// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab

#include "crimson/osd/osd_operations/snaptrim_event.h"
#include "crimson/osd/ops_executer.h"
#include "crimson/osd/pg.h"
#include <seastar/core/sleep.hh>

namespace {
  seastar::logger& logger() {
    return crimson::get_logger(ceph_subsys_osd);
  }
}

namespace crimson {
  template <>
  struct EventBackendRegistry<osd::SnapTrimEvent> {
    static std::tuple<> get_backends() {
      return {};
    }
  };

  template <>
  struct EventBackendRegistry<osd::SnapTrimObjSubEvent> {
    static std::tuple<> get_backends() {
      return {};
    }
  };
}

namespace crimson::osd {

PG::interruptible_future<>
PG::SnapTrimMutex::lock(SnapTrimEvent &st_event) noexcept
{
  return st_event.enter_stage<interruptor>(wait_pg
  ).then_interruptible([this] {
    return mutex.lock();
  });
}

void SnapTrimEvent::SubOpBlocker::dump_detail(Formatter *f) const
{
  f->open_array_section("dependent_operations");
  {
    for (const auto &kv : subops) {
      f->dump_unsigned("op_id", kv.first);
    }
  }
  f->close_section();
}

template <class... Args>
void SnapTrimEvent::SubOpBlocker::emplace_back(Args&&... args)
{
  subops.emplace_back(std::forward<Args>(args)...);
};

SnapTrimEvent::remove_or_update_iertr::future<>
SnapTrimEvent::SubOpBlocker::wait_completion()
{
  return interruptor::do_for_each(subops, [](auto&& kv) {
    return std::move(kv.second);
  });
}

void SnapTrimEvent::print(std::ostream &lhs) const
{
  lhs << "SnapTrimEvent("
      << "pgid=" << pg->get_pgid()
      << " snapid=" << snapid
      << " needs_pause=" << needs_pause
      << ")";
}

void SnapTrimEvent::dump_detail(Formatter *f) const
{
  f->open_object_section("SnapTrimEvent");
  f->dump_stream("pgid") << pg->get_pgid();
  f->close_section();
}

SnapTrimEvent::snap_trim_ertr::future<seastar::stop_iteration>
SnapTrimEvent::start()
{
  logger().debug("{}: {}", *this, __func__);
  return with_pg(
    pg->get_shard_services(), pg
  ).finally([ref=IRef{this}, this] {
    logger().debug("{}: complete", *ref);
    return handle.complete();
  });
}

CommonPGPipeline& SnapTrimEvent::client_pp()
{
  return pg->request_pg_pipeline;
}

