Merge remote-tracking branch 'github/eliminate_gettimeofday_cached'

4 files changed, 64 insertions, 23 deletions

diff --git a/src/or/circuitmux_ewma.c b/src/or/circuitmux_ewma.c
index 4b80124a77..a360327f8e 100644
--- a/src/or/circuitmux_ewma.c
+++ b/src/or/circuitmux_ewma.c
@@ -28,7 +28,7 @@
  *
  **/
 
-#define TOR_CIRCUITMUX_EWMA_C_
+#define CIRCUITMUX_EWMA_PRIVATE
 
 #include "orconfig.h"
 
@@ -169,8 +169,6 @@ TO_EWMA_POL_CIRC_DATA(circuitmux_policy_circ_data_t *pol)
 
 static void add_cell_ewma(ewma_policy_data_t *pol, cell_ewma_t *ewma);
 static int compare_cell_ewma_counts(const void *p1, const void *p2);
-static unsigned cell_ewma_tick_from_timeval(const struct timeval *now,
-                                            double *remainder_out);
 static circuit_t * cell_ewma_to_circuit(cell_ewma_t *ewma);
 static inline double get_scale_factor(unsigned from_tick, unsigned to_tick);
 static cell_ewma_t * pop_first_cell_ewma(ewma_policy_data_t *pol);
@@ -239,6 +237,13 @@ circuitmux_policy_t ewma_policy = {
   /*.cmp_cmux =*/ ewma_cmp_cmux
 };
 
+/** Have we initialized the ewma tick-counting logic? */
+static int ewma_ticks_initialized = 0;
+/** At what monotime_coarse_t did the current tick begin? */
+static monotime_coarse_t start_of_current_tick;
+/** What is the number of the current tick? */
+static unsigned current_tick_num;
+
 /*** EWMA method implementations using the below EWMA helper functions ***/
 
 /** Compute and return the current cell_ewma tick. */
@@ -421,8 +426,6 @@ ewma_notify_xmit_cells(circuitmux_t *cmux,
   ewma_policy_circ_data_t *cdata = NULL;
   unsigned int tick;
   double fractional_tick, ewma_increment;
-  /* The current (hi-res) time */
-  struct timeval now_hires;
   cell_ewma_t *cell_ewma, *tmp;
 
   tor_assert(cmux);
@@ -435,8 +438,7 @@ ewma_notify_xmit_cells(circuitmux_t *cmux,
   cdata = TO_EWMA_POL_CIRC_DATA(pol_circ_data);
 
   /* Rescale the EWMAs if needed */
-  tor_gettimeofday_cached(&now_hires);
-  tick = cell_ewma_tick_from_timeval(&now_hires, &fractional_tick);
+  tick = cell_ewma_get_current_tick_and_fraction(&fractional_tick);
 
   if (tick != pol->active_circuit_pqueue_last_recalibrated) {
     scale_active_circuits(pol, tick);
@@ -597,24 +599,45 @@ cell_ewma_to_circuit(cell_ewma_t *ewma)
    rescale.
  */
 
-/** Given a timeval <b>now</b>, compute the cell_ewma tick in which it occurs
- * and the fraction of the tick that has elapsed between the start of the tick
- * and <b>now</b>.  Return the former and store the latter in
- * *<b>remainder_out</b>.
+/**
+ * Initialize the system that tells which ewma tick we are in.
+ */
+STATIC void
+cell_ewma_initialize_ticks(void)
+{
+  if (ewma_ticks_initialized)
+    return;
+  monotime_coarse_get(&start_of_current_tick);
+  crypto_rand((char*)&current_tick_num, sizeof(current_tick_num));
+  ewma_ticks_initialized = 1;
+}
+
+/** Compute the current cell_ewma tick and the fraction of the tick that has
+ * elapsed between the start of the tick and the current time.  Return the
+ * former and store the latter in *<b>remainder_out</b>.
  *
  * These tick values are not meant to be shared between Tor instances, or used
  * for other purposes. */
-
-static unsigned
-cell_ewma_tick_from_timeval(const struct timeval *now,
-                            double *remainder_out)
+STATIC unsigned
+cell_ewma_get_current_tick_and_fraction(double *remainder_out)
 {
-  unsigned res = (unsigned) (now->tv_sec / EWMA_TICK_LEN);
-  /* rem */
-  double rem = (now->tv_sec % EWMA_TICK_LEN) +
-    ((double)(now->tv_usec)) / 1.0e6;
-  *remainder_out = rem / EWMA_TICK_LEN;
-  return res;
+  if (BUG(!ewma_ticks_initialized)) {
+    cell_ewma_initialize_ticks(); // LCOV_EXCL_LINE
+  }
+  monotime_coarse_t now;
+  monotime_coarse_get(&now);
+  int32_t msec_diff = monotime_coarse_diff_msec32(&start_of_current_tick,
+                                                  &now);
+  if (msec_diff > (1000*EWMA_TICK_LEN)) {
+    unsigned ticks_difference = msec_diff / (1000*EWMA_TICK_LEN);
+    monotime_coarse_add_msec(&start_of_current_tick,
+                             &start_of_current_tick,
+                             ticks_difference * 1000 * EWMA_TICK_LEN);
+    current_tick_num += ticks_difference;
+    msec_diff %= 1000*EWMA_TICK_LEN;
+  }
+  *remainder_out = ((double)msec_diff) / (1.0e3 * EWMA_TICK_LEN);
+  return current_tick_num;
 }
 
