Having Trouble with exit(1) - Stalling Program

Having Trouble with exit(1) - Stalling Program

AceBlkwell

Member #13,038

July 2011

I am still working on the Vivace tutorial. I'm working with sound now. Due to an oversight on my part I didn't catch the file downloaded didn't have the same name as the code. The program would drop into a "must_init" function design to cut down on repetitive coding. The program wouldn't print via the printf command so I didn't realize the program was crashing within this function. The Include section included stdio.h but I also included cstdio. It solved the print problem but not the crash/hang.
It appears the exit(1) command is where the program is stalling. I have to close the program within the IDE to get it to clear out. There is no window or console that pops up. This also made it a pain to run down.

Having said all of that, my question is, why would exit(1) stall? Is there a better command? I'm compiling with g++.

Reading over the code, could the problem with the function being void, yet exit appears to be trying to return something?

If you are interested here are the snippets of code involved

#SelectExpand
  1
  2ALLEGRO_SAMPLE* elephant = al_load_sample("elephant.wav");// file was actually audio_elephant.wav
  3must_init(elephant, "elephant");
  4
  5void must_init(bool test, const char *description)
  6{
  7  if(test) return;
  8  printf("couldn't initialize %s\n", description);
  9    exit(1); // after including cstdio this is where it's stalling. It's not making it out of the function. 
 10}

Thanks

DanielH

Member #934

January 2001

If not too big, post the entire file. Got to be something else. Nothing looks wrong with function. Except, I'd make it cleaner.

void must_init(bool test, const char *description)
{
  //if(test) return;
  if (!test)
  {
    printf("couldn't initialize %s\n", description);
    exit(1); // after including cstdio this is where it's stalling. It's not making it out of the function. 
  }
}

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AceBlkwell

Member #13,038

July 2011

Here is the code. Keep in mind
1- The name of the sound file is still wrong, for the sake of the failure
2- It's a little patch work because we started with a working program then was asked to replace sections as the lessons progressed.
3- I added iostream so I could use std::cout. I haven't found a good "step" IDE since MSQuick C. So I use std::cout to see if a program is making it to a given point or what variable values are at that point.
4- allcolor_A5.h is my own file for colors obliviously. This way I don't' have to al_map_rgb(0,255,0), I can just use BR_GREEN.

