src/filter_load_balance.cpp

   1 /* This file is part of Metaproxy.
   2    Copyright (C) 2005-2010 Index Data
   3
   4 Metaproxy is free software; you can redistribute it and/or modify it under
   5 the terms of the GNU General Public License as published by the Free
   6 Software Foundation; either version 2, or (at your option) any later
   7 version.
   8
   9 Metaproxy is distributed in the hope that it will be useful, but WITHOUT ANY
  10 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12 for more details.
  13
  14 You should have received a copy of the GNU General Public License
  15 along with this program; if not, write to the Free Software
  16 Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  17 */
  18
  19 #include "config.hpp"
  20 #include "session.hpp"
  21 #include "package.hpp"
  22 #include "filter.hpp"
  23 #include "filter_load_balance.hpp"
  24 #include "util.hpp"
  25
  26
  27 #include <boost/thread/mutex.hpp>
  28
  29 #include <yaz/diagbib1.h>
  30 #include <yaz/log.h>
  31 #include <yaz/zgdu.h>
  32
  33 // remove max macro if already defined (defined later in <limits>)
  34 #ifdef max
  35 #undef max
  36 #endif
  37
  38 //#include <iostream>
  39 #include <list>
  40 #include <map>
  41 #include <limits>
  42
  43 namespace mp = metaproxy_1;
  44 namespace yf = mp::filter;
  45
  46 namespace metaproxy_1
  47 {
  48     namespace filter
  49     {
  50         class LoadBalance::Impl
  51         {
  52         public:
  53             Impl();
  54             ~Impl();
  55             void process(metaproxy_1::Package & package);
  56             void configure(const xmlNode * ptr);
  57         private:
  58             // statistic manipulating functions,
  59             void add_dead(unsigned long session_id);
  60             //void clear_dead(unsigned long session_id);
  61             void add_package(unsigned long session_id);
  62             void remove_package(unsigned long session_id);
  63             void add_session(unsigned long session_id, std::string target);
  64             void remove_session(unsigned long session_id);
  65             std::string find_session_target(unsigned long session_id);
  66
  67             // cost functions
  68             unsigned int cost(std::string target);
  69             unsigned int dead(std::string target);
  70
  71             // local classes
  72             class TargetStat {
  73             public:
  74                 unsigned int sessions;
  75                 unsigned int packages;
  76                 unsigned int deads;
  77                 unsigned int cost() {
  78                     unsigned int c = sessions + packages + deads;
  79                     return c;
  80                 }
  81             };
  82
  83             // local protected databases
  84             boost::mutex m_mutex;
  85             std::map<std::string, TargetStat> m_target_stat;
  86             std::map<unsigned long, std::string> m_session_target;
  87         };
  88     }
  89 }
  90
  91 // define Pimpl wrapper forwarding to Impl
  92
  93 yf::LoadBalance::LoadBalance() : m_p(new Impl)
  94 {
  95 }
  96
  97 yf::LoadBalance::~LoadBalance()
  98 {  // must have a destructor because of boost::scoped_ptr
  99 }
 100
 101 void yf::LoadBalance::configure(const xmlNode *xmlnode, bool test_only)
 102 {
 103     m_p->configure(xmlnode);
 104 }
 105
 106 void yf::LoadBalance::process(mp::Package &package) const
 107 {
 108     m_p->process(package);
 109 }
 110
 111
 112 yf::LoadBalance::Impl::Impl()
 113 {
 114 }
 115
 116 yf::LoadBalance::Impl::~Impl()
 117 {
 118 }
 119
 120 void yf::LoadBalance::Impl::configure(const xmlNode *xmlnode)
 121 {
 122 }
 123
 124 void yf::LoadBalance::Impl::process(mp::Package &package)
 125 {
 126     bool is_closed_front = false;
 127
 128     // checking for closed front end packages
 129     if (package.session().is_closed())
 130     {
 131         is_closed_front = true;
 132     }
 133
 134     Z_GDU *gdu_req = package.request().get();
 135
 136     // passing anything but z3950 packages
 137     if (gdu_req && gdu_req->which == Z_GDU_Z3950)
 138     {
 139         // target selecting only on Z39.50 init request
 140         if (gdu_req->u.z3950->which == Z_APDU_initRequest)
 141         {
 142             yazpp_1::GDU base_req(gdu_req);
 143             Z_APDU *apdu = base_req.get()->u.z3950;
 144
 145             Z_InitRequest *org_init = base_req.get()->u.z3950->u.initRequest;
 146             mp::odr odr_en(ODR_ENCODE);
 147
 148             std::list<std::string> vhosts;
 149             mp::util::remove_vhost_otherinfo(&(org_init->otherInfo), vhosts);
 150             // get lowest of all vhosts.. Remove them if individually if
 151             // they turn out to be bad..
