column_family.cc

//  Copyright (c) 2013, Facebook, Inc.  All rights reserved.
//  This source code is licensed under the BSD-style license found in the
//  LICENSE file in the root directory of this source tree. An additional grant
//  of patent rights can be found in the PATENTS file in the same directory.
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.

#include "db/column_family.h"

#include <vector>
#include <string>
#include <algorithm>

#include "db/version_set.h"

namespace rocksdb {

SuperVersion::SuperVersion(const int num_memtables) {
  to_delete.resize(num_memtables);
}

SuperVersion::~SuperVersion() {
  for (auto td : to_delete) {
    delete td;
  }
}

SuperVersion* SuperVersion::Ref() {
  refs.fetch_add(1, std::memory_order_relaxed);
  return this;
}

bool SuperVersion::Unref() {
  assert(refs > 0);
  // fetch_sub returns the previous value of ref
  return refs.fetch_sub(1, std::memory_order_relaxed) == 1;
}

void SuperVersion::Cleanup() {
  assert(refs.load(std::memory_order_relaxed) == 0);
  imm->Unref(&to_delete);
  MemTable* m = mem->Unref();
  if (m != nullptr) {
    to_delete.push_back(m);
  }
  current->Unref();
}

void SuperVersion::Init(MemTable* new_mem, MemTableListVersion* new_imm,
                        Version* new_current) {
  mem = new_mem;
  imm = new_imm;
  current = new_current;
  mem->Ref();
  imm->Ref();
  current->Ref();
  refs.store(1, std::memory_order_relaxed);
}

ColumnFamilyData::ColumnFamilyData(uint32_t id, const std::string& name,
                                   Version* dummy_versions,
                                   const ColumnFamilyOptions& options)
    : id(id),
      name(name),
      dummy_versions(dummy_versions),
      current(nullptr),
      options(options),
      mem(nullptr),
      imm(options.min_write_buffer_number_to_merge),
      super_version(nullptr) {}

ColumnFamilyData::~ColumnFamilyData() {
  if (super_version != nullptr) {
    bool is_last_reference __attribute__((unused));
    is_last_reference = super_version->Unref();
    assert(is_last_reference);
    super_version->Cleanup();
    delete super_version;
  }
  // List must be empty
  assert(dummy_versions->next_ == dummy_versions);
  delete dummy_versions;

  if (mem != nullptr) {
    delete mem->Unref();
  }
  std::vector<MemTable*> to_delete;
  imm.current()->Unref(&to_delete);
  for (MemTable* m : to_delete) {
    delete m;
  }
}

void ColumnFamilyData::CreateNewMemtable() {
  assert(current != nullptr);
  if (mem != nullptr) {
    delete mem->Unref();
  }
  mem = new MemTable(current->vset_->icmp_, options);
  mem->Ref();
}

ColumnFamilySet::ColumnFamilySet() : max_column_family_(0) {}

ColumnFamilySet::~ColumnFamilySet() {
  for (auto& cfd : column_family_data_) {
    delete cfd.second;
  }
  for (auto& cfd : droppped_column_families_) {
    delete cfd;
  }
}

ColumnFamilyData* ColumnFamilySet::GetDefault() const {
  auto ret = GetColumnFamily(0);
  assert(ret != nullptr);  // default column family should always exist
  return ret;
}

ColumnFamilyData* ColumnFamilySet::GetColumnFamily(uint32_t id) const {
  auto cfd_iter = column_family_data_.find(id);
  if (cfd_iter != column_family_data_.end()) {
    return cfd_iter->second;
  } else {
    return nullptr;
  }
}

bool ColumnFamilySet::Exists(uint32_t id) {
  return column_family_data_.find(id) != column_family_data_.end();
}

bool ColumnFamilySet::Exists(const std::string& name) {
  return column_families_.find(name) != column_families_.end();
}

uint32_t ColumnFamilySet::GetID(const std::string& name) {
  auto cfd_iter = column_families_.find(name);
  assert(cfd_iter != column_families_.end());
  return cfd_iter->second;
}

uint32_t ColumnFamilySet::GetNextColumnFamilyID() {
  return ++max_column_family_;
}

ColumnFamilyData* ColumnFamilySet::CreateColumnFamily(
    const std::string& name, uint32_t id, Version* dummy_versions,
    const ColumnFamilyOptions& options) {
  assert(column_families_.find(name) == column_families_.end());
  column_families_.insert({name, id});
  ColumnFamilyData* new_cfd =
      new ColumnFamilyData(id, name, dummy_versions, options);
  column_family_data_.insert({id, new_cfd});
  max_column_family_ = std::max(max_column_family_, id);
  return new_cfd;
}

void ColumnFamilySet::DropColumnFamily(uint32_t id) {
  auto cfd = column_family_data_.find(id);
  assert(cfd != column_family_data_.end());
  column_families_.erase(cfd->second->name);
  cfd->second->current->Unref();
  droppped_column_families_.push_back(cfd->second);
  column_family_data_.erase(cfd);
}

}  // namespace rocksdb