Merge branch 'feature3630-rebased'

changes/feature3630

@@ -0,0 +1,8 @@
+  o Major features (networking):
+    - Add a new TokenBucketRefillInterval option to refill token buckets
+      more frequently than once per second. This should improve network
+      performance, alleviate queueing problems, and make traffic less
+      bursty. Implements proposal 183; closes ticket 3630. Design by
+      Florian Tschorsch and Björn Scheuermann; implementation by
+      Florian Tschorsch.
+

doc/tor.1.txt

@@ -737,6 +737,13 @@ The following options are useful only for clients (that is, if
     unattached waiting for an appropriate circuit, before we fail it. (Default:
     2 minutes.)
 
+**TokenBucketRefillInterval** __NUM__ [**msec**|**second**]::
+    Set the refill interval of Tor's token bucket to NUM milliseconds.
+    NUM must be between 1 and 1000, inclusive.  Note that the configured
+    bandwidth limits are still expressed in bytes per second: this
+    option only affects the frequency with which Tor checks to see whether
+    previously exhausted connections may read again. (Default: 10 msec.)
+
 **TrackHostExits** __host__,__.domain__,__...__::
     For each value in the comma separated list, Tor will track recent
     connections to hosts that match this value and attempt to reuse the same

src/common/compat_libevent.c

@@ -169,6 +169,7 @@ struct event_base *the_event_base = NULL;
 
 #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)
@@ -236,6 +237,10 @@ tor_libevent_initialize(tor_libevent_cfg *torcfg)
       "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. */
@@ -598,26 +603,29 @@ 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.
+ * to fire after msec_per_tick ticks have elapsed.
 */
 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);
-  }
+  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)
 {

src/common/compat_libevent.h

@@ -62,6 +62,7 @@ int tor_event_base_loopexit(struct event_base *base, struct timeval *tv);
 typedef struct tor_libevent_cfg {
   int disable_iocp;
   int num_cpus;
+  int msec_per_tick;
 } tor_libevent_cfg;
 
 void tor_libevent_initialize(tor_libevent_cfg *cfg);
@@ -73,7 +74,6 @@ void tor_check_libevent_header_compatibility(void);
 const char *tor_libevent_get_version_str(void);
 
 #ifdef USE_BUFFEREVENTS
-#define TOR_LIBEVENT_TICKS_PER_SECOND 3
 const struct timeval *tor_libevent_get_one_tick_timeout(void);
 int tor_libevent_using_iocp_bufferevents(void);
 int tor_set_bufferevent_rate_limit(struct bufferevent *bev,

src/or/config.c

@@ -386,6 +386,7 @@ static config_var_t _option_vars[] = {
   OBSOLETE("SysLog"),
   V(TestSocks,                   BOOL,     "0"),
   OBSOLETE("TestVia"),
+  V(TokenBucketRefillInterval,   MSEC_INTERVAL, "10 msec"),
   V(TrackHostExits,              CSV,      NULL),
   V(TrackHostExitsExpire,        INTERVAL, "30 minutes"),
   OBSOLETE("TrafficShaping"),
@@ -3165,6 +3166,11 @@ options_validate(or_options_t *old_options, or_options_t *options,
     REJECT("TransPort and TransListenAddress are disabled in this build.");
 #endif
 
+  if (options->TokenBucketRefillInterval <= 0
+      || options->TokenBucketRefillInterval > 1000) {
+    REJECT("TokenBucketRefillInterval must be between 1 and 1000 inclusive.");
+  }
+
   if (options->AccountingMax &&
       (is_listening_on_low_port(options->ORPort, options->ORListenAddress) ||
        is_listening_on_low_port(options->DirPort, options->DirListenAddress)))
@@ -3967,6 +3973,12 @@ options_transition_allowed(const or_options_t *old,
     return -1;
   }
 
+  if (old->TokenBucketRefillInterval != new_val->TokenBucketRefillInterval) {
+    *msg = tor_strdup("While Tor is running, changing TokenBucketRefill"
+                      "Interval is not allowed");
+    return -1;
+  }
+
   if (old->DisableIOCP != new_val->DisableIOCP) {
     *msg = tor_strdup("While Tor is running, changing DisableIOCP "
                       "is not allowed.");
@@ -5633,6 +5645,7 @@ init_libevent(const or_options_t *options)
   memset(&cfg, 0, sizeof(cfg));
   cfg.disable_iocp = options->DisableIOCP;
   cfg.num_cpus = get_num_cpus(options);
+  cfg.msec_per_tick = options->TokenBucketRefillInterval;
 
   tor_libevent_initialize(&cfg);
 

