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darshan-core.c 57.9 KB
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/*
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 * Copyright (C) 2015 University of Chicago.
 * See COPYRIGHT notice in top-level directory.
 *
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 */

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#define _XOPEN_SOURCE 500
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#define _GNU_SOURCE
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#include "darshan-runtime-config.h"

#include <stdio.h>
#ifdef HAVE_MNTENT_H
#include <mntent.h>
#endif
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#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <limits.h>
#include <pthread.h>
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#include <fcntl.h>
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#include <sys/types.h>
#include <sys/stat.h>
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#include <sys/mman.h>
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#include <sys/vfs.h>
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#include <zlib.h>
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#include <mpi.h>
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#include <assert.h>
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#include "uthash.h"
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#include "darshan.h"
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#include "darshan-core.h"
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#include "darshan-dynamic.h"
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extern char* __progname;
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extern char* __progname_full;
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/* internal variable delcarations */
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static struct darshan_core_runtime *darshan_core = NULL;
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static pthread_mutex_t darshan_core_mutex = PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP;
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static int my_rank = -1;
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static int nprocs = -1;
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static int darshan_mem_alignment = 1;
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/* paths prefixed with the following directories are not traced by darshan */
char* darshan_path_exclusions[] = {
"/etc/",
"/dev/",
"/usr/",
"/bin/",
"/boot/",
"/lib/",
"/opt/",
"/sbin/",
"/sys/",
"/proc/",
NULL
};

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#ifdef DARSHAN_BGQ
extern void bgq_runtime_initialize();
#endif

/* array of init functions for modules which need to be statically
 * initialized by darshan at startup time
 */
void (*mod_static_init_fns[])(void) =
{
#ifdef DARSHAN_BGQ
    &bgq_runtime_initialize,
#endif
    NULL
};

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#define DARSHAN_CORE_LOCK() pthread_mutex_lock(&darshan_core_mutex)
#define DARSHAN_CORE_UNLOCK() pthread_mutex_unlock(&darshan_core_mutex)

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/* FS mount information */
#define DARSHAN_MAX_MNTS 64
#define DARSHAN_MAX_MNT_PATH 256
#define DARSHAN_MAX_MNT_TYPE 32
struct mnt_data
{
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    int block_size;
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    char path[DARSHAN_MAX_MNT_PATH];
    char type[DARSHAN_MAX_MNT_TYPE];
};
static struct mnt_data mnt_data_array[DARSHAN_MAX_MNTS];
static int mnt_data_count = 0;

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/* prototypes for internal helper functions */
static void darshan_log_record_hints_and_ver(
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    struct darshan_core_runtime* core);
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static void darshan_get_exe_and_mounts(
    struct darshan_core_runtime *core, int argc, char **argv);
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static void darshan_add_name_record_ref(
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    struct darshan_core_runtime *core, darshan_record_id rec_id,
    char *name, darshan_module_id mod_id);
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static int darshan_block_size_from_path(
    const char *path);
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static void darshan_get_user_name(
    char *user);
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static void darshan_get_logfile_name(
    char* logfile_name, int jobid, struct tm* start_tm);
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static void darshan_get_shared_records(
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    struct darshan_core_runtime *core, darshan_record_id **shared_recs,
    int *shared_rec_cnt);
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static int darshan_log_open_all(
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    char *logfile_name, MPI_File *log_fh);
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static int darshan_deflate_buffer(
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    void **pointers, int *lengths, int count, char *comp_buf,
    int *comp_buf_length);
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static int darshan_log_write_name_record_hash(
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    MPI_File log_fh, struct darshan_core_runtime *core,
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    uint64_t *inout_off);
static int darshan_log_append_all(
    MPI_File log_fh, struct darshan_core_runtime *core, void *buf,
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    int count, uint64_t *inout_off);
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static void darshan_core_cleanup(
    struct darshan_core_runtime* core);
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/* *********************************** */

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void darshan_core_initialize(int argc, char **argv)
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{
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    struct darshan_core_runtime *init_core = NULL;
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    int internal_timing_flag = 0;
    double init_start, init_time, init_max;
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    char *envstr;
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    char *jobid_str;
    int jobid;
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    int ret;
    int tmpval;
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    int i;
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#ifdef __DARSHAN_ENABLE_MMAP_LOGS
    int mmap_fd;
    int mmap_size;
    int sys_page_size;
    char cuser[L_cuserid] = {0};
    char *mmap_log_dir;
#endif
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    DARSHAN_MPI_CALL(PMPI_Comm_size)(MPI_COMM_WORLD, &nprocs);
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    DARSHAN_MPI_CALL(PMPI_Comm_rank)(MPI_COMM_WORLD, &my_rank);
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    if(getenv("DARSHAN_INTERNAL_TIMING"))
        internal_timing_flag = 1;

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    if(internal_timing_flag)
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        init_start = DARSHAN_MPI_CALL(PMPI_Wtime)();

    /* setup darshan runtime if darshan is enabled and hasn't been initialized already */
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    if(!getenv("DARSHAN_DISABLE") && !darshan_core)
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    {
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        #if (__DARSHAN_MEM_ALIGNMENT < 1)
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            #error Darshan must be configured with a positive value for --with-mem-align
        #endif
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        envstr = getenv(DARSHAN_MEM_ALIGNMENT_OVERRIDE);
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        if(envstr)
        {
            ret = sscanf(envstr, "%d", &tmpval);
            /* silently ignore if the env variable is set poorly */
            if(ret == 1 && tmpval > 0)
            {
                darshan_mem_alignment = tmpval;
            }
        }
        else
        {
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            darshan_mem_alignment = __DARSHAN_MEM_ALIGNMENT;
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        }

        /* avoid floating point errors on faulty input */
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        if(darshan_mem_alignment < 1)
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        {
            darshan_mem_alignment = 1;
        }
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        /* Use DARSHAN_JOBID_OVERRIDE for the env var for __DARSHAN_JOBID */
        envstr = getenv(DARSHAN_JOBID_OVERRIDE);
        if(!envstr)
        {
            envstr = __DARSHAN_JOBID;
        }

        /* find a job id */
        jobid_str = getenv(envstr);
        if(jobid_str)
        {
            /* in cobalt we can find it in env var */
            ret = sscanf(jobid_str, "%d", &jobid);
        }
        if(!jobid_str || ret != 1)
        {
            /* use pid as fall back */
            jobid = getpid();
        }

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        /* allocate structure to track darshan core runtime information */
        init_core = malloc(sizeof(*init_core));
        if(init_core)
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        {
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            memset(init_core, 0, sizeof(*init_core));
            init_core->wtime_offset = DARSHAN_MPI_CALL(PMPI_Wtime)();