#SelectExpand
   1
   2#include <stdio.h>
   3#include <stdlib.h>
   4#include <allegro5/allegro5.h>
   5#include <allegro5/allegro_font.h>
   6#include <allegro5/allegro_primitives.h>
   7#include <allegro5/allegro_audio.h>
   8#include <allegro5/allegro_acodec.h>
   9#include <allcolor_A5.h>
  10#include <iostream>
  11#include <cstdio>
  12
  13#define KEY_SEEN     1
  14#define KEY_RELEASED 2
  15
  16void must_init(bool test, const char *description)
  17{
if(test) return;
printf("couldn't initialize %s\n", description);
  exit(1);
  21}
  22
  23int main()
  24{
  must_init(al_init(), "allegro");
  must_init(al_install_keyboard(), "keyboard");
  must_init(al_install_mouse(), "mouse");
  must_init(al_install_audio(), "audio");
  must_init(al_init_acodec_addon(), "audio codecs");
  must_init(al_reserve_samples(16), "reserve samples");
  31
  ALLEGRO_SAMPLE* elephant = al_load_sample("elephant.wav");
  must_init(elephant, "elephant");
  34
  ALLEGRO_TIMER* timer = al_create_timer(1.0 / 30.0);
  must_init(timer, "timer");
  37
  ALLEGRO_EVENT_QUEUE* queue = al_create_event_queue();
  must_init(queue, "queue");
  40
  al_set_new_display_option(ALLEGRO_SAMPLE_BUFFERS, 1, ALLEGRO_SUGGEST);
  al_set_new_display_option(ALLEGRO_SAMPLES, 8, ALLEGRO_SUGGEST);
  al_set_new_bitmap_flags(ALLEGRO_MIN_LINEAR | ALLEGRO_MAG_LINEAR);
  44
  ALLEGRO_DISPLAY* disp = al_create_display(640, 480);
  must_init(disp, "display");
  47
  ALLEGRO_FONT* font = al_create_builtin_font();
  must_init(font, "font");
  50
  must_init(al_init_primitives_addon(), "primitives");
  al_register_event_source(queue, al_get_keyboard_event_source());
  al_register_event_source(queue, al_get_display_event_source(disp));
  al_register_event_source(queue, al_get_timer_event_source(timer));
  al_register_event_source(queue, al_get_mouse_event_source());
  56
  bool done = false;
  bool redraw = true;
  ALLEGRO_EVENT event;
  60
  float x, y;
      x = 100;
      y = 100;
  float dx, dy;
     dx = 0;
     dy = 0;
  unsigned char key[ALLEGRO_KEY_MAX];
  memset(key, 0, sizeof(key));
  69
  al_grab_mouse(disp);
  al_hide_mouse_cursor(disp);
  al_start_timer(timer);
  73
  74
  //   ALLEGRO_KEYBOARD_STATE ks;
  while(1)
  {
      al_wait_for_event(queue, &event);
  79
 /*     switch(event.type)
      {
          case ALLEGRO_EVENT_TIMER:
              if(key[ALLEGRO_KEY_UP])
                  y-=2;
              if(key[ALLEGRO_KEY_DOWN])
                  y+=2;
              if(key[ALLEGRO_KEY_LEFT])
                  x-=2;
              if(key[ALLEGRO_KEY_RIGHT])
                  x+=2;
  91
              if(key[ALLEGRO_KEY_ESCAPE])
                  done = true;
  94
  95
              for(int i = 0; i < ALLEGRO_KEY_MAX; i++)
                  key[i] &= KEY_SEEN;
  98
              redraw = true;
              break;
 101
          case ALLEGRO_EVENT_KEY_DOWN:
              key[event.keyboard.keycode] = KEY_SEEN | KEY_RELEASED;
              break;
          case ALLEGRO_EVENT_KEY_UP:
              key[event.keyboard.keycode] &= KEY_RELEASED;
              break;
 108
          case ALLEGRO_EVENT_DISPLAY_CLOSE:
              done = true;
              break;
      }*/
      switch(event.type)
      {
          case ALLEGRO_EVENT_TIMER:
              if(key[ALLEGRO_KEY_ESCAPE])
                  done = true;
 118
              x += dx;
              y += dy;
 121
              if(x < 0)
              {
                  x *= -1;
                  dx *= -1;
              }
              if(x > 640)
              {
                  x -= (x - 640) * 2;
                  dx *= -1;
              }
              if(y < 0)
              {
                  y *= -1;
                  dy *= -1;
              }
              if(y > 480)
              {
                  y -= (y - 480) * 2;
                  dy *= -1;
              }
 142
              dx *= 0.9;
              dy *= 0.9;
 145
              for(int i = 0; i < ALLEGRO_KEY_MAX; i++)
                  key[i] &= KEY_SEEN;
 148
              redraw = true;
              break;
 151
          case ALLEGRO_EVENT_MOUSE_AXES:
              dx += event.mouse.dx * 0.1;
              dy += event.mouse.dy * 0.1;
              al_set_mouse_xy(disp, 320, 240);
              break;
 157
          case ALLEGRO_EVENT_KEY_DOWN:
              if(event.keyboard.keycode == ALLEGRO_KEY_E)
                  al_play_sample(elephant, 1.0, 0.0, 1.0, ALLEGRO_PLAYMODE_ONCE, NULL);
              if(event.keyboard.keycode != ALLEGRO_KEY_ESCAPE)
                       break;
          case ALLEGRO_EVENT_KEY_UP:
              key[event.keyboard.keycode] &= KEY_RELEASED;
              break;
 166
          case ALLEGRO_EVENT_DISPLAY_CLOSE:
              done = true;
              break;
      }
      if(done)
          break;
 173
      if(redraw && al_is_event_queue_empty(queue))
      {
 176
          al_clear_to_color(al_map_rgb(0, 0, 0));
          al_draw_text(font, al_map_rgb(255, 255, 255), 640/2, 480/2, ALLEGRO_ALIGN_CENTER, "Knock knock, it's Nelly");
          al_draw_filled_rectangle(x, y, x + 10, y + 10, al_map_rgb(255, 0, 0));
 180
          al_flip_display();
 182
          redraw = false;
      }
  }
 186
  al_destroy_sample(elephant);
  al_destroy_font(font);
  al_destroy_display(disp);
  al_destroy_timer(timer);
  al_destroy_event_queue(queue);
 192
  return 0;
 194}

DanielH

Member #934

January 2001

At which step is it freezing? When it is loading the file?

