Roxen.git/ server/ base_server/ fsgc.pike > fce991af13e5dac3b513d13c09b7bcc89aaed881 [Annotate]

// 

// Unified file system garbage collector. 

// 

// 2013-09-12 Henrik Grubbström 

// 

#if constant(Filesystem.Monitor.basic) 

// #define FSGC_DEBUG 

// #define FSGC_PRETEND 

#ifdef FSGC_DEBUG 

#define GC_WERR(X...)       werror(X) 

#else 

#define GC_WERR(X...) 

#endif 

/* Some notes: 

 * 

 *   There are multiple data for a file that may affect the garbage policy: 

 * 

 *     * The age of the file. 

 * 

 *     * The size of the file. 

 * 

 *   Garbage collection for a root may be triggered by several factors: 

 * 

 *     * A maxium age for a file has been reached. 

 * 

 *     * Too many files under a root. 

 * 

 *     * The total size of the files under a root is too large. 

 * 

 *   Symlinks are not followed and not garbage collected due 

 *   to the inherent risks of escaping directory structures 

 *   and/or removing manually added stuff. 

 */ 

//! Filesystem garbage collector for a single root directory. 

class FSGarb 

{ 

  inherit Filesystem.Monitor.basic : basic; 

  int num_files; 

  int total_size; 

  string modid; 

  string root; 

  int max_age; 

  int max_files; 

  int max_size; 

  mapping(string:object) handle_lookup = ([]); 

  ADT.Priority_queue pending_gc = ADT.Priority_queue(); 

  //! If set, move files to this directory instead of deleting them. 

  //! 

  //! If set to @[root] or @expr{""@} keep the files as is. 

  string quarantine; 

  protected int rm(string path) 

  { 

    GC_WERR("FSGC: Zap %O\n", path); 

    if (quarantine) { 

      if ((quarantine == root) || (quarantine == "")) return 0; 

      if (!has_prefix(path, root)) return 0; 

      string rel = path[sizeof(root)..]; 

      // First try the trivial case. 

      if (mv(path, quarantine + rel)) return 1; 

      string dirs = dirname(rel); 

      if (sizeof(dirs)) { 

        if (Stdio.mkdirhier(quarantine + dirs)) { 

          // Try again with the directory existing. 

          if (mv(path, quarantine + rel)) return 1; 

        } 

      } 

      // Different filesystems? 

      if (Stdio.cp(path, quarantine + rel)) { 

        return predef::rm(path); 

      } 

      werror("FSGC: Failed to copy file %O to %O: %s.\n", 

             path, quarantine + rel, strerror(errno())); 

      return 0; 

    } else { 

      return predef::rm(path); 

    } 

  } 

  void check_threshold() 

  { 

    GC_WERR("FSGC: Checking thresholds...\n" 

            "      total_size: %d max_size: %d\n" 

            "      num_files: %d max_files: %d\n", 

            total_size, max_size, 

            num_files, max_files); 

    while ((max_size && (total_size > max_size)) || 

           (max_files && (num_files > max_files))) { 

      GC_WERR("FSGC: Filesystem limits exceeded forcing early removal.\n"); 

      if (!zap_one_file()) break; 

    } 

  } 

  protected int zap_one_file() 

  { 

    if (!sizeof(pending_gc)) return 0; 

    // Pop the next pending file from the queue. 

    Monitor m = pending_gc->pop(); 

    m_delete(handle_lookup, m->path); 

    // Account for the deletion immediately, and 

    // make sure it isn't counted twice. 

    int bytes = m->st->size; 

    m->st->size = 0; 

    m->st->isreg = 0; 

    GC_WERR("Deleting file %O...\n", m->path); 

    if (rm(m->path)) { 

      num_files--; 

      total_size -= bytes; 

      // Make sure the deletion is notified properly soon. 

      m->next_poll = time(1); 

      monitor_queue->adjust(m); 