 152             while (1)
 153             {
 154                 std::string target;
 155                 std::list<std::string>::iterator ivh = vhosts.begin();
 156
 157                 Package init_pkg(package.session(), package.origin());
 158                 init_pkg.copy_filter(package);
 159
 160                 unsigned int cost = std::numeric_limits<unsigned int>::max();
 161                 {
 162                     boost::mutex::scoped_lock scoped_lock(m_mutex);
 163
 164                     for (; ivh != vhosts.end(); )
 165                     {
 166                         if ((*ivh).size() != 0)
 167                         {
 168                             unsigned int vhcost
 169                                 = yf::LoadBalance::Impl::cost(*ivh);
 170                             yaz_log(YLOG_LOG, "Consider %s cost=%u vhcost=%u",
 171                                     (*ivh).c_str(), cost, vhcost);
 172                             if (cost > vhcost)
 173                             {
 174                                 cost = vhcost;
 175                                 target = *ivh;
 176                                 ivh = vhosts.erase(ivh);
 177                             }
 178                             else
 179                                 ivh++;
 180                         }
 181                         else
 182                             ivh++;
 183                     }
 184                 }
 185                 if (target.length() == 0)
 186                     break;
 187                 // copying new target into init package
 188
 189                 yazpp_1::GDU init_gdu(base_req);
 190                 Z_InitRequest *init_req = init_gdu.get()->u.z3950->u.initRequest;
 191
 192                 mp::util::set_vhost_otherinfo(&(init_req->otherInfo),
 193                                               odr_en, target, 1);
 194
 195                 init_pkg.request() = init_gdu;
 196
 197                 // moving all package types
 198                 init_pkg.move();
 199
 200                 // checking for closed back end packages
 201                 if (!init_pkg.session().is_closed())
 202                 {
 203                     add_session(package.session().id(), target);
 204
 205                     package.response() = init_pkg.response();
 206                     return;
 207                 }
 208             }
 209             mp::odr odr;
 210             package.response() = odr.create_initResponse(
 211                 apdu, YAZ_BIB1_TEMPORARY_SYSTEM_ERROR,
 212                 "load_balance: no available targets");
 213             package.session().close();
 214             return;
 215         }
 216         // frontend Z39.50 close request is added to statistics and marked
 217         else if (gdu_req->u.z3950->which == Z_APDU_close)
 218         {
 219             is_closed_front = true;
 220             boost::mutex::scoped_lock scoped_lock(m_mutex);
 221             add_package(package.session().id());
 222         }
 223         // any other Z39.50 package is added to statistics
 224         else
 225         {
 226             boost::mutex::scoped_lock scoped_lock(m_mutex);
 227             add_package(package.session().id());
 228         }
 229     }
 230
 231     // moving all package types
 232     package.move();
 233
 234     bool is_closed_back = false;
 235
 236     // checking for closed back end packages
 237     if (package.session().is_closed())
 238         is_closed_back = true;
 239
 240     Z_GDU *gdu_res = package.response().get();
 241
 242     // passing anything but z3950 packages
 243     if (gdu_res && gdu_res->which == Z_GDU_Z3950)
 244     {
 245         // session closing only on Z39.50 close response
 246         if (gdu_res->u.z3950->which == Z_APDU_close)
 247         {
 248             is_closed_back = true;
 249             boost::mutex::scoped_lock scoped_lock(m_mutex);
 250             remove_package(package.session().id());
 251         }
 252         // any other Z39.50 package is removed from statistics
 253         else
 254         {
 255             boost::mutex::scoped_lock scoped_lock(m_mutex);
 256             remove_package(package.session().id());
 257         }
 258     }
 259
 260     // finally removing sessions and marking deads
 261     if (is_closed_back || is_closed_front)
 262     {
 263         boost::mutex::scoped_lock scoped_lock(m_mutex);
 264
 265         // marking backend dead if backend closed without fronted close
 266         if (is_closed_front == false)
 267             add_dead(package.session().id());
 268
 269         remove_session(package.session().id());
 270
 271         // making sure that package is closed
 272         package.session().close();
 273     }
 274 }
 275
 276 // statistic manipulating functions,
 277 void yf::LoadBalance::Impl::add_dead(unsigned long session_id)
 278 {
 279     std::string target = find_session_target(session_id);
 280
 281     if (target.size() != 0)
 282     {
 283         std::map<std::string, TargetStat>::iterator itarg;
 284         itarg = m_target_stat.find(target);