I'm staring at it and don't see anything. I can test it later tonight when I'm home. I don't normally use exit.

cstdio over stdio.h if you are using C++.

Quote:

The difference (which is neither minor nor a matter of style) is that stdio. h and other C-like libraries when imported in a C++ file may pollute the global namespace, while the corresponding C++ headers (cstdio, cstdlib, cassert) place the corresponding functions, variables, etc., in the std namespace.

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AceBlkwell

Member #13,038

July 2011

The program gets down to

ALLEGRO_SAMPLE* elephant = al_load_sample("elephant.wav");
must_init(elephant, "elephant");

It attempts to load the sound file. Then enters must_init. While in must_init, it gets down past printf but doesn't come back out of the function. There is only one command after printf, exit(1) so I assume that's where it's stalling.

void must_init(bool test, const char *description)
{
if(test) return;
printf("couldn't initialize %s\n", description);
exit(1);
}

All the other inits are successful so it never gets to exit(1).

DanielH

Member #934

January 2001

I don't think it's the exit, but for testing purposes. Add another printf test string after the exit before the function ends.

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AceBlkwell

Member #13,038

July 2011

Daniel, don't waste a lot of time on it. I was just curious if there was an alternative to exit(1) or if it was problematic with C++.

To your suggestion, here are my results.

Before File load
Before must_init in main
After If return in must_init
couldn't initialize elephant
After printf in must_init

If didn't make it after exit(1)

#SelectExpand
  1
  2void must_init(bool test, const char *description)
  3{
  4       if(test) return;
  5  std::cout<<"After If return in must_init"<<std::endl;                     //
  6      printf("couldn't initialize %s\n", description);
  7  std::cout<<"After printf in must_init"<<std::endl;                        //
  8      exit(1);
  9    std::cout<<"After exit(1) in must_init"<<std::endl;                       //
 10}
 11
 12
 13int main()
 14{
 15    must_init(al_init(), "allegro");
 16    must_init(al_install_keyboard(), "keyboard");
 17    must_init(al_install_mouse(), "mouse");
 18    must_init(al_install_audio(), "audio");
 19    must_init(al_init_acodec_addon(), "audio codecs");
 20    must_init(al_reserve_samples(16), "reserve samples");
 21
 22    std::cout<<"Before File load"<<std::endl;                                //
 23    ALLEGRO_SAMPLE* elephant = al_load_sample("elephant.wav");
 24    std::cout<<"Before must_init in main"<<std::endl;                        //
 25    must_init(elephant, "elephant");
 26    std::cout<<"After must_init in main"<<std::endl;                      //

DanielH

Member #934

January 2001

#SelectExpand
  1// remove exit
  2bool must_init(bool test, const char *description)
  3{
  4    if (!test)
  5    {
  6        std::cout << "couldn't initialize" << description < <std::endl;
  7    }
  8
  9    return test;
 10}
 11
 12int main()
 13{
 14    if (!(must_init(al_init(), "allegro")) return -1;
 15
 16}

This is mine

    // what are we attempting
    std::cout << "Initializing Allegro Library: ";
    if (!al_init())
    {
        std::cout << "failed" << std::endl;
        return -1;
    }
    std::cout << "pass" << std::endl;

