修改Tracker服务器相关bug

Change-Id: Id3ec61034575bd794724be98f832f8c065448b92
diff --git a/src/main/java/com/pt/constant/Constants.java b/src/main/java/com/pt/constant/Constants.java
index a54704c..142ab1c 100644
--- a/src/main/java/com/pt/constant/Constants.java
+++ b/src/main/java/com/pt/constant/Constants.java
@@ -39,4 +39,7 @@
             return value;
         }
     }
+
+    public static final double MIN_SHARE_RATIO_THRESHOLD = 0.5; // 最低共享率要求
+    public static final long DOWNLOAD_EXEMPTION_BYTES = 20L * 1024L * 1024L * 1024L; // 20GB下载量豁免
 }