ceph/src/common/Finisher.cc

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3
   4 #include "common/config.h"
   5 #include "Finisher.h"
   6
   7 #include "common/debug.h"
   8 #define dout_subsys ceph_subsys_finisher
   9 #undef dout_prefix
  10 #define dout_prefix *_dout << "finisher(" << this << ") "
  11
  12 void Finisher::start()
  13 {
  14   ldout(cct, 10) << __func__ << dendl;
  15   finisher_thread.create(thread_name.c_str());
  16 }
  17
  18 void Finisher::stop()
  19 {
  20   ldout(cct, 10) << __func__ << dendl;
  21   finisher_lock.Lock();
  22   finisher_stop = true;
  23   // we don't have any new work to do, but we want the worker to wake up anyway
  24   // to process the stop condition.
  25   finisher_cond.Signal();
  26   finisher_lock.Unlock();
  27   finisher_thread.join(); // wait until the worker exits completely
  28   ldout(cct, 10) << __func__ << " finish" << dendl;
  29 }
  30
  31 void Finisher::wait_for_empty()
  32 {
  33   finisher_lock.Lock();
  34   while (!finisher_queue.empty() || finisher_running) {
  35     ldout(cct, 10) << "wait_for_empty waiting" << dendl;
  36     finisher_empty_wait = true;
  37     finisher_empty_cond.Wait(finisher_lock);
  38   }
  39   ldout(cct, 10) << "wait_for_empty empty" << dendl;
  40   finisher_empty_wait = false;
  41   finisher_lock.Unlock();
  42 }
  43
  44 void *Finisher::finisher_thread_entry()
  45 {
  46   finisher_lock.Lock();
  47   ldout(cct, 10) << "finisher_thread start" << dendl;
  48
  49   utime_t start;
  50   uint64_t count = 0;
  51   while (!finisher_stop) {
  52     /// Every time we are woken up, we process the queue until it is empty.
  53     while (!finisher_queue.empty()) {
  54       // To reduce lock contention, we swap out the queue to process.
  55       // This way other threads can submit new contexts to complete while we are working.
  56       vector<Context*> ls;
  57       list<pair<Context*,int> > ls_rval;
  58       ls.swap(finisher_queue);
  59       ls_rval.swap(finisher_queue_rval);
  60       finisher_running = true;
  61       finisher_lock.Unlock();
  62       ldout(cct, 10) << "finisher_thread doing " << ls << dendl;
  63
  64       if (logger) {
  65         start = ceph_clock_now();
  66         count = ls.size();
  67       }
  68
  69       // Now actually process the contexts.
  70       for (vector<Context*>::iterator p = ls.begin();
  71            p != ls.end();
  72            ++p) {
  73         if (*p) {
  74           (*p)->complete(0);
  75         } else {
  76           // When an item is NULL in the finisher_queue, it means
  77           // we should instead process an item from finisher_queue_rval,
  78           // which has a parameter for complete() other than zero.
  79           // This preserves the order while saving some storage.
  80           assert(!ls_rval.empty());
  81           Context *c = ls_rval.front().first;
  82           c->complete(ls_rval.front().second);
  83           ls_rval.pop_front();
  84         }
  85       }
  86       ldout(cct, 10) << "finisher_thread done with " << ls << dendl;
  87       ls.clear();
  88       if (logger) {
  89         logger->dec(l_finisher_queue_len, count);
  90         logger->tinc(l_finisher_complete_lat, ceph_clock_now() - start);
  91       }
  92
  93       finisher_lock.Lock();
  94       finisher_running = false;
  95     }
  96     ldout(cct, 10) << "finisher_thread empty" << dendl;
  97     if (unlikely(finisher_empty_wait))
  98       finisher_empty_cond.Signal();
  99     if (finisher_stop)
 100       break;
 101
 102     ldout(cct, 10) << "finisher_thread sleeping" << dendl;
 103     finisher_cond.Wait(finisher_lock);
 104   }
 105   // If we are exiting, we signal the thread waiting in stop(),
 106   // otherwise it would never unblock
 107   finisher_empty_cond.Signal();
 108
 109   ldout(cct, 10) << "finisher_thread stop" << dendl;
 110   finisher_stop = false;
 111   finisher_lock.Unlock();
 112   return 0;
 113 }
 114