src/Transients.h

   1 /*
   2  * Copyright (C) 1996-2017 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 "store/Controlled.h"
  18 #include <vector>
  19
  20 // StoreEntry restoration info not already stored by Ipc::StoreMap
  21 struct TransientsMapExtraItem {
  22     char url[MAX_URL+1]; ///< Request-URI; TODO: decrease MAX_URL by one
  23     RequestFlags reqFlags; ///< request flags
  24     Http::MethodType reqMethod; ///< request method; extensions are not supported
  25 };
  26 typedef Ipc::StoreMapItems<TransientsMapExtraItem> TransientsMapExtras;
  27 typedef Ipc::StoreMap TransientsMap;
  28
  29 /// Keeps track of store entries being delivered to clients that arrived before
  30 /// those entries were [fully] cached. This shared table is necessary to sync
  31 /// the entry-writing worker with entry-reading worker(s).
  32 class Transients: public Store::Controlled, public Ipc::StoreMapCleaner
  33 {
  34 public:
  35     Transients();
  36     virtual ~Transients();
  37
  38     /// return a local, previously collapsed entry
  39     StoreEntry *findCollapsed(const sfileno xitIndex);
  40
  41     /// add an in-transit entry suitable for collapsing future requests
  42     void startWriting(StoreEntry *e, const RequestFlags &reqFlags, const HttpRequestMethod &reqMethod);
  43
  44     /// called when the in-transit entry has been successfully cached
  45     void completeWriting(const StoreEntry &e);
  46
  47     /// the calling entry writer no longer expects to cache this entry
  48     void abandon(const StoreEntry &e);
  49
  50     /// whether an in-transit entry is now abandoned by its writer
  51     bool abandoned(const StoreEntry &e) const;
  52
  53     /// number of entry readers some time ago
  54     int readers(const StoreEntry &e) const;
  55
  56     /// the caller is done writing or reading this entry
  57     void disconnect(MemObject &mem_obj);
  58
  59     /* Store API */
  60     virtual StoreEntry *get(const cache_key *) override;
  61     virtual void create() override {}
  62     virtual void init() override;
  63     virtual uint64_t maxSize() const override;
  64     virtual uint64_t minSize() const override;
  65     virtual uint64_t currentSize() const override;
  66     virtual uint64_t currentCount() const override;
  67     virtual int64_t maxObjectSize() const override;
  68     virtual void getStats(StoreInfoStats &stats) const override;
  69     virtual void stat(StoreEntry &e) const override;
  70     virtual void reference(StoreEntry &e) override;
  71     virtual bool dereference(StoreEntry &e) override;
  72     virtual void markForUnlink(StoreEntry &e) override;
  73     virtual void unlink(StoreEntry &e) override;
  74     virtual void maintain() override;
  75     virtual bool smpAware() const override { return true; }
  76
  77     static int64_t EntryLimit();
  78
  79 protected:
  80     StoreEntry *copyFromShm(const sfileno index);
  81     bool copyToShm(const StoreEntry &e, const sfileno index, const RequestFlags &reqFlags, const HttpRequestMethod &reqMethod);
  82
  83     bool abandonedAt(const sfileno index) const;
  84
  85     // Ipc::StoreMapCleaner API
  86     virtual void noteFreeMapSlice(const Ipc::StoreMapSliceId sliceId) override;
  87
  88 private:
  89     /// shared packed info indexed by Store keys, for creating new StoreEntries
  90     TransientsMap *map;
  91
  92     /// shared packed info that standard StoreMap does not store for us
  93     typedef TransientsMapExtras Extras;
  94     Ipc::Mem::Pointer<Extras> extras;
  95
  96     typedef std::vector<StoreEntry*> Locals;
  97     /// local collapsed entries indexed by transient ID, for syncing old StoreEntries
  98     Locals *locals;
  99 };
 100
 101 // TODO: Why use Store as a base? We are not really a cache.
 102
 103 #endif /* SQUID_TRANSIENTS_H */
 104