source: libcfa/src/concurrency/alarm.cfa@ 1539bbd

//
// 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 : Sun Jan  5 08:41:36 2020
// Update Count     : 69
//

#define __cforall_thread__

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

#include "alarm.hfa"
#include "kernel_private.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;
        next = 0;
        set = false;
        kernel_alarm = false;
}

void ?{}( alarm_node_t & this, processor   * proc, Time alarm, Duration period ) with( this ) {
        this.proc = proc;
        this.alarm = alarm;
        this.period = period;
        next = 0;
        set = false;
        kernel_alarm = true;
}

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

#if !defined(NDEBUG) && (defined(__CFA_DEBUG__) || defined(__CFA_VERIFY__))
bool validate( alarm_list_t * this ) {
        alarm_node_t ** it = &this->head;
        while( (*it) ) {
                it = &(*it)->next;
        }

        return it == this->tail;
}
#endif

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

        verify( validate( this ) );
}

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 );

        verify( validate( this ) );
}

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 = 0p;
        }
        verify( validate( this ) );
        return head;
}

static inline void remove_at( alarm_list_t * this, alarm_node_t * n, __alarm_it_t it ) {
        verify( it );
        verify( (*it) == n );

        (*it) = n->next;
        if( !n-> next ) {
                this->tail = it;
        }
        n->next = 0p;

        verify( validate( this ) );
}

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

        verify( validate( this ) );

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

        verify( validate( this ) );
}

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->head;

                insert( alarms, this );
                if( first ) {
                        __kernel_set_timer( alarms->head->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( &event_kernel->alarms, 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( __cfaabi_dbg_ctx );

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

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