Add properties to adjust FD initial value and max interval

Patch by brandonwilliams, reviewed by jbellis for CASSANDRA-4375

CHANGES.txt

@@ -14,6 +14,7 @@
  * Paginate batchlog replay (CASSANDRA-6569)
  * skip blocking on streaming during drain (CASSANDRA-6603)
  * Improve error message when schema doesn't match loaded sstable (CASSANDRA-6262)
+ * Add properties to adjust FD initial value and max interval (CASSANDRA-4375)
 
 
 1.2.13

src/java/org/apache/cassandra/gms/FailureDetector.java

@@ -45,6 +45,7 @@ public class FailureDetector implements IFailureDetector, FailureDetectorMBean
 {
     public static final String MBEAN_NAME = "org.apache.cassandra.net:type=FailureDetector";
     private static final int SAMPLE_SIZE = 1000;
+    protected static final int INITIAL_VALUE = getInitialValue();
 
     public static final IFailureDetector instance = new FailureDetector();
     private static final Logger logger = LoggerFactory.getLogger(FailureDetector.class);
@@ -72,6 +73,18 @@ public class FailureDetector implements IFailureDetector, FailureDetectorMBean
         }
     }
 
+    private static int getInitialValue()
+    {
+        String newvalue = System.getProperty("cassandra.fd_initial_value_ms");
+        if (newvalue != null)
+        {
+            logger.info("Overriding FD INITIAL_VALUE to {}ms", newvalue);
+            return Integer.parseInt(newvalue);
+        }
+        else
+            return Gossiper.intervalInMillis * 30;
+    }
+
     public String getAllEndpointStates()
     {
         StringBuilder sb = new StringBuilder();
@@ -280,13 +293,26 @@ class ArrivalWindow
     // in the event of a long partition, never record an interval longer than the rpc timeout,
     // since if a host is regularly experiencing connectivity problems lasting this long we'd
     // rather mark it down quickly instead of adapting
-    private final double MAX_INTERVAL_IN_MS = DatabaseDescriptor.getRpcTimeout();
+    // this value defaults to the same initial value the FD is seeded with
+    private final int MAX_INTERVAL_IN_MS = getMaxInterval();
 
     ArrivalWindow(int size)
     {
         arrivalIntervals = new BoundedStatsDeque(size);
     }
 
+    private static int getMaxInterval()
+    {
+        String newvalue = System.getProperty("cassandra.fd_max_interval_ms");
+        if (newvalue != null)
+        {
+            logger.info("Overriding FD MAX_INTERVAL to {}ms", newvalue);
+            return Integer.parseInt(newvalue);
+        }
+        else
+            return FailureDetector.INITIAL_VALUE;
+    }
+
     synchronized void add(double value)
     {
         if (tLast > 0L)
@@ -302,7 +328,7 @@ class ArrivalWindow
             // We use a very large initial interval since the "right" average depends on the cluster size
             // and it's better to err high (false negatives, which will be corrected by waiting a bit longer)
             // than low (false positives, which cause "flapping").
-            arrivalIntervals.add(Gossiper.intervalInMillis * 30);
+            arrivalIntervals.add(FailureDetector.INITIAL_VALUE);
         }
         tLast = value;
     }