Catch attempts to enable debug_mode too late

Debug mode needs to be enabled before any event is setup or any
event_base is created.  Otherwise, we will not have recorded when events
were first setup or added, and so it will look like a bug later when we
delete or free them.

I have already confused myself because of this requirement, so let's
make Libevent catch it for the next poor forgetful developer like me.

diff --git a/event.c b/event.c
index 4e2f19a78b23d686f9527d84a4c760d88fd30056..cfd2db9f291d304538c8749ff303fadd9ff872a8 100644 (file)
--- a/event.c
+++ b/event.c
@@ -178,6 +178,8 @@ eq_debug_entry(const struct event_debug_entry *a,
 }
 
 int _event_debug_mode_on = 0;
+/* Set if it's too late to enable event_debug_mode. */
+static int event_debug_mode_too_late = 0;
 static void *_event_debug_map_lock = NULL;
 static HT_HEAD(event_debug_map, event_debug_entry) global_debug_map =
        HT_INITIALIZER();
@@ -207,6 +209,7 @@ HT_GENERATE(event_debug_map, event_debug_entry, node, hash_debug_entry,
                }                                                       \
                EVLOCK_UNLOCK(_event_debug_map_lock, 0);                \
        }                                                               \
+       event_debug_mode_too_late = 1;                                  \
        } while (0)
 /* Macro: record that ev is no longer setup */
 #define _event_debug_note_teardown(ev) do {                            \
@@ -219,6 +222,7 @@ HT_GENERATE(event_debug_map, event_debug_entry, node, hash_debug_entry,
                        mm_free(dent);                                  \
                EVLOCK_UNLOCK(_event_debug_map_lock, 0);                \
        }                                                               \
+       event_debug_mode_too_late = 1;                                  \
        } while (0)
 /* Macro: record that ev is now added */
 #define _event_debug_note_add(ev)      do {                            \
@@ -236,6 +240,7 @@ HT_GENERATE(event_debug_map, event_debug_entry, node, hash_debug_entry,
                }                                                       \
                EVLOCK_UNLOCK(_event_debug_map_lock, 0);                \
        }                                                               \
+       event_debug_mode_too_late = 1;                                  \
        } while (0)
 /* Macro: record that ev is no longer added */
 #define _event_debug_note_del(ev) do {                                 \
@@ -253,6 +258,7 @@ HT_GENERATE(event_debug_map, event_debug_entry, node, hash_debug_entry,
                }                                                       \
                EVLOCK_UNLOCK(_event_debug_map_lock, 0);                \
        }                                                               \
+       event_debug_mode_too_late = 1;                                  \
        } while (0)
 /* Macro: assert that ev is setup (i.e., okay to add or inspect) */
 #define _event_debug_assert_is_setup(ev) do {                          \
@@ -285,7 +291,6 @@ HT_GENERATE(event_debug_map, event_debug_entry, node, hash_debug_entry,
                EVLOCK_UNLOCK(_event_debug_map_lock, 0);                \
        }                                                               \
        } while (0)
-
 #else
 #define _event_debug_note_setup(ev) \
        ((void)0)
@@ -479,6 +484,9 @@ event_enable_debug_mode(void)
 #ifndef _EVENT_DISABLE_DEBUG_MODE
        if (_event_debug_mode_on)
                event_errx(1, "%s was called twice!", __func__);
+       if (event_debug_mode_too_late)
+               event_errx(1, "%s must be called *before* creating any events "
+                   "or event_bases",__func__);
 
        _event_debug_mode_on = 1;
 
@@ -513,6 +521,7 @@ event_base_new_with_config(const struct event_config *cfg)
        int should_check_environment;
 
 #ifndef _EVENT_DISABLE_DEBUG_MODE
+       event_debug_mode_too_late = 1;
        if (_event_debug_mode_on && !_event_debug_map_lock) {
                EVTHREAD_ALLOC_LOCK(_event_debug_map_lock, 0);
        }