src/store/Storage.h

   1 /*
   2  * Copyright (C) 1996-2023 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_SRC_STORE_STORAGE_H
  10 #define SQUID_SRC_STORE_STORAGE_H
  11
  12 #include "base/RefCount.h"
  13 #include "http/RequestMethod.h"
  14 #include "store/forward.h"
  15 #include "store_key_md5.h"
  16
  17 class StoreInfoStats;
  18
  19 namespace Store {
  20
  21 /// A "response storage" abstraction.
  22 /// This API is shared among Controller and Controlled classes.
  23 class Storage: public RefCountable
  24 {
  25 public:
  26     ~Storage() override {}
  27
  28     /// create system resources needed for this store to operate in the future
  29     virtual void create() = 0;
  30
  31     /// Start preparing the store for use. To check readiness, callers should
  32     /// use readable() and writable() methods.
  33     virtual void init() = 0;
  34
  35     /**
  36      * The maximum size the store will support in normal use. Inaccuracy is
  37      * permitted, but may throw estimates for memory etc out of whack.
  38      */
  39     virtual uint64_t maxSize() const = 0;
  40
  41     /// the minimum size the store will shrink to via normal housekeeping
  42     virtual uint64_t minSize() const = 0;
  43
  44     /// current size
  45     virtual uint64_t currentSize() const = 0;
  46
  47     /// the total number of objects stored right now
  48     virtual uint64_t currentCount() const = 0;
  49
  50     /// the maximum size of a storable object; -1 if unlimited
  51     virtual int64_t maxObjectSize() const = 0;
  52
  53     /// collect statistics
  54     virtual void getStats(StoreInfoStats &stats) const = 0;
  55
  56     /**
  57      * Output stats to the provided store entry.
  58      * TODO: make these calls asynchronous
  59      */
  60     virtual void stat(StoreEntry &e) const = 0;
  61
  62     /// Prevent new get() calls from returning the matching entry.
  63     /// If the matching entry is unused, it may be removed from the store now.
  64     /// The store entry is matched using either `e` attachment info or `e.key`.
  65     virtual void evictCached(StoreEntry &e) = 0;
  66
  67     /// An evictCached() equivalent for callers that did not get() a StoreEntry.
  68     /// Callers with StoreEntry objects must use evictCached() instead.
  69     virtual void evictIfFound(const cache_key *) = 0;
  70
  71     /// called once every main loop iteration; TODO: Move to UFS code.
  72     virtual int callback() { return 0; }
  73
  74     /// perform regular periodic maintenance; TODO: move to UFSSwapDir::Maintain
  75     virtual void maintain() = 0;
  76
  77     /// prepare for shutdown
  78     virtual void sync() {}
  79 };
  80
  81 } // namespace Store
  82
  83 #endif /* SQUID_SRC_STORE_STORAGE_H */
  84