ACE/FAQ/APG/Processes

// $Id: Process_Manager_Death.cpp 94310 2011-07-09 19:10:06Z schmidt $
 
#include "ace/Log_Msg.h"
#include "ace/Process_Manager.h"
#include "ace/Reactor.h"
 
static const int NCHILDREN = 2;
 
// Listing 1 code/ch10
class DeathHandler: public ACE_Event_Handler
{
public:
  DeathHandler () : count_(0)
  {
    ACE_TRACE ("DeathHandler::DeathHandler");
  }
 
  virtual int handle_exit (ACE_Process * process)
  {
    ACE_TRACE ("DeathHandler::handle_exit");
 
    ACE_DEBUG
      ((LM_DEBUG,
        ACE_TEXT ("Process %d exited with exit code %d\n"),
        process->getpid (), process->return_value ()));
 
    if (++count_ == NCHILDREN)
      ACE_Reactor::instance ()->end_reactor_event_loop ();
 
    return 0;
  }
 
private:
  int count_;
};
// Listing 1
// Listing 0 code/ch10
int ACE_TMAIN (int argc, ACE_TCHAR *argv[])
{
  if (argc > 1)      // Running as a child.
    return 0;
 
  // Instantiate a process manager with space for
  // 10 processes.
  ACE_Process_Manager pm (10, ACE_Reactor::instance ());
 
  // Create a process termination handler.
  DeathHandler handler;
 
  // Specify the options for the new processes to be spawned.
  ACE_Process_Options options;
  options.command_line (ACE_TEXT ("%s a"), argv[0]);
 
  // Spawn two child processes.
  pid_t pids[NCHILDREN];
  pm.spawn_n (NCHILDREN, options, pids);
 
  // Register handler to be called when these processes exit.
  for (int i = 0; i < NCHILDREN; i++)
    pm.register_handler (&handler, pids[i]);
 
  // Run the reactor event loop waiting for events to occur.
  ACE_Reactor::instance ()->run_reactor_event_loop ();
 
  return 0;
}
// Listing 0

// $Id: Process_Manager_Spawn.cpp 80826 2008-03-04 14:51:23Z wotte $
 
#include "ace/OS_NS_unistd.h"
#include "ace/Log_Msg.h"
// Listing 0 code/ch10
#include "ace/Process_Manager.h"
 
static const int NCHILDREN = 2;
 
int ACE_TMAIN (int argc, ACE_TCHAR *argv[])
{
  if (argc > 1)     // Running as a child.
    {
      ACE_OS::sleep (10);
    }
  else             // Running as a parent.
    {
      // Get the processwide process manager.
      ACE_Process_Manager* pm = ACE_Process_Manager::instance ();
 
      // Specify the options for the new processes
      // to be spawned.
      ACE_Process_Options options;
      options.command_line (ACE_TEXT ("%s a"), argv[0]);
 
      // Spawn two child processes.
      pid_t pids[NCHILDREN];
      pm->spawn_n (NCHILDREN, options, pids);
 
      // Destroy the first child.
      pm->terminate (pids[0]);
 
      // Wait for the child we just terminated.
      ACE_exitcode status;
      pm->wait (pids[0], &status);
 
      // Get the results of the termination.
 
#if !defined(ACE_WIN32)
      if (WIFSIGNALED (status) != 0)
        ACE_DEBUG ((LM_DEBUG,
                    ACE_TEXT ("%d died because of a signal ")
                    ACE_TEXT ("of type %d\n"),
                    pids[0], WTERMSIG (status)));
#else
      ACE_DEBUG
        ((LM_DEBUG,
          ACE_TEXT ("The process terminated with exit code %d\n"),
          status));
#endif /*ACE_WIN32*/
 
      // Wait for all (only one left) of the
      // children to exit.
      pm->wait (0);
    }
 
  return 0;
}
// Listing 0

// $Id: Process_Mutex.cpp 95466 2012-01-20 19:31:23Z johnnyw $
 
#include "ace/OS_NS_unistd.h"
#include "ace/Log_Msg.h"
#include "ace/Process.h"
#include "ace/Process_Mutex.h"
 