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#ifndef __DARSHAN_ENABLE_MMAP_LOGS
            /* just allocate memory for each log file region */
            init_core->log_hdr_p = malloc(sizeof(struct darshan_header));
            init_core->log_job_p = malloc(sizeof(struct darshan_job));
            init_core->log_exemnt_p = malloc(DARSHAN_EXE_LEN+1);
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            init_core->log_name_p = malloc(DARSHAN_NAME_RECORD_BUF_SIZE);
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            init_core->log_mod_p = malloc(DARSHAN_MOD_MEM_MAX);

            if(!(init_core->log_hdr_p) || !(init_core->log_job_p) ||
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               !(init_core->log_exemnt_p) || !(init_core->log_name_p) ||
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               !(init_core->log_mod_p))
            {
                free(init_core);
                return;
            }
            /* if allocation succeeds, zero fill memory regions */
            memset(init_core->log_hdr_p, 0, sizeof(struct darshan_header));
            memset(init_core->log_job_p, 0, sizeof(struct darshan_job));
            memset(init_core->log_exemnt_p, 0, DARSHAN_EXE_LEN+1);
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            memset(init_core->log_name_p, 0, DARSHAN_NAME_RECORD_BUF_SIZE);
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            memset(init_core->log_mod_p, 0, DARSHAN_MOD_MEM_MAX);
#else
            /* if mmap logs are enabled, we need to initialize the mmap region
             * before setting the corresponding log file region pointers
             */

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            sys_page_size = sysconf(_SC_PAGESIZE);
            assert(sys_page_size > 0);
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            mmap_size = sizeof(struct darshan_header) + DARSHAN_JOB_RECORD_SIZE +
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                + DARSHAN_NAME_RECORD_BUF_SIZE + DARSHAN_MOD_MEM_MAX;
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            if(mmap_size % sys_page_size)
                mmap_size = ((mmap_size / sys_page_size) + 1) * sys_page_size;
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            envstr = getenv(DARSHAN_MMAP_LOG_PATH_OVERRIDE);
            if(envstr)
                mmap_log_dir = envstr;
            else
                mmap_log_dir = DARSHAN_DEF_MMAP_LOG_PATH;

            darshan_get_user_name(cuser);

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            /* construct a unique temporary log file name for this process
             * to write mmap log data to
             */
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            snprintf(init_core->mmap_log_name, PATH_MAX,
                "/%s/%s_%s_id%d_mmap-log-%d.darshan",
                mmap_log_dir, cuser, __progname, jobid, my_rank);
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            /* create the temporary mmapped darshan log */
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            mmap_fd = open(init_core->mmap_log_name, O_CREAT|O_RDWR|O_EXCL , 0644);
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            if(mmap_fd < 0)
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            {
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                fprintf(stderr, "darshan library warning: "
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                    "unable to create darshan log file %s\n", init_core->mmap_log_name);
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                free(init_core);
                return;
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            }

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            /* TODO: what's more expensive? truncate or write zeros? perf test this call and later accesses */
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            /* allocate the necessary space in the log file */
            ret = ftruncate(mmap_fd, mmap_size);
            if(ret < 0)
            {
                fprintf(stderr, "darshan library warning: "
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                    "unable to allocate darshan log file %s\n", init_core->mmap_log_name);
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                free(init_core);
                close(mmap_fd);
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                unlink(init_core->mmap_log_name);
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                return;
            }

            /* memory map buffers for getting at least some summary i/o data
             * into a log file if darshan does not shut down properly
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             */
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            void *mmap_p = mmap(NULL, mmap_size, PROT_WRITE, MAP_SHARED, mmap_fd, 0);
            if(mmap_p == MAP_FAILED)
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            {
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                fprintf(stderr, "darshan library warning: "
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                    "unable to mmap darshan log file %s\n", init_core->mmap_log_name);
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                free(init_core);
                close(mmap_fd);
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                unlink(init_core->mmap_log_name);
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                return;
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            }

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            /* close darshan log file (this does *not* unmap the log file) */
            close(mmap_fd);

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            /* set the memory pointers for each log file region */
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            init_core->log_hdr_p = (struct darshan_header *)mmap_p;
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            init_core->log_job_p = (struct darshan_job *)
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                ((char *)init_core->log_hdr_p + sizeof(struct darshan_header));
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            init_core->log_exemnt_p = (char *)
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                ((char *)init_core->log_job_p + sizeof(struct darshan_job));
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            init_core->log_name_p = (void *)
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                ((char *)init_core->log_exemnt_p + DARSHAN_EXE_LEN + 1);
            init_core->log_mod_p = (void *)
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                ((char *)init_core->log_name_p + DARSHAN_NAME_RECORD_BUF_SIZE);
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            /* set header fields needed for the mmap log mechanism */
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            init_core->log_hdr_p->comp_type = DARSHAN_NO_COMP;
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            init_core->log_hdr_p->name_map.off =
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                sizeof(struct darshan_header) + DARSHAN_JOB_RECORD_SIZE;
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#endif

            /* set known header fields for the log file */
            strcpy(init_core->log_hdr_p->version_string, DARSHAN_LOG_VERSION);
            init_core->log_hdr_p->magic_nr = DARSHAN_MAGIC_NR;
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            /* set known job-level metadata fields for the log file */
            init_core->log_job_p->uid = getuid();
            init_core->log_job_p->start_time = time(NULL);
            init_core->log_job_p->nprocs = nprocs;
            init_core->log_job_p->jobid = (int64_t)jobid;
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            /* if we are using any hints to write the log file, then record those
             * hints with the darshan job information
             */
            darshan_log_record_hints_and_ver(init_core);

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            /* collect information about command line and mounted file systems */
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            darshan_get_exe_and_mounts(init_core, argc, argv);
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            /* bootstrap any modules with static initialization routines */
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            i = 0;
            while(mod_static_init_fns[i])
            {
                (*mod_static_init_fns[i])();
                i++;
            }

            darshan_core = init_core;
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        }
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    }

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    /* reduce so all ranks agree on the job start time */
    DARSHAN_MPI_CALL(PMPI_Allreduce)(MPI_IN_PLACE, &init_core->log_job_p->start_time,
        1, MPI_INT64_T, MPI_MIN, MPI_COMM_WORLD);

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    if(internal_timing_flag)
    {
        init_time = DARSHAN_MPI_CALL(PMPI_Wtime)() - init_start;
        DARSHAN_MPI_CALL(PMPI_Reduce)(&init_time, &init_max, 1,
            MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
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        if(my_rank == 0)
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        {
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            fprintf(stderr, "#darshan:<op>\t<nprocs>\t<time>\n");
            fprintf(stderr, "darshan:init\t%d\t%f\n", nprocs, init_max);
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        }
    }

    return;
}

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void darshan_core_shutdown()
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{
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    struct darshan_core_runtime *final_core;
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    struct darshan_header out_header;
    struct darshan_job out_job;
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    int internal_timing_flag = 0;
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    struct tm *start_tm;
    time_t start_time_tmp;
    int64_t last_end_time;
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    double start_log_time;
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    double tm_end;
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    double open1, open2;
    double job1, job2;
    double rec1, rec2;
    double mod1[DARSHAN_MAX_MODS] = {0};
    double mod2[DARSHAN_MAX_MODS] = {0};
    double header1, header2;
    char *logfile_name;
    int local_mod_use[DARSHAN_MAX_MODS] = {0};
    int global_mod_use_count[DARSHAN_MAX_MODS] = {0};
    darshan_record_id *shared_recs;
    darshan_record_id *mod_shared_recs;
    int shared_rec_cnt = 0;
    int ret = 0;
    int all_ret = 0;
    int i;
    uint64_t gz_fp = 0;
    MPI_File log_fh;
    MPI_Status status;
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    if(getenv("DARSHAN_INTERNAL_TIMING"))
        internal_timing_flag = 1;

