mesa/src/gallium/auxiliary/util/u_debug_refcnt.c

#if defined(DEBUG) && (!defined(PIPE_OS_WINDOWS) || defined(PIPE_SUBSYSTEM_WINDOWS_USER))

/* see http://www.mozilla.org/performance/refcnt-balancer.html for what do with the output
 * on Linux, use tools/addr2line.sh to postprocess it before anything else
 **/
#include <util/u_debug.h>
#include <util/u_debug_refcnt.h>
#include <util/u_debug_stack.h>
#include <util/u_debug_symbol.h>
#include <util/u_string.h>
#include <util/u_hash_table.h>
#include <os/os_thread.h>
#include <os/os_stream.h>

int debug_refcnt_state;

struct os_stream* stream;

/* TODO: maybe move this serial machinery to a stand-alone module and expose it? */
static pipe_mutex serials_mutex;
static struct util_hash_table* serials_hash;
static unsigned serials_last;

static unsigned hash_ptr(void* p)
{
   return (unsigned)(uintptr_t)p;
}

static int compare_ptr(void* a, void* b)
{
   if(a == b)
      return 0;
   else if(a < b)
      return -1;
   else
      return 1;
}

static boolean debug_serial(void* p, unsigned* pserial)
{
   unsigned serial;
   boolean found = TRUE;
   pipe_mutex_lock(serials_mutex);
   if(!serials_hash)
      serials_hash = util_hash_table_create(hash_ptr, compare_ptr);
   serial = (unsigned)(uintptr_t)util_hash_table_get(serials_hash, p);
   if(!serial)
   {
      /* time to stop logging... (you'll have a 100 GB logfile at least at this point)
       * TODO: avoid this
       */
      serial = ++serials_last;
      if(!serial)
      {
         debug_error("More than 2^32 objects detected, aborting.\n");
         os_abort();
      }

      util_hash_table_set(serials_hash, p, (void*)(uintptr_t)serial);
      found = FALSE;
   }
   pipe_mutex_unlock(serials_mutex);
   *pserial = serial;
   return found;
}

static void debug_serial_delete(void* p)
{
   pipe_mutex_lock(serials_mutex);
   util_hash_table_remove(serials_hash, p);
   pipe_mutex_unlock(serials_mutex);
}

#define STACK_LEN 64

static void dump_stack(const char* symbols[STACK_LEN])
{
   unsigned i;
   for(i = 0; i < STACK_LEN; ++i)
   {
      if(symbols[i])
         os_stream_printf(stream, "%s\n", symbols[i]);
   }
   os_stream_write(stream, "\n", 1);
}

void debug_reference_slowpath(const struct pipe_reference* p, void* pget_desc, int change)
{
   if(debug_refcnt_state < 0)
      return;

   if(!debug_refcnt_state)
   {
      const char* filename = debug_get_option("GALLIUM_REFCNT_LOG", NULL);
      if(filename && filename[0])
         stream = os_file_stream_create(filename);

      if(stream)
         debug_refcnt_state = 1;
      else
         debug_refcnt_state = -1;
   }

   if(debug_refcnt_state > 0)
   {
      struct debug_stack_frame frames[STACK_LEN];
      const char* symbols[STACK_LEN];
      char buf[1024];

      void (*get_desc)(char*, const struct pipe_reference*) = pget_desc;
      unsigned i;
      unsigned refcnt = p->count;
      unsigned serial;
      boolean existing = debug_serial((void*)p, &serial);

      debug_backtrace_capture(frames, 1, STACK_LEN);
      for(i = 0; i < STACK_LEN; ++i)
      {
         if(frames[i].function)
            symbols[i] = debug_symbol_name_cached(frames[i].function);
         else
            symbols[i] = 0;
      }

      get_desc(buf, p);

      if(!existing)
      {
         os_stream_printf(stream, "<%s> %p %u Create\n", buf, p, serial);
         dump_stack(symbols);

         /* this is there to provide a gradual change even if we don't see the initialization */
         for(i = 1; i <= refcnt - change; ++i)
         {
            os_stream_printf(stream, "<%s> %p %u AddRef %u\n", buf, p, serial, i);
            dump_stack(symbols);
         }
      }

      if(change)
      {
         os_stream_printf(stream, "<%s> %p %u %s %u\n", buf, p, serial, change > 0 ? "AddRef" : "Release", refcnt);
         dump_stack(symbols);
      }

      if(!refcnt)
      {
         debug_serial_delete((void*)p);
         os_stream_printf(stream, "<%s> %p %u Destroy\n", buf, p, serial);
         dump_stack(symbols);
      }

      os_stream_flush(stream);
   }
}
#endif