    } else { 

      GC_WERR("Failed to delete file %O: %s\n", 

              m->path, strerror(errno())); 

      // Restore the state in case the file is altered externally. 

      m->st->size = bytes; 

      m->st->isreg = 1; 

    } 

    return 1; 

  } 

  int st_to_pri(Stdio.Stat st) 

  { 

    return st->mtime - st->size / 1024; 

  } 

  protected void remove_pending(Monitor m) 

  { 

    // Register us for threshold-based deletion. 

    object handle = m_delete(handle_lookup, m->path); 

    if (handle) { 

      pending_gc->adjust_pri(handle, -0x80000000); 

      pending_gc->pop(); 

    } 

  } 

  protected class Monitor { 

    inherit basic::Monitor; 

    protected void create(string path, 

                          MonitorFlags flags, 

                          int max_dir_check_interval, 

                          int file_interval_factor, 

                          int stable_time) 

    { 

      ::create(path, flags, max_dir_check_interval, 

               file_interval_factor, stable_time); 

      GC_WERR("%O->create(%O, %O, %O, %O, %O)\n", 

              this_object(), path, flags, max_dir_check_interval, 

              file_interval_factor, stable_time); 

    } 

    void check_for_release(int mask, int flags) 

    { 

      GC_WERR("%O->check_for_relase(0x%x, 0x%x)\n", 

              this_object(), mask, flags); 

      ::check_for_release(mask, flags); 

      if (!monitors[path]) { 

        // We've been relased. 

        // Make sure to update our parent (if any) soon. 

        array a = path/"/"; 

        Monitor m = monitors[canonic_path(a[..sizeof(a)-2]*"/")]; 

        if (m) { 

          GC_WERR("Waking up our parent dir: %O\n", m); 

          m->next_poll = time(1)-1; 

          monitor_queue->adjust(m); 

        } 

      } 

    } 

    protected void file_exists(string path, Stdio.Stat st) 

    { 

      ::file_exists(path, st); 

      // Make sure we get the stable change callback... 

      last_change = st->mtime; 

      if (st->isreg) { 

        num_files++; 

        total_size += st->size; 

        // Register us for threadhold-based deletion. 

        handle_lookup[path] = pending_gc->push(st_to_pri(st), this); 

        check_threshold(); 

      } 

    } 

    // NB: Needs to be visible so that reconfigure() can call it. 

    void update(Stdio.Stat st) 

    { 

      int delta = max_dir_check_interval || basic::max_dir_check_interval; 

      if (!next_poll) { 

        // Attempt to distribute polls evenly at startup. 

        delta = 1 + random(delta); 

        if (st) { 

          last_change = st->mtime; 

        } 

      } 

      ::update(st); 

      // We're only interested in stable time, so there's no reason 

      // to scan as frequently as the default implementation. 

      if (last_change <= time(1)) { 

        // Time until stable. 

        int d = last_change + (stable_time || basic::stable_time) - time(1); 

        GC_WERR("%O: last: %s, d: %d, delta: %d\n", 

                this_object(), ctime(last_change) - "\n", d, delta); 

        if (d < 0) d = 1; 

        if (d < delta) delta = d; 

      } 

      next_poll = time(1) + (delta || 1); 

      GC_WERR("%O->update(%O) ==> next: %s\n", 

              this_object(), st, ctime(next_poll) - "\n"); 

      monitor_queue->adjust(this); 

    } 

    protected string _sprintf(int c) 

    { 

      return sprintf("FSGarb.Monitor(%O, %O, last: %d, next: %s, st: %O)", 

                     path, flags, last_change, ctime(next_poll) - "\n", st); 

    } 

    int(0..1) check(MonitorFlags|void flags) 

    { 

      int(0..1) ret = ::check(flags); 

      return ret; 

    } 

    int(0..1) status_change(Stdio.Stat old_st, Stdio.Stat st, 

                            MonitorFlags old_flags, MonitorFlags flags) 

    { 

      GC_WERR("Status change %O(0x%x) ==> %O(0x%x) for %O!\n", 

              old_st, old_flags, st, flags, this_object()); 

      int res = ::status_change(old_st, st, old_flags, flags); 

      if (st->isdir && (flags & MF_RECURSE)) { 

        foreach(files, string file) { 

          file = canonic_path(Stdio.append_path(path, file)); 

          if (!monitors[file]) { 

            // Lost update due to race-condition: 

            // 

            //   Exist ==> Deleted ==> Exists 

            // 

            // with no update of directory inbetween. 

