state.c

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#include <stdlib.h>
#include <math.h>
#include <string.h>

#include <core/core.h>
#include <core/init.h>
#include <core/timer.h>
#include <gvt/ccgs.h>
#include <datatypes/list.h>
#include <scheduler/process.h>
#include <scheduler/scheduler.h>
#include <mm/state.h>
#include <communication/communication.h>
#include <mm/mm.h>
#include <statistics/statistics.h>

bool LogState(struct lp_struct *lp)
{
    bool take_snapshot = false;
    state_t *new_state;

    if (unlikely(is_blocked_state(lp->state))) {
        return take_snapshot;
    }
    // Keep track of the invocations to LogState
    lp->from_last_ckpt++;

    if (lp->state_log_forced) {
        lp->state_log_forced = false;
        lp->from_last_ckpt = 0;

        take_snapshot = true;
        goto skip_switch;
    }
    // Switch on the checkpointing mode
    switch (rootsim_config.checkpointing) {

    case STATE_SAVING_COPY:
        take_snapshot = true;
        break;

    case STATE_SAVING_PERIODIC:
        if (lp->from_last_ckpt >= lp->ckpt_period) {
            take_snapshot = true;
            lp->from_last_ckpt = 0;
        }
        break;

    default:
        rootsim_error(true, "State saving mode not supported.");
    }

 skip_switch:

    // Shall we take a log?
    if (take_snapshot) {

        // Allocate the state buffer
        new_state = rsalloc(sizeof(*new_state));

        // Associate the checkpoint with current LVT and last-executed event
        new_state->lvt = lvt(lp);
        new_state->last_event = lp->bound;

        // Log simulation model buffers
        new_state->log = log_state(lp);

        // Log members of lp_struct which must be restored
        new_state->state = lp->state;
        new_state->base_pointer = lp->current_base_pointer;

        // Early evaluation of simulation termination.
        new_state->simulation_completed = ccgs_lp_can_halt(lp);

        // Log library-related states
        memcpy(&new_state->numerical, &lp->numerical, sizeof(numerical_state_t));

        if(&topology_settings && topology_settings.write_enabled) {
            new_state->topology = rsalloc(topology_global.chkp_size);
            memcpy(new_state->topology, lp->topology, topology_global.chkp_size);
        }

        if(&abm_settings) {
            new_state->region_data = abm_do_checkpoint(lp->region);
        }

        // Link the new checkpoint to the state chain
        list_insert_tail(lp->queue_states, new_state);

    }

    return take_snapshot;
}

void RestoreState(struct lp_struct *lp, state_t * restore_state)
{
    // Restore simulation model buffers
    log_restore(lp, restore_state);

    // Restore members of lp_struct which have been checkpointed
    lp->current_base_pointer = restore_state->base_pointer;
    lp->state = restore_state->state;

    // Restore library-related states
    memcpy(&lp->numerical, &restore_state->numerical,
           sizeof(numerical_state_t));

    if(&topology_settings && topology_settings.write_enabled){
        memcpy(lp->topology, restore_state->topology,
                topology_global.chkp_size);
    }

    if(&abm_settings)
        abm_restore_checkpoint(restore_state->region_data, lp->region);

#ifdef HAVE_CROSS_STATE
    lp->ECS_index = 0;
    lp->wait_on_rendezvous = 0;
    lp->wait_on_object = 0;
#endif
}

unsigned int silent_execution(struct lp_struct *lp, msg_t *evt, msg_t *final_evt)
{
    unsigned int events = 0;
    unsigned short int old_state;

    // current state can be either idle READY, BLOCKED or ROLLBACK, so we save it and then put it back in place
    old_state = lp->state;
    lp->state = LP_STATE_SILENT_EXEC;

    // This is true if the restored state was taken exactly after the new bound
    if (evt == final_evt)
        goto out;

    evt = list_next(evt);
    final_evt = list_next(final_evt);

    // Reprocess events. Outgoing messages are explicitly discarded, as this part of
    // the simulation has been already executed at least once
    while (evt != NULL && evt != final_evt) {

        if (unlikely(!reprocess_control_msg(evt))) {
            evt = list_next(evt);
            continue;
        }

        events++;
        activate_LP(lp, evt);
        evt = list_next(evt);
    }

 out:
    lp->state = old_state;
    return events;
}

void rollback(struct lp_struct *lp)
{
    state_t *restore_state, *s;
    msg_t *last_correct_event;
    msg_t *last_restored_event;
    unsigned int reprocessed_events;

    // Sanity check
    if (unlikely(lp->state != LP_STATE_ROLLBACK)) {
        rootsim_error(false, "I'm asked to roll back LP %d's execution, but rollback_bound is not set. Ignoring...\n",
                  lp->gid.to_int);
        return;
    }

    // Discard any possible execution state related to a blocked execution
    memcpy(&lp->context, &lp->default_context, sizeof(LP_context_t));

    statistics_post_data(lp, STAT_ROLLBACK, 1.0);

    last_correct_event = lp->bound;
    // Send antimessages
    send_antimessages(lp, last_correct_event->timestamp);

    // Find the state to be restored, and prune the wrongly computed states
    restore_state = list_tail(lp->queue_states);
    while (restore_state != NULL && restore_state->lvt > last_correct_event->timestamp) {   // It's > rather than >= because we have already taken into account simultaneous events
        s = restore_state;
        restore_state = list_prev(restore_state);
        log_delete(s->log);
#ifndef NDEBUG
        s->last_event = (void *)0xBABEBEEF;
#endif
        list_delete_by_content(lp->queue_states, s);
    }
    // Restore the simulation state and correct the state base pointer
    RestoreState(lp, restore_state);

    last_restored_event = restore_state->last_event;
    reprocessed_events = silent_execution(lp, last_restored_event, last_correct_event);
    statistics_post_data(lp, STAT_SILENT, (double)reprocessed_events);

    // TODO: silent execution resets the LP state to the previous
    // value, so it should be the last function to be called within rollback()
    // Control messages must be rolled back as well
    rollback_control_message(lp, last_correct_event->timestamp);
}

state_t *find_time_barrier(struct lp_struct *lp, simtime_t simtime)
{
    state_t *barrier_state;

    if (unlikely(D_EQUAL(simtime, 0.0))) {
        return list_head(lp->queue_states);
    }

    barrier_state = list_tail(lp->queue_states);

    // Must point to the state with lvt immediately before the GVT
    while (barrier_state != NULL && barrier_state->lvt >= simtime) {
        barrier_state = list_prev(barrier_state);
    }
    if (barrier_state == NULL) {
        barrier_state = list_head(lp->queue_states);
    }

/*
    // TODO Search for the first full log before the gvt
    while(true) {
        if(is_incremental(current->log) == false)
            break;
        current = list_prev(current);
    }
*/

    return barrier_state;
}

void SetState(void *new_state)
{
    current->current_base_pointer = new_state;
}

void set_checkpoint_mode(int ckpt_mode)
{
    rootsim_config.checkpointing = ckpt_mode;
}

void set_checkpoint_period(struct lp_struct *lp, int period)
{
    lp->ckpt_period = period;
}

void force_LP_checkpoint(struct lp_struct *lp)
{
    lp->state_log_forced = true;
}