/**

 * This file is part of the CernVM File System.

 */

#ifndef CVMFS_NFS_MAPS_LEVELDB_H_

#define CVMFS_NFS_MAPS_LEVELDB_H_

#include "nfs_maps.h"

#include <pthread.h>

#include <string>

#include "atomic.h"

#include "hash.h"

#include "leveldb/env.h"

namespace leveldb {

class DB;

class Cache;

class FilterPolicy;

}

namespace perf {

class Counter;

class Statistics;

}

class NfsMapsLeveldb : public NfsMaps {

 public:

  virtual ~NfsMapsLeveldb();

  virtual uint64_t GetInode(const PathString &path);

  virtual bool GetPath(const uint64_t inode, PathString *path);

  virtual void SetInodeResidue(unsigned residue_class, unsigned remainder);

  virtual std::string GetStatistics();

  static NfsMapsLeveldb *Create(

    const std::string &leveldb_dir,

    const uint64_t root_inode,

    const bool rebuild,

    perf::Statistics *statistics);

 private:

  class ForkAwareEnv;

  struct FuncArg {

    void (*function)(void*);

    void *arg;

    class ForkAwareEnv *env;

  };

  /**

   * Leveldb's background threads must not be started before cvmfs has forked.

   * Before forking, we run the processes in specially created threads.

   * We make sure, these threads are terminated before forking.

   */

   public:

    explicit ForkAwareEnv(NfsMapsLeveldb *maps);

    void StartThread(void (*f)(void*), void* a);

    void Schedule(void (*function)(void*), void* arg);

    void WaitForBGThreads();

    void SleepForMicroseconds(int micros);

   private:

    static void *MainFakeThread(void *data);

    NfsMapsLeveldb *maps_;

    atomic_int32 num_bg_threads_;

  };

  NfsMapsLeveldb();

  void PutInode2Path(const uint64_t inode, const PathString &path);

  void PutPath2Inode(const shash::Md5 &path, const uint64_t inode);

  uint64_t FindInode(const shash::Md5 &path);

  leveldb::DB *db_inode2path_;

  leveldb::DB *db_path2inode_;

  leveldb::Cache *cache_inode2path_;

  leveldb::Cache *cache_path2inode_;

  const leveldb::FilterPolicy *filter_inode2path_;

  const leveldb::FilterPolicy *filter_path2inode_;

  ForkAwareEnv *fork_aware_env_;

  uint64_t root_inode_;

  uint64_t seq_;

  pthread_mutex_t *lock_;

  bool spawned_;

  unsigned inode_residue_class_;

  unsigned inode_remainder_;

  perf::Counter *n_db_added_;

};

#endif  // CVMFS_NFS_MAPS_LEVELDB_H_