#ifndef __ShutdownRequested_h_
#define __ShutdownRequested_h_

#include "../shared/PipeConditionVar.h"

// Some processes try to run forever.  High level modules can request a 
// shutdown message, but it's harder for support modules, like the database.
// By default the database module will retry a query until it succeeds.  While
// a thread is waiting on a result from the database, it won't request anything
// new from its input queue.  So it won't know that we are trying to shut down.
//
// The downside is that anyone using the database, or a similar resource, has
// to accept that the database request might have aborted, rather than
// succeeded, because of this flag.  So the high level request is not in
// full control.  It should check for the shutdown condition before trying to
// review any results from the database.  And it can't give do any special
// processing on shutdown which might require the database.
//
// But it's still an improvement.  This way the abort requet has to make its
// way out of low level routines up through high level routines.  The
// alternative is to have a two way communiction from the initial shutdown
// request through the high level modules to the low level modules and
// back, or to risk the process locking up because its lost in one of these
// low level routines.
//
// There really isn't a happy medium.  Do you usually do infinite retries, but
// when attempting to shut down you allow retries for a minute?  A minute for
// each module?  If you have a minute total, then you really have the same
// problem all over again.  If one of the items shutting down gets stuck until
// the timeout, then everything after that will get no time to shut down.
//
// Ultimately we choose this route for its simplicity.  One common data 
// structure controls everything.  Without this we'd be likely to have almost
// as many shutdown sequences as we have modules.
//

// This is intially false, but can be set to true.
bool shutdownInProgress();

// This tells everyone that we are shutting down.
// Handles the people polling and waiting.
void requestShutdown();

// This will wait forever for a shutdown request.
void waitForShutdown();

// These are set once when a shutdown is requested.
// It makes no sense to clear these.
PipeConditionVar *requestShutdownConditionVar();
void releaseShutdownConditionVar(PipeConditionVar *cond);


#endif