it does get messy

#SelectExpand
  1int32_t init()
  2{
std::cout << "Initialization Begin" << std::endl;
  4
std::cout << "Initializing Allegro Library: ";
if (!al_init())
{
  std::cout << "failed" << std::endl;
  return -1;
}
std::cout << "pass" << std::endl;
 12
std::cout << "Initializing Mouse: ";
if (!al_install_mouse())
{
  std::cout << "failed" << std::endl;
  return -1;
}
std::cout << "pass" << std::endl;
 20
std::cout << "Initializing Keyboard: ";
if (!al_install_keyboard())
{
  std::cout << "failed" << std::endl;
  return -1;
}
std::cout << "pass" << std::endl;
 28
std::cout << "Initializing Image Addon: ";
if (!al_init_image_addon())
{
  std::cout << "failed" << std::endl;
  return -1;
}
std::cout << "pass" << std::endl;
 36
std::cout << "Creating Display: ";
al_set_new_display_flags(ALLEGRO_WINDOWED | ALLEGRO_RESIZABLE);
if (!(this->m_display = al_create_display(App::SCREEN_W, App::SCREEN_H)))
{
  std::cout << "failed" << std::endl;
  return -1;
}
std::cout << "pass" << std::endl;
 45
ALLEGRO_BITMAP* icon = al_load_bitmap("data\\images\\icon.png");
if (icon)
{
  al_set_display_icon(this->m_display, icon);
  al_destroy_bitmap(icon);
}
al_set_window_title(this->m_display, App::APPNAME);
 53
std::cout << "Creating Event Queue: ";
if (!(this->m_queue = al_create_event_queue()))
{
  std::cout << "failed" << std::endl;
  return -1;
}
std::cout << "pass" << std::endl;
 61
std::cout << "Creating Logic Timer: ";
if (!(this->m_timer = al_create_timer(1.0/App::TIMING)))
{
  std::cout << "failed" << std::endl;
  return -1;
}
std::cout << "pass" << std::endl;
 69
al_register_event_source(this->m_queue, al_get_display_event_source(this->m_display));
al_register_event_source(this->m_queue, al_get_timer_event_source(this->m_timer));
al_register_event_source(this->m_queue, al_get_keyboard_event_source());
al_register_event_source(this->m_queue, al_get_mouse_event_source());
 74
al_start_timer(this->m_timer);
 76
std::cout << "Initialization Complete" << std::endl << std::endl;
 78
return 0;
 80}

Personally, I don't like leaving things hanging. My shutdown function always gets called even if there is an error in init. In it, every object I allocated is checked and unallocated.

int main()
{
    if (init() ==0)
    {
        // proceed
        loop();
    }
    shutdown():
}

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AceBlkwell

Member #13,038

July 2011

Thanks for the insight Daniel. I appreciate the time.

Edgar Reynaldo

Major Reynaldo

May 2007

~~NVM~~

That said, avoid nasty things like exit and abort. It's easy enough to return non-zero in main.

Also, must init should also report success, not just failure.

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DanielH

Member #934

January 2001

I'm home and tested your code. It does just as expected. runs and exits after failing to load elephant.

output: "couldn't initialize elephant"

I put a wav file of my own and the program plays it when I press E. Some issues, how to exit program? You turned off the mouse cursor so I could not press the close button. You don't have any key presses that close the program either. I was able to close it pressing Alt+f4.

{"name":"613302","src":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/c\/b\/cbe4db979eece65810032c1c2bb1fb22.png","w":789,"h":590,"tn":"\/\/djungxnpq2nug.cloudfront.net\/image\/cache\/c\/b\/cbe4db979eece65810032c1c2bb1fb22"}

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AceBlkwell

Member #13,038

July 2011

Could be my computer at work. I ran it from home. Still Eclipse IDE but on Linux. It worked just like you said. Must have just been the computer at work. Doesn't make sense.
The lesson before was for the mouse. It was showing how to capture it in the window. On my work (Windows 10) I can Alt Tab to another window and the mouse will go with me. On Linux I almost had to reboot the computer. No matter which program I tabbed to, the mouse stayed with the elephant program.
As for the Esc key, the code has been so jumbled up, I'm not sure why it doesn't work but it didn't.
In any case there doesn't seem to be anything wrong with exit(1) which was my first question. Sorry if I wasted your time. Thanks again for the help.

Edgar Reynaldo

Major Reynaldo

May 2007

If your program was hanging, it was probably because of a loose thread that was still running. Probably allegro's audio or window thread.

AceBlkwell

Member #13,038

July 2011

Could be Edgar.

I still think it's something to do with Windows /Eclipse IDE / Mingw32. Or a combo there of. Here is why I say that
- I can run the program from outside of the IDE and it will print the "could not init XXXX" line and quit.
- Moving too quick, I duplicated my mistake with the Gameplay code, as the audio files all started with audio_XXXXXX. It was a new program and it did the same thing. No printing and it would just hang. I've have to check a box in Eclipse to get it to stop. Fortunately this time I only made the mistake once .

Thanks for the follow up.

Edgar Reynaldo

Major Reynaldo

May 2007

If you're using the same code as before, you haven't shutdown audio or allegro itself.

Dizzy Egg

Member #10,824

March 2009

This code is horrible to me; why call every library initialisation method and then pass an optional null into a void method with a null as bool? Why not just have a setup function that returns a bool result and determine whether or not to continue or not based on setup success?

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AceBlkwell

Member #13,038

July 2011

Yeah, I didn't create the code so I can't say why they did what they did. I figured the programmer knew more about it than I did. It seems to work well enough if the ducks are in a row.