source: src/libcfa/concurrency/alarm.c@ a724ac1

//                              -*- 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.
//
// alarm.c --
//
// Author           : Thierry Delisle
// Created On       : Fri Jun 2 11:31:25 2017
// Last Modified By : Thierry Delisle
// Last Modified On : --
// Update Count     : 0
//

extern "C" {
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include <unistd.h>
#include <sys/time.h>
}

#include "alarm.h"
#include "kernel_private.h"
#include "libhdr.h"
#include "preemption.h"

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

__cfa_time_t __kernel_get_time() {
        timespec curr;
        clock_gettime( CLOCK_REALTIME, &curr );
        __cfa_time_t curr_time = ((__cfa_time_t)curr.tv_sec * TIMEGRAN) + curr.tv_nsec;
        LIB_DEBUG_DO(
                char text[256];
                __attribute__((unused)) int len = snprintf( text, 256, "Kernel : current time is %lu\n", curr_time );
                LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
        );
        return curr_time;
}

void __kernel_set_timer( __cfa_time_t alarm ) {

        LIB_DEBUG_DO(
                char text[256];
                __attribute__((unused)) int len = snprintf( text, 256, "Kernel : set timer to %lu\n", (__cfa_time_t)alarm );
                LIB_DEBUG_WRITE( STDERR_FILENO, text, len );
        );

        itimerval val;
        val.it_value.tv_sec = alarm / TIMEGRAN;                 // seconds
        val.it_value.tv_usec = (alarm % TIMEGRAN) / ( TIMEGRAN / 1_000_000L ); // microseconds
        val.it_interval.tv_sec = 0;
        val.it_interval.tv_usec = 0;
        setitimer( ITIMER_REAL, &val, NULL );
}

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

void ?{}( alarm_node_t * this, thread_desc * thrd, __cfa_time_t alarm = 0, __cfa_time_t period = 0 ) {
        this->thrd = thrd;
        this->alarm = alarm;
        this->period = period;
        this->next = 0;
        this->set = false;
        this->kernel_alarm = false;
}

void ?{}( alarm_node_t * this, processor   * proc, __cfa_time_t alarm = 0, __cfa_time_t period = 0 ) {
        this->proc = proc;
        this->alarm = alarm;
        this->period = period;
        this->next = 0;
        this->set = false;
        this->kernel_alarm = true;
}

void ^?{}( alarm_node_t * this ) {
        if( this->set ) {
                unregister_self( this );
        }
}

static inline void insert_at( alarm_list_t * this, alarm_node_t * n, __alarm_it_t p ) {
        assert( !n->next );
        if( p == this->tail ) {
                this->tail = &n->next;
        }
        else {
                n->next = *p;
        }
        *p = n;
}

void insert( alarm_list_t * this, alarm_node_t * n ) {
        alarm_node_t ** it = &this->head;
        while( (*it) && (n->alarm > (*it)->alarm) ) {
                it = &(*it)->next;
        }

        insert_at( this, n, it );
}

alarm_node_t * pop( alarm_list_t * this ) {
        alarm_node_t * head = this->head;
        if( head ) {
                this->head = head->next;
                if( !head->next ) {
                        this->tail = &this->head;
                }
                head->next = NULL;
        }
        return head;
}

static inline void remove_at( alarm_list_t * this, alarm_node_t * n, __alarm_it_t it ) {
        assert( it );
        assert( (*it)->next == n );

        (*it)->next = n->next;
        if( !n-> next ) {
                this->tail = it;
        }
        n->next = NULL;
}

static inline void remove( alarm_list_t * this, alarm_node_t * n ) {
        alarm_node_t ** it = &this->head;
        while( (*it) && (*it)->next != n ) {
                it = &(*it)->next;
        }

        if( *it ) { remove_at( this, n, it ); }
}

void register_self( alarm_node_t * this ) {
        disable_interrupts();
        assert( !systemProcessor->pending_alarm );
        lock( &systemProcessor->alarm_lock );
        {
                bool first = !systemProcessor->alarms.head;

                insert( &systemProcessor->alarms, this );
                if( systemProcessor->pending_alarm ) {
                        tick_preemption();
                }
                if( first ) {
                        __kernel_set_timer( systemProcessor->alarms.head->alarm - __kernel_get_time() );
                }
        }
        unlock( &systemProcessor->alarm_lock );
        this->set = true;
        enable_interrupts();
}

void unregister_self( alarm_node_t * this ) {
        disable_interrupts();
        lock( &systemProcessor->alarm_lock );
        remove( &systemProcessor->alarms, this );
        unlock( &systemProcessor->alarm_lock );
        disable_interrupts();
        this->set = false;
}