/*
 * Example LAM/MPI CR self program
 * Josh Hursey
 * April 9, 2006
 *
 * To compile:
 * $ mpicc -g -export -o personal-cr personal-cr.c
 *
 * To Run:
 * $ mpirun -np 2 \
 *     -ssi cr_self_prefix my_personal \
 *     -ssi rpi crtcp \
 *     -ssi cr self \
 *     personal-cr
 *
 * To Checkpoint:
 * $ lamcheckpoint -ssi cr self -pid XXXX
 * 
 * To Restart: (Don't use lamrestart)
 * $ mpirun -np 2 \
 *     -ssi cr_self_prefix my_personal \
 *     -ssi rpi crtcp \
 *     -ssi cr self \
 *     -ssi cr_self_do_restart 1
 *     personal-cr
 */
#include <stdio.h>
#include <mpi.h>

#define LIMIT 20

/************************
 * Function Declarations
 ************************/
/* Default LAM/MPI cr self callback functions */
int lam_cr_self_checkpoint(void);
int lam_cr_self_continue(void);
int lam_cr_self_restart(void);

/* LAM/MPI cr self callback functions */
int my_personal_checkpoint(void);
int my_personal_continue(void);
int my_personal_restart(void);

/*******************
 * Global Variables
 *******************/
int current_step  = 0;
char ckpt_file[128] = "my-personal-cr-file.ckpt";

/*********
 *  Main
 *********/
int main(int argc, char *argv[]) {
    int rank, size;
    
    current_step = 0;

    /*
     * If we are restarting, then our callback is called 
     * from inside MPI_Init.
     * It is safe to initialize global variables before calling
     * MPI_Init with out fear of overwriting the values that
     * the restart callback might change them too.
     */
    MPI_Init(&argc, &argv);
    MPI_Comm_rank(MPI_COMM_WORLD, &rank);
    MPI_Comm_size(MPI_COMM_WORLD, &size);
    
    for(; current_step <  LIMIT; current_step += 1) {
        printf("%d of %d: Step %d\n", rank, size, current_step);
        sleep(1);
    }

    MPI_Finalize();
    return 0;
}

/* LAM/MPI default cr self callbacks for checkpoint */
int lam_cr_self_checkpoint(void) {
    printf("lam_cr_self_checkpoint callback...\n");
    
    return 0;
}

int lam_cr_self_continue(void) {
    printf("lam_cr_self_continue callback...\n");
    
    return 0;
}

int lam_cr_self_restart(void) {
    printf("lam_cr_self_restart callback...\n");
    
    return 0;
}

/* LAM/MPI cr self callback for checkpoint */
int my_personal_checkpoint() {
    FILE *fp;
        
    printf("my_personal_checkpoint callback...\n");
    
    /*
     * Open our checkpoint file
     */
    if( NULL == (fp = fopen(ckpt_file, "w")) ) {
        fprintf(stderr, "Error: Unable to open file (%s)\n", ckpt_file);
        return;
    }
    
    /*
     * Save the process state
     */
    fprintf(fp, "%d\n", current_step);
    
    /*
     * Close the checkpoint file
     */
    fclose(fp);
    
    return 0;
}

int my_personal_continue() {
    printf("my_personal_continue callback...\n");
    /* Don't need to do anything here since we are in the
     *  state that we want to be in already.
     */
    return 0;
}

int my_personal_restart() {
    FILE *fp;

    printf("my_personal_restart callback...\n");

    /*
     * Open our checkpoint file
     */
    if( NULL == (fp = fopen(ckpt_file, "r")) ) {
        fprintf(stderr, "Error: Unable to open file (%s)\n", ckpt_file);
        return;
    }

    /*
     * Access the process state that we saved and 
     * update the current step variable.
     */
    fscanf(fp, "%d", &current_step);
    
    fclose(fp);

    printf("my_personal_restart: Restarting from step %d\n", current_step);    
    
    return 0;
}