// Listing 1 code/ch10
class GResourceUser
{
public:
  GResourceUser (ACE_Process_Mutex &mutex) : gmutex_(mutex)
  {
    ACE_TRACE ("GResourceUser::GResourceUser");
  }
 
  void run (void)
  {
    ACE_TRACE ("GResourceUser::run");
 
    int count = 0;
    while (count++ < 10)
      {
        int result = this->gmutex_.acquire ();
        ACE_TEST_ASSERT (result == 0);
 
        ACE_DEBUG ((LM_DEBUG,
                    ACE_TEXT ("(%P| %t) has the mutex\n")));
 
        // Access Global resource
        ACE_OS::sleep (1);
 
        result = this->gmutex_.release ();
        ACE_TEST_ASSERT (result == 0);
        ACE_OS::sleep (1);     // Give other process a chance.
      }
  }
 
private:
  ACE_Process_Mutex &gmutex_;
};
// Listing 1
 
// Listing 0 code/ch10
int ACE_TMAIN (int argc, ACE_TCHAR *argv[])
{
  if (argc > 1)      // Run as the child.
    {
      // Create or get the global mutex.
      ACE_Process_Mutex mutex ("GlobalMutex");
 
      GResourceUser acquirer (mutex);
      acquirer.run ();
    }
  else              // Run as the parent.
    {
      ACE_Process_Options options;
      options.command_line (ACE_TEXT ("%s a"), argv[0]);
      ACE_Process processa, processb;
 
      pid_t pida = processa.spawn (options);
      pid_t pidb = processb.spawn (options);
 
      ACE_DEBUG ((LM_DEBUG,
                  ACE_TEXT ("Spawned processes; pids %d:%d\n"),
                  pida, pidb));
 
      if (processa.wait() == -1)
        ACE_ERROR_RETURN ((LM_ERROR, ACE_TEXT ("%p\n"),
                           ACE_TEXT ("processa wait")), -1);
 
      if (processb.wait() == -1)
        ACE_ERROR_RETURN ((LM_ERROR, ACE_TEXT ("%p\n"),
                           ACE_TEXT ("processb wait")), -1);
    }
 
  return 0;
}
// Listing 0

// $Id: Spawn.cpp 80826 2008-03-04 14:51:23Z wotte $
 
#include "ace/OS_NS_stdio.h"
#include "ace/OS_NS_fcntl.h"
#include "ace/OS_NS_pwd.h"
#include "ace/os_include/os_pwd.h"
#include "ace/OS_NS_stdlib.h"
#include "ace/OS_NS_string.h"
#include "ace/OS_NS_unistd.h"
#include "ace/OS_NS_pwd.h"
#include "ace/Process.h"
#include "ace/Log_Msg.h"
 
// Listing 1 code/ch10
class Manager : public ACE_Process
{
public:
  Manager (const ACE_TCHAR* program_name)
  {
    ACE_TRACE ("Manager::Manager");
    ACE_OS::strcpy (programName_, program_name);
  }
 
  int doWork (void)
  {
    ACE_TRACE ("Manager::doWork");
 
    // Spawn the new process; prepare() hook is called first.
    ACE_Process_Options options;
    pid_t pid = this->spawn (options);
    if (pid == ACE_INVALID_PID)
      ACE_ERROR_RETURN((LM_ERROR, ACE_TEXT ("%p\n"),
                        ACE_TEXT ("spawn")), -1);
 
    // Wait forever for my child to exit.
    if (this->wait () == -1)
      ACE_ERROR_RETURN ((LM_ERROR, ACE_TEXT ("%p\n"),
                         ACE_TEXT ("wait")), -1);
 
    // Dump whatever happened.
    this->dumpRun ();
    return 0;
  }
// Listing 1
 
private:
  // Listing 3 code/ch10
  int dumpRun (void)
  {
    ACE_TRACE ("Manager::dumpRun");
 
    if (ACE_OS::lseek (this->outputfd_, 0, SEEK_SET) == -1)
      ACE_ERROR_RETURN ((LM_ERROR, ACE_TEXT ("%p\n"),
                         ACE_TEXT ("lseek")), -1);
 
    char buf[1024];
    ssize_t length = 0;
 
    // Read the contents of the error stream written
    // by the child and print it out.
    while ((length = ACE_OS::read (this->outputfd_,
                                   buf, sizeof(buf)-1)) > 0)
      {
        buf[length] = 0;
        ACE_DEBUG ((LM_DEBUG, ACE_TEXT ("%C\n"), buf));
      }
 
