inode_index.h

#ifndef GASSYFS_INODE_INDEX_H_
#define GASSYFS_INODE_INDEX_H_
#include <unordered_map>
#include <fuse.h>
#include "inode.h"

/*
 * This container maps inode number to inode pointer. Each inode has an
 * associated reference count, and when the reference count falls to zero that
 * inode is removed. The reference count corresponds to the number of
 * outstanding references that the kernel inode cache has for an inode.
 */
class InodeIndex {
 public:
  /*
   * insert an inode into the index. this is the same as `get` but asserts
   * that the inode is not in the index. reference counts start at one.
   */
  void add(Inode::Ptr inode);

  /*
   * increase the reference count on an inode. if the inode isn't present in
   * the index it is added with an initial count of one.
   */
  void get(Inode::Ptr inode);

  // decrease the reference count by given amount.
  void put(fuse_ino_t ino, long int dec);

  // lookup inodes by type
  Inode::Ptr inode(fuse_ino_t ino);
  DirInode::Ptr dir_inode(fuse_ino_t ino);
  SymlinkInode::Ptr symlink_inode(fuse_ino_t ino);

  uint64_t nfiles();

 private:
  std::unordered_map<fuse_ino_t,
    std::pair<long int, Inode::Ptr>> refs_;
};

#endif