SnapTrimEvent::snap_trim_ertr::future<seastar::stop_iteration>
SnapTrimEvent::with_pg(
  ShardServices &shard_services, Ref<PG> _pg)
{
  return interruptor::with_interruption([&shard_services, this] {
    return enter_stage<interruptor>(
      client_pp().wait_for_active
    ).then_interruptible([this] {
      return with_blocking_event<PGActivationBlocker::BlockingEvent,
                                 interruptor>([this] (auto&& trigger) {
        return pg->wait_for_active_blocker.wait(std::move(trigger));
      });
    }).then_interruptible([this] {
      return enter_stage<interruptor>(
        client_pp().recover_missing);
    }).then_interruptible([] {
      //return do_recover_missing(pg, get_target_oid());
      return seastar::now();
    }).then_interruptible([this] {
      return enter_stage<interruptor>(
        client_pp().get_obc);
    }).then_interruptible([this] {
      return pg->snaptrim_mutex.lock(*this);
    }).then_interruptible([this] {
      return enter_stage<interruptor>(
        client_pp().process);
    }).then_interruptible([&shard_services, this] {
      return interruptor::async([this] {
        std::vector<hobject_t> to_trim;
        using crimson::common::local_conf;
        const auto max =
          local_conf().get_val<uint64_t>("osd_pg_max_concurrent_snap_trims");
        // we need to look for at least 1 snaptrim, otherwise we'll misinterpret
        // the ENOENT below and erase snapid.
        int r = snap_mapper.get_next_objects_to_trim(
          snapid,
          max,
          &to_trim);
        if (r == -ENOENT) {
          to_trim.clear(); // paranoia
          return to_trim;
        } else if (r != 0) {
          logger().error("{}: get_next_objects_to_trim returned {}",
                         *this, cpp_strerror(r));
          ceph_abort_msg("get_next_objects_to_trim returned an invalid code");
        } else {
          assert(!to_trim.empty());
        }
        logger().debug("{}: async almost done line {}", *this, __LINE__);
        return to_trim;
      }).then_interruptible([&shard_services, this] (const auto& to_trim) {
        if (to_trim.empty()) {
          // the legit ENOENT -> done
          logger().debug("{}: to_trim is empty! Stopping iteration", *this);
	  pg->snaptrim_mutex.unlock();
          return snap_trim_iertr::make_ready_future<seastar::stop_iteration>(
            seastar::stop_iteration::yes);
        }
        return [&shard_services, this](const auto &to_trim) {
	  for (const auto& object : to_trim) {
	    logger().debug("{}: trimming {}", *this, object);
	    auto [op, fut] = shard_services.start_operation_may_interrupt<
	      interruptor, SnapTrimObjSubEvent>(
	      pg,
	      object,
	      snapid);
	    subop_blocker.emplace_back(
	      op->get_id(),
	      std::move(fut)
	    );
	  }
	  return interruptor::now();
	}(to_trim).then_interruptible([this] {
	  return enter_stage<interruptor>(wait_subop);
	}).then_interruptible([this] {
          logger().debug("{}: awaiting completion", *this);
          return subop_blocker.wait_completion();
        }).finally([this] {
	  pg->snaptrim_mutex.unlock();
	}).safe_then_interruptible([this] {
          if (!needs_pause) {
            return interruptor::now();
          }
          // let's know operators we're waiting
          return enter_stage<interruptor>(
            wait_trim_timer
          ).then_interruptible([this] {
            using crimson::common::local_conf;
            const auto time_to_sleep =
              local_conf().template get_val<double>("osd_snap_trim_sleep");
            logger().debug("{}: time_to_sleep {}", *this, time_to_sleep);
            // TODO: this logic should be more sophisticated and distinguish
            // between SSDs, HDDs and the hybrid case
            return seastar::sleep(
              std::chrono::milliseconds(std::lround(time_to_sleep * 1000)));
          });
        }).safe_then_interruptible([this] {
          logger().debug("{}: all completed", *this);
          return snap_trim_iertr::make_ready_future<seastar::stop_iteration>(
            seastar::stop_iteration::no);
        });
      });
    });
  }, [this](std::exception_ptr eptr) -> snap_trim_ertr::future<seastar::stop_iteration> {
    logger().debug("{}: interrupted {}", *this, eptr);
    return crimson::ct_error::eagain::make();
  }, pg);
}


CommonPGPipeline& SnapTrimObjSubEvent::client_pp()
{
  return pg->request_pg_pipeline;
}

SnapTrimObjSubEvent::remove_or_update_iertr::future<>
SnapTrimObjSubEvent::start()
{
  logger().debug("{}: start", *this);
  return with_pg(
    pg->get_shard_services(), pg
  ).finally([ref=IRef{this}, this] {
    logger().debug("{}: complete", *ref);
    return handle.complete();
  });
}

SnapTrimObjSubEvent::remove_or_update_iertr::future<>
SnapTrimObjSubEvent::remove_clone(
  ObjectContextRef obc,
  ObjectContextRef head_obc,
  ceph::os::Transaction& txn,
  std::vector<pg_log_entry_t>& log_entries
) {
  const auto p = std::find(
    head_obc->ssc->snapset.clones.begin(),
    head_obc->ssc->snapset.clones.end(),
    coid.snap);
  if (p == head_obc->ssc->snapset.clones.end()) {
    logger().error("{}: Snap {} not in clones",
                   *this, coid.snap);
    return crimson::ct_error::enoent::make();
  }
  assert(p != head_obc->ssc->snapset.clones.end());
  snapid_t last = coid.snap;
  delta_stats.num_bytes -= head_obc->ssc->snapset.get_clone_bytes(last);

  if (p != head_obc->ssc->snapset.clones.begin()) {
    // not the oldest... merge overlap into next older clone
    std::vector<snapid_t>::iterator n = p - 1;
    hobject_t prev_coid = coid;
    prev_coid.snap = *n;

