ) );
    return true;
  } else {
    LOG(1, "INFO: "+toString(address)+" is already present pool.");
    return false;
  }
}

/** Removes a worker from the pool.
 *
 * @param address host and service address of the listening worker
 * @return true - removed successfully, false - not removed
 */
bool WorkerPool::removeWorker(const WorkerAddress& address)
{
  Pool_t::iterator iter = pool.find( address );
  if (iter != pool.end()) {
    Idle_Queue_t::iterator idleiter = getIdleWorker(address);
    if (idleiter != idle_queue.end())
      idle_queue.erase(idleiter);
    Busy_Queue_t::iterator busyiter = busy_queue.find(address);
    if (busyiter != busy_queue.end())
      busy_queue.erase(busyiter);
    ASSERT( idleiter != idle_queue.end() || busyiter != busy_queue.end(),
        "WorkerPool::removeWorker() - Worker "+toString(address)
        +" is in pool but neither idle nor busy!");
    ASSERT( !(idleiter != idle_queue.end() && busyiter != busy_queue.end()),
        "WorkerPool::removeWorker() - Worker "+toString(address)
        +" is in pool and both idle and busy!");
    pool.erase(iter);
    LOG(1, "INFO: Removed worker " << address << " from pool.");
    return true;
  } else {
    ELOG(1, "Worker "+toString(address)+" is not present pool.");
    return false;
  }
}

/** Sends shutdown to all current workers in the pool.
 *
 */
void WorkerPool::removeAllWorkers()
{
  // empty pool and queue
  idle_queue.clear();
  busy_queue.clear();
  pool.clear();
}

/** Helper function to mark a worker as busy.
 *
 * Removes from idle_queue and places into busy_queue.
 * Sets \a iter to Idle_Queue_t::end().
 *
 * @param iter iterator on idle worker
 */
void WorkerPool::markWorkerBusy(Idle_Queue_t::iterator &iter)
{
  const WorkerAddress returnaddress = iter->second;
  if (isWorkerBusy(returnaddress))
    return;
  const priority_t priority = iter->first;

  // remove from idle queue
  idle_queue.erase(iter);

  // insert into busy queue
#ifndef NDEBUG
  std::pair< Busy_Queue_t::iterator, bool > inserter =
#endif
  busy_queue.insert( make_pair(returnaddress, priority) );
  ASSERT( inserter.second,
      "WorkerPool::sendJobToWorker() - Worker "+toString(inserter.first->first)+" is already busy.");

  LOG(1, "INFO: Worker " << returnaddress << " is now marked busy.");
}

/** Helper function to unmark a worker as busy.
 *
 * Removes worker from busy_queue and returns it to idle_queue.
 *
 * @param address address of worker
 */
void WorkerPool::unmarkWorkerBusy(const WorkerAddress &address)
{
  if (isWorkerBusy(address)) {
    Busy_Queue_t::const_iterator iter = busy_queue.find(address);
    const priority_t priority = iter->second;
    busy_queue.erase(address);
    idle_queue.insert( make_pair( priority, address) );

    LOG(1, "INFO: Worker " << address << " is now marked idle.");
  }
}