    ACE_OS::close (this->outputfd_);
    return 0;
  }
 // Listing 3
 
 // Listing 2 code/ch10
  // prepare() is inherited from ACE_Process.
  int prepare (ACE_Process_Options &options)
  {
    ACE_TRACE ("Manager::prepare");
 
    options.command_line (ACE_TEXT ("%s 1"), this->programName_);
    if (this->setStdHandles (options) == -1 ||
        this->setEnvVariable (options) == -1)
      return -1;
#if !defined (ACE_WIN32) && !defined (ACE_LACKS_PWD_FUNCTIONS)
    return this->setUserID (options);
#else
    return 0;
#endif
  }
 
  int setStdHandles (ACE_Process_Options &options)
  {
    ACE_TRACE ("Manager::setStdHandles");
 
    ACE_OS::unlink ("output.dat");
    this->outputfd_ =
      ACE_OS::open ("output.dat", O_RDWR | O_CREAT);
    return options.set_handles
      (ACE_STDIN, ACE_STDOUT, this->outputfd_);
  }
 
  int setEnvVariable (ACE_Process_Options &options)
  {
    ACE_TRACE ("Manager::setEnvVariables");
    return options.setenv
      (ACE_TEXT ("PRIVATE_VAR=/that/seems/to/be/it"));
  }
 // Listing 2
 
#if !defined (ACE_LACKS_PWD_FUNCTIONS)
 // Listing 10 code/ch10
  int setUserID (ACE_Process_Options &options)
  {
    ACE_TRACE ("Manager::setUserID");
    passwd* pw = ACE_OS::getpwnam ("nobody");
    if (pw == 0)
      return -1;
    options.seteuid (pw->pw_uid);
    return 0;
  }
 // Listing 10
#endif /* !ACE_LACKS_PWD_FUNCTIONS */
 
private:
  ACE_HANDLE outputfd_;
  ACE_TCHAR programName_[256];
};
 
// Listing 4 code/ch10
class Slave
{
public:
  Slave ()
  {
    ACE_TRACE ("Slave::Slave");
  }
 
  int doWork (void)
  {
    ACE_TRACE ("Slave::doWork");
 
    ACE_DEBUG ((LM_INFO,
                ACE_TEXT ("(%P) started at %T, parent is %d\n"),
                ACE_OS::getppid ()));
    this->showWho ();
    ACE_DEBUG ((LM_INFO,
                ACE_TEXT ("(%P) the private environment is %s\n"),
                ACE_OS::getenv ("PRIVATE_VAR")));
 
    ACE_TCHAR str[128];
    ACE_OS::sprintf (str, ACE_TEXT ("(%d) Enter your command\n"),
                     static_cast<int>(ACE_OS::getpid ()));
    ACE_OS::write (ACE_STDOUT, str, ACE_OS::strlen (str));
    this->readLine (str);
    ACE_DEBUG ((LM_DEBUG, ACE_TEXT ("(%P) Executed: %C\n"),
                str));
    return 0;
  }
// Listing 4
 
  void showWho (void)
  {
    ACE_TRACE ("Slave::showWho");
#if !defined (ACE_LACKS_PWD_FUNCTIONS)
    passwd *pw = ::getpwuid (ACE_OS::geteuid ());
    ACE_DEBUG ((LM_INFO,
                ACE_TEXT ("(%P) Running this process as:%s\n"),
                pw->pw_name));
#endif
  }
 
  ACE_TCHAR* readLine (ACE_TCHAR* str)
  {
    ACE_TRACE ("Slave::readLine");
 
    int i = 0;
    while (true)
      {
        ssize_t retval = ACE_OS::read (ACE_STDIN, &str[i], 1);
        if (retval > 0)
          {
            if (str[i] == '\n')
              {
                str[++i] = 0;
                return str;
              }
            i++;
          }
        else
          return str;
      }
  }
};
 
// Listing 0 code/ch10
int ACE_TMAIN (int argc, ACE_TCHAR *argv[])
{
  if (argc > 1)   // Slave mode
    {
      Slave s;
      return s.doWork ();
    }
 
  // Else, Master mode
  Manager m (argv[0]);
  return m.doWork ();
}
// Listing 0