    // does the classical OSD really need is_present_clone(prev_coid)?
    delta_stats.num_bytes -= head_obc->ssc->snapset.get_clone_bytes(*n);
    head_obc->ssc->snapset.clone_overlap[*n].intersection_of(
      head_obc->ssc->snapset.clone_overlap[*p]);
    delta_stats.num_bytes += head_obc->ssc->snapset.get_clone_bytes(*n);
  }
  delta_stats.num_objects--;
  if (obc->obs.oi.is_dirty()) {
    delta_stats.num_objects_dirty--;
  }
  if (obc->obs.oi.is_omap()) {
    delta_stats.num_objects_omap--;
  }
  if (obc->obs.oi.is_whiteout()) {
    logger().debug("{}: trimming whiteout on {}",
                   *this, coid);
    delta_stats.num_whiteouts--;
  }
  delta_stats.num_object_clones--;

  obc->obs.exists = false;
  head_obc->ssc->snapset.clones.erase(p);
  head_obc->ssc->snapset.clone_overlap.erase(last);
  head_obc->ssc->snapset.clone_size.erase(last);
  head_obc->ssc->snapset.clone_snaps.erase(last);

  log_entries.emplace_back(
    pg_log_entry_t{
      pg_log_entry_t::DELETE,
      coid,
      osd_op_p.at_version,
      obc->obs.oi.version,
      0,
      osd_reqid_t(),
      obc->obs.oi.mtime, // will be replaced in `apply_to()`
      0}
    );
  txn.remove(
    pg->get_collection_ref()->get_cid(),
    ghobject_t{coid, ghobject_t::NO_GEN, shard_id_t::NO_SHARD});
  obc->obs.oi = object_info_t(coid);
  return OpsExecuter::snap_map_remove(coid, pg->snap_mapper, pg->osdriver, txn);
}

void SnapTrimObjSubEvent::remove_head_whiteout(
  ObjectContextRef obc,
  ObjectContextRef head_obc,
  ceph::os::Transaction& txn,
  std::vector<pg_log_entry_t>& log_entries
) {
  // NOTE: this arguably constitutes minor interference with the
  // tiering agent if this is a cache tier since a snap trim event
  // is effectively evicting a whiteout we might otherwise want to
  // keep around.
  const auto head_oid = coid.get_head();
  logger().info("{}: {} removing {}",
                *this, coid, head_oid);
  log_entries.emplace_back(
    pg_log_entry_t{
      pg_log_entry_t::DELETE,
      head_oid,
      osd_op_p.at_version,
      head_obc->obs.oi.version,
      0,
      osd_reqid_t(),
      obc->obs.oi.mtime, // will be replaced in `apply_to()`
      0}
    );
  logger().info("{}: remove snap head", *this);
  object_info_t& oi = head_obc->obs.oi;
  delta_stats.num_objects--;
  if (oi.is_dirty()) {
    delta_stats.num_objects_dirty--;
  }
  if (oi.is_omap()) {
    delta_stats.num_objects_omap--;
  }
  if (oi.is_whiteout()) {
    logger().debug("{}: trimming whiteout on {}",
                   *this, oi.soid);
    delta_stats.num_whiteouts--;
  }
  head_obc->obs.exists = false;
  head_obc->obs.oi = object_info_t(head_oid);
  txn.remove(pg->get_collection_ref()->get_cid(),
             ghobject_t{head_oid, ghobject_t::NO_GEN, shard_id_t::NO_SHARD});
}

SnapTrimObjSubEvent::interruptible_future<>
SnapTrimObjSubEvent::adjust_snaps(
  ObjectContextRef obc,
  ObjectContextRef head_obc,
  const std::set<snapid_t>& new_snaps,
  ceph::os::Transaction& txn,
  std::vector<pg_log_entry_t>& log_entries
) {
  head_obc->ssc->snapset.clone_snaps[coid.snap] =
    std::vector<snapid_t>(new_snaps.rbegin(), new_snaps.rend());

