Make evloop into a subsystem.

Note that the event base object is _not_ created from the initialize
function, since it is configuration-dependent.  This will wait until
configuration is integrated into subsystems.

Closes ticket 30806.

4 files changed, 69 insertions, 0 deletions

diff --git a/src/lib/evloop/.may_include b/src/lib/evloop/.may_include
index 273de7bb94..54aa75fbff 100644
--- a/src/lib/evloop/.may_include
+++ b/src/lib/evloop/.may_include
@@ -8,6 +8,7 @@ lib/log/*.h
 lib/malloc/*.h
 lib/net/*.h
 lib/string/*.h
+lib/subsys/*.h
 lib/testsupport/*.h
 lib/thread/*.h
 lib/time/*.h
diff --git a/src/lib/evloop/evloop_sys.c b/src/lib/evloop/evloop_sys.c
new file mode 100644
index 0000000000..56641a3175
--- /dev/null
+++ b/src/lib/evloop/evloop_sys.c
@@ -0,0 +1,49 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2019, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * @file evloop_sys.c
+ * @brief Subsystem definition for the event loop module
+ **/
+
+#include "orconfig.h"
+#include "lib/subsys/subsys.h"
+#include "lib/evloop/compat_libevent.h"
+#include "lib/evloop/evloop_sys.h"
+#include "lib/log/log.h"
+
+static int
+subsys_evloop_initialize(void)
+{
+  if (tor_init_libevent_rng() < 0) {
+    log_warn(LD_NET, "Problem initializing libevent RNG.");
+    return -1;
+  }
+  return 0;
+}
+
+static void
+subsys_evloop_postfork(void)
+{
+#ifdef TOR_UNIT_TESTS
+  tor_libevent_postfork();
+#endif
+}
+
+static void
+subsys_evloop_shutdown(void)
+{
+  tor_libevent_free_all();
+}
+
+const struct subsys_fns_t sys_evloop = {
+  .name = "evloop",
+  .supported = true,
+  .level = -20,
+  .initialize = subsys_evloop_initialize,
+  .shutdown = subsys_evloop_shutdown,
+  .postfork = subsys_evloop_postfork,
+};
diff --git a/src/lib/evloop/evloop_sys.h b/src/lib/evloop/evloop_sys.h
new file mode 100644
index 0000000000..e6155c25b0
--- /dev/null
+++ b/src/lib/evloop/evloop_sys.h
@@ -0,0 +1,17 @@
+/* Copyright (c) 2001 Matej Pfajfar.
+ * Copyright (c) 2001-2004, Roger Dingledine.
+ * Copyright (c) 2004-2006, Roger Dingledine, Nick Mathewson.
+ * Copyright (c) 2007-2019, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * @file evloop_sys.h
+ * @brief Declare subsystem object for the event loop module.
+ **/
+
+#ifndef TOR_LIB_EVLOOP_EVLOOP_SYS_H
+#define TOR_LIB_EVLOOP_EVLOOP_SYS_H
+
+extern const struct subsys_fns_t sys_evloop;
+
+#endif /* !defined(TOR_LIB_EVLOOP_EVLOOP_SYS_H) */
diff --git a/src/lib/evloop/include.am b/src/lib/evloop/include.am
index 6595b3a34b..41cd2f45c5 100644
--- a/src/lib/evloop/include.am
+++ b/src/lib/evloop/include.am
@@ -8,6 +8,7 @@ endif
 # ADD_C_FILE: INSERT SOURCES HERE.
 src_lib_libtor_evloop_a_SOURCES =			\
 	src/lib/evloop/compat_libevent.c		\
+	src/lib/evloop/evloop_sys.c			\
 	src/lib/evloop/procmon.c			\
 	src/lib/evloop/timers.c				\
 	src/lib/evloop/token_bucket.c			\
@@ -21,6 +22,7 @@ src_lib_libtor_evloop_testing_a_CFLAGS = $(AM_CFLAGS) $(TEST_CFLAGS)
 # ADD_C_FILE: INSERT HEADERS HERE.
 noinst_HEADERS +=					\
 	src/lib/evloop/compat_libevent.h		\
+	src/lib/evloop/evloop_sys.h			\
 	src/lib/evloop/procmon.h			\
 	src/lib/evloop/timers.h				\
 	src/lib/evloop/token_bucket.h			\