From e40ca9938647c8ad6922f8006bbf35b90229608a Mon Sep 17 00:00:00 2001
From: Simon McVittie <simon.mcvittie@collabora.co.uk>
Date: Fri, 13 May 2011 11:44:25 +0100
Subject: [PATCH 7/7] DBusConnection: optionally trace refs/unrefs

---
 dbus/dbus-connection.c |   84 +++++++++++++++++++++++++++++++++++++++++-------
 1 files changed, 72 insertions(+), 12 deletions(-)

diff --git a/dbus/dbus-connection.c b/dbus/dbus-connection.c
index c08c70f..541b115 100644
--- a/dbus/dbus-connection.c
+++ b/dbus/dbus-connection.c
@@ -43,6 +43,7 @@
 #include "dbus-threads-internal.h"
 #include "dbus-bus.h"
 #include "dbus-marshal-basic.h"
+#include "dbus-valgrind-internal.h"
 
 #ifdef DBUS_DISABLE_CHECKS
 #define TOOK_LOCK_CHECK(connection)
@@ -206,6 +207,47 @@
  * @{
  */
 
+#ifdef DBUS_ENABLE_VERBOSE_MODE
+static void
+_dbus_connection_trace_ref (DBusConnection *connection,
+    int old_refcount,
+    int new_refcount,
+    const char *why)
+{
+  static int enabled = -1;
+
+  if (enabled < 0)
+    {
+      const char *s = _dbus_getenv ("DBUS_CONNECTION_TRACE");
+
+      enabled = FALSE;
+
+      if (s && *s)
+        {
+          if (*s == '0')
+            enabled = FALSE;
+          else if (*s == '1')
+            enabled = TRUE;
+          else
+            _dbus_warn ("DBUS_CONNECTION_TRACE should be 0 or 1 if set, "
+                "not '%s'", s);
+        }
+    }
+
+  if (enabled)
+    {
+      if (RUNNING_ON_VALGRIND)
+        VALGRIND_PRINTF_BACKTRACE ("DBusConnection %p %d -> %d refs (%s)",
+            connection, old_refcount, new_refcount, why);
+      else
+        _dbus_verbose ("DBusConnection %p %d -> %d refs (%s)",
+            connection, old_refcount, new_refcount, why);
+    }
+}
+#else
+#define _dbus_connection_trace_ref(c,o,n,w) do {} while (0)
+#endif
+
 /**
  * Internal struct representing a message filter function 
  */
@@ -1364,7 +1406,8 @@ _dbus_connection_new_for_transport (DBusTransport *transport)
   _dbus_transport_ref (transport);
 
   CONNECTION_UNLOCK (connection);
-  
+
+  _dbus_connection_trace_ref (connection, 0, 1, "new_for_transport");
   return connection;
   
  error:
@@ -1411,13 +1454,19 @@ _dbus_connection_new_for_transport (DBusTransport *transport)
  */
 DBusConnection *
 _dbus_connection_ref_unlocked (DBusConnection *connection)
-{  
+{
+  dbus_int32_t old_refcount;
+
   _dbus_assert (connection != NULL);
   _dbus_assert (connection->generation == _dbus_current_generation);
 
   HAVE_LOCK_CHECK (connection);
 
-  _dbus_atomic_inc (&connection->refcount);
+  old_refcount = _dbus_atomic_inc (&connection->refcount);
+  _dbus_connection_trace_ref (connection, old_refcount, old_refcount + 1,
+      "ref_unlocked");
+  /* unused if not verbose */
+  (void) old_refcount;
 
   return connection;
 }
@@ -1431,15 +1480,18 @@ _dbus_connection_ref_unlocked (DBusConnection *connection)
 void
 _dbus_connection_unref_unlocked (DBusConnection *connection)
 {
-  dbus_bool_t last_unref;
+  dbus_int32_t old_refcount;
 
   HAVE_LOCK_CHECK (connection);
-  
+
   _dbus_assert (connection != NULL);
 
-  last_unref = (_dbus_atomic_dec (&connection->refcount) == 1);
+  old_refcount = _dbus_atomic_dec (&connection->refcount);
+
+  _dbus_connection_trace_ref (connection, old_refcount, old_refcount - 1,
+      "unref_unlocked");
 
-  if (last_unref)
+  if (old_refcount == 1)
     _dbus_connection_last_unref (connection);
 }
 
@@ -2640,10 +2692,15 @@ dbus_connection_open_private (const char     *address,
 DBusConnection *
 dbus_connection_ref (DBusConnection *connection)
 {
+  dbus_int32_t old_refcount;
+
   _dbus_return_val_if_fail (connection != NULL, NULL);
   _dbus_return_val_if_fail (connection->generation == _dbus_current_generation, NULL);
-
-  _dbus_atomic_inc (&connection->refcount);
+  old_refcount = _dbus_atomic_inc (&connection->refcount);
+  _dbus_connection_trace_ref (connection, old_refcount, old_refcount + 1,
+      "ref");
+  /* unused if not verbose */
+  (void) old_refcount;
 
   return connection;
 }
@@ -2781,14 +2838,17 @@ _dbus_connection_last_unref (DBusConnection *connection)
 void
 dbus_connection_unref (DBusConnection *connection)
 {
-  dbus_bool_t last_unref;
+  dbus_int32_t old_refcount;
 
   _dbus_return_if_fail (connection != NULL);
   _dbus_return_if_fail (connection->generation == _dbus_current_generation);
 
-  last_unref = (_dbus_atomic_dec (&connection->refcount) == 1);
+  old_refcount = _dbus_atomic_dec (&connection->refcount);
+
+  _dbus_connection_trace_ref (connection, old_refcount, old_refcount - 1,
+      "unref");
 
-  if (last_unref)
+  if (old_refcount == 1)
     {
 #ifndef DBUS_DISABLE_CHECKS
       if (_dbus_transport_get_is_connected (connection->transport))
-- 
1.7.5.4