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    start_log_time = DARSHAN_MPI_CALL(PMPI_Wtime)();
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    /* disable darhan-core while we shutdown */
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    DARSHAN_CORE_LOCK();
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    if(!darshan_core)
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    {
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        DARSHAN_CORE_UNLOCK();
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        return;
    }
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    final_core = darshan_core;
    darshan_core = NULL;
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    DARSHAN_CORE_UNLOCK();

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    memcpy(&out_job, final_core->log_job_p, sizeof(struct darshan_job));

#ifdef __DARSHAN_ENABLE_MMAP_LOGS
    /* TODO: can we get rid of out_ header and job?? */
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    /* XXX just copy mmap files somewhere else to avoid corruption */
    DARSHAN_MPI_CALL(PMPI_Barrier)(MPI_COMM_WORLD);
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    char cp_cmd[500] = {0};
    sprintf(cp_cmd, "cp %s ~/Desktop", final_core->mmap_log_name);
    system(cp_cmd);
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    DARSHAN_MPI_CALL(PMPI_Barrier)(MPI_COMM_WORLD);

    /* indicate in the metadata field of the temporary darshan log file that
     * the darshan shutdown process was invoked on the data in the log. since
     * we have no way of knowing how far the shutdown process got, the data
     * could potentially be in inconsistent or corrupt state. in this case,
     * darshan currently does not generate a log file at all.
     */
    char *m = final_core->log_job_p->metadata + strlen(final_core->log_job_p->metadata);
    int meta_remain = DARSHAN_JOB_METADATA_LEN - strlen(final_core->log_job_p->metadata) - 1;
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    /* TODO: do we ever check for darshan_shutdown? */
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    snprintf(m, meta_remain, "darshan_shutdown=yes\n");
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#endif
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    /* we also need to set which modules were registered on this process and
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     * call into those modules and give them a chance to perform any necessary
     * pre-shutdown steps.
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     */
    for(i = 0; i < DARSHAN_MAX_MODS; i++)
    {
        if(final_core->mod_array[i])
        {
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            local_mod_use[i] = 1;
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            final_core->mod_array[i]->funcs.begin_shutdown();
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        }
    }
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    final_core->comp_buf = malloc(DARSHAN_COMP_BUF_SIZE);
    if(!(final_core->comp_buf))
    {
        darshan_core_cleanup(final_core);
        return;
    }
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    logfile_name = malloc(PATH_MAX);
    if(!logfile_name)
    {
        darshan_core_cleanup(final_core);
        return;
    }

    /* set the log file name on rank 0 */
    if(my_rank == 0)
    {
        /* use human readable start time format in log filename */
        start_time_tmp = final_core->log_job_p->start_time;
        start_tm = localtime(&start_time_tmp);

        darshan_get_logfile_name(logfile_name, final_core->log_job_p->jobid, start_tm);
    }

    /* broadcast log file name */
    DARSHAN_MPI_CALL(PMPI_Bcast)(logfile_name, PATH_MAX, MPI_CHAR, 0,
        MPI_COMM_WORLD);

    if(strlen(logfile_name) == 0)
    {
        /* failed to generate log file name */
        free(logfile_name);
        darshan_core_cleanup(final_core);
        return;
    }
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    final_core->log_job_p->end_time = time(NULL);
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    /* reduce to report last end time across all ranks at rank 0 */
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    DARSHAN_MPI_CALL(PMPI_Reduce)(&final_core->log_job_p->end_time, &last_end_time,
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        1, MPI_INT64_T, MPI_MAX, 0, MPI_COMM_WORLD);
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    if(my_rank == 0)
    {
        out_job.end_time = last_end_time;
    }

    /* reduce the number of times a module was opened globally and bcast to everyone */
    DARSHAN_MPI_CALL(PMPI_Allreduce)(local_mod_use, global_mod_use_count,
        DARSHAN_MAX_MODS, MPI_INT, MPI_SUM, MPI_COMM_WORLD);

    /* get a list of records which are shared across all processes */
    darshan_get_shared_records(final_core, &shared_recs, &shared_rec_cnt);

    if(internal_timing_flag)
        open1 = DARSHAN_MPI_CALL(PMPI_Wtime)();
    /* collectively open the darshan log file */
    ret = darshan_log_open_all(logfile_name, &log_fh);
    if(internal_timing_flag)
        open2 = DARSHAN_MPI_CALL(PMPI_Wtime)();

    /* error out if unable to open log file */
    DARSHAN_MPI_CALL(PMPI_Allreduce)(&ret, &all_ret, 1, MPI_INT,
        MPI_LOR, MPI_COMM_WORLD);
    if(all_ret != 0)
    {
        if(my_rank == 0)
        {
            fprintf(stderr, "darshan library warning: unable to open log file %s\n",
                logfile_name);
        }
        free(logfile_name);
        darshan_core_cleanup(final_core);
        return;
    }

    if(internal_timing_flag)
        job1 = DARSHAN_MPI_CALL(PMPI_Wtime)();
    /* rank 0 is responsible for writing the compressed darshan job information */
    if(my_rank == 0)
    {
        void *pointers[2] = {&out_job, final_core->log_exemnt_p};
        int lengths[2] = {sizeof(struct darshan_job), strlen(final_core->log_exemnt_p)};
        int comp_buf_sz = 0;

        /* compress the job info and the trailing mount/exe data */
        all_ret = darshan_deflate_buffer(pointers, lengths, 2,
            final_core->comp_buf, &comp_buf_sz);
        if(all_ret)
        {
            fprintf(stderr, "darshan library warning: unable to compress job data\n");
            unlink(logfile_name);
        }
        else
        {
            /* write the job information, preallocing space for the log header */
            gz_fp += sizeof(struct darshan_header);
            all_ret = DARSHAN_MPI_CALL(PMPI_File_write_at)(log_fh, gz_fp,
                final_core->comp_buf, comp_buf_sz, MPI_BYTE, &status);
            if(all_ret != MPI_SUCCESS)
            {
                fprintf(stderr,
                        "darshan library warning: unable to write job data to log file %s\n",
                        logfile_name);
                unlink(logfile_name);

            }
            gz_fp += comp_buf_sz;
        }
    }

    /* error out if unable to write job information */
    DARSHAN_MPI_CALL(PMPI_Bcast)(&all_ret, 1, MPI_INT, 0, MPI_COMM_WORLD);
    if(all_ret != 0)
    {
        free(logfile_name);
        darshan_core_cleanup(final_core);
        return;
    }
    if(internal_timing_flag)
        job2 = DARSHAN_MPI_CALL(PMPI_Wtime)();

    if(internal_timing_flag)
        rec1 = DARSHAN_MPI_CALL(PMPI_Wtime)();
    /* write the record name->id hash to the log file */
567 568 569
    out_header.name_map.off = gz_fp;
    ret = darshan_log_write_name_record_hash(log_fh, final_core, &gz_fp);
    out_header.name_map.len = gz_fp - out_header.name_map.off;
570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603

    /* error out if unable to write record hash */
    DARSHAN_MPI_CALL(PMPI_Allreduce)(&ret, &all_ret, 1, MPI_INT,
        MPI_LOR, MPI_COMM_WORLD);
    if(all_ret != 0)
    {
        if(my_rank == 0)
        {
            fprintf(stderr,
                "darshan library warning: unable to write record hash to log file %s\n",
                logfile_name);
            unlink(logfile_name);
        }
        free(logfile_name);
        darshan_core_cleanup(final_core);
        return;
    }
    if(internal_timing_flag)
        rec2 = DARSHAN_MPI_CALL(PMPI_Wtime)();

    mod_shared_recs = malloc(shared_rec_cnt * sizeof(darshan_record_id));
    assert(mod_shared_recs);

