1 files changed, 102 insertions, 4 deletions

diff --git a/src/common/compat_libevent.c b/src/common/compat_libevent.c
index 6d89be804b..3201738701 100644
--- a/src/common/compat_libevent.c
+++ b/src/common/compat_libevent.c
@@ -19,6 +19,10 @@
 
 #ifdef HAVE_EVENT2_EVENT_H
 #include <event2/event.h>
+#include <event2/thread.h>
+#ifdef USE_BUFFEREVENTS
+#include <event2/bufferevent.h>
+#endif
 #else
 #include <event.h>
 #endif
@@ -163,11 +167,24 @@ struct event_base *the_event_base = NULL;
 #endif
 #endif
 
+#ifdef USE_BUFFEREVENTS
+static int using_iocp_bufferevents = 0;
+static void tor_libevent_set_tick_timeout(int msec_per_tick);
+
+int
+tor_libevent_using_iocp_bufferevents(void)
+{
+  return using_iocp_bufferevents;
+}
+#endif
+
 /** 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 +194,32 @@ 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) {
+      evthread_use_windows_threads();
+      event_config_set_flag(cfg, EVENT_BASE_FLAG_STARTUP_IOCP);
+      using_iocp_bufferevents = 1;
+    }
+#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
@@ -195,6 +237,10 @@ tor_libevent_initialize(void)
       "You have a *VERY* old version of libevent.  It is likely to be buggy; "
       "please build Tor with a more recent version.");
 #endif
+
+#ifdef USE_BUFFEREVENTS
+  tor_libevent_set_tick_timeout(torcfg->msec_per_tick);
+#endif
 }
 
 /** Return the current Libevent event base that we're set up to use. */
@@ -240,7 +286,7 @@ tor_decode_libevent_version(const char *v)
 
   /* Try the new preferred "1.4.11-stable" format.
    * Also accept "1.4.14b-stable". */
-  fields = sscanf(v, "%u.%u.%u%c%c", &major, &minor, &patchlevel, &c, &e);
+  fields = tor_sscanf(v, "%u.%u.%u%c%c", &major, &minor, &patchlevel, &c, &e);
   if (fields == 3 ||
       ((fields == 4 || fields == 5 ) && (c == '-' || c == '_')) ||
       (fields == 5 && TOR_ISALPHA(c) && (e == '-' || e == '_'))) {
@@ -248,7 +294,7 @@ tor_decode_libevent_version(const char *v)
   }
 
   /* Try the old "1.3e" format. */
-  fields = sscanf(v, "%u.%u%c%c", &major, &minor, &c, &extra);
+  fields = tor_sscanf(v, "%u.%u%c%c", &major, &minor, &c, &extra);
   if (fields == 3 && TOR_ISALPHA(c)) {
     return V_OLD(major, minor, c);
   } else if (fields == 2) {
@@ -552,3 +598,55 @@ 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 msec_per_tick ticks have elapsed.
+*/
+const struct timeval *
+tor_libevent_get_one_tick_timeout(void)
+{
+  tor_assert(one_tick);
+  return one_tick;
+}
+
+/** Initialize the common timeout that we'll use to refill the buckets every
+ * time a tick elapses. */
+static void
+tor_libevent_set_tick_timeout(int msec_per_tick)
+{
+  struct event_base *base = tor_libevent_get_base();
+  struct timeval tv;
+
+  tor_assert(! one_tick);
+  tv.tv_sec = msec_per_tick / 1000;
+  tv.tv_usec = (msec_per_tick % 1000) * 1000;
+  one_tick = event_base_init_common_timeout(base, &tv);
+}
+
+static struct bufferevent *
+tor_get_root_bufferevent(struct bufferevent *bev)
+{
+  struct bufferevent *u;
+  while ((u = bufferevent_get_underlying(bev)) != NULL)
+    bev = u;
+  return bev;
+}
+
+int
+tor_set_bufferevent_rate_limit(struct bufferevent *bev,
+                               struct ev_token_bucket_cfg *cfg)
+{
+  return bufferevent_set_rate_limit(tor_get_root_bufferevent(bev), cfg);
+}
+
+int
+tor_add_bufferevent_to_rate_limit_group(struct bufferevent *bev,
+                                        struct bufferevent_rate_limit_group *g)
+{
+  return bufferevent_add_to_rate_limit_group(tor_get_root_bufferevent(bev), g);
+}
+#endif
+