            // 

            // Create the lost submonitor again. 

            res = 1; 

            monitor(file, old_flags | MF_AUTO | MF_HARD, 

                    max_dir_check_interval, 

                    file_interval_factor, 

                    stable_time); 

            monitors[file]->check(); 

          } 

        } 

      } 

      num_files += st->isreg - old_st->isreg; 

      if (old_st->isreg) { 

        total_size -= old_st->size; 

        if (!st->isreg) { 

          remove_pending(this); 

        } 

      } 

      if (st->isreg) { 

        total_size += st->size; 

        // Register us for threshold-based deletion. 

        if (!old_st->isreg) { 

          handle_lookup[path] = pending_gc->push(st_to_pri(st), this); 

        } else { 

          object handle = handle_lookup[path]; 

          if (handle && (st_to_pri(st) != st_to_pri(old_st))) { 

            pending_gc->adjust_pri(handle, st_to_pri(st)); 

          } 

        } 

      } 

      check_threshold(); 

      return res; 

    } 

    void file_created(string path, Stdio.Stat st) 

    { 

      GC_WERR("File %O %O created (%O).\n", path, st, this_object()); 

      if (st->isreg) { 

        num_files++; 

        total_size += st->size; 

        // Register us for threshold-based deletion. 

        handle_lookup[path] = pending_gc->push(st_to_pri(st), this); 

        check_threshold(); 

      } 

    } 

    void file_deleted(string path, Stdio.Stat old_st) 

    { 

      GC_WERR("File %O %O deleted (%O).\n", path, old_st, this_object()); 

      if (old_st->isreg) { 

        num_files--; 

        total_size -= old_st->size; 

        remove_pending(this); 

        check_threshold(); 

      } 

    } 

  } 

  protected void create(string modid, string path, int max_age, 

                        int|void max_size, int|void max_files, 

                        string|void quarantine) 

  { 

    GC_WERR("FSGC: Max age: %d\n", max_age); 

    GC_WERR("FSGC: Max size: %d\n", max_size); 

    GC_WERR("FSGC: Max files: %d\n", max_files); 

    this_program::modid = modid; 

    this_program::max_age = max_age; 

    this_program::max_size = max_size; 

    this_program::max_files = max_files; 

    root = canonic_path(path); 

    if (quarantine) { 

      if (sizeof(quarantine)) { 

        quarantine = canonic_path(quarantine); 

      } 

      this::quarantine = quarantine; 

    } 

    ::create(max_age/file_interval_factor, 0, max_age); 

    // Workaround for too strict type-check in Pike 7.8. 

    int flags = 3; 

    monitor(root, flags); 

  } 

  void stable_data_change(string path, Stdio.Stat st) 

  { 

    GC_WERR("FSGC: Deleting stale file: %O\n", path); 

    if (path == root) return; 

    // Override accelerated stable change notification. 

    if (st->mtime > time(1) - stable_time) { 

      GC_WERR("FSGC: Keeping file: %O\n", path); 

      return; 

    } 

    rm(path); 

  } 

  void reconfigure(int new_max_age, int|void new_max_size, 

                   int|void new_max_files) 

  { 

    if (!zero_type(new_max_size)) { 

      GC_WERR("FSGC: New max size: %d\n", new_max_size); 

      max_size = new_max_size; 

    } 

    if (!zero_type(new_max_files)) { 

      GC_WERR("FSGC: New max files: %d\n", new_max_files); 

      max_files = new_max_files; 