    /* loop over globally used darshan modules and:
     *      - perform shared file reductions, if possible
     *      - get final output buffer
     *      - compress (zlib) provided output buffer
     *      - append compressed buffer to log file
     *      - add module index info (file offset/length) to log header
     *      - shutdown the module
     */
    for(i = 0; i < DARSHAN_MAX_MODS; i++)
    {
        struct darshan_core_module* this_mod = final_core->mod_array[i];
604
        struct darshan_core_name_record_ref *ref = NULL;
605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626
        int mod_shared_rec_cnt = 0;
        void* mod_buf = NULL;
        int mod_buf_sz = 0;
        int j;

        if(global_mod_use_count[i] == 0)
        {
            if(my_rank == 0)
            {
                out_header.mod_map[i].off = 0;
                out_header.mod_map[i].len = 0;
            }
            continue;
        }

        if(internal_timing_flag)
            mod1[i] = DARSHAN_MPI_CALL(PMPI_Wtime)();

        /* set the shared file list for this module */
        memset(mod_shared_recs, 0, shared_rec_cnt * sizeof(darshan_record_id));
        for(j = 0; j < shared_rec_cnt; j++)
        {
627
            HASH_FIND(hlink, final_core->name_hash, &shared_recs[j],
628 629 630 631 632 633 634 635 636 637 638 639 640 641 642
                sizeof(darshan_record_id), ref);
            assert(ref);
            if(DARSHAN_MOD_FLAG_ISSET(ref->global_mod_flags, i))
            {
                mod_shared_recs[mod_shared_rec_cnt++] = shared_recs[j];
            }
        }

        /* if module is registered locally, get the corresponding output buffer
         * 
         * NOTE: this function can be used to run collective operations across
         * modules, if there are file records shared globally.
         */
        if(this_mod)
        {
643 644 645
            mod_buf = final_core->mod_array[i]->rec_buf_start;
            mod_buf_sz = final_core->mod_array[i]->rec_buf_p - mod_buf;
            this_mod->funcs.get_output_data(MPI_COMM_WORLD, mod_shared_recs,
646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673
                mod_shared_rec_cnt, &mod_buf, &mod_buf_sz);
        }

        /* append this module's data to the darshan log */
        out_header.mod_map[i].off = gz_fp;
        ret = darshan_log_append_all(log_fh, final_core, mod_buf, mod_buf_sz, &gz_fp);
        out_header.mod_map[i].len = gz_fp - out_header.mod_map[i].off;

        /* error out if the log append failed */
        DARSHAN_MPI_CALL(PMPI_Allreduce)(&ret, &all_ret, 1, MPI_INT,
            MPI_LOR, MPI_COMM_WORLD);
        if(all_ret != 0)
        {
            if(my_rank == 0)
            {
                fprintf(stderr,
                    "darshan library warning: unable to write %s module data to log file %s\n",
                    darshan_module_names[i], logfile_name);
                unlink(logfile_name);
            }
            free(logfile_name);
            darshan_core_cleanup(final_core);
            return;
        }

        /* shutdown module if registered locally */
        if(this_mod)
        {
674
            this_mod->funcs.shutdown();
675 676 677 678 679 680 681 682 683 684 685 686 687 688 689
        }
        if(internal_timing_flag)
            mod2[i] = DARSHAN_MPI_CALL(PMPI_Wtime)();
    }

    if(internal_timing_flag)
        header1 = DARSHAN_MPI_CALL(PMPI_Wtime)();
    /* write out log header, after running 2 reduction on header variables:
     *  1) reduce 'partial_flag' variable to determine which modules ran out
     *     of memory for storing I/O data
     *  2) reduce 'mod_ver' array to determine which log format version each
     *     module used for this output log
     */
    DARSHAN_MPI_CALL(PMPI_Reduce)(&(final_core->log_hdr_p->partial_flag),
        &(out_header.partial_flag), 1, MPI_UINT32_T, MPI_BOR, 0, MPI_COMM_WORLD);
690 691 692
    DARSHAN_MPI_CALL(PMPI_Reduce)(&(final_core->log_hdr_p->mod_ver),
        &(out_header.mod_ver), DARSHAN_MAX_MODS, MPI_UINT32_T, MPI_MAX,
        0, MPI_COMM_WORLD);
693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729
    if(my_rank == 0)
    {
        /* rank 0 is responsible for writing the log header */
        /* initialize the remaining header fields */
        strcpy(out_header.version_string, DARSHAN_LOG_VERSION);
        out_header.magic_nr = DARSHAN_MAGIC_NR;
        out_header.comp_type = DARSHAN_ZLIB_COMP;

        all_ret = DARSHAN_MPI_CALL(PMPI_File_write_at)(log_fh, 0, &out_header,
            sizeof(struct darshan_header), MPI_BYTE, &status);
        if(all_ret != MPI_SUCCESS)
        {
            fprintf(stderr, "darshan library warning: unable to write header to log file %s\n",
                    logfile_name);
            unlink(logfile_name);
        }
    }

    /* error out if unable to write log header */
    DARSHAN_MPI_CALL(PMPI_Bcast)(&all_ret, 1, MPI_INT, 0, MPI_COMM_WORLD);
    if(all_ret != 0)
    {
        free(logfile_name);
        darshan_core_cleanup(final_core);
        return;
    }
    if(internal_timing_flag)
        header2 = DARSHAN_MPI_CALL(PMPI_Wtime)();

    DARSHAN_MPI_CALL(PMPI_File_close)(&log_fh);

    /* if we got this far, there are no errors, so rename from *.darshan_partial
     * to *-<logwritetime>.darshan, which indicates that this log file is
     * complete and ready for analysis
     */
    if(my_rank == 0)
    {
730
        mode_t chmod_mode = S_IRUSR;
731
#ifdef __DARSHAN_GROUP_READABLE_LOGS
732
        chmod_mode |= S_IRGRP;
733
#endif
734 735 736 737

        if(getenv("DARSHAN_LOGFILE"))
        {
            chmod(logfile_name, chmod_mode);
738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754
        }
        else
        {
            char* tmp_index;
            double end_log_time;
            char* new_logfile_name;

            new_logfile_name = malloc(PATH_MAX);
            if(new_logfile_name)
            {
                new_logfile_name[0] = '\0';
                end_log_time = DARSHAN_MPI_CALL(PMPI_Wtime)();
                strcat(new_logfile_name, logfile_name);
                tmp_index = strstr(new_logfile_name, ".darshan_partial");
                sprintf(tmp_index, "_%d.darshan", (int)(end_log_time-start_log_time+1));
                rename(logfile_name, new_logfile_name);
                /* set permissions on log file */
755
                chmod(new_logfile_name, chmod_mode);
756 757 758 759 760
                free(new_logfile_name);
            }
        }
    }