 /* Default value for the CircuitPriorityHalflifeMsec consensus parameter in
@@ -678,6 +701,8 @@ cmux_ewma_set_options(const or_options_t *options,
   double halflife;
   const char *source;
 
+  cell_ewma_initialize_ticks();
+
   /* Both options and consensus can be NULL. This assures us to either get a
    * valid configured value or the default one. */
   halflife = get_circuit_priority_halflife(options, consensus, &source);
@@ -788,3 +813,12 @@ pop_first_cell_ewma(ewma_policy_data_t *pol)
                               offsetof(cell_ewma_t, heap_index));
 }
 
+/**
+ * Drop all resources held by circuitmux_ewma.c, and deinitialize the
+ * module. */
+void
+circuitmux_ewma_free_all(void)
+{
+  ewma_ticks_initialized = 0;
+}
+
diff --git a/src/or/circuitmux_ewma.h b/src/or/circuitmux_ewma.h
index 2ef8c2586d..f0c4c36095 100644
--- a/src/or/circuitmux_ewma.h
+++ b/src/or/circuitmux_ewma.h
@@ -19,5 +19,12 @@ extern circuitmux_policy_t ewma_policy;
 void cmux_ewma_set_options(const or_options_t *options,
                            const networkstatus_t *consensus);
 
+void circuitmux_ewma_free_all(void);
+
+#ifdef CIRCUITMUX_EWMA_PRIVATE
+STATIC unsigned cell_ewma_get_current_tick_and_fraction(double *remainder_out);
+STATIC void cell_ewma_initialize_ticks(void);
+#endif
+
 #endif /* !defined(TOR_CIRCUITMUX_EWMA_H) */
 
diff --git a/src/or/connection.c b/src/or/connection.c
index de0f0485b0..c2673ade16 100644
--- a/src/or/connection.c
+++ b/src/or/connection.c
@@ -3440,7 +3440,6 @@ connection_handle_read(connection_t *conn)
 {
   int res;
 
-  tor_gettimeofday_cache_clear();
   res = connection_handle_read_impl(conn);
   return res;
 }
@@ -3983,7 +3982,6 @@ int
 connection_handle_write(connection_t *conn, int force)
 {
     int res;
-    tor_gettimeofday_cache_clear();
     conn->in_connection_handle_write = 1;
     res = connection_handle_write_impl(conn, force);
     conn->in_connection_handle_write = 0;
diff --git a/src/or/main.c b/src/or/main.c
index c03e80dc03..cf0df9ba79 100644
--- a/src/or/main.c
+++ b/src/or/main.c
@@ -59,6 +59,7 @@
 #include "circuitbuild.h"
 #include "circuitlist.h"
 #include "circuituse.h"
+#include "circuitmux_ewma.h"
 #include "command.h"
 #include "compress.h"
 #include "config.h"
@@ -3590,6 +3591,7 @@ tor_free_all(int postfork)
   consdiffmgr_free_all();
   hs_free_all();
   dos_free_all();
+  circuitmux_ewma_free_all();
   if (!postfork) {
     config_free_all();
     or_state_free_all();