src/filter_load_balance.cpp

   1 /* $Id: filter_load_balance.cpp,v 1.3 2007-01-03 16:25:24 marc Exp $
   2    Copyright (c) 2005-2006, Index Data.
   3
   4    See the LICENSE file for details
   5  */
   6
   7 #include "config.hpp"
   8 #include "session.hpp"
   9 #include "package.hpp"
  10 #include "filter.hpp"
  11 #include "filter_load_balance.hpp"
  12 #include "util.hpp"
  13
  14 #include <boost/thread/mutex.hpp>
  15 #include <boost/date_time/posix_time/posix_time.hpp>
  16
  17 #include <yaz/zgdu.h>
  18
  19 #include <iostream>
  20 #include <list>
  21 #include <map>
  22 #include <limits>
  23
  24 namespace mp = metaproxy_1;
  25 namespace yf = mp::filter;
  26
  27 namespace metaproxy_1 {
  28     namespace filter {
  29         class LoadBalance::Impl {
  30         public:
  31             Impl();
  32             ~Impl();
  33             void process(metaproxy_1::Package & package);
  34             void configure(const xmlNode * ptr);
  35         private:
  36             // statistic manipulating functions,
  37             void add_dead(unsigned long session_id);
  38             //void clear_dead(unsigned long session_id);
  39             void add_package(unsigned long session_id);
  40             void remove_package(unsigned long session_id);
  41             void add_session(unsigned long session_id, std::string target);
  42             void remove_session(unsigned long session_id);
  43             std::string find_session_target(unsigned long session_id);
  44
  45             // cost functions
  46             unsigned int cost(std::string target);
  47             unsigned int dead(std::string target);
  48
  49             // local classes
  50             class TargetStat {
  51             public:
  52                 unsigned int sessions;
  53                 unsigned int packages;
  54                 unsigned int deads;
  55                 unsigned int cost() {
  56                     unsigned int c = sessions + packages + deads;
  57                     std::cout << "stats  c:" << c
  58                               << " s:" << sessions
  59                               << " p:" << packages
  60                               << " d:" << deads
  61                               <<"\n";
  62                     return c;
  63                 }
  64             };
  65
  66             // local protected databases
  67             boost::mutex m_mutex;
  68             std::map<std::string, TargetStat> m_target_stat;
  69             std::map<unsigned long, std::string> m_session_target;
  70         };
  71     }
  72 }
  73
  74 // define Pimpl wrapper forwarding to Impl
  75
  76 yf::LoadBalance::LoadBalance() : m_p(new Impl)
  77 {
  78 }
  79
  80 yf::LoadBalance::~LoadBalance()
  81 {  // must have a destructor because of boost::scoped_ptr
  82 }
  83
  84 void yf::LoadBalance::configure(const xmlNode *xmlnode)
  85 {
  86     m_p->configure(xmlnode);
  87 }
  88
  89 void yf::LoadBalance::process(mp::Package &package) const
  90 {
  91     m_p->process(package);
  92 }
  93
  94
  95 // define Implementation stuff
  96
  97
  98
  99 yf::LoadBalance::Impl::Impl()
 100 {
 101 }
 102
 103 yf::LoadBalance::Impl::~Impl()
 104 {
 105 }
 106
 107 void yf::LoadBalance::Impl::configure(const xmlNode *xmlnode)
 108 {
 109 }
 110
 111 void yf::LoadBalance::Impl::process(mp::Package &package)
 112 {
 113
 114     bool is_closed_front = false;
 115
 116     // checking for closed front end packages
 117     if (package.session().is_closed()){
 118         is_closed_front = true;
 119     }
 120
 121     Z_GDU *gdu_req = package.request().get();
 122
 123     // passing anything but z3950 packages
 124     if (gdu_req && gdu_req->which == Z_GDU_Z3950){
 125
 126         // target selecting only on Z39.50 init request
 127         if (gdu_req->u.z3950->which == Z_APDU_initRequest){
 128
 129             mp::odr odr_en(ODR_ENCODE);
 130             Z_InitRequest *org_init = gdu_req->u.z3950->u.initRequest;
 131
 132             // extracting virtual hosts
 133             std::list<std::string> vhosts;
 134
 135             mp::util::remove_vhost_otherinfo(&(org_init->otherInfo), vhosts);
 136
 137             // choosing one target according to load-balancing algorithm
 138
 139             if (vhosts.size()){
 140                 std::string target;
 141                 unsigned int cost = std::numeric_limits<unsigned int>::max();
 142
 143                 { //locking scope for local databases
 144                     boost::mutex::scoped_lock scoped_lock(m_mutex);
 145
 146                     // load-balancing algorithm goes here
 147                     //target = *vhosts.begin();
 148                     for(std::list<std::string>::const_iterator ivh
 149                             = vhosts.begin();
 150                         ivh != vhosts.end();
 151                         ivh++){
 152                         if ((*ivh).size() != 0){
 153                             unsigned int vhcost
 154                                 = yf::LoadBalance::Impl::cost(*ivh);
 155                             if (cost > vhcost){
 156                                 cost = vhcost;
 157                                 target = *ivh;
 158                             }
 159                         }
 160                      }
 161
 162                     // updating local database
 163                     add_session(package.session().id(), target);