    } 

    if (new_max_age != max_age) { 

      GC_WERR("FSGC: New max age: %d\n", new_max_age); 

      this_program::max_age = new_max_age; 

      int old_stable_time = stable_time; 

      set_max_dir_check_interval(stable_time = new_max_age); 

      if (stable_time < old_stable_time) { 

        // We need to adjust the scan times for the monitors. 

        foreach(values(monitors), Monitor m) { 

          m->next_poll = 0; 

          m->update(m->st); 

        } 

      } 

    } 

    check_threshold(); 

  } 

  int check(mixed ... args) 

  { 

    int res = ::check(@args); 

    GC_WERR("FSGC: check(%{%O, %}) ==> %O\n", args, res); 

    return res; 

  } 

  protected string _sprintf(int c, mapping|void opts) 

  { 

    return sprintf("FSGarb(%O, %d)", root, stable_time); 

  } 

  array(Stdio.Stat) get_stats() 

  { 

    return filter(values(monitors)->st, 

                  lambda(Stdio.Stat st) { 

                    return st && st->isreg; 

                  }); 

  } 

} 

mapping(string:FSGarb) fsgarbs = ([]); 

Thread.Thread meta_fsgc_thread; 

void meta_fsgc() 

{ 

  // Sleep a bit to avoid the startup race. 

  sleep(60); 

  while(meta_fsgc_thread) { 

    int max_sleep = 60; 

    foreach(fsgarbs; string id; FSGarb g) { 

      int seconds = g && g->check(); 

      if (seconds < max_sleep) max_sleep = seconds; 

    } 

    if (max_sleep < 1) max_sleep = 1; 

    GC_WERR("FSGC: Sleeping %d seconds...\n", max_sleep); 

    while(meta_fsgc_thread && max_sleep--) { 

      sleep(1); 

    } 

  } 

} 

//! Wrapper keeping a @[FSGarb] alive. 

//! 

//! When this object is destructed (eg by refcount), the corresponding 

//! @[FSGarb] will be killed. This is to make sure stale @[FSGarb]s aren't 

//! left running after module reloads or reconfigurations. 

class FSGarbWrapper(string id) 

{ 

  protected void destroy() 

  { 

    GC_WERR("FSGC: FSGarbWrapper %O destructed.\n", id); 

    FSGarb g = m_delete(fsgarbs, id); 

    if (g) destruct(g); 

  } 

  protected string _sprintf(int c, mapping|void opts) 

  { 

    return sprintf("FSGarbWrapper(%O)", id); 

  } 

  void reconfigure(int max_age, int|void max_size, int|void max_files) 

  { 

    FSGarb g = fsgarbs[id]; 

    if (g) g->reconfigure(max_age, max_size, max_files); 

  } 

} 

FSGarbWrapper register_fsgarb(string modid, string path, int max_age, 

                              int|void max_size, int|void max_files, 

                              string|void quarantine) 

{ 

  if ((path == "") || (path == "/") || (max_age <= 0)) return 0; 

  string id = modid + "\0" + path + "\0" + gethrtime(); 

  FSGarb g = FSGarb(modid, path, max_age, max_size, max_files, 

                    quarantine); 

  fsgarbs[id] = g; 

  GC_WERR("FSGC: Register garb on %O ==> id: %O\n", path, id); 

  return FSGarbWrapper(id); 

} 

void name_thread(object thread, string name); 

protected void start_fsgarb() 

{ 

  meta_fsgc_thread = Thread.Thread(meta_fsgc); 

  name_thread(meta_fsgc_thread, "Filesystem GC"); 

} 

protected void stop_fsgarb() 

{ 

  Thread.Thread th = meta_fsgc_thread; 

  if (th) { 

    meta_fsgc_thread = UNDEFINED; 

    th->wait(); 

    name_thread(th, UNDEFINED); 

  } 

} 

#endif /* Filesystem.Monitor.basic */