pdns/mplexer.hh

   1 /*
   2  * This file is part of PowerDNS or dnsdist.
   3  * Copyright -- PowerDNS.COM B.V. and its contributors
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of version 2 of the GNU General Public License as
   7  * published by the Free Software Foundation.
   8  *
   9  * In addition, for the avoidance of any doubt, permission is granted to
  10  * link this program with OpenSSL and to (re)distribute the binaries
  11  * produced as the result of such linking.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22 #ifndef PDNS_MPLEXER_HH
  23 #define PDNS_MPLEXER_HH
  24 #include <boost/function.hpp>
  25 #include <boost/any.hpp>
  26 #include <boost/shared_array.hpp>
  27 #include <boost/tuple/tuple.hpp>
  28 #include <boost/tuple/tuple_comparison.hpp>
  29 #include <vector>
  30 #include <map>
  31 #include <stdexcept>
  32 #include <string>
  33 #include <sys/time.h>
  34
  35 class FDMultiplexerException : public std::runtime_error
  36 {
  37 public:
  38   FDMultiplexerException(const std::string& str) : std::runtime_error(str)
  39   {}
  40 };
  41
  42
  43 /** Very simple FD multiplexer, based on callbacks and boost::any parameters
  44     As a special service, this parameter is kept around and can be modified,
  45     allowing for state to be stored inside the multiplexer.
  46
  47     It has some "interesting" semantics
  48 */
  49
  50 class FDMultiplexer
  51 {
  52 public:
  53   typedef boost::any funcparam_t;
  54 protected:
  55
  56   typedef boost::function< void(int, funcparam_t&) > callbackfunc_t;
  57   struct Callback
  58   {
  59     callbackfunc_t d_callback;
  60     funcparam_t d_parameter;
  61     struct timeval d_ttd;
  62   };
  63
  64 public:
  65   FDMultiplexer() : d_inrun(false)
  66   {}
  67   virtual ~FDMultiplexer()
  68   {}
  69
  70   /* tv will be updated to 'now' before run returns */
  71   /* timeout is in ms */
  72   virtual int run(struct timeval* tv, int timeout=500) = 0;
  73
  74   //! Add an fd to the read watch list - currently an fd can only be on one list at a time!
  75   virtual void addReadFD(int fd, callbackfunc_t toDo, const funcparam_t& parameter=funcparam_t())
  76   {
  77     this->addFD(d_readCallbacks, fd, toDo, parameter);
  78   }
  79
  80   //! Add an fd to the write watch list - currently an fd can only be on one list at a time!
  81   virtual void addWriteFD(int fd, callbackfunc_t toDo, const funcparam_t& parameter=funcparam_t())
  82   {
  83     this->addFD(d_writeCallbacks, fd, toDo, parameter);
  84   }
  85
  86   //! Remove an fd from the read watch list. You can't call this function on an fd that is closed already!
  87   /** WARNING: references to 'parameter' become invalid after this function! */
  88   virtual void removeReadFD(int fd)
  89   {
  90     this->removeFD(d_readCallbacks, fd);
  91   }
  92
  93   //! Remove an fd from the write watch list. You can't call this function on an fd that is closed already!
  94   /** WARNING: references to 'parameter' become invalid after this function! */
  95   virtual void removeWriteFD(int fd)
  96   {
  97     this->removeFD(d_writeCallbacks, fd);
  98   }
  99
 100   virtual void setReadTTD(int fd, struct timeval tv, int timeout)
 101   {
 102     if(!d_readCallbacks.count(fd))
 103       throw FDMultiplexerException("attempt to timestamp fd not in the multiplexer");
 104     tv.tv_sec += timeout;
 105     d_readCallbacks[fd].d_ttd=tv;
 106   }
 107
 108   virtual funcparam_t& getReadParameter(int fd)
 109   {
 110     if(!d_readCallbacks.count(fd))
 111       throw FDMultiplexerException("attempt to look up data in multiplexer for unlisted fd "+std::to_string(fd));
 112     return d_readCallbacks[fd].d_parameter;
 113   }
 114
 115   virtual std::vector<std::pair<int, funcparam_t> > getTimeouts(const struct timeval& tv)
 116   {
 117     std::vector<std::pair<int, funcparam_t> > ret;
 118     for(callbackmap_t::iterator i=d_readCallbacks.begin(); i!=d_readCallbacks.end(); ++i)
 119       if(i->second.d_ttd.tv_sec && boost::tie(tv.tv_sec, tv.tv_usec) > boost::tie(i->second.d_ttd.tv_sec, i->second.d_ttd.tv_usec))
 120         ret.push_back(std::make_pair(i->first, i->second.d_parameter));
 121     return ret;
 122   }
 123
 124   typedef FDMultiplexer* getMultiplexer_t();
 125   typedef std::multimap<int, getMultiplexer_t*> FDMultiplexermap_t;
 126
 127   static FDMultiplexermap_t& getMultiplexerMap()
 128   {
 129     static FDMultiplexermap_t theMap;
 130     return theMap;
 131   }
 132
 133   virtual std::string getName() = 0;
 134
 135 protected:
 136   typedef std::map<int, Callback> callbackmap_t;
 137   callbackmap_t d_readCallbacks, d_writeCallbacks;
 138
 139   virtual void addFD(callbackmap_t& cbmap, int fd, callbackfunc_t toDo, const funcparam_t& parameter)=0;
 140   virtual void removeFD(callbackmap_t& cbmap, int fd)=0;
 141   bool d_inrun;
 142   callbackmap_t::iterator d_iter;
 143
 144   void accountingAddFD(callbackmap_t& cbmap, int fd, callbackfunc_t toDo, const funcparam_t& parameter)
 145   {
 146     Callback cb;
 147     cb.d_callback=toDo;
 148     cb.d_parameter=parameter;
 149     memset(&cb.d_ttd, 0, sizeof(cb.d_ttd));
 150
 151     if(cbmap.count(fd))
 152       throw FDMultiplexerException("Tried to add fd "+std::to_string(fd)+ " to multiplexer twice");
 153     cbmap[fd]=cb;
 154   }
 155
 156   void accountingRemoveFD(callbackmap_t& cbmap, int fd)
 157   {
 158     if(!cbmap.erase(fd))
 159       throw FDMultiplexerException("Tried to remove unlisted fd "+std::to_string(fd)+ " from multiplexer");
 160   }
 161 };
 162
 163 class SelectFDMultiplexer : public FDMultiplexer
 164 {
 165 public:
 166   SelectFDMultiplexer()
 167   {}
 168   virtual ~SelectFDMultiplexer()
 169   {}
 170
 171   virtual int run(struct timeval* tv, int timeout=500);
 172
 173   virtual void addFD(callbackmap_t& cbmap, int fd, callbackfunc_t toDo, const funcparam_t& parameter);
 174   virtual void removeFD(callbackmap_t& cbmap, int fd);
 175   std::string getName()
 176   {
 177     return "select";
 178   }
 179 };
 180
 181 #endif
 182