epoch.c

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// -*-Mode: C++;-*- // technically C99

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#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>

#include "env.h"
#include "epoch.h"
#include "loadmap.h"
#include "name.h"
#include "thread_data.h"
#include "hpcrun_return_codes.h"
#include "monitor.h"
#include <trampoline/common/trampoline.h>
#include <messages/messages.h>
#include <cct/cct_bundle.h>

void
hpcrun_reset_epoch(epoch_t* epoch)
{
  epoch->next = NULL;
  TD_GET(core_profile_trace_data.epoch) = epoch;
}

void
hpcrun_epoch_init(cct_ctxt_t* ctxt)
{
  TMSG(EPOCH,"init");
  thread_data_t* td    = hpcrun_get_thread_data();
  epoch_t*       epoch = td->core_profile_trace_data.epoch;

  hpcrun_cct_bundle_init(&(epoch->csdata), ctxt);

  epoch->loadmap = hpcrun_getLoadmap();
  epoch->next  = NULL;
}

epoch_t*
hpcrun_check_for_new_loadmap(epoch_t* epoch)
{
  /* ugh, nasty race condition here:

  1. shared library epoch has changed since the last profile
  signal, so we enter the if;

  2. somebody else dlclose()'s a library which holds something
  located in our backtrace.  this is not in itself a problem,
  since we don't bother doing anything on dlclose()...;

  3. somebody else (thread in step 2 or a different thread)
  dlopen()'s a new shared object, which begins an entirely
  new loadmap--one which does not include the shared object
  which resides in our backtrace;

  4. we create a new epoch which receives the loadmap from step 3,
  not step 1, which is wrong.

  attempt to take baby steps to stop this.  more drastic action
  would involve grabbing the loadmap lock, but I believe that would
  be unacceptably slow (both in the atomic instruction overhead
  and the simple fact that most programs are not frequent users
  of dl*). */

  hpcrun_loadmap_t* current = hpcrun_getLoadmap();

  if(epoch->loadmap != current) {
    TMSG(LOADMAP, "Need new loadmap!");
    TMSG(MALLOC," -new_epoch-");
    epoch_t* newepoch = hpcrun_malloc(sizeof(epoch_t));

    TMSG(EPOCH, "check_new_epoch creating new epoch (new loadmap/cct pair)...");

    memcpy(newepoch, epoch, sizeof(epoch_t));
    hpcrun_cct_bundle_init(&(epoch->csdata), (epoch->csdata).ctxt);

    hpcrun_trampoline_remove();

    newepoch->loadmap = current;
    newepoch->next  = epoch;

    TD_GET(core_profile_trace_data.epoch) = newepoch;
    return newepoch;
  }
  else {
    return epoch;
  }
}

int
hpcrun_epoch_fini(epoch_t *x){

  TMSG(EPOCH,"--Fini");
  return HPCRUN_OK;
}

void
hpcrun_epoch_reset(void)
{
  //
  // create a new epoch list:
  //  preserve current loadmap
  //  re-init cct
  // reset epoch list for thread to point be a list consisting of only the new epoch
  //
  TMSG(EPOCH_RESET,"--started");
  epoch_t *epoch = hpcrun_get_thread_epoch();
  epoch_t *newepoch = hpcrun_malloc(sizeof(epoch_t));
  memcpy(newepoch, epoch, sizeof(epoch_t));
  TMSG(EPOCH_RESET, "check new loadmap = old loadmap = %d", newepoch->loadmap == epoch->loadmap);
  hpcrun_cct_bundle_init(&(newepoch->csdata), newepoch->csdata_ctxt); // reset cct
  hpcrun_reset_epoch(newepoch);
  TMSG(EPOCH_RESET," ==> no new epoch for next sample = %d", newepoch->loadmap == hpcrun_getLoadmap());
}