src/or/connection.c

@@ -2388,22 +2388,23 @@ connection_bucket_init(void)
   }
 }
 
-/** Refill a single <b>bucket</b> called <b>name</b> with bandwidth rate
- * <b>rate</b> and bandwidth burst <b>burst</b>, assuming that
- * <b>seconds_elapsed</b> seconds have passed since the last call.
- **/
+/** Refill a single <b>bucket</b> called <b>name</b> with bandwidth rate per
+ * second <b>rate</b> and bandwidth burst <b>burst</b>, assuming that
+ * <b>milliseconds_elapsed</b> milliseconds have passed since the last
+ * call. */
 static void
 connection_bucket_refill_helper(int *bucket, int rate, int burst,
-                                int seconds_elapsed, const char *name)
+                                int milliseconds_elapsed,
+                                const char *name)
 {
   int starting_bucket = *bucket;
-  if (starting_bucket < burst && seconds_elapsed) {
-    if (((burst - starting_bucket)/seconds_elapsed) < rate) {
+  if (starting_bucket < burst && milliseconds_elapsed > 0) {
+    int64_t incr = (((int64_t)rate) * milliseconds_elapsed) / 1000;
+    if ((burst - starting_bucket) < incr) {
       *bucket = burst;  /* We would overflow the bucket; just set it to
                          * the maximum. */
     } else {
-      int incr = rate*seconds_elapsed;
-      *bucket += incr;
+      *bucket += (int)incr;
       if (*bucket > burst || *bucket < starting_bucket) {
         /* If we overflow the burst, or underflow our starting bucket,
          * cap the bucket value to burst. */
@@ -2416,41 +2417,46 @@ connection_bucket_refill_helper(int *bucket, int rate, int burst,
   }
 }
 
-/** A second has rolled over; increment buckets appropriately. */
+/** Time has passed; increment buckets appropriately. */
 void
-connection_bucket_refill(int seconds_elapsed, time_t now)
+connection_bucket_refill(int milliseconds_elapsed, time_t now)
 {
   const or_options_t *options = get_options();
   smartlist_t *conns = get_connection_array();
-  int relayrate, relayburst;
+  int bandwidthrate, bandwidthburst, relayrate, relayburst;
+
+  bandwidthrate = (int)options->BandwidthRate;
+  bandwidthburst = (int)options->BandwidthBurst;
 
   if (options->RelayBandwidthRate) {
     relayrate = (int)options->RelayBandwidthRate;
     relayburst = (int)options->RelayBandwidthBurst;
   } else {
-    relayrate = (int)options->BandwidthRate;
-    relayburst = (int)options->BandwidthBurst;
+    relayrate = bandwidthrate;
+    relayburst = bandwidthburst;
   }
 
-  tor_assert(seconds_elapsed >= 0);
+  tor_assert(milliseconds_elapsed >= 0);
 
   write_buckets_empty_last_second =
     global_relayed_write_bucket <= 0 || global_write_bucket <= 0;
 
   /* refill the global buckets */
   connection_bucket_refill_helper(&global_read_bucket,
-                                  (int)options->BandwidthRate,
-                                  (int)options->BandwidthBurst,
-                                  seconds_elapsed, "global_read_bucket");
+                                  bandwidthrate, bandwidthburst,
+                                  milliseconds_elapsed,
+                                  "global_read_bucket");
   connection_bucket_refill_helper(&global_write_bucket,
-                                  (int)options->BandwidthRate,
-                                  (int)options->BandwidthBurst,
-                                  seconds_elapsed, "global_write_bucket");
+                                  bandwidthrate, bandwidthburst,
+                                  milliseconds_elapsed,
+                                  "global_write_bucket");
   connection_bucket_refill_helper(&global_relayed_read_bucket,
-                                  relayrate, relayburst, seconds_elapsed,
+                                  relayrate, relayburst,
+                                  milliseconds_elapsed,
                                   "global_relayed_read_bucket");
   connection_bucket_refill_helper(&global_relayed_write_bucket,
-                                  relayrate, relayburst, seconds_elapsed,
+                                  relayrate, relayburst,
+                                  milliseconds_elapsed,
                                   "global_relayed_write_bucket");
 
