Pagination calculate

apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/query/AlarmQuery.java

@@ -28,6 +28,7 @@ import org.apache.skywalking.apm.collector.storage.ui.common.Pagination;
 import org.apache.skywalking.apm.collector.ui.graphql.Query;
 import org.apache.skywalking.apm.collector.ui.service.AlarmService;
 import org.apache.skywalking.apm.collector.ui.utils.DurationUtils;
+import org.apache.skywalking.apm.collector.ui.utils.PaginationUtils;
 
 /**
  * @author peng-yongsheng
@@ -53,16 +54,15 @@ public class AlarmQuery implements Query {
         long start = DurationUtils.INSTANCE.durationToSecondTimeBucket(duration.getStