fix backoff overflow #107

src/main/java/com/github/nkzawa/backo/Backoff.java

@@ -17,6 +17,10 @@ public class Backoff {
             int deviation = (int) Math.floor(rand * this.jitter * ms);
             ms = (((int) Math.floor(rand * 10)) & 1) == 0 ? ms - deviation : ms + deviation;
         }
+        if (ms < this.ms) {
+            // overflow happened
+            ms = Long.MAX_VALUE;
+        }
         return Math.min(ms, this.max);
     }
 

src/test/java/com/github/nkzawa/backo/BackoffTest.java

@@ -19,4 +19,17 @@ public class BackoffTest {
         assertTrue(100 == b.duration());
         assertTrue(200 == b.duration());
     }
+
+    @Test
+    public void durationOverflow() {
+        Backoff b = new Backoff();
+        b.setMin(100);
+        b.setMax(10000);
+        b.setJitter(1.0);
+
+        for (int i = 0; i < 100; i++) {
+            long duration = b.duration();
+            assertTrue(100 <= duration && duration <= 10000);
+        }
+    }
 }