src/adaptation/ServiceGroups.h

   1 #ifndef SQUID_ADAPTATION__SERVICE_GROUPS_H
   2 #define SQUID_ADAPTATION__SERVICE_GROUPS_H
   3
   4 #include "SquidString.h"
   5 #include "Array.h"
   6 #include "RefCount.h"
   7 #include "adaptation/Elements.h"
   8 #include "adaptation/forward.h"
   9
  10 namespace Adaptation
  11 {
  12
  13 // Interface for grouping adaptation services together.
  14 // Specific groups differ in how the first and the next services are selected
  15 class ServiceGroup: public RefCountable
  16 {
  17 public:
  18     typedef RefCount<ServiceGroup> Pointer;
  19
  20     typedef Vector<String> Store;
  21     typedef String Id;
  22     typedef unsigned int Pos; // Vector<>::poistion_type
  23     friend class ServicePlan;
  24
  25 public:
  26     ServiceGroup(const String &aKind, bool areAllServicesSame);
  27     virtual ~ServiceGroup();
  28
  29     virtual void parse();
  30     virtual void finalize(); // called after all are parsed
  31
  32     bool wants(const ServiceFilter &filter) const;
  33
  34 protected:
  35     ///< whether this group has a service at the specified pos
  36     bool has(const Pos pos) const {
  37         // does not check that the service at pos still exists
  38         return pos < services.size(); // unsigned pos is never negative
  39     }
  40
  41     /// these methods control group iteration; used by ServicePlan
  42
  43     /// find next to try after failure, starting with pos
  44     bool findReplacement(const ServiceFilter &filter, Pos &pos) const;
  45     /// find next to link after success, starting with pos
  46     bool findLink(const ServiceFilter &filter, Pos &pos) const;
  47
  48 private:
  49     ServicePointer at(const Pos pos) const;
  50     bool findService(const ServiceFilter &filter, Pos &pos) const;
  51
  52     void checkUniqueness(const Pos checkedPos) const;
  53     void finalizeMsg(const char *msg, const String &culprit, bool error) const;
  54
  55 public:
  56     String kind;
  57     Id id;
  58     Store services;
  59
  60     Method method; /// based on the first added service
  61     VectPoint point; /// based on the first added service
  62
  63     const bool allServicesSame; // whether we can freely substitute services
  64 };
  65
  66 // a group of equivalent services; one service per set is usually used
  67 class ServiceSet: public ServiceGroup
  68 {
  69 public:
  70     ServiceSet();
  71
  72 protected:
  73     virtual bool replace(Pos &pos) const { return has(++pos); }
  74     virtual bool advance(Pos &pos) const { return false; }
  75 };
  76
  77 // corner case: a group consisting of one service
  78 class SingleService: public ServiceGroup
  79 {
  80 public:
  81     SingleService(const String &aServiceKey);
  82
  83 protected:
  84     virtual bool replace(Pos &pos) const { return false; }
  85     virtual bool advance(Pos &pos) const { return false; }
  86 };
  87
  88 /// a group of services that must be used one after another
  89 class ServiceChain: public ServiceGroup
  90 {
  91 public:
  92     ServiceChain();
  93
  94 protected:
  95     virtual bool replace(Pos &pos) const { return false; }
  96     virtual bool advance(Pos &pos) const { return has(++pos); }
  97 };
  98
  99 /// a temporary service chain built upon another service request
 100 class DynamicServiceChain: public ServiceChain
 101 {
 102 public:
 103     DynamicServiceChain(const String &srvcs, const ServiceGroupPointer prev);
 104 };
 105
 106
 107 /** iterates services stored in a group; iteration is not linear because we
 108     need to both replace failed services and advance to the next chain link */
 109 class ServicePlan {
 110 public:
 111     typedef unsigned int Pos; // Vector<>::poistion_type
 112
 113 public:
 114     ServicePlan();
 115     explicit ServicePlan(const ServiceGroupPointer &g, const ServiceFilter &filter);
 116
 117     ///< true iff there are no more services planned
 118     bool exhausted() const { return atEof; }
 119
 120     /// returns nil if the plan is complete
 121     ServicePointer current() const; ///< current service
 122     ServicePointer replacement(const ServiceFilter &filter); ///< next to try after failure
 123     ServicePointer next(const ServiceFilter &filter); ///< next in chain after success
 124
 125     std::ostream &print(std::ostream &os) const;
 126
 127 private:
 128     ServiceGroupPointer group; ///< the group we are iterating
 129     Pos pos; ///< current service position within the group
 130     bool atEof; ///< cached information for better performance
 131 };
 132
 133 inline
 134 std::ostream &operator <<(std::ostream &os, const ServicePlan &p)
 135 {
 136     return p.print(os);
 137 }
 138
 139 typedef Vector<ServiceGroupPointer> Groups;
 140 extern Groups &AllGroups();
 141 extern ServiceGroupPointer FindGroup(const ServiceGroup::Id &id);
 142
 143
 144 } // namespace Adaptation
 145
 146 #endif /* SQUID_ADAPTATION__SERVICE_GROUPS_H */
 147