 164                     yf::LoadBalance::Impl::cost(target);
 165                     add_package(package.session().id());
 166                 }
 167
 168                 // copying new target into init package
 169                 mp::util::set_vhost_otherinfo(&(org_init->otherInfo),
 170                                               odr_en, target);
 171                 package.request() = gdu_req;
 172         }
 173
 174         }
 175         // frontend Z39.50 close request is added to statistics and marked
 176         else if (gdu_req->u.z3950->which == Z_APDU_close){
 177             is_closed_front = true;
 178             boost::mutex::scoped_lock scoped_lock(m_mutex);
 179             add_package(package.session().id());
 180         }
 181         // any other Z39.50 package is added to statistics
 182         else {
 183             boost::mutex::scoped_lock scoped_lock(m_mutex);
 184             add_package(package.session().id());
 185         }
 186     }
 187
 188     // moving all package types
 189     package.move();
 190
 191
 192     // checking for closed back end packages
 193     if (package.session().is_closed()) {
 194         boost::mutex::scoped_lock scoped_lock(m_mutex);
 195
 196         // marking backend dead if backend closed without fronted close
 197         if (is_closed_front == false)
 198             add_dead(package.session().id());
 199
 200         remove_session(package.session().id());
 201     }
 202
 203     Z_GDU *gdu_res = package.response().get();
 204
 205     // passing anything but z3950 packages
 206     if (gdu_res && gdu_res->which == Z_GDU_Z3950){
 207
 208         // session closing only on Z39.50 close response
 209         if (gdu_res->u.z3950->which == Z_APDU_close){
 210             boost::mutex::scoped_lock scoped_lock(m_mutex);
 211             remove_package(package.session().id());
 212
 213             // marking backend dead if backend closed without fronted close
 214             if (is_closed_front == false)
 215                 add_dead(package.session().id());
 216
 217             //remove_session(package.session().id());
 218         }
 219         // any other Z39.50 package is removed from statistics
 220         else {
 221             boost::mutex::scoped_lock scoped_lock(m_mutex);
 222             remove_package(package.session().id());
 223         }
 224     }
 225 }
 226
 227 // getting timestamp for receiving of package
 228 //boost::posix_time::ptime receive_time
 229 //    = boost::posix_time::microsec_clock::local_time();
 230 // //<< receive_time << " "
 231 // //<< to_iso_string(receive_time) << " "
 232 //<< to_iso_extended_string(receive_time) << " "
 233
 234
 235 // statistic manipulating functions,
 236 void yf::LoadBalance::Impl::add_dead(unsigned long session_id){
 237
 238
 239     std::string target = find_session_target(session_id);
 240
 241     if (target.size() != 0){
 242         std::map<std::string, TargetStat>::iterator itarg;
 243         itarg = m_target_stat.find(target);
 244         if (itarg != m_target_stat.end()){
 245             itarg->second.deads += 1;
 246             std::cout << "add_dead " << session_id << " " << target
 247                       << " d:" << itarg->second.deads << "\n";
 248         }
 249     }
 250 };
 251
 252 //void yf::LoadBalance::Impl::clear_dead(unsigned long session_id){
 253 //    std::cout << "clear_dead " << session_id << "\n";
 254 //};
 255
 256 void yf::LoadBalance::Impl::add_package(unsigned long session_id){
 257
 258     std::string target = find_session_target(session_id);
 259
 260     if (target.size() != 0){
 261         std::map<std::string, TargetStat>::iterator itarg;
 262         itarg = m_target_stat.find(target);
 263         if (itarg != m_target_stat.end()){
 264             itarg->second.packages += 1;
 265             std::cout << "add_package " << session_id << " " << target
 266                       << " p:" << itarg->second.packages << "\n";
 267         }
 268     }
 269 };
 270
 271 void yf::LoadBalance::Impl::remove_package(unsigned long session_id){
 272     std::string target = find_session_target(session_id);
 273
 274     if (target.size() != 0){
 275         std::map<std::string, TargetStat>::iterator itarg;
 276         itarg = m_target_stat.find(target);
 277         if (itarg != m_target_stat.end()
 278             && itarg->second.packages > 0){
 279             itarg->second.packages -= 1;
 280             std::cout << "remove_package " << session_id << " " << target
 281                       << " p:" << itarg->second.packages << "\n";
 282         }
 283     }
 284 };
 285
 286 void yf::LoadBalance::Impl::add_session(unsigned long session_id,
 287                                         std::string target){
 288
 289     // finding and adding session
 290     std::map<unsigned long, std::string>::iterator isess;
 291     isess = m_session_target.find(session_id);
 292     if (isess == m_session_target.end()){
 293         m_session_target.insert(std::make_pair(session_id, target));
 294     }
 295
 296     // finding and adding target statistics
 297     std::map<std::string, TargetStat>::iterator itarg;
 298     itarg = m_target_stat.find(target);
 299     if (itarg == m_target_stat.end()){
 300         TargetStat stat;
 301         stat.sessions = 1;
 302         stat.packages = 0;  // no idea why the defaut constructor TargetStat()
 303         stat.deads = 0;     // is not initializig this correctly to zero ??
