Allow setting a dump hook

If users want to be notified when a heap dump occurs, they can set this hook.

include/jemalloc/internal/prof_externs.h

@@ -48,14 +48,12 @@ extern size_t lg_prof_sample;
 
 extern bool prof_booted;
 
-/*
- * A hook to mock out backtrace functionality.  This can be handy, since it's
- * otherwise difficult to guarantee that two allocations are reported as coming
- * from the exact same stack trace in the presence of an optimizing compiler.
- */
 void prof_backtrace_hook_set(prof_backtrace_hook_t hook);
 prof_backtrace_hook_t prof_backtrace_hook_get();
 
+void prof_dump_hook_set(prof_dump_hook_t hook);
+prof_dump_hook_t prof_dump_hook_get();
+
 /* Functions only accessed in prof_inlines.h */
 prof_tdata_t *prof_tdata_init(tsd_t *tsd);
 prof_tdata_t *prof_tdata_reinit(tsd_t *tsd, prof_tdata_t *tdata);

include/jemalloc/internal/prof_hook.h

@@ -13,4 +13,9 @@
  */
 typedef void (*prof_backtrace_hook_t)(void **, unsigned *, unsigned);
 
+/*
+ * A callback hook that notifies about recently dumped heap profile.
+ */
+typedef void (*prof_dump_hook_t)(const char *filename);
+
 #endif /* JEMALLOC_INTERNAL_PROF_HOOK_H */