TAO/orbsvcs/LoadBalancer/Signal_Handler.h

   1 // -*- C++ -*-
   2
   3 //=============================================================================
   4 /**
   5  * @file   Signal_Handler.h
   6  *
   7  * @author Ossama Othman <ossama@uci.edu>
   8  */
   9 //=============================================================================
  10
  11
  12 #ifndef TAO_LB_SIGNAL_HANDLER_H
  13 #define TAO_LB_SIGNAL_HANDLER_H
  14
  15 #include "ace/Task.h"
  16
  17 #if !defined (ACE_LACKS_PRAGMA_ONCE)
  18 #pragma once
  19 #endif /* ACE_LACKS_PRAGMA_ONCE */
  20
  21 #include "tao/ORB.h"
  22 #include "tao/PortableServer/PortableServer.h"
  23 #include "ace/Signal.h"
  24
  25 /**
  26  * @class TAO_LB_Signal_Handler
  27  *
  28  * @brief Active object designed to handle signals synchronously.
  29  *
  30  * This class handles signals synchronously in the multi-threaded case,
  31  * and asynchronously through a Reactor in the single-threaded case.
  32  * @par
  33  * The goal of this signal handler is to ensure proper cleanup of
  34  * resources created by servants upon interruption by signals.  For
  35  * example, suppose a user sends a
  36  * SIGINT (e.g. types CTRL-C) signal to an application.  The servants
  37  * in that application should be shutdown gracefully so that all
  38  * resources handled by those servants are cleaned up.  This is
  39  * particularly important for resources that are not cleaned up
  40  * automatically.
  41  */
  42 class TAO_LB_Signal_Handler : public ACE_Task_Base
  43 {
  44 public:
  45   /// Constructor.
  46   TAO_LB_Signal_Handler (CORBA::ORB_ptr orb,
  47                          PortableServer::POA_ptr poa);
  48
  49   /// Run by a daemon thread to handle signals synchronously.
  50   virtual int svc ();
  51
  52   /// Active object activation method.
  53   /**
  54    * This override blocks all signals in the calling thread before
  55    * spawning the synchronous signal handler.
  56    */
  57   virtual int activate (long flags = THR_NEW_LWP | THR_JOINABLE,
  58                         int n_threads = 1,
  59                         int force_active = 0,
  60                         long priority = ACE_DEFAULT_THREAD_PRIORITY,
  61                         int grp_id = -1,
  62                         ACE_Task_Base *task = 0,
  63                         ACE_hthread_t thread_handles[] = 0,
  64                         void *stack[] = 0,
  65                         size_t stack_size[] = 0,
  66                         ACE_thread_t thread_ids[] = 0,
  67                         const char* thr_name[] = 0);
  68
  69   /// Called when object is signaled by OS (either via UNIX signals or
  70   /// when a Win32 object becomes signaled).
  71   virtual int handle_signal (int signum, siginfo_t * = 0, ucontext_t * = 0);
  72
  73 protected:
  74   /// Template method that initiates the cleanup process.
  75   virtual int perform_cleanup (int signum);
  76
  77 private:
  78 #ifdef ACE_HAS_THREADS
  79   /// Block all signals before spawning the threads.  Then, unblock
  80   /// these signals when this handler is destroyed.
  81   ACE_Sig_Guard signal_guard_;
  82 #endif  /* ACE_HAS_THREADS */
  83
  84   /// The set of signals which this handler will handle.
  85   ACE_Sig_Set sigset_;
  86
  87   /// Pseudo-reference to the ORB in which the LoadManager is running.
  88   CORBA::ORB_var orb_;
  89
  90   /// Reference to the POA within which the LoadManager servant is
  91   /// registered.
  92   PortableServer::POA_var poa_;
  93 };
  94
  95 #endif  /* TAO_LB_SIGNAL_HANDLER_H */