src/Transients.h

   1 /*
   2  * Copyright (C) 1996-2014 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_TRANSIENTS_H
  10 #define SQUID_TRANSIENTS_H
  11
  12 #include "http/MethodType.h"
  13 #include "ipc/mem/Page.h"
  14 #include "ipc/mem/PageStack.h"
  15 #include "ipc/StoreMap.h"
  16 #include "Store.h"
  17 #include <vector>
  18
  19 // StoreEntry restoration info not already stored by Ipc::StoreMap
  20 struct TransientsMapExtraItem {
  21     char url[MAX_URL+1]; ///< Request-URI; TODO: decrease MAX_URL by one
  22     RequestFlags reqFlags; ///< request flags
  23     Http::MethodType reqMethod; ///< request method; extensions are not supported
  24 };
  25 typedef Ipc::StoreMapItems<TransientsMapExtraItem> TransientsMapExtras;
  26 typedef Ipc::StoreMap TransientsMap;
  27
  28 /// Keeps track of store entries being delivered to clients that arrived before
  29 /// those entries were [fully] cached. This shared table is necessary to sync
  30 /// the entry-writing worker with entry-reading worker(s).
  31 class Transients: public Store, public Ipc::StoreMapCleaner
  32 {
  33 public:
  34     Transients();
  35     virtual ~Transients();
  36
  37     /// return a local, previously collapsed entry
  38     StoreEntry *findCollapsed(const sfileno xitIndex);
  39
  40     /// add an in-transit entry suitable for collapsing future requests
  41     void startWriting(StoreEntry *e, const RequestFlags &reqFlags, const HttpRequestMethod &reqMethod);
  42
  43     /// called when the in-transit entry has been successfully cached
  44     void completeWriting(const StoreEntry &e);
  45
  46     /// the calling entry writer no longer expects to cache this entry
  47     void abandon(const StoreEntry &e);
  48
  49     /// whether an in-transit entry is now abandoned by its writer
  50     bool abandoned(const StoreEntry &e) const;
  51
  52     /// number of entry readers some time ago
  53     int readers(const StoreEntry &e) const;
  54
  55     /// the caller is done writing or reading this entry
  56     void disconnect(MemObject &mem_obj);
  57
  58     /* Store API */
  59     virtual int callback();
  60     virtual StoreEntry * get(const cache_key *);
  61     virtual void get(String const key , STOREGETCLIENT callback, void *cbdata);
  62     virtual void init();
  63     virtual uint64_t maxSize() const;
  64     virtual uint64_t minSize() const;
  65     virtual uint64_t currentSize() const;
  66     virtual uint64_t currentCount() const;
  67     virtual int64_t maxObjectSize() const;
  68     virtual void getStats(StoreInfoStats &stats) const;
  69     virtual void stat(StoreEntry &) const;
  70     virtual StoreSearch *search(String const url, HttpRequest *);
  71     virtual void reference(StoreEntry &);
  72     virtual bool dereference(StoreEntry &, bool);
  73     virtual void markForUnlink(StoreEntry &e);
  74     virtual void maintain();
  75
  76     static int64_t EntryLimit();
  77
  78 protected:
  79     StoreEntry *copyFromShm(const sfileno index);
  80     bool copyToShm(const StoreEntry &e, const sfileno index, const RequestFlags &reqFlags, const HttpRequestMethod &reqMethod);
  81
  82     bool abandonedAt(const sfileno index) const;
  83
  84     // Ipc::StoreMapCleaner API
  85     virtual void noteFreeMapSlice(const Ipc::StoreMapSliceId sliceId);
  86
  87 private:
  88     /// shared packed info indexed by Store keys, for creating new StoreEntries
  89     TransientsMap *map;
  90
  91     /// shared packed info that standard StoreMap does not store for us
  92     typedef TransientsMapExtras Extras;
  93     Ipc::Mem::Pointer<Extras> extras;
  94
  95     typedef std::vector<StoreEntry*> Locals;
  96     /// local collapsed entries indexed by transient ID, for syncing old StoreEntries
  97     Locals *locals;
  98 };
  99
 100 // TODO: Why use Store as a base? We are not really a cache.
 101
 102 #endif /* SQUID_TRANSIENTS_H */
 103