//                              -*- Mode: CFA -*-
//
// Cforall Version 1.0.0 Copyright (C) 2016 University of Waterloo
//
// The contents of this file are covered under the licence agreement in the
// file "LICENCE" distributed with Cforall.
//
// monitor_desc.c --
//
// Author           : Thierry Delisle
// Created On       : Thd Feb 23 12:27:26 2017
// Last Modified By : Thierry Delisle
// Last Modified On : --
// Update Count     : 0
//

#include "monitor"

#include "kernel_private.h"

void enter(monitor_desc * this) {
	lock( &this->lock );
	thread_desc * thrd = this_thread();

	if( !this->owner ) {
		//No one has the monitor, just take it
		this->owner = thrd;
		this->recursion = 1;
	}
	else if( this->owner == thrd) {
		//We already have the monitor, just not how many times we took it
		assert( this->recursion > 0 );
		this->recursion += 1;
	}
	else {
		//Some one else has the monitor, wait in line for it
		append( &this->entry_queue, thrd );
		ScheduleInternal( &this->lock );

		//ScheduleInternal will unlock spinlock, no need to unlock ourselves
		return; 
	}

	unlock( &this->lock );
}

void leave(monitor_desc * this) {
	lock( &this->lock );

	thread_desc * thrd = this_thread();
	assert( thrd == this->owner );

	//Leaving a recursion level, decrement the counter
	this->recursion -= 1;

	//If we left the last level of recursion it means we are changing who owns the monitor
	thread_desc * new_owner = 0;
	if( this->recursion == 0) {
		//Get the next thread in the list
		new_owner = this->owner = pop_head( &this->entry_queue );

		//We are passing the monitor to someone else, which means recursion level is not 0
		this->recursion = new_owner ? 1 : 0;
	}	

	unlock( &this->lock );

	//If we have a new owner, we need to wake-up the thread
	if( new_owner ) {
		ScheduleThread( new_owner );
	}
}

void enter(monitor_desc ** monitors, int count) {
	for(int i = 0; i < count; i++) {
		// printf("%d\n", i);
		enter( monitors[i] );
	}
}

void leave(monitor_desc ** monitors, int count) {
	for(int i = count - 1; i >= 0; i--) {
		// printf("%d\n", i);
		leave( monitors[i] );
	}
}