761
#ifdef __DARSHAN_ENABLE_MMAP_LOGS
762 763
    /* remove the temporary mmap log files */
    unlink(final_core->mmap_log_name);
764
#endif
765 766

    free(logfile_name);
767 768
    free(shared_recs);
    free(mod_shared_recs);
769
    darshan_core_cleanup(final_core);
770

771
    if(internal_timing_flag)
772
    {
773 774 775 776 777
        double open_tm, open_slowest;
        double header_tm, header_slowest;
        double job_tm, job_slowest;
        double rec_tm, rec_slowest;
        double mod_tm[DARSHAN_MAX_MODS], mod_slowest[DARSHAN_MAX_MODS];
778 779 780 781
        double all_tm, all_slowest;

        tm_end = DARSHAN_MPI_CALL(PMPI_Wtime)();

782 783 784 785
        open_tm = open2 - open1;
        header_tm = header2 - header1;
        job_tm = job2 - job1;
        rec_tm = rec2 - rec1;
786
        all_tm = tm_end - start_log_time;
787 788 789 790
        for(i = 0;i < DARSHAN_MAX_MODS; i++)
        {
            mod_tm[i] = mod2[i] - mod1[i];
        }
791

792 793 794 795 796 797 798 799
        DARSHAN_MPI_CALL(PMPI_Reduce)(&open_tm, &open_slowest, 1,
            MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
        DARSHAN_MPI_CALL(PMPI_Reduce)(&header_tm, &header_slowest, 1,
            MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
        DARSHAN_MPI_CALL(PMPI_Reduce)(&job_tm, &job_slowest, 1,
            MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
        DARSHAN_MPI_CALL(PMPI_Reduce)(&rec_tm, &rec_slowest, 1,
            MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
800 801
        DARSHAN_MPI_CALL(PMPI_Reduce)(&all_tm, &all_slowest, 1,
            MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
802 803
        DARSHAN_MPI_CALL(PMPI_Reduce)(mod_tm, mod_slowest, DARSHAN_MAX_MODS,
            MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD);
804 805 806

        if(my_rank == 0)
        {
807
            fprintf(stderr, "#darshan:<op>\t<nprocs>\t<time>\n");
808 809 810 811 812 813 814 815 816 817
            fprintf(stderr, "darshan:log_open\t%d\t%f\n", nprocs, open_slowest);
            fprintf(stderr, "darshan:job_write\t%d\t%f\n", nprocs, job_slowest);
            fprintf(stderr, "darshan:hash_write\t%d\t%f\n", nprocs, rec_slowest);
            fprintf(stderr, "darshan:header_write\t%d\t%f\n", nprocs, header_slowest);
            for(i = 0; i < DARSHAN_MAX_MODS; i++)
            {
                if(global_mod_use_count[i])
                    fprintf(stderr, "darshan:%s_shutdown\t%d\t%f\n", darshan_module_names[i],
                        nprocs, mod_slowest[i]);
            }
818
            fprintf(stderr, "darshan:core_shutdown\t%d\t%f\n", nprocs, all_slowest);
819
        }
820
    }
821

822 823
    return;
}
824

825
/* *********************************** */
826

827
/* record any hints used to write the darshan log in the job data */
828
static void darshan_log_record_hints_and_ver(struct darshan_core_runtime* core)
829 830
{
    char* hints;
831
    char* job_hints;
832 833 834 835 836 837
    int meta_remain = 0;
    char* m;

    /* check environment variable to see if the default MPI file hints have
     * been overridden
     */
838
    hints = getenv(DARSHAN_LOG_HINTS_OVERRIDE);
839 840
    if(!hints)
    {
841
        hints = __DARSHAN_LOG_HINTS;
842 843 844 845 846
    }

    if(!hints || strlen(hints) < 1)
        return;

847 848
    job_hints = strdup(hints);
    if(!job_hints)
849 850 851
        return;

    meta_remain = DARSHAN_JOB_METADATA_LEN -
852
        strlen(core->log_job_p->metadata) - 1;
853 854
    if(meta_remain >= (strlen(PACKAGE_VERSION) + 9))
    {
855
        sprintf(core->log_job_p->metadata, "lib_ver=%s\n", PACKAGE_VERSION);
856 857
        meta_remain -= (strlen(PACKAGE_VERSION) + 9);
    }
858
    if(meta_remain >= (3 + strlen(job_hints)))
859
    {
860
        m = core->log_job_p->metadata + strlen(core->log_job_p->metadata);
861
        /* We have room to store the hints in the metadata portion of
862
         * the job structure.  We just prepend an h= to the hints list.  The
863 864 865
         * metadata parser will ignore = characters that appear in the value
         * portion of the metadata key/value pair.
         */
866
        sprintf(m, "h=%s\n", job_hints);
867
    }
868
    free(job_hints);
869 870 871 872

    return;
}

873 874 875 876 877 878 879 880 881 882 883 884 885 886
static int mnt_data_cmp(const void* a, const void* b)
{
    const struct mnt_data *d_a = (const struct mnt_data*)a;
    const struct mnt_data *d_b = (const struct mnt_data*)b;

    if(strlen(d_a->path) > strlen(d_b->path))
        return(-1);
    else if(strlen(d_a->path) < strlen(d_b->path))
        return(1);
    else
        return(0);
}

/* adds an entry to table of mounted file systems */
887
static void add_entry(char* buf, int* space_left, struct mntent *entry)
888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911
{
    int ret;
    char tmp_mnt[256];
    struct statfs statfsbuf;

    strncpy(mnt_data_array[mnt_data_count].path, entry->mnt_dir,
        DARSHAN_MAX_MNT_PATH-1);
    strncpy(mnt_data_array[mnt_data_count].type, entry->mnt_type,
        DARSHAN_MAX_MNT_TYPE-1);
    /* NOTE: we now try to detect the preferred block size for each file 
     * system using fstatfs().  On Lustre we assume a size of 1 MiB 
     * because fstatfs() reports 4 KiB. 
     */
#ifndef LL_SUPER_MAGIC
#define LL_SUPER_MAGIC 0x0BD00BD0
#endif
    ret = statfs(entry->mnt_dir, &statfsbuf);
    if(ret == 0 && statfsbuf.f_type != LL_SUPER_MAGIC)
        mnt_data_array[mnt_data_count].block_size = statfsbuf.f_bsize;
    else if(ret == 0 && statfsbuf.f_type == LL_SUPER_MAGIC)
        mnt_data_array[mnt_data_count].block_size = 1024*1024;
    else
        mnt_data_array[mnt_data_count].block_size = 4096;

912
    /* store mount information with the job-level metadata in darshan log */
913
    ret = snprintf(tmp_mnt, 256, "\n%s\t%s",
914 915 916
        entry->mnt_type, entry->mnt_dir);
    if(ret < 256 && strlen(tmp_mnt) <= (*space_left))
    {
917
        strcat(buf, tmp_mnt);
918 919 920 921 922 923 924
        (*space_left) -= strlen(tmp_mnt);
    }

    mnt_data_count++;
    return;
}

925
/* darshan_get_exe_and_mounts()
926 927
 *
 * collects command line and list of mounted file systems into a string that
928
 * will be stored with the job-level metadata
929
 */
930
static void darshan_get_exe_and_mounts(struct darshan_core_runtime *core,
931
    int argc, char **argv)
932 933 934 935
{
    FILE* tab;
    struct mntent *entry;
    char* exclude;
936 937 938 939
    char* truncate_string = "<TRUNCATED>";
    int truncate_offset;
    int space_left = DARSHAN_EXE_LEN;
    int i;
940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960
    int tmp_index = 0;
    int skip = 0;

