libminifi/include/core/repository/LegacyVolatileContentRepository.h

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <map>
#include <memory>
#include <string>
#include <string_view>

#include "AtomicRepoEntries.h"
#include "io/AtomicEntryStream.h"
#include "core/ContentRepository.h"
#include "properties/Configure.h"
#include "core/Connectable.h"
#include "core/logging/LoggerFactory.h"
#include "utils/GeneralUtils.h"
#include "VolatileRepositoryData.h"
#include "utils/Literals.h"

namespace org::apache::nifi::minifi::core::repository {
/**
 * Purpose: Stages content into a volatile area of memory. Note that when the maximum number
 * of entries is consumed we will rollback a session to wait for others to be freed.
 */
class LegacyVolatileContentRepository : public core::ContentRepositoryImpl {
 public:
  static const char *minimal_locking;

  explicit LegacyVolatileContentRepository(std::string_view name = className<LegacyVolatileContentRepository>())
    : core::ContentRepositoryImpl(name),
      repo_data_(15000, static_cast<size_t>(10_MiB * 0.75)),
      minimize_locking_(true),
      logger_(logging::LoggerFactory<LegacyVolatileContentRepository>::getLogger()) {
  }

  ~LegacyVolatileContentRepository() override {
    logger_->log_debug("Clearing repository");
    if (!minimize_locking_) {
      std::lock_guard<std::mutex> lock(map_mutex_);
      for (const auto &item : master_list_) {
        delete item.second;
      }
      master_list_.clear();
    }
  }

  uint64_t getRepositorySize() const override {
    return repo_data_.getRepositorySize();
  }

  uint64_t getMaxRepositorySize() const override {
    return repo_data_.getMaxRepositorySize();
  }

  uint64_t getRepositoryEntryCount() const override {
    return master_list_.size();
  }

  bool isFull() const override {
    return repo_data_.isFull();
  }

  bool initialize(const std::shared_ptr<Configure> &configure) override;

  std::shared_ptr<io::BaseStream> write(const minifi::ResourceClaim &claim, bool append) override;

  std::shared_ptr<io::BaseStream> read(const minifi::ResourceClaim &claim) override;

  bool exists(const minifi::ResourceClaim &claim) override;

  bool close(const minifi::ResourceClaim &claim) override {
    return remove(claim);
  }

  void clearOrphans() override {
    // there are no persisted orphans to delete
  }

 protected:
  bool removeKey(const std::string& content_path) override;

 private:
  VolatileRepositoryData repo_data_;
  bool minimize_locking_;

  // mutex and master list that represent a cache of Atomic entries. this exists so that we don't have to walk the atomic entry list.
  // The idea is to reduce the computational complexity while keeping access as maximally lock free as we can.
  std::mutex map_mutex_;
  std::map<ResourceClaim::Path, AtomicEntry<ResourceClaim::Path>*> master_list_;
  std::shared_ptr<logging::Logger> logger_;
};

}  // namespace org::apache::nifi::minifi::core::repository