  // we still do a 'modify' event on this object just to trigger a
  // snapmapper.update ... :(
  obc->obs.oi.prior_version = obc->obs.oi.version;
  obc->obs.oi.version = osd_op_p.at_version;
  ceph::bufferlist bl;
  encode(obc->obs.oi,
    bl,
    pg->get_osdmap()->get_features(CEPH_ENTITY_TYPE_OSD, nullptr));
  txn.setattr(
    pg->get_collection_ref()->get_cid(),
    ghobject_t{coid, ghobject_t::NO_GEN, shard_id_t::NO_SHARD},
    OI_ATTR,
    bl);
  log_entries.emplace_back(
    pg_log_entry_t{
      pg_log_entry_t::MODIFY,
      coid,
      obc->obs.oi.version,
      obc->obs.oi.prior_version,
      0,
      osd_reqid_t(),
      obc->obs.oi.mtime,
      0}
    );
  return OpsExecuter::snap_map_modify(
    coid, new_snaps, pg->snap_mapper, pg->osdriver, txn);
}

void SnapTrimObjSubEvent::update_head(
  ObjectContextRef obc,
  ObjectContextRef head_obc,
  ceph::os::Transaction& txn,
  std::vector<pg_log_entry_t>& log_entries
) {
  const auto head_oid = coid.get_head();
  logger().info("{}: writing updated snapset on {}, snapset is {}",
                *this, head_oid, head_obc->ssc->snapset);
  log_entries.emplace_back(
    pg_log_entry_t{
      pg_log_entry_t::MODIFY,
      head_oid,
      osd_op_p.at_version,
      head_obc->obs.oi.version,
      0,
      osd_reqid_t(),
      obc->obs.oi.mtime,
      0}
    );

  head_obc->obs.oi.prior_version = head_obc->obs.oi.version;
  head_obc->obs.oi.version = osd_op_p.at_version;

  std::map<std::string, ceph::bufferlist, std::less<>> attrs;
  ceph::bufferlist bl;
  encode(head_obc->ssc->snapset, bl);
  attrs[SS_ATTR] = std::move(bl);

  bl.clear();
  head_obc->obs.oi.encode_no_oid(bl,
    pg->get_osdmap()->get_features(CEPH_ENTITY_TYPE_OSD, nullptr));
  attrs[OI_ATTR] = std::move(bl);
  txn.setattrs(
    pg->get_collection_ref()->get_cid(),
    ghobject_t{head_oid, ghobject_t::NO_GEN, shard_id_t::NO_SHARD},
    attrs);
}

SnapTrimObjSubEvent::remove_or_update_iertr::future<
  SnapTrimObjSubEvent::remove_or_update_ret_t>
SnapTrimObjSubEvent::remove_or_update(
  ObjectContextRef obc,
  ObjectContextRef head_obc)
{
  auto citer = head_obc->ssc->snapset.clone_snaps.find(coid.snap);
  if (citer == head_obc->ssc->snapset.clone_snaps.end()) {
    logger().error("{}: No clone_snaps in snapset {} for object {}",
                   *this, head_obc->ssc->snapset, coid);
    return crimson::ct_error::enoent::make();
  }
  const auto& old_snaps = citer->second;
  if (old_snaps.empty()) {
    logger().error("{}: no object info snaps for object {}",
                   *this, coid);
    return crimson::ct_error::enoent::make();
  }
  if (head_obc->ssc->snapset.seq == 0) {
    logger().error("{}: no snapset.seq for object {}",
                   *this, coid);
    return crimson::ct_error::enoent::make();
  }
  const OSDMapRef& osdmap = pg->get_osdmap();
  std::set<snapid_t> new_snaps;
  for (const auto& old_snap : old_snaps) {
    if (!osdmap->in_removed_snaps_queue(pg->get_info().pgid.pgid.pool(),
                                        old_snap)
        && old_snap != snap_to_trim) {
      new_snaps.insert(old_snap);
    }
  }

  return seastar::do_with(ceph::os::Transaction{}, [=, this](auto &txn) {
  std::vector<pg_log_entry_t> log_entries{};

  int64_t num_objects_before_trim = delta_stats.num_objects;
  osd_op_p.at_version = pg->next_version();
  auto ret = remove_or_update_iertr::now();
  if (new_snaps.empty()) {
    // remove clone from snapset
    logger().info("{}: {} snaps {} -> {} ... deleting",
                  *this, coid, old_snaps, new_snaps);
    ret = remove_clone(obc, head_obc, txn, log_entries);
  } else {
    // save adjusted snaps for this object
    logger().info("{}: {} snaps {} -> {}",
                  *this, coid, old_snaps, new_snaps);
    ret = adjust_snaps(obc, head_obc, new_snaps, txn, log_entries);
  }
  return std::move(ret).safe_then_interruptible(
    [&txn, obc, num_objects_before_trim, log_entries=std::move(log_entries), head_obc=std::move(head_obc), this]() mutable {
    osd_op_p.at_version = pg->next_version();

