1 files changed, 52 insertions, 2 deletions

diff --git a/src/common/compat_libevent.c b/src/common/compat_libevent.c
index 3ad9be145..7924036e6 100644
--- a/src/common/compat_libevent.c
+++ b/src/common/compat_libevent.c
@@ -165,9 +165,11 @@ struct event_base *the_event_base = NULL;
 
 /** Initialize the Libevent library and set up the event base. */
 void
-tor_libevent_initialize(void)
+tor_libevent_initialize(tor_libevent_cfg *torcfg)
 {
   tor_assert(the_event_base == NULL);
+  /* some paths below don't use torcfg, so avoid unused variable warnings */
+  (void)torcfg;
 
 #ifdef __APPLE__
   if (MACOSX_KQUEUE_IS_BROKEN ||
@@ -177,7 +179,29 @@ tor_libevent_initialize(void)
 #endif
 
 #ifdef HAVE_EVENT2_EVENT_H
-  the_event_base = event_base_new();
+  {
+    struct event_config *cfg = event_config_new();
+
+#if defined(MS_WINDOWS) && defined(USE_BUFFEREVENTS)
+    if (! torcfg->disable_iocp)
+      event_config_set_flag(cfg, EVENT_BASE_FLAG_STARTUP_IOCP);
+#endif
+
+#if defined(LIBEVENT_VERSION_NUMBER) && LIBEVENT_VERSION_NUMBER >= V(2,0,7)
+    if (torcfg->num_cpus > 0)
+      event_config_set_num_cpus_hint(cfg, torcfg->num_cpus);
+#endif
+
+#if LIBEVENT_VERSION_NUMBER >= V(2,0,9)
+    /* We can enable changelist support with epoll, since we don't give
+     * Libevent any dup'd fds.  This lets us avoid some syscalls. */
+    event_config_set_flag(cfg, EVENT_BASE_FLAG_EPOLL_USE_CHANGELIST);
+#endif
+
+    the_event_base = event_base_new_with_config(cfg);
+
+    event_config_free(cfg);
+  }
 #else
   the_event_base = event_init();
 #endif
@@ -552,3 +576,29 @@ periodic_timer_free(periodic_timer_t *timer)
   tor_free(timer);
 }
 
+#ifdef USE_BUFFEREVENTS
+static const struct timeval *one_tick = NULL;
+/**
+ * Return a special timeout to be passed whenever libevent's O(1) timeout
+ * implementation should be used. Only use this when the timer is supposed
+ * to fire after 1 / TOR_LIBEVENT_TICKS_PER_SECOND seconds have passed.
+*/
+const struct timeval *
+tor_libevent_get_one_tick_timeout(void)
+{
+  if (PREDICT_UNLIKELY(one_tick == NULL)) {
+    struct event_base *base = tor_libevent_get_base();
+    struct timeval tv;
+    if (TOR_LIBEVENT_TICKS_PER_SECOND == 1) {
+      tv.tv_sec = 1;
+      tv.tv_usec = 0;
+    } else {
+      tv.tv_sec = 0;
+      tv.tv_usec = 1000000 / TOR_LIBEVENT_TICKS_PER_SECOND;
+    }
+    one_tick = event_base_init_common_timeout(base, &tv);
+  }
+  return one_tick;
+}
+#endif
+