    /* skip these fs types */
    static char* fs_exclusions[] = {
        "tmpfs",
        "proc",
        "sysfs",
        "devpts",
        "binfmt_misc",
        "fusectl",
        "debugfs",
        "securityfs",
        "nfsd",
        "none",
        "rpc_pipefs",
        "hugetlbfs",
        "cgroup",
        NULL
    };

961 962 963
    /* record exe and arguments */
    for(i=0; i<argc; i++)
    {
964 965
        strncat(core->log_exemnt_p, argv[i], space_left);
        space_left = DARSHAN_EXE_LEN-strlen(core->log_exemnt_p);
966 967
        if(i < (argc-1))
        {
968 969
            strncat(core->log_exemnt_p, " ", space_left);
            space_left = DARSHAN_EXE_LEN-strlen(core->log_exemnt_p);
970 971 972 973 974 975 976 977
        }
    }

    /* if we don't see any arguments, then use glibc symbol to get
     * program name at least (this happens in fortran)
     */
    if(argc == 0)
    {
978 979 980 981
        strncat(core->log_exemnt_p, __progname_full, space_left);
        space_left = DARSHAN_EXE_LEN-strlen(core->log_exemnt_p);
        strncat(core->log_exemnt_p, " <unknown args>", space_left);
        space_left = DARSHAN_EXE_LEN-strlen(core->log_exemnt_p);
982 983 984 985 986 987
    }

    if(space_left == 0)
    {
        /* we ran out of room; mark that string was truncated */
        truncate_offset = DARSHAN_EXE_LEN - strlen(truncate_string);
988
        sprintf(&(core->log_exemnt_p[truncate_offset]), "%s",
989 990 991
            truncate_string);
    }

992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018
    /* we make two passes through mounted file systems; in the first pass we
     * grab any non-nfs mount points, then on the second pass we grab nfs
     * mount points
     */

    tab = setmntent("/etc/mtab", "r");
    if(!tab)
        return;
    /* loop through list of mounted file systems */
    while(mnt_data_count<DARSHAN_MAX_MNTS && (entry = getmntent(tab)) != NULL)
    {
        /* filter out excluded fs types */
        tmp_index = 0;
        skip = 0;
        while((exclude = fs_exclusions[tmp_index]))
        {
            if(!(strcmp(exclude, entry->mnt_type)))
            {
                skip =1;
                break;
            }
            tmp_index++;
        }

        if(skip || (strcmp(entry->mnt_type, "nfs") == 0))
            continue;

1019
        add_entry(core->log_exemnt_p, &space_left, entry);
1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031
    }
    endmntent(tab);

    tab = setmntent("/etc/mtab", "r");
    if(!tab)
        return;
    /* loop through list of mounted file systems */
    while(mnt_data_count<DARSHAN_MAX_MNTS && (entry = getmntent(tab)) != NULL)
    {
        if(strcmp(entry->mnt_type, "nfs") != 0)
            continue;

1032
        add_entry(core->log_exemnt_p, &space_left, entry);
1033 1034 1035
    }
    endmntent(tab);

1036
    /* sort mount points in order of longest path to shortest path.  This is
1037 1038 1039 1040 1041 1042 1043
     * necessary so that if we try to match file paths to mount points later
     * we don't match on "/" every time.
     */
    qsort(mnt_data_array, mnt_data_count, sizeof(mnt_data_array[0]), mnt_data_cmp);
    return;
}

1044
static int darshan_block_size_from_path(const char *path)
1045
{
1046
    int i;
1047
    int block_size = -1;
1048

1049
    for(i=0; i<mnt_data_count; i++)
1050
    {
1051
        if(!(strncmp(mnt_data_array[i].path, path, strlen(mnt_data_array[i].path))))
1052
        {
1053 1054
            block_size = mnt_data_array[i].block_size;
            break;;
1055 1056 1057
        }
    }

1058
    return block_size;
1059 1060
}

1061
static void darshan_get_user_name(char *cuser)
1062
{
1063
    char* logname_string;
1064

1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081
    /* get the username for this job.  In order we will try each of the
     * following until one of them succeeds:
     *
     * - cuserid()
     * - getenv("LOGNAME")
     * - snprintf(..., geteuid());
     *
     * Note that we do not use getpwuid() because it generally will not
     * work in statically compiled binaries.
     */

#ifndef __DARSHAN_DISABLE_CUSERID
    cuserid(cuser);
#endif

    /* if cuserid() didn't work, then check the environment */
    if(strcmp(cuser, "") == 0)
1082
    {
1083 1084
        logname_string = getenv("LOGNAME");
        if(logname_string)
1085
        {
1086
            strncpy(cuser, logname_string, (L_cuserid-1));
1087 1088 1089
        }
    }

1090 1091 1092 1093 1094 1095 1096
    /* if cuserid() and environment both fail, then fall back to uid */
    if(strcmp(cuser, "") == 0)
    {
        uid_t uid = geteuid();
        snprintf(cuser, L_cuserid, "%u", uid);
    }

1097 1098 1099
    return;
}

1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142
/* construct the darshan log file name */
static void darshan_get_logfile_name(char* logfile_name, int jobid, struct tm* start_tm)
{
    char* user_logfile_name;
    char* logpath;
    char* logpath_override = NULL;
#ifdef __DARSHAN_LOG_ENV
    char env_check[256];
    char* env_tok;
#endif
    uint64_t hlevel;
    char hname[HOST_NAME_MAX];
    uint64_t logmod;
    char cuser[L_cuserid] = {0};
    int ret;

    /* first, check if user specifies a complete logpath to use */
    user_logfile_name = getenv("DARSHAN_LOGFILE");
    if(user_logfile_name)
    {
        if(strlen(user_logfile_name) >= (PATH_MAX-1))
        {
            fprintf(stderr, "darshan library warning: user log file name too long.\n");
            logfile_name[0] = '\0';
        }
        else
        {
            strcpy(logfile_name, user_logfile_name);
        }
    }
    else
    {
        /* otherwise, generate the log path automatically */

        /* Use DARSHAN_LOG_PATH_OVERRIDE for the value or __DARSHAN_LOG_PATH */
        logpath = getenv(DARSHAN_LOG_PATH_OVERRIDE);
        if(!logpath)
        {
#ifdef __DARSHAN_LOG_PATH
            logpath = __DARSHAN_LOG_PATH;
#endif
        }

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        darshan_get_user_name(cuser);
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        /* generate a random number to help differentiate the log */
        hlevel=DARSHAN_MPI_CALL(PMPI_Wtime)() * 1000000;
        (void)gethostname(hname, sizeof(hname));
        logmod = darshan_hash((void*)hname,strlen(hname),hlevel);

