stasis-bLSM/mergeManager.cpp

/*
 * mergeManager.cpp
 *
 *  Created on: May 19, 2010
 *      Author: sears
 */

#include "mergeManager.h"
#include "mergeStats.h"
#include "logstore.h"
#include "math.h"
mergeStats* mergeManager:: get_merge_stats(int mergeLevel) {
  if (mergeLevel == 0) {
    return c0;
  } else if (mergeLevel == 1) {
    return c1;
  } else if(mergeLevel == 2) {
    return c2;
  } else {
    abort();
  }
}

mergeManager::~mergeManager() {
  pthread_mutex_destroy(&mut);
  pthread_mutex_destroy(&throttle_mut);
  pthread_mutex_destroy(&dummy_throttle_mut);
  pthread_cond_destroy(&dummy_throttle_cond);
  delete c0;
  delete c1;
  delete c2;
}

void mergeManager::new_merge(mergeStats * s) {
  pthread_mutex_lock(&mut);
  if(s->merge_count) {
    if(s->merge_level == 0) {
      // target_size was set during startup
    } else if(s->merge_level == 1) {
      assert(c0->target_size);
      c1->target_size = (pageid_t)(*ltable->R() * (double)c0->target_size); //c1_queueSize > s->bytes_out ? c1_queueSize : s->bytes_out;
      assert(c1->target_size);
    } else if(s->merge_level == 2) {
      // target_size is infinity...
    } else { abort(); }
  }
  pthread_mutex_unlock(&mut);
}
void mergeManager::set_c0_size(int64_t size) {
  c0->target_size = size;
}

/**
 * This function is invoked periodically by the merge threads.  It updates mergeManager's statistics, and applies
 * backpressure as necessary.
 *
 * Here is the backpressure algorithm.
 *
 * We want to maintain these two invariants:
 *   - for each byte consumed by the app->c0 threads, a byte is consumed by the c0->c1 merge thread.
 *   - for each byte consumed by the c0->c1 thread, the c1->c2 thread consumes a byte
 *
 * More concretely (and taking into account varying values of R):
 *   capacity(C_i) - current_size(C_i) >= size(C_i_mergeable) - bytes_consumed_by_next_merger
 *
 * where:
 *   capacity c0 = c0_queue_size
 *   capacity c1 = c1_queue_size
 *
 *   current_size(c_i) = sum(bytes_out_delta) - sum(bytes_in_large_delta)
 *
 * bytes_consumed_by_merger = sum(bytes_in_small_delta)
 */
void mergeManager::tick(mergeStats * s, bool block) {
  pageid_t tick_length_bytes = 10*1024;

  if(true || s->bytes_in_small_delta > tick_length_bytes) {

    s->current_size = s->base_size + s->bytes_out - s->bytes_in_large;

    if(block) {
//      pthread_mutex_lock(&mut);
      struct timeval now;
      gettimeofday(&now, 0);
      double elapsed_delta = tv_to_double(&now) - ts_to_double(&s->last_tick);
      double bps = 0; //  = (double)s->bytes_in_small_delta / (double)elapsed_delta;

      s->lifetime_elapsed += elapsed_delta;
      s->lifetime_consumed += s->bytes_in_small_delta;
      double decay = 0.9999; // XXX set this in some principled way.  Surely, it should depend on tick_length (once that's working...)
      s->window_elapsed = (decay * s->window_elapsed) + elapsed_delta;
      s->window_consumed = (decay * s->window_consumed) + s->bytes_in_small_delta;

      double_to_ts(&s->last_tick, tv_to_double(&now));

      s->bytes_in_small_delta = 0;

      int64_t overshoot = 0;
      int64_t overshoot_fudge = 1024*1024; // XXX set based on avg / max tuple size?
      int spin = 0;
      double total_sleep = 0.0;
      do{

        double c0_c1_progress = ((double)(c1->bytes_in_large + c1->bytes_in_small)) / (double)(c0->mergeable_size + c1->base_size);
        double c1_c2_progress = ((double)(c2->bytes_in_large + c2->bytes_in_small)) / (double)(c1->mergeable_size + c2->base_size);