    // save head snapset
    logger().debug("{}: {} new snapset {} on {}",
                   *this, coid, head_obc->ssc->snapset, head_obc->obs.oi);
    if (head_obc->ssc->snapset.clones.empty() && head_obc->obs.oi.is_whiteout()) {
      remove_head_whiteout(obc, head_obc, txn, log_entries);
    } else {
      update_head(obc, head_obc, txn, log_entries);
    }
    // Stats reporting - Set number of objects trimmed
    if (num_objects_before_trim > delta_stats.num_objects) {
      //int64_t num_objects_trimmed =
      //  num_objects_before_trim - delta_stats.num_objects;
      //add_objects_trimmed_count(num_objects_trimmed);
    }
  }).safe_then_interruptible(
    [&txn, log_entries=std::move(log_entries)] () mutable {
    return remove_or_update_iertr::make_ready_future<remove_or_update_ret_t>(
      std::make_pair(std::move(txn), std::move(log_entries)));
  });
  });
}

SnapTrimObjSubEvent::remove_or_update_iertr::future<>
SnapTrimObjSubEvent::with_pg(
  ShardServices &shard_services, Ref<PG> _pg)
{
  return enter_stage<interruptor>(
    client_pp().wait_for_active
  ).then_interruptible([this] {
    return with_blocking_event<PGActivationBlocker::BlockingEvent,
                               interruptor>([this] (auto&& trigger) {
      return pg->wait_for_active_blocker.wait(std::move(trigger));
    });
  }).then_interruptible([this] {
    return enter_stage<interruptor>(
      client_pp().recover_missing);
  }).then_interruptible([] {
    //return do_recover_missing(pg, get_target_oid());
    return seastar::now();
  }).then_interruptible([this] {
    return enter_stage<interruptor>(
      client_pp().get_obc);
  }).then_interruptible([this] {
    logger().debug("{}: getting obc for {}", *this, coid);
    // end of commonality
    // with_clone_obc_direct lock both clone's and head's obcs
    return pg->obc_loader.with_clone_obc_direct<RWState::RWWRITE>(
      coid,
      [this](auto head_obc, auto clone_obc) {
      logger().debug("{}: got clone_obc={}", *this, clone_obc->get_oid());
      return enter_stage<interruptor>(
        client_pp().process
      ).then_interruptible(
        [this,clone_obc=std::move(clone_obc), head_obc=std::move(head_obc)]() mutable {
        logger().debug("{}: processing clone_obc={}", *this, clone_obc->get_oid());
        return remove_or_update(
          clone_obc, head_obc
        ).safe_then_unpack_interruptible([clone_obc, this]
                                         (auto&& txn, auto&& log_entries) mutable {
          auto [submitted, all_completed] = pg->submit_transaction(
            std::move(clone_obc),
            std::move(txn),
            std::move(osd_op_p),
            std::move(log_entries));
          return submitted.then_interruptible(
            [all_completed=std::move(all_completed), this] () mutable {
            return enter_stage<interruptor>(
              wait_repop
            ).then_interruptible([all_completed=std::move(all_completed)] () mutable {
              return std::move(all_completed);
            });
          });
        });
      });
    }).handle_error_interruptible(
      remove_or_update_iertr::pass_further{},
      crimson::ct_error::assert_all{"unexpected error in SnapTrimObjSubEvent"}
    );
  });
}

void SnapTrimObjSubEvent::print(std::ostream &lhs) const
{
  lhs << "SnapTrimObjSubEvent("
      << "coid=" << coid
      << " snapid=" << snap_to_trim
      << ")";
}

void SnapTrimObjSubEvent::dump_detail(Formatter *f) const
{
  f->open_object_section("SnapTrimObjSubEvent");
  f->dump_stream("coid") << coid;
  f->close_section();
}

} // namespace crimson::osd
