Adjust download schedules per teor's #20534 recommendataions

changes/bug20534

@@ -2,5 +2,7 @@
     - Remove the maximum delay on exponential-backoff scheduling.
       Since we now allow an infinite number of failures (see ticket
       20536), we must now allow the time to grow longer on each failure.
-      Fixes bug 20534; bugfix on 0.2.9.1-alpha.
-
+      Fixes part of bug 20534; bugfix on 0.2.9.1-alpha.
+    - Use initial delays and decrements in download scheduling closer to
+      those from 0.2.8. Fixes another part of bug 20534; bugfix on
+      0.2.9.1-alpha.

src/or/config.c

@@ -501,7 +501,7 @@ static config_var_t option_vars_[] = {
    * When clients have authorities and fallbacks available, they use these
    * schedules: (we stagger the times to avoid thundering herds) */
   V(ClientBootstrapConsensusAuthorityDownloadSchedule, CSV_INTERVAL,
-    "10, 11, 3600, 10800, 25200, 54000, 111600, 262800" /* 3 days + 1 hour */),
+    "6, 11, 3600, 10800, 25200, 54000, 111600, 262800" /* 3 days + 1 hour */),
   V(ClientBootstrapConsensusFallbackDownloadSchedule, CSV_INTERVAL,
     "0, 1, 4, 11, 3600, 10800, 25200, 54000, 111600, 262800"),
   /* When clients only have authorities available, they use this schedule: */
@@ -512,7 +512,7 @@ static config_var_t option_vars_[] = {
    * blackholed. Clients will try 3 directories simultaneously.
    * (Relays never use simultaneous connections.) */
   V(ClientBootstrapConsensusMaxInProgressTries, UINT, "3"),
-  V(TestingBridgeDownloadSchedule, CSV_INTERVAL, "3600, 900, 900, 3600"),
+  V(TestingBridgeDownloadSchedule, CSV_INTERVAL, "1200, 900, 900, 3600"),
   V(TestingClientMaxIntervalWithoutRequest, INTERVAL, "10 minutes"),
   V(TestingDirConnectionMaxStall, INTERVAL, "5 minutes"),
   V(TestingConsensusMaxDownloadTries, UINT, "8"),

src/or/directory.c

@@ -3798,7 +3798,7 @@ next_random_exponential_delay(int delay, int max_delay)
   int max_increment;
 
   if (delay)
-    max_increment = delay; /* no more than double. */
+    max_increment = delay * 4; /* no more than quintuple. */
   else
     max_increment = 1; /* we're always willing to slow down a little. */