git.m6w6.name Git - m6w6/libmemcached/blob - util/signal.cc

   1 /*  vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
   2  *
   3  *  Data Differential Utility library
   4  *
   5  *  Copyright (C) 2012 Data Differential, http://datadifferential.com/
   6  *
   7  *  Redistribution and use in source and binary forms, with or without
   8  *  modification, are permitted provided that the following conditions are
   9  *  met:
  10  *
  11  *      * Redistributions of source code must retain the above copyright
  12  *  notice, this list of conditions and the following disclaimer.
  13  *
  14  *      * Redistributions in binary form must reproduce the above
  15  *  copyright notice, this list of conditions and the following disclaimer
  16  *  in the documentation and/or other materials provided with the
  17  *  distribution.
  18  *
  19  *      * The names of its contributors may not be used to endorse or
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  21  *  written permission.
  22  *
  23  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  24  *  "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  25  *  LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  26  *  A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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  33  *  OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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  35  */
  36
  37 #include <config.h>
  38
  39 #include <cassert>
  40 #include <cerrno>
  41 #include <csignal>
  42 #include <cstdlib>
  43 #include <cstring>
  44 #include <iostream>
  45
  46 #include <util/signal.hpp>
  47
  48 namespace datadifferential {
  49 namespace util {
  50
  51 #define MAGIC_MEMORY 123569
  52
  53 bool SignalThread::is_shutdown()
  54 {
  55   bool ret;
  56   pthread_mutex_lock(&shutdown_mutex);
  57   ret= bool(__shutdown != SHUTDOWN_RUNNING);
  58   pthread_mutex_unlock(&shutdown_mutex);
  59
  60   return ret;
  61 }
  62
  63 void SignalThread::set_shutdown(shutdown_t arg)
  64 {
  65   pthread_mutex_lock(&shutdown_mutex);
  66   __shutdown= arg;
  67   pthread_mutex_unlock(&shutdown_mutex);
  68
  69   if (arg == SHUTDOWN_GRACEFUL)
  70   {
  71     if (pthread_kill(thread, SIGUSR2) == 0)
  72     {
  73       void *retval;
  74       pthread_join(thread, &retval);
  75     }
  76   }
  77 }
  78
  79 shutdown_t SignalThread::get_shutdown()
  80 {
  81   shutdown_t local;
  82   pthread_mutex_lock(&shutdown_mutex);
  83   local= __shutdown;
  84   pthread_mutex_unlock(&shutdown_mutex);
  85
  86   return local;
  87 }
  88
  89 void SignalThread::post()
  90 {
  91   sem_post(&lock);
  92 }
  93
  94 void SignalThread::test()
  95 {
  96   assert(magic_memory == MAGIC_MEMORY);
  97   assert(sigismember(&set, SIGABRT));
  98   assert(sigismember(&set, SIGINT));
  99   assert(sigismember(&set, SIGQUIT));
 100   assert(sigismember(&set, SIGTERM));
 101   assert(sigismember(&set, SIGUSR2));
 102 }
 103
 104 SignalThread::~SignalThread()
 105 {
 106   if (not is_shutdown())
 107   {
 108     set_shutdown(SHUTDOWN_GRACEFUL);
 109   }
 110
 111 #if 0
 112   if (pthread_equal(thread, pthread_self()) != 0 and (pthread_kill(thread, 0) == ESRCH) == true)
 113   {
 114     void *retval;
 115     pthread_join(thread, &retval);
 116   }
 117 #endif
 118   sem_destroy(&lock);
 119 }
 120
 121 extern "C" {
 122
 123 static void *sig_thread(void *arg)
 124 {
 125   SignalThread *context= (SignalThread*)arg;
 126
 127   context->test();
 128   context->post();
 129
 130   while (context->get_shutdown() == SHUTDOWN_RUNNING)
 131   {
 132     int sig;
 133
 134     if (context->wait(sig) == -1)
 135     {
 136       std::cerr << "sigwait() returned errno:" << strerror(errno) << std::endl;
 137       continue;
 138     }
 139
 140     switch (sig)
 141     {
 142     case SIGUSR2:
 143       break;
 144
 145     case SIGABRT:
 146     case SIGINT:
 147     case SIGQUIT:
 148     case SIGTERM:
 149       if (context->is_shutdown() == false)
 150       {
 151         context->set_shutdown(SHUTDOWN_FORCED);
 152       }
 153
 154       if (context->exit_on_signal())
 155       {
 156         exit(EXIT_SUCCESS);
 157       }
 158
 159       break;
 160
 161     default:
 162       std::cerr << "Signal handling thread got unexpected signal " <<  strsignal(sig) << std::endl;
 163       break;
 164     }
 165   }
 166
 167   return NULL;
 168 }
 169
 170 }
 171
 172 SignalThread::SignalThread(bool exit_on_signal_arg) :
 173   _exit_on_signal(exit_on_signal_arg),
 174   magic_memory(MAGIC_MEMORY),
 175   thread(pthread_self())
 176 {
 177   pthread_mutex_init(&shutdown_mutex, NULL);
 178   sigemptyset(&set);
 179
 180   sigaddset(&set, SIGABRT);
 181   sigaddset(&set, SIGINT);
 182   sigaddset(&set, SIGQUIT);
 183   sigaddset(&set, SIGTERM);
 184   sigaddset(&set, SIGUSR2);
 185
 186   sem_init(&lock, 0, 0);
 187 }
 188
 189
 190 bool SignalThread::setup()
 191 {
 192   set_shutdown(SHUTDOWN_RUNNING);
 193
 194   int error;
 195   if ((error= pthread_sigmask(SIG_BLOCK, &set, NULL)) != 0)
 196   {
 197     std::cerr << "pthread_sigmask() died during pthread_sigmask(" << strerror(error) << ")" << std::endl;
 198     return false;
 199   }
 200
 201   if ((error= pthread_create(&thread, NULL, &sig_thread, this)) != 0)
 202   {
 203     std::cerr << "pthread_create() died during pthread_create(" << strerror(error) << ")" << std::endl;
 204     return false;
 205   }
 206
 207   sem_wait(&lock);
 208
 209   return true;
 210 }
 211
 212 } /* namespace util */
 213 } /* namespace datadifferential */