src/store/Storage.h

   1 /*
   2  * Copyright (C) 1996-2016 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_STORAGE_H
  10 #define SQUID_STORE_STORAGE_H
  11
  12 #include "base/RefCount.h"
  13 #include "store/forward.h"
  14
  15 class StoreInfoStats;
  16
  17 namespace Store {
  18
  19 /// A "response storage" abstraction.
  20 /// This API is shared among Controller and Controlled classes.
  21 class Storage: public RefCountable
  22 {
  23 public:
  24     virtual ~Storage() {}
  25
  26     /// create system resources needed for this store to operate in the future
  27     virtual void create() = 0;
  28
  29     /// Start preparing the store for use. To check readiness, callers should
  30     /// use readable() and writable() methods.
  31     virtual void init() = 0;
  32
  33     /// Retrieve a store entry from the store (blocking)
  34     virtual StoreEntry *get(const cache_key *) = 0;
  35
  36     /**
  37      * The maximum size the store will support in normal use. Inaccuracy is
  38      * permitted, but may throw estimates for memory etc out of whack.
  39      */
  40     virtual uint64_t maxSize() const = 0;
  41
  42     /// the minimum size the store will shrink to via normal housekeeping
  43     virtual uint64_t minSize() const = 0;
  44
  45     /// current size
  46     virtual uint64_t currentSize() const = 0;
  47
  48     /// the total number of objects stored right now
  49     virtual uint64_t currentCount() const = 0;
  50
  51     /// the maximum size of a storable object; -1 if unlimited
  52     virtual int64_t maxObjectSize() const = 0;
  53
  54     /// collect statistics
  55     virtual void getStats(StoreInfoStats &stats) const = 0;
  56
  57     /**
  58      * Output stats to the provided store entry.
  59      \todo make these calls asynchronous
  60      */
  61     virtual void stat(StoreEntry &e) const = 0;
  62
  63     /// expect an unlink() call after the entry becomes idle
  64     virtual void markForUnlink(StoreEntry &e) = 0;
  65
  66     /// remove the entry from the store
  67     virtual void unlink(StoreEntry &e) = 0;
  68
  69     /// called once every main loop iteration; TODO: Move to UFS code.
  70     virtual int callback() { return 0; }
  71
  72     /// perform regular periodic maintenance; TODO: move to UFSSwapDir::Maintain
  73     virtual void maintain() = 0;
  74
  75     /// prepare for shutdown
  76     virtual void sync() {}
  77
  78     /// whether this storage is capable of serving multiple workers;
  79     /// a true result does not imply [lack of] non-SMP support because
  80     /// [only] some SMP-aware storages also support non-SMP configss
  81     virtual bool smpAware() const = 0;
  82 };
  83
  84 } // namespace Store
  85
  86 #endif /* SQUID_STORE_STORAGE_H */
  87