#ifndef NODETREETRAVERSER_HPP_
#define NODETREETRAVERSER_HPP_

/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8
// Name        : NodeTreeTraverser.cpp
// Author      : Avi
// Revision    : $Revision: #26 $ 
//
// Copyright 2009- ECMWF.
// This software is licensed under the terms of the Apache Licence version 2.0 
// which can be obtained at http://www.apache.org/licenses/LICENSE-2.0. 
// In applying this licence, ECMWF does not waive the privileges and immunities 
// granted to it by virtue of its status as an intergovernmental organisation 
// nor does it submit to any jurisdiction. 
//
// Description :
// This class will traverse the node tree periodically, It is tied to a server.
// This implementation uses a strand to ensure sequential processing of the node dependency traversal
// in the the presence of multiple threads, without the need of explicit locking. i.e mutex's
//
// For testing we make the distinction between the poll period, and calendar update interval
// Some suites require a real time calendar. Hence we must make sure that
// poll interval is in sync with real time.
/////////1/////////2/////////3/////////4/////////5/////////6/////////7/////////8

#include <boost/asio.hpp>
#include <boost/date_time/posix_time/posix_time_types.hpp>

class BaseServer;
class ServerEnvironment;
//#define DEBUG_TRAVERSER 1

class NodeTreeTraverser {
   NodeTreeTraverser(const NodeTreeTraverser&) = delete;
   const NodeTreeTraverser& operator=(const NodeTreeTraverser&) = delete;
public:
	NodeTreeTraverser( BaseServer* s,  boost::asio::io_service& io, const ServerEnvironment& serverEnv);
	~NodeTreeTraverser();

	/// If first time Starts traversing Node tree and resolving dependencies.
	/// This essentially starts Jobs scheduling. Calling start more than once does nothing.
	/// On subsequent calls to start resume is called. Which may cause immediate
	/// job generation. (i.e for those nodes whose node are free of time dependencies)
	/// Timer will be aligned to the minute boundary
	void start();

	/// Suspends job scheduling (for real time calendars/suite)
 	/// Shutdown & suspend (are very similar) shutdown operate at the top/level.
 	/// Both should have effect of stopping job submission and not the event loop
 	///
 	/// During a system session, a node can be placed into suspend mode.
 	/// In suspend mode, no jobs are submitted. (**** However node which are
 	/// free to run are marked****).
 	///
 	/// When the session is resumed, those node than were marked, have
 	/// the task's submitted. ( This means that job dependent on a time dependency
 	/// does not need to be held for the following day)
	void stop();

   /// terminate: This will cancel the timer and any pending async operation
   /// If timer has already expired, then the handler function will be
   /// passed an operation aborted error code.
	/// Called when the server is exiting. We must be sure to cancel all
	/// async handlers or the server, will not stop.
   void terminate();

   /// This can be called at the end of a *USER* command(force,alter,requeue,etc), hence time_now may be >= poll_time
   /// If this is the case, we will defer job generation
   void traverse_node_tree_and_job_generate(const boost::posix_time::ptime& time_now, bool user_cmd_context) const;

private:
	void traverse(const boost::system::error_code& error );
	void do_traverse();
	void start_timer();
	void update_suite_calendar_and_traverse_node_tree(const boost::posix_time::ptime& time_now);

	BaseServer* server_;
	const ServerEnvironment& serverEnv_;
 	boost::asio::deadline_timer timer_;
	boost::posix_time::ptime last_time_;        // ensure poll is in sync
	boost::posix_time::ptime next_poll_time_;   // Keep as sync as possible with hard real times
	boost::posix_time::time_duration interval_; // Job submission interval
#ifdef DEBUG_TRAVERSER
 	int count_;
#endif
 	bool firstTime_;
 	bool running_;
};

#endif