 304        m_target_stat.insert(std::make_pair(target, stat));
 305         std::cout << "add_session " << session_id << " " << target
 306                   << " s:1\n";
 307     } else {
 308         itarg->second.sessions += 1;
 309         std::cout << "add_session " << session_id << " " << target
 310                   << " s:" << itarg->second.sessions << "\n";
 311     }
 312
 313
 314 };
 315
 316 void yf::LoadBalance::Impl::remove_session(unsigned long session_id){
 317
 318     std::string target;
 319
 320     // finding session
 321     std::map<unsigned long, std::string>::iterator isess;
 322     isess = m_session_target.find(session_id);
 323     if (isess == m_session_target.end())
 324         return;
 325     else
 326         target = isess->second;
 327
 328     // finding target statistics
 329     std::map<std::string, TargetStat>::iterator itarg;
 330     itarg = m_target_stat.find(target);
 331     if (itarg == m_target_stat.end()){
 332         m_session_target.erase(isess);
 333         return;
 334     }
 335
 336     // counting session down
 337     if (itarg->second.sessions > 0)
 338         itarg->second.sessions -= 1;
 339
 340     std::cout << "remove_session " << session_id << " " << target
 341               << " s:" << itarg->second.sessions << "\n";
 342
 343     // clearing empty sessions and targets
 344     if (itarg->second.sessions == 0 && itarg->second.deads == 0 ){
 345         m_target_stat.erase(itarg);
 346         m_session_target.erase(isess);
 347     }
 348 };
 349
 350 std::string
 351 yf::LoadBalance::Impl::find_session_target(unsigned long session_id){
 352
 353     std::string target;
 354     std::map<unsigned long, std::string>::iterator isess;
 355     isess = m_session_target.find(session_id);
 356     if (isess != m_session_target.end())
 357         target = isess->second;
 358     return target;
 359 }
 360
 361
 362 // cost functions
 363 unsigned int yf::LoadBalance::Impl::cost(std::string target){
 364
 365     unsigned int cost;
 366
 367     if (target.size() != 0){
 368         std::map<std::string, TargetStat>::iterator itarg;
 369         itarg = m_target_stat.find(target);
 370         if (itarg != m_target_stat.end()){
 371             cost = itarg->second.cost();
 372         }
 373     }
 374
 375     std::cout << "cost " << target << " c:" << cost << "\n";
 376     return cost;
 377 };
 378
 379 unsigned int yf::LoadBalance::Impl::dead(std::string target){
 380     std::cout << "dead " << target << "\n";
 381     return 0;
 382 };
 383
 384
 385
 386
 387 static mp::filter::Base* filter_creator()
 388 {
 389     return new mp::filter::LoadBalance;
 390 }
 391
 392 extern "C" {
 393     struct metaproxy_1_filter_struct metaproxy_1_filter_load_balance = {
 394         0,
 395         "load_balance",
 396         filter_creator
 397     };
 398 }
 399
 400
 401 /*
 402  * Local variables:
 403  * c-basic-offset: 4
 404  * indent-tabs-mode: nil
 405  * c-file-style: "stroustrup"
 406  * End:
 407  * vim: shiftwidth=4 tabstop=8 expandtab
 408  */