 285         if (itarg != m_target_stat.end()
 286             && itarg->second.deads < std::numeric_limits<unsigned int>::max())
 287         {
 288             itarg->second.deads += 1;
 289             // std:.cout << "add_dead " << session_id << " " << target
 290             //          << " d:" << itarg->second.deads << "\n";
 291         }
 292     }
 293 }
 294
 295 void yf::LoadBalance::Impl::add_package(unsigned long session_id)
 296 {
 297     std::string target = find_session_target(session_id);
 298
 299     if (target.size() != 0)
 300     {
 301         std::map<std::string, TargetStat>::iterator itarg;
 302         itarg = m_target_stat.find(target);
 303         if (itarg != m_target_stat.end()
 304             && itarg->second.packages
 305                < std::numeric_limits<unsigned int>::max())
 306         {
 307             itarg->second.packages += 1;
 308         }
 309     }
 310 }
 311
 312 void yf::LoadBalance::Impl::remove_package(unsigned long session_id)
 313 {
 314     std::string target = find_session_target(session_id);
 315
 316     if (target.size() != 0)
 317     {
 318         std::map<std::string, TargetStat>::iterator itarg;
 319         itarg = m_target_stat.find(target);
 320         if (itarg != m_target_stat.end()
 321             && itarg->second.packages > 0)
 322         {
 323             itarg->second.packages -= 1;
 324         }
 325     }
 326 }
 327
 328 void yf::LoadBalance::Impl::add_session(unsigned long session_id,
 329                                         std::string target)
 330 {
 331     // finding and adding session
 332     std::map<unsigned long, std::string>::iterator isess;
 333     isess = m_session_target.find(session_id);
 334     if (isess == m_session_target.end())
 335     {
 336         m_session_target.insert(std::make_pair(session_id, target));
 337     }
 338
 339     // finding and adding target statistics
 340     std::map<std::string, TargetStat>::iterator itarg;
 341     itarg = m_target_stat.find(target);
 342     if (itarg == m_target_stat.end())
 343     {
 344         TargetStat stat;
 345         stat.sessions = 1;
 346         stat.packages = 0;
 347         stat.deads = 0;
 348         m_target_stat.insert(std::make_pair(target, stat));
 349     }
 350     else if (itarg->second.sessions < std::numeric_limits<unsigned int>::max())
 351     {
 352         itarg->second.sessions += 1;
 353     }
 354 }
 355
 356 void yf::LoadBalance::Impl::remove_session(unsigned long session_id)
 357 {
 358     std::string target;
 359
 360     // finding session
 361     std::map<unsigned long, std::string>::iterator isess;
 362     isess = m_session_target.find(session_id);
 363     if (isess == m_session_target.end())
 364         return;
 365     else
 366         target = isess->second;
 367
 368     // finding target statistics
 369     std::map<std::string, TargetStat>::iterator itarg;
 370     itarg = m_target_stat.find(target);
 371     if (itarg == m_target_stat.end())
 372     {
 373         m_session_target.erase(isess);
 374         return;
 375     }
 376
 377     // counting session down
 378     if (itarg->second.sessions > 0)
 379         itarg->second.sessions -= 1;
 380
 381     if (itarg->second.sessions == 0 && itarg->second.deads == 0)
 382     {
 383         m_target_stat.erase(itarg);
 384         m_session_target.erase(isess);
 385     }
 386 }
 387
 388 std::string yf::LoadBalance::Impl::find_session_target(unsigned long session_id)
 389 {
 390     std::string target;
 391     std::map<unsigned long, std::string>::iterator isess;
 392     isess = m_session_target.find(session_id);
 393     if (isess != m_session_target.end())
 394         target = isess->second;
 395     return target;
 396 }
 397
 398
 399 // cost functions
 400 unsigned int yf::LoadBalance::Impl::cost(std::string target)
 401 {
 402     unsigned int cost = 0;
 403
 404     if (target.size() != 0)
 405     {
 406         std::map<std::string, TargetStat>::iterator itarg;
 407         itarg = m_target_stat.find(target);
 408         if (itarg != m_target_stat.end())
 409             cost = itarg->second.cost();
 410     }
 411     return cost;
 412 }
 413
 414 unsigned int yf::LoadBalance::Impl::dead(std::string target)
 415 {
 416     unsigned int dead = 0;
 417
 418     if (target.size() != 0)
 419     {
 420         std::map<std::string, TargetStat>::iterator itarg;
 421         itarg = m_target_stat.find(target);
 422         if (itarg != m_target_stat.end())
 423             dead = itarg->second.deads;
 424     }
 425     return dead;
 426 }
 427
 428
 429 static mp::filter::Base* filter_creator()
 430 {
 431     return new mp::filter::LoadBalance;
 432 }
 433
 434 extern "C" {
 435     struct metaproxy_1_filter_struct metaproxy_1_filter_load_balance = {
 436         0,
 437         "load_balance",
 438         filter_creator
 439     };
 440 }
 441
 442
 443 /*
 444  * Local variables:
 445  * c-basic-offset: 4
 446  * c-file-style: "Stroustrup"
 447  * indent-tabs-mode: nil
 448  * End:
 449  * vim: shiftwidth=4 tabstop=8 expandtab
 450  */
 451