src/store/Controlled.h

   1 /*
   2  * Copyright (C) 1996-2019 The Squid Software Foundation and contributors
   3  *
   4  * Squid software is distributed under GPLv2+ license and includes
   5  * contributions from numerous individuals and organizations.
   6  * Please see the COPYING and CONTRIBUTORS files for details.
   7  */
   8
   9 #ifndef SQUID_STORE_CONTROLLED_H
  10 #define SQUID_STORE_CONTROLLED_H
  11
  12 #include "store/Storage.h"
  13
  14 namespace Store {
  15
  16 /// Storage controlled by a Controller.
  17 /// This API is shared among Disks, Disk, Memory caches and Transients.
  18 class Controlled: public Storage
  19 {
  20 public:
  21     /// \returns a possibly unlocked/unregistered stored entry with key (or nil)
  22     /// The returned entry might not match the caller's Store ID or method. The
  23     /// caller must abandon()/release() the entry or register it with Root().
  24     /// This method must not trigger slow I/O operations (e.g., disk swap in).
  25     virtual StoreEntry *get(const cache_key *) = 0;
  26
  27     /// somebody needs this entry (many cache replacement policies need to know)
  28     virtual void reference(StoreEntry &e) = 0;
  29
  30     /// somebody no longer needs this entry (usually after calling reference())
  31     /// return false iff the idle entry should be destroyed
  32     virtual bool dereference(StoreEntry &e) = 0;
  33
  34     /// make stored metadata and HTTP headers the same as in the given entry
  35     virtual void updateHeaders(StoreEntry *) {}
  36
  37     /// If Transients entry cannot be attached to this storage, return false.
  38     /// If the entry is not found, return false. Otherwise, return true after
  39     /// tying the entry to this cache and setting inSync to updateAnchored().
  40     virtual bool anchorToCache(StoreEntry &, bool &/*inSync*/) { return false; }
  41
  42     /// Update a local Transients entry with fresh info from this cache (if any).
  43     /// Return true iff the cache supports Transients entries and
  44     /// the given local Transients entry is now in sync with this storage.
  45     virtual bool updateAnchored(StoreEntry &) { return false; }
  46 };
  47
  48 } // namespace Store
  49
  50 #endif /* SQUID_STORE_CONTROLLED_H */
  51