From 8e894e49b33c54ffeacfa98c7aceffed93326911 Mon Sep 17 00:00:00 2001
From: imhao183 <wildfirechat86@gmail.com>
Date: Fri, 23 Oct 2020 11:24:44 +0800
Subject: [PATCH] =?UTF-8?q?=E8=A7=A3=E5=86=B3=E6=8B=89=E5=8F=96=E5=8E=86?=
 =?UTF-8?q?=E5=8F=B2=E6=B6=88=E6=81=AF=E9=97=AE=E9=A2=98?=
MIME-Version: 1.0
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---
 .../io/moquette/persistence/DatabaseStore.java |  2 +-
 .../win/liyufan/im/MessageShardingUtil.java    | 18 ++++++++++++++----
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/broker/src/main/java/io/moquette/persistence/DatabaseStore.java b/broker/src/main/java/io/moquette/persistence/DatabaseStore.java
index 24f2934e..b9174314 100644
--- a/broker/src/main/java/io/moquette/persistence/DatabaseStore.java
+++ b/broker/src/main/java/io/moquette/persistence/DatabaseStore.java
@@ -761,7 +761,7 @@ public class DatabaseStore {
 
         int month = 0;
         while (messages.size() < count && !DBUtil.IsEmbedDB && month++ < 24) {
-            String nexTable = MessageShardingUtil.getPreviousMessageTable(before[0]);
+            String nexTable = MessageShardingUtil.getMessageTable(beforeUid, -month);
 
             int size = messages.size();
             hasMore = true;
diff --git a/broker/src/main/java/win/liyufan/im/MessageShardingUtil.java b/broker/src/main/java/win/liyufan/im/MessageShardingUtil.java
index 6cd733aa..1b8f04a3 100644
--- a/broker/src/main/java/win/liyufan/im/MessageShardingUtil.java
+++ b/broker/src/main/java/win/liyufan/im/MessageShardingUtil.java
@@ -84,7 +84,7 @@ public class MessageShardingUtil {
         }
 
         Calendar calendar = Calendar.getInstance();
-        if (mid != Long.MAX_VALUE) {
+        if (mid != Long.MAX_VALUE && mid != 0) {
             mid >>= (nodeIdWidth + rotateIdWidth);
             Date date = new Date(mid + T201801010000);
             calendar.setTime(date);
@@ -99,6 +99,10 @@ public class MessageShardingUtil {
     }
 
     public static String getPreviousMessageTable(long mid) {
+        return getMessageTable(mid, -1);
+    }
+
+    public static String getMessageTable(long mid, int offset) {
         if (DBUtil.IsEmbedDB) {
             return null;
         }
@@ -110,11 +114,17 @@ public class MessageShardingUtil {
         int month = calendar.get(Calendar.MONTH);
         int year = calendar.get(Calendar.YEAR);
         year %= 3;
-        month = month - 1;
-        if (month == -1) {
-            month = 11;
+
+        month = month + offset;
+        while (month < 0) {
+            month += 12;
             year = (year + 3 - 1)%3;
         }
+        while (month >= 12) {
+            month -= 12;
+            year = (year + 1)%3;
+        }
+
         return "t_messages_" + (year * 12 + month);
     }
 }