//
// 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.
//
// alarm.c --
//
// Author           : Thierry Delisle
// Created On       : Fri Jun 2 11:31:25 2017
// Last Modified By : Peter A. Buhr
// Last Modified On : Wed Jun 17 16:11:35 2020
// Update Count     : 75
//

#define __cforall_thread__

#include <errno.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/time.h>

#include "alarm.hfa"
#include "kernel/fwd.hfa"
#include "preemption.hfa"

//=============================================================================================
// Clock logic
//=============================================================================================

Time __kernel_get_time() {
	timespec curr;
	clock_gettime( CLOCK_MONOTONIC_RAW, &curr );		// CLOCK_REALTIME
	return (Time){ curr };
}

void __kernel_set_timer( Duration alarm ) {
	verifyf(alarm >= 1`us || alarm == 0, "Setting timer to < 1us (%jins)", alarm`ns);
	setitimer( ITIMER_REAL, &(itimerval){ alarm }, 0p );
}

//=============================================================================================
// Alarm logic
//=============================================================================================

void ?{}( alarm_node_t & this, $thread * thrd, Time alarm, Duration period) with( this ) {
	this.thrd = thrd;
	this.alarm = alarm;
	this.period = period;
	set = false;
	type = User;
}

void ?{}( alarm_node_t & this, processor * proc, Time alarm, Duration period ) with( this ) {
	this.proc = proc;
	this.alarm = alarm;
	this.period = period;
	set = false;
	type = Kernel;
}
void ?{}( alarm_node_t & this, Alarm_Callback callback, Time alarm, Duration period ) with( this ) {
	this.alarm = alarm;
	this.period = period;
	this.callback = callback;
	set = false;
	type = Callback;
}

void ^?{}( alarm_node_t & this ) {
	if( this.set ) {
		unregister_self( &this );
	}
}

void insert( alarm_list_t * this, alarm_node_t * n ) {
	alarm_node_t * it = & (*this)`first;
	while( it && (n->alarm > it->alarm) ) {
		it = & (*it)`next;
	}
	if ( it ) {
		insert_before( *it, *n );
	} else {
		insert_last(*this, *n);
	}

	verify( validate( *this ) );
}

alarm_node_t * pop( alarm_list_t * this ) {
	verify( validate( *this ) );
	alarm_node_t * head = & (*this)`first;
	if( head ) {
		remove(*head);
	}
	verify( validate( *this ) );
	return head;
}

void register_self( alarm_node_t * this ) {
	alarm_list_t & alarms = event_kernel->alarms;

	disable_interrupts();
	lock( event_kernel->lock __cfaabi_dbg_ctx2 );
	{
		verify( validate( alarms ) );
		bool first = ! & alarms`first;

		insert( &alarms, this );
		if( first ) {
			__kernel_set_timer( alarms`first.alarm - __kernel_get_time() );
		}
	}
	unlock( event_kernel->lock );
	this->set = true;
	enable_interrupts( __cfaabi_dbg_ctx );
}

void unregister_self( alarm_node_t * this ) {
	disable_interrupts();
	lock( event_kernel->lock __cfaabi_dbg_ctx2 );
	{
		verify( validate( event_kernel->alarms ) );
		remove( *this );
	}
	unlock( event_kernel->lock );
	enable_interrupts( __cfaabi_dbg_ctx );
	this->set = false;
}

//=============================================================================================
// Utilities
//=============================================================================================

void sleep( Duration duration ) {
	alarm_node_t node = { active_thread(), __kernel_get_time() + duration, 0`s };

	register_self( &node );
	park();

	/* paranoid */ verify( !node.set );
	/* paranoid */ verify( & node`next == 0p );
	/* paranoid */ verify( & node`prev == 0p );
}

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