   /* refill the per-connection buckets */
@@ -2458,18 +2464,20 @@ connection_bucket_refill(int seconds_elapsed, time_t now)
   {
     if (connection_speaks_cells(conn)) {
       or_connection_t *or_conn = TO_OR_CONN(conn);
+      int orbandwidthrate = or_conn->bandwidthrate;
+      int orbandwidthburst = or_conn->bandwidthburst;
       if (connection_bucket_should_increase(or_conn->read_bucket, or_conn)) {
         connection_bucket_refill_helper(&or_conn->read_bucket,
-                                        or_conn->bandwidthrate,
-                                        or_conn->bandwidthburst,
-                                        seconds_elapsed,
+                                        orbandwidthrate,
+                                        orbandwidthburst,
+                                        milliseconds_elapsed,
                                         "or_conn->read_bucket");
       }
       if (connection_bucket_should_increase(or_conn->write_bucket, or_conn)) {
         connection_bucket_refill_helper(&or_conn->write_bucket,
-                                        or_conn->bandwidthrate,
-                                        or_conn->bandwidthburst,
-                                        seconds_elapsed,
+                                        orbandwidthrate,
+                                        orbandwidthburst,
+                                        milliseconds_elapsed,
                                         "or_conn->write_bucket");
       }
     }
@@ -2553,7 +2561,10 @@ connection_bucket_init(void)
     burst = options->BandwidthBurst;
   }
 
-  rate /= TOR_LIBEVENT_TICKS_PER_SECOND;
+  /* This can't overflow, since TokenBucketRefillInterval <= 1000,
+   * and rate started out less than INT32_MAX. */
+  rate = (rate * options->TokenBucketRefillInterval) / 1000;
+
   bucket_cfg = ev_token_bucket_cfg_new((uint32_t)rate, (uint32_t)burst,
                                        (uint32_t)rate, (uint32_t)burst,
                                        tick);

src/or/connection_or.c

@@ -580,7 +580,12 @@ connection_or_update_token_buckets_helper(or_connection_t *conn, int reset,
   {
     const struct timeval *tick = tor_libevent_get_one_tick_timeout();
     struct ev_token_bucket_cfg *cfg, *old_cfg;
-    int rate_per_tick = rate / TOR_LIBEVENT_TICKS_PER_SECOND;
+    int64_t rate64 = (((int64_t)rate) * options->TokenBucketRefillInterval)
+      / 1000;
+    /* This can't overflow, since TokenBucketRefillInterval <= 1000,
+     * and rate started out less than INT_MAX. */
+    int rate_per_tick = (int) rate64;
+
     cfg = ev_token_bucket_cfg_new(rate_per_tick, burst, rate_per_tick,
                                   burst, tick);
     old_cfg = conn->bucket_cfg;

src/or/main.c

@@ -91,10 +91,10 @@ static int stats_prev_global_read_bucket;
 /** What was the write bucket before the last second_elapsed_callback() call?
  * (used to determine how many bytes we've written). */
 static int stats_prev_global_write_bucket;
-#else
+#endif
+
 static uint64_t stats_prev_n_read = 0;
 static uint64_t stats_prev_n_written = 0;
-#endif
 
 /* XXX we might want to keep stats about global_relayed_*_bucket too. Or not.*/
 /** How many bytes have we read since we started the process? */
@@ -1507,9 +1507,6 @@ second_elapsed_callback(periodic_timer_t *timer, void *arg)
   size_t bytes_written;
   size_t bytes_read;
   int seconds_elapsed;
-#ifdef USE_BUFFEREVENTS
-  uint64_t cur_read,cur_written;
-#endif
   const or_options_t *options = get_options();
   (void)timer;
   (void)arg;
@@ -1523,30 +1520,28 @@ second_elapsed_callback(periodic_timer_t *timer, void *arg)
   /* the second has rolled over. check more stuff. */
   seconds_elapsed = current_second ? (int)(now - current_second) : 0;
 #ifdef USE_BUFFEREVENTS
-  connection_get_rate_limit_totals(&cur_read, &cur_written);
-  bytes_written = (size_t)(cur_written - stats_prev_n_written);
-  bytes_read = (size_t)(cur_read - stats_prev_n_read);
+  {
+    uint64_t cur_read,cur_written;
+    connection_get_rate_limit_totals(&cur_read, &cur_written);
+    bytes_written = (size_t)(cur_written - stats_prev_n_written);
+    bytes_read = (size_t)(cur_read - stats_prev_n_read);
+    stats_n_bytes_read += bytes_read;
+    stats_n_bytes_written += bytes_written;
+    if (accounting_is_enabled(options) && seconds_elapsed >= 0)
+      accounting_add_bytes(bytes_read, bytes_written, seconds_elapsed);
+    stats_prev_n_written = cur_written;
+    stats_prev_n_read = cur_read;
+  }
 #else
-  bytes_written = stats_prev_global_write_bucket - global_write_bucket;
-  bytes_read = stats_prev_global_read_bucket - global_read_bucket;
+  bytes_read = (size_t)(stats_n_bytes_read - stats_prev_n_read);
+  bytes_written = (size_t)(stats_n_bytes_written - stats_prev_n_written);
+  stats_prev_n_read = stats_n_bytes_read;
+  stats_prev_n_written = stats_n_bytes_written;
 #endif
-  stats_n_bytes_read += bytes_read;
-  stats_n_bytes_written += bytes_written;
-  if (accounting_is_enabled(options) && seconds_elapsed >= 0)
-    accounting_add_bytes(bytes_read, bytes_written, seconds_elapsed);
+
   control_event_bandwidth_used((uint32_t)bytes_read,(uint32_t)bytes_written);
   control_event_stream_bandwidth_used();
 