        double c0_c1_bps = c1->window_consumed / c1->window_elapsed;
        double c1_c2_bps = c2->window_consumed / c2->window_elapsed;

        if(s->merge_level == 0) {
          pageid_t c0_c1_bytes_remaining = (pageid_t)((1.0-c0_c1_progress) * (double)c0->mergeable_size);
          pageid_t c0_bytes_left = c0->target_size - c0->current_size;
          overshoot = overshoot_fudge + c0_c1_bytes_remaining - c0_bytes_left;
          bps = c0_c1_bps;
          if(!c0->mergeable_size) { overshoot = -1; }
          if(c0->mergeable_size && ! c1->active) { overshoot = c0->current_size + overshoot_fudge; }
        } else if (s->merge_level == 1) {
          pageid_t c1_c2_bytes_remaining = (pageid_t)((1.0-c1_c2_progress) * (double)c1->mergeable_size);
          pageid_t c1_bytes_left = c1->target_size - c1->current_size;
          overshoot = overshoot_fudge + c1_c2_bytes_remaining - c1_bytes_left;
          if(!c1->mergeable_size) { overshoot = -1; }
          if(c1->mergeable_size && ! c2->active) { overshoot = c1->current_size + overshoot_fudge; }
          bps = c1_c2_bps;
        }

  //#define PP_THREAD_INFO
  #ifdef PP_THREAD_INFO
          printf("#%d mbps %6.1f overshoot %9lld current_size = %9lld ",s->merge_level, bps / (1024.0*1024.0), overshoot, s->current_size);
  #endif
          pretty_print(stdout);
        if(overshoot > 0) {
          // throttle
          // it took "elapsed" seconds to process "tick_length_bytes" mb
          double sleeptime = 2.0 * (double)overshoot / bps;


          struct timespec sleep_until;

          double max_c0_sleep = 0.1;
          double max_c1_sleep = 0.1;
          double max_sleep = s->merge_level == 0 ? max_c0_sleep : max_c1_sleep;
          if(sleeptime < 0.01) { sleeptime = 0.01; }
          if(sleeptime > max_sleep) { sleeptime = max_sleep; }

          spin ++;
          total_sleep += sleeptime;

          if((spin > 20) || (total_sleep > (max_sleep * 10))) {
            if(bps > 1) {
              printf("\nMerge thread %d Overshoot: %lld Throttle min(1, %6f) spin %d, total_sleep %6.3f\n", s->merge_level, overshoot, sleeptime, spin, total_sleep);
            }
          }

          double_to_ts(&sleep_until, sleeptime + tv_to_double(&now));
          pthread_cond_timedwait(&dummy_throttle_cond, &ltable->header_mut, &sleep_until);
          gettimeofday(&now, 0);
        }
      } while(overshoot > overshoot_fudge);
    } else {
      pretty_print(stdout);
    }
//    pthread_mutex_unlock(&mut);
  }
}

mergeManager::mergeManager(logtable<datatuple> *ltable):
  ltable(ltable),
  c0(new mergeStats(this, 0)),
  c1(new mergeStats(this, 1)),
  c2(new mergeStats(this, 2)) {
  pthread_mutex_init(&mut, 0);
  pthread_mutex_init(&throttle_mut, 0);
  pthread_mutex_init(&dummy_throttle_mut, 0);
  pthread_cond_init(&dummy_throttle_cond, 0);
  struct timeval tv;
  gettimeofday(&tv, 0);
  double_to_ts(&c0->last_tick, tv_to_double(&tv));
  double_to_ts(&c1->last_tick, tv_to_double(&tv));
  double_to_ts(&c2->last_tick, tv_to_double(&tv));
}

void mergeManager::pretty_print(FILE * out) {
  pageid_t mb = 1024 * 1024;
  logtable<datatuple> * lt = (logtable<datatuple>*)ltable;
  bool have_c0  = false;
  bool have_c0m = false;
  bool have_c1  = false;
  bool have_c1m = false;
  bool have_c2  = false;
  if(lt) {
//    pthread_mutex_lock(&lt->header_mut);
    have_c0  = NULL != lt->get_tree_c0();
    have_c0m = NULL != lt->get_tree_c0_mergeable();
    have_c1  = NULL != lt->get_tree_c1();
    have_c1m = NULL != lt->get_tree_c1_mergeable() ;
    have_c2  = NULL != lt->get_tree_c2();
//    pthread_mutex_unlock(&lt->header_mut);
  }