        /* see if darshan was configured using the --with-logpath-by-env
         * argument, which allows the user to specify an absolute path to
         * place logs via an env variable.
         */
#ifdef __DARSHAN_LOG_ENV
        /* just silently skip if the environment variable list is too big */
        if(strlen(__DARSHAN_LOG_ENV) < 256)
        {
            /* copy env variable list to a temporary buffer */
            strcpy(env_check, __DARSHAN_LOG_ENV);
            /* tokenize the comma-separated list */
            env_tok = strtok(env_check, ",");
            if(env_tok)
            {
                do
                {
                    /* check each env variable in order */
                    logpath_override = getenv(env_tok);
                    if(logpath_override)
                    {
                        /* stop as soon as we find a match */
                        break;
                    }
                }while((env_tok = strtok(NULL, ",")));
            }
        }
#endif

        if(logpath_override)
        {
            ret = snprintf(logfile_name, PATH_MAX,
                "%s/%s_%s_id%d_%d-%d-%d-%" PRIu64 ".darshan_partial",
                logpath_override,
                cuser, __progname, jobid,
                (start_tm->tm_mon+1),
                start_tm->tm_mday,
                (start_tm->tm_hour*60*60 + start_tm->tm_min*60 + start_tm->tm_sec),
                logmod);
            if(ret == (PATH_MAX-1))
            {
                /* file name was too big; squish it down */
                snprintf(logfile_name, PATH_MAX,
                    "%s/id%d.darshan_partial",
                    logpath_override, jobid);
            }
        }
        else if(logpath)
        {
            ret = snprintf(logfile_name, PATH_MAX,
                "%s/%d/%d/%d/%s_%s_id%d_%d-%d-%d-%" PRIu64 ".darshan_partial",
                logpath, (start_tm->tm_year+1900),
                (start_tm->tm_mon+1), start_tm->tm_mday,
                cuser, __progname, jobid,
                (start_tm->tm_mon+1),
                start_tm->tm_mday,
                (start_tm->tm_hour*60*60 + start_tm->tm_min*60 + start_tm->tm_sec),
                logmod);
            if(ret == (PATH_MAX-1))
            {
                /* file name was too big; squish it down */
                snprintf(logfile_name, PATH_MAX,
                    "%s/id%d.darshan_partial",
                    logpath, jobid);
            }
        }
        else
        {
            logfile_name[0] = '\0';
        }
    }

    return;
}

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static void darshan_add_name_record_ref(struct darshan_core_runtime *core,
    darshan_record_id rec_id, char *name, darshan_module_id mod_id)
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{
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    struct darshan_core_name_record_ref *ref;
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    int record_size = sizeof(darshan_record_id) + strlen(name) + 1;

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    if((record_size + core->log_hdr_p->name_map.len) > DARSHAN_NAME_RECORD_BUF_SIZE)
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        return;

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    ref = malloc(sizeof(*ref));
    if(ref)
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    {
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        memset(ref, 0, sizeof(*ref));
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        ref->name_record = (struct darshan_name_record *)
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            ((char *)core->log_name_p + core->log_hdr_p->name_map.len);
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        memset(ref->name_record, 0, record_size);
        ref->name_record->id = rec_id;
        strcpy(ref->name_record->name, name);

        if(!DARSHAN_MOD_FLAG_ISSET(ref->mod_flags, mod_id))
        {
            DARSHAN_MOD_FLAG_SET(ref->mod_flags, mod_id);
        }
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        /* add the record to the hash table */
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        HASH_ADD(hlink, core->name_hash, name_record->id,
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            sizeof(darshan_record_id), ref);
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        core->log_hdr_p->name_map.len += record_size;
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    }

    return;
}

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static void darshan_get_shared_records(struct darshan_core_runtime *core,
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    darshan_record_id **shared_recs, int *shared_rec_cnt)
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{
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    int i, j;
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    int tmp_cnt = HASH_CNT(hlink, core->name_hash);
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    struct darshan_core_name_record_ref *tmp, *ref;
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    darshan_record_id *id_array;
    uint64_t *mod_flags;
    uint64_t *global_mod_flags;

    /* broadcast root's number of records to all other processes */
    DARSHAN_MPI_CALL(PMPI_Bcast)(&tmp_cnt, 1, MPI_INT, 0, MPI_COMM_WORLD);

    /* use root record count to allocate data structures */
    id_array = malloc(tmp_cnt * sizeof(darshan_record_id));
    mod_flags = malloc(tmp_cnt * sizeof(uint64_t));
    global_mod_flags = malloc(tmp_cnt * sizeof(uint64_t));
    *shared_recs = malloc(tmp_cnt * sizeof(darshan_record_id));
    assert(id_array && mod_flags && global_mod_flags && *shared_recs);

    memset(mod_flags, 0, tmp_cnt * sizeof(uint64_t));
    memset(global_mod_flags, 0, tmp_cnt * sizeof(uint64_t));
    memset(*shared_recs, 0, tmp_cnt * sizeof(darshan_record_id));
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    /* first, determine list of records root process has opened */
    if(my_rank == 0)
    {
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        i = 0;
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        HASH_ITER(hlink, core->name_hash, ref, tmp)
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        {
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            id_array[i++] = ref->name_record->id;
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        }
    }

    /* broadcast root's list of records to all other processes */
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    DARSHAN_MPI_CALL(PMPI_Bcast)(id_array, (tmp_cnt * sizeof(darshan_record_id)),
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        MPI_BYTE, 0, MPI_COMM_WORLD);

    /* everyone looks to see if they opened the same records as root */
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    for(i=0; i<tmp_cnt; i++)
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    {
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        HASH_FIND(hlink, core->name_hash, &id_array[i], sizeof(darshan_record_id), ref);
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        if(ref)
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        {
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            /* we opened that record too, save the mod_flags */
            mod_flags[i] = ref->mod_flags;
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        }
    }

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    /* now allreduce so everyone agrees which files are shared and
     * which modules accessed them collectively
     */
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    DARSHAN_MPI_CALL(PMPI_Allreduce)(mod_flags, global_mod_flags, tmp_cnt,
        MPI_UINT64_T, MPI_BAND, MPI_COMM_WORLD);
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    j = 0;
    for(i=0; i<tmp_cnt; i++)
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    {
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        if(global_mod_flags[i] != 0)
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        {
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            (*shared_recs)[j++] = id_array[i];
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            /* set global_mod_flags so we know which modules collectively
             * accessed this module. we need this info to support shared
             * file reductions
             */
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            HASH_FIND(hlink, core->name_hash, &id_array[i], sizeof(darshan_record_id), ref);
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            assert(ref);
            ref->global_mod_flags = global_mod_flags[i];
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        }
    }
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    *shared_rec_cnt = j;
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    free(id_array);
    free(mod_flags);
    free(global_mod_flags);
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    return;
}

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static int darshan_log_open_all(char *logfile_name, MPI_File *log_fh)
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{
    char *hints;
    char *tok_str;
    char *orig_tok_str;
    char *key;
    char *value;
    char *saveptr = NULL;
    int ret;
    MPI_Info info;

    /* check environment variable to see if the default MPI file hints have
     * been overridden
     */
    MPI_Info_create(&info);

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    hints = getenv(DARSHAN_LOG_HINTS_OVERRIDE);
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    if(!hints)
    {
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        hints = __DARSHAN_LOG_HINTS;
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    }

    if(hints && strlen(hints) > 0)
    {
        tok_str = strdup(hints);
        if(tok_str)
        {
            orig_tok_str = tok_str;
            do
            {
                /* split string on semicolon */
                key = strtok_r(tok_str, ";", &saveptr);
                if(key)
                {
                    tok_str = NULL;
                    /* look for = sign splitting key/value pairs */
                    value = index(key, '=');
                    if(value)
                    {
                        /* break key and value into separate null terminated strings */
                        value[0] = '\0';
                        value++;
                        if(strlen(key) > 0)
                            MPI_Info_set(info, key, value);
                    }
                }
            }while(key != NULL);
            free(orig_tok_str);
        }
    }