-  if (seconds_elapsed > 0)
-    connection_bucket_refill(seconds_elapsed, now);
-#ifdef USE_BUFFEREVENTS
-  stats_prev_n_written = cur_written;
-  stats_prev_n_read = cur_read;
-#else
-  stats_prev_global_read_bucket = global_read_bucket;
-  stats_prev_global_write_bucket = global_write_bucket;
-#endif
-
   if (server_mode(options) &&
       !we_are_hibernating() &&
       seconds_elapsed > 0 &&
@@ -1594,6 +1589,57 @@ second_elapsed_callback(periodic_timer_t *timer, void *arg)
   current_second = now; /* remember which second it is, for next time */
 }
 
+#ifndef USE_BUFFEREVENTS
+/** Timer: used to invoke refill_callback(). */
+static periodic_timer_t *refill_timer = NULL;
+
+/** Libevent callback: invoked periodically to refill token buckets
+ * and count r/w bytes. It is only used when bufferevents are disabled. */
+static void
+refill_callback(periodic_timer_t *timer, void *arg)
+{
+  static struct timeval current_millisecond;
+  struct timeval now;
+
+  size_t bytes_written;
+  size_t bytes_read;
+  int milliseconds_elapsed = 0;
+  int seconds_rolled_over = 0;
+
+  const or_options_t *options = get_options();
+
+  (void)timer;
+  (void)arg;
+
+  tor_gettimeofday(&now);
+
+  /* If this is our first time, no time has passed. */
+  if (current_millisecond.tv_sec) {
+    long mdiff = tv_mdiff(&current_millisecond, &now);
+    if (mdiff > INT_MAX)
+      mdiff = INT_MAX;
+    milliseconds_elapsed = (int)mdiff;
+    seconds_rolled_over = (int)(now.tv_sec - current_millisecond.tv_sec);
+  }
+
+  bytes_written = stats_prev_global_write_bucket - global_write_bucket;
+  bytes_read = stats_prev_global_read_bucket - global_read_bucket;
+
+  stats_n_bytes_read += bytes_read;
+  stats_n_bytes_written += bytes_written;
+  if (accounting_is_enabled(options) && milliseconds_elapsed >= 0)
+    accounting_add_bytes(bytes_read, bytes_written, seconds_rolled_over);
+
+  if (milliseconds_elapsed > 0)
+    connection_bucket_refill(milliseconds_elapsed, now.tv_sec);
+
+  stats_prev_global_read_bucket = global_read_bucket;
+  stats_prev_global_write_bucket = global_write_bucket;
+
+  current_millisecond = now; /* remember what time it is, for next time */
+}
+#endif
+
 #ifndef MS_WINDOWS
 /** Called when a possibly ignorable libevent error occurs; ensures that we
  * don't get into an infinite loop by ignoring too many errors from
@@ -1791,6 +1837,22 @@ do_main_loop(void)
     tor_assert(second_timer);
   }
 
+#ifndef USE_BUFFEREVENTS
+  if (!refill_timer) {
+    struct timeval refill_interval;
+    int msecs = get_options()->TokenBucketRefillInterval;
+
+    refill_interval.tv_sec =  msecs/1000;
+    refill_interval.tv_usec = (msecs%1000)*1000;
+
+    refill_timer = periodic_timer_new(tor_libevent_get_base(),
+                                      &refill_interval,
+                                      refill_callback,
+                                      NULL);
+    tor_assert(refill_timer);
+  }
+#endif
+
   for (;;) {
     if (nt_service_is_stopping())
       return 0;

src/or/or.h

@@ -3107,6 +3107,8 @@ typedef struct {
                   * log whether it was DNS-leaking or not? */
   int HardwareAccel; /**< Boolean: Should we enable OpenSSL hardware
                       * acceleration where available? */
+  /** Token Bucket Refill resolution in milliseconds. */
+  int TokenBucketRefillInterval;
   char *AccelName; /**< Optional hardware acceleration engine name. */
   char *AccelDir; /**< Optional hardware acceleration engine search dir. */
   int UseEntryGuards; /**< Boolean: Do we try to enter from a smallish number