  double c0_c1_progress = 100.0 * (c1->bytes_in_large + c1->bytes_in_small) / (c0->mergeable_size + c1->base_size); // c1->bytes_in_small / c0->mergeable_size;
  double c1_c2_progress = 100.0 * (c2->bytes_in_large + c2->bytes_in_small) / (c1->mergeable_size + c2->base_size); //c2->bytes_in_small / c1->mergeable_size;

  assert((!c1->active) || (c0_c1_progress >= -1 && c0_c1_progress < 102));
  assert((!c2->active) || (c1_c2_progress >= -1 && c1_c2_progress < 102));

  fprintf(out,"[merge progress MB/s window (lifetime)]: app [%s %6lldMB %6.1fsec %4.1f (%4.1f)] %s %s [%s %3.0f%% %4.1f (%4.1f)] %s %s [%s %3.0f%% %4.1f (%4.1f)] %s ",
      c0->active ? "RUN" : "---", (uint64_t)(c0->lifetime_consumed / mb), c0->lifetime_elapsed, c0->window_consumed/(((double)mb)*c0->window_elapsed), c0->lifetime_consumed/(((double)mb)*c0->lifetime_elapsed),
      have_c0 ? "C0" : "..",
      have_c0m ? "C0'" : "...",
      c1->active ? "RUN" : "---", c0_c1_progress, c1->window_consumed/(((double)mb)*c1->window_elapsed), c1->lifetime_consumed/(((double)mb)*c1->lifetime_elapsed),
      have_c1 ? "C1" : "..",
      have_c1m ? "C1'" : "...",
      c2->active ? "RUN" : "---", c1_c2_progress, c2->window_consumed/(((double)mb)*c2->window_elapsed), c2->lifetime_consumed/(((double)mb)*c2->lifetime_elapsed),
      have_c2 ? "C2" : "..");
#define PP_SIZES
  #ifdef PP_SIZES
  fprintf(out, "[size in small/large, out, mergeable] C0 %4lld %4lld %4lld %4lld %4lld %4lld ",
          c0->target_size/mb, c0->current_size/mb, c0->bytes_in_small/mb,
          c0->bytes_in_large/mb, c0->bytes_out/mb, c0->mergeable_size/mb);

  fprintf(out, "C1 %4lld %4lld %4lld %4lld %4lld %4lld ",
          c1->target_size/mb, c1->current_size/mb, c1->bytes_in_small/mb,
          c1->bytes_in_large/mb, c1->bytes_out/mb, c1->mergeable_size/mb);

  fprintf(out, "C2 ---- %4lld %4lld %4lld %4lld %4lld ",
          /*----*/            c2->current_size/mb, c2->bytes_in_small/mb,
          c2->bytes_in_large/mb, c2->bytes_out/mb, c2->mergeable_size/mb);
#endif
//  fprintf(out, "Throttle: %6.1f%% (cur) %6.1f%% (overall) ", 100.0*(last_throttle_seconds/(last_elapsed_seconds)), 100.0*(throttle_seconds/(elapsed_seconds)));
//  fprintf(out, "C0 size %4lld resident %4lld ",
//               2*c0_queueSize/mb,
//               (c0->bytes_out - c0->bytes_in_large)/mb);
//  fprintf(out, "C1 size %4lld resident %4lld\r",
//               2*c1_queueSize/mb,
//               (c1->bytes_out - c1->bytes_in_large)/mb);
//  fprintf(out, "C2 size %4lld\r",
//               2*c2_queueSize/mb);
//  fprintf(out, "C1 MB/s (eff; active) %6.1f  C2 MB/s %6.1f\r",
//                ((double)c1_totalConsumed)/((double)c1_totalWorktime),
//                ((double)c2_totalConsumed)/((double)c2_totalWorktime));
  fflush(out);
  fprintf(out, "\r");
}