s3fs-fuse/src/cache.h

/*
 * s3fs - FUSE-based file system backed by Amazon S3
 *
 * Copyright(C) 2007 Randy Rizun <rrizun@gmail.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */

#ifndef S3FS_CACHE_H_
#define S3FS_CACHE_H_

#include "common.h"

//
// Struct for stats cache
//
struct stat_cache_entry {
  struct stat       stbuf;
  unsigned long     hit_count;
  struct timespec   cache_date;
  headers_t         meta;
  bool              isforce;
  bool              noobjcache;  // Flag: cache is no object for no listing.
  unsigned long     notruncate;  // 0<:   not remove automatically at checking truncate

  stat_cache_entry() : hit_count(0), isforce(false), noobjcache(false), notruncate(0L) {
    memset(&stbuf, 0, sizeof(struct stat));
    cache_date.tv_sec  = 0;
    cache_date.tv_nsec = 0;
    meta.clear();
  }
};

typedef std::map<std::string, stat_cache_entry*> stat_cache_t; // key=path

//
// Struct for symbolic link cache
//
struct symlink_cache_entry {
  std::string       link;
  unsigned long     hit_count;
  struct timespec   cache_date;  // The function that operates timespec uses the same as Stats

  symlink_cache_entry() : link(""), hit_count(0) {
    cache_date.tv_sec  = 0;
    cache_date.tv_nsec = 0;
  }
};

typedef std::map<std::string, symlink_cache_entry*> symlink_cache_t;

//
// Class
//
// [NOTE] About Symbolic link cache
// The Stats cache class now also has a symbolic link cache.
// It is possible to take out the Symbolic link cache in another class,
// but the cache out etc. should be synchronized with the Stats cache
// and implemented in this class.
// Symbolic link cache size and timeout use the same settings as Stats
// cache. This simplifies user configuration, and from a user perspective,
// the symbolic link cache appears to be included in the Stats cache.
//
class StatCache
{
  private:
    static StatCache       singleton;
    static pthread_mutex_t stat_cache_lock;
    stat_cache_t           stat_cache;
    bool                   IsExpireTime;
    bool                   IsExpireIntervalType;    // if this flag is true, cache data is updated at last access time.
    time_t                 ExpireTime;
    unsigned long          CacheSize;
    bool                   IsCacheNoObject;
    symlink_cache_t        symlink_cache;

  private:
    StatCache();
    ~StatCache();

    void Clear(void);
    bool GetStat(const std::string& key, struct stat* pst, headers_t* meta, bool overcheck, const char* petag, bool* pisforce);
    // Truncate stat cache
    bool TruncateCache(void);
    // Truncate symbolic link cache
    bool TruncateSymlink(void);

  public:
    // Reference singleton
    static StatCache* getStatCacheData(void) {
      return &singleton;
    }

    // Attribute
    unsigned long GetCacheSize(void) const;
    unsigned long SetCacheSize(unsigned long size);
    time_t GetExpireTime(void) const;
    time_t SetExpireTime(time_t expire, bool is_interval = false);
    time_t UnsetExpireTime(void);
    bool SetCacheNoObject(bool flag);
    bool EnableCacheNoObject(void) {
      return SetCacheNoObject(true);
    }
    bool DisableCacheNoObject(void) {
      return SetCacheNoObject(false);
    }
    bool GetCacheNoObject(void) const {
      return IsCacheNoObject;
    }

    // Get stat cache
    bool GetStat(const std::string& key, struct stat* pst, headers_t* meta, bool overcheck = true, bool* pisforce = NULL) {
      return GetStat(key, pst, meta, overcheck, NULL, pisforce);
    }
    bool GetStat(const std::string& key, struct stat* pst, bool overcheck = true) {
      return GetStat(key, pst, NULL, overcheck, NULL, NULL);
    }
    bool GetStat(const std::string& key, headers_t* meta, bool overcheck = true) {
      return GetStat(key, NULL, meta, overcheck, NULL, NULL);
    }
    bool HasStat(const std::string& key, bool overcheck = true) {
      return GetStat(key, NULL, NULL, overcheck, NULL, NULL);
    }
    bool HasStat(const std::string& key, const char* etag, bool overcheck = true) {
      return GetStat(key, NULL, NULL, overcheck, etag, NULL);
    }

    // Cache For no object
    bool IsNoObjectCache(const std::string& key, bool overcheck = true);
    bool AddNoObjectCache(const std::string& key);

    // Add stat cache
    bool AddStat(const std::string& key, headers_t& meta, bool forcedir = false, bool no_truncate = false);

    // Change no truncate flag
    void ChangeNoTruncateFlag(const std::string& key, bool no_truncate);

    // Delete stat cache
    bool DelStat(const char* key, bool lock_already_held = false);
    bool DelStat(std::string& key, bool lock_already_held = false) {
      return DelStat(key.c_str(), lock_already_held);
    }

    // Cache for symbolic link
    bool GetSymlink(const std::string& key, std::string& value);
    bool AddSymlink(const std::string& key, const std::string& value);
    bool DelSymlink(const char* key, bool lock_already_held = false);
};

//
// Functions
//
bool convert_header_to_stat(const char* path, const headers_t& meta, struct stat* pst, bool forcedir = false);

#endif // S3FS_CACHE_H_

/*
* Local variables:
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* End:
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*/