    /* open the darshan log file for writing */
    ret = DARSHAN_MPI_CALL(PMPI_File_open)(MPI_COMM_WORLD, logfile_name,
        MPI_MODE_CREATE | MPI_MODE_WRONLY | MPI_MODE_EXCL, info, log_fh);
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    if(ret != MPI_SUCCESS)
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        return(-1);

    MPI_Info_free(&info);
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    return(0);
}

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static int darshan_deflate_buffer(void **pointers, int *lengths, int count,
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    char *comp_buf, int *comp_buf_length)
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{
    int ret = 0;
    int i;
    int total_target = 0;
    z_stream tmp_stream;

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    /* just return if there is no data */
    for(i = 0; i < count; i++)
    {
        total_target += lengths[i];
    }
    if(total_target)
    {
        total_target = 0;
    }
    else
    {
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        *comp_buf_length = 0;
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        return(0);
    }

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    memset(&tmp_stream, 0, sizeof(tmp_stream));
    tmp_stream.zalloc = Z_NULL;
    tmp_stream.zfree = Z_NULL;
    tmp_stream.opaque = Z_NULL;

    /* initialize the zlib compression parameters */
    /* TODO: check these parameters? */
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//    ret = deflateInit2(&tmp_stream, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
//        15 + 16, 8, Z_DEFAULT_STRATEGY);
    ret = deflateInit(&tmp_stream, Z_DEFAULT_COMPRESSION);
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    if(ret != Z_OK)
    {
        return(-1);
    }

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    tmp_stream.next_out = (unsigned char *)comp_buf;
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    tmp_stream.avail_out = DARSHAN_COMP_BUF_SIZE;
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    /* loop over the input pointers */
    for(i = 0; i < count; i++)
    {
        total_target += lengths[i];
        tmp_stream.next_in = pointers[i];
        tmp_stream.avail_in = lengths[i];
        /* while we have not finished consuming all of the data available to
         * this point in the loop
         */
        while(tmp_stream.total_in < total_target)
        {
            if(tmp_stream.avail_out == 0)
            {
                /* We ran out of buffer space for compression.  In theory,
                 * we could start using some of the file_array buffer space
                 * without having to malloc again.  In practice, this case 
                 * is going to be practically impossible to hit.
                 */
                deflateEnd(&tmp_stream);
                return(-1);
            }

            /* compress data */
            ret = deflate(&tmp_stream, Z_NO_FLUSH);
            if(ret != Z_OK)
            {
                deflateEnd(&tmp_stream);
                return(-1);
            }
        }
    }

    /* flush compression and end */
    ret = deflate(&tmp_stream, Z_FINISH);
    if(ret != Z_STREAM_END)
    {
        deflateEnd(&tmp_stream);
        return(-1);
    }
    deflateEnd(&tmp_stream);

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    *comp_buf_length = tmp_stream.total_out;
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    return(0);
}

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/* NOTE: the map written to file may contain duplicate id->name entries if a
 *       record is opened by multiple ranks, but not all ranks
 */
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static int darshan_log_write_name_record_hash(MPI_File log_fh,
    struct darshan_core_runtime *core, uint64_t *inout_off)
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{
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    struct darshan_core_name_record_ref *ref;
    struct darshan_name_record *name_rec;
    char *my_buf, *shared_buf;
    char *tmp_p;
    int rec_len;
    int shared_buf_len;
    int name_rec_buf_len;
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    int ret;
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    name_rec_buf_len = core->log_hdr_p->name_map.len;
    if(my_rank > 0)
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    {
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        name_rec = core->log_name_p;
        my_buf = core->log_name_p;
        shared_buf = core->comp_buf;
        shared_buf_len = 0;
        while(name_rec_buf_len > 0)
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        {
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            HASH_FIND(hlink, core->name_hash, &(name_rec->id),
                sizeof(darshan_record_id), ref);
            assert(ref);
            rec_len = sizeof(darshan_record_id) + strlen(name_rec->name) + 1;

            if(ref->global_mod_flags)
            {
                HASH_DELETE(hlink, core->name_hash, ref);
                memcpy(shared_buf, name_rec, rec_len);
                ref->name_record = (struct darshan_name_record *)shared_buf;
                HASH_ADD(hlink, core->name_hash, name_record->id,
                    sizeof(darshan_record_id), ref);

                shared_buf += rec_len;
                shared_buf_len += rec_len;
            }
            else
            {
                if(my_buf != (char *)name_rec)
                {
                    HASH_DELETE(hlink, core->name_hash, ref);
                    memcpy(my_buf, name_rec, rec_len);
                    ref->name_record =(struct darshan_name_record *)my_buf;
                    HASH_ADD(hlink, core->name_hash, name_record->id,
                        sizeof(darshan_record_id), ref);
                }
                my_buf += rec_len;
            }

            tmp_p = (char *)name_rec + rec_len;
            name_rec = (struct darshan_name_record *)tmp_p;
            name_rec_buf_len -= rec_len;
        }
        name_rec_buf_len = core->log_hdr_p->name_map.len - shared_buf_len;

        name_rec = (struct darshan_name_record *)core->comp_buf;
        while(shared_buf_len > 0)
        {
            HASH_FIND(hlink, core->name_hash, &(name_rec->id),
                sizeof(darshan_record_id), ref);
            assert(ref);
            rec_len = sizeof(darshan_record_id) + strlen(name_rec->name) + 1;

            HASH_DELETE(hlink, core->name_hash, ref);
            memcpy(my_buf, name_rec, rec_len);
            ref->name_record = (struct darshan_name_record *)my_buf;
            HASH_ADD(hlink, core->name_hash, name_record->id,
                sizeof(darshan_record_id), ref);

            tmp_p = (char *)name_rec + rec_len;
            name_rec = (struct darshan_name_record *)tmp_p;
            my_buf += rec_len;
            shared_buf_len -= rec_len;
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        }
    }
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    /* collectively write out the record hash to the darshan log */
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    ret = darshan_log_append_all(log_fh, core, core->log_name_p,
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        name_rec_buf_len, inout_off);
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    return(ret);
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}

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/* NOTE: inout_off contains the starting offset of this append at the beginning
 *       of the call, and contains the ending offset at the end of the call.
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 *       This variable is only valid on the root rank (rank 0).
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 */
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static int darshan_log_append_all(MPI_File log_fh, struct darshan_core_runtime *core,
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    void *buf, int count, uint64_t *inout_off)
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{
    MPI_Offset send_off, my_off;
    MPI_Status status;
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    int comp_buf_sz = 0;
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    int ret;

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    /* compress the input buffer */
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    ret = darshan_deflate_buffer((void **)&buf, &count, 1,
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        core->comp_buf, &comp_buf_sz);
    if(ret < 0)
        comp_buf_sz = 0;

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    /* figure out where everyone is writing using scan */
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    send_off = comp_buf_sz;
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    if(my_rank == 0)
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    {
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        send_off += *inout_off; /* rank 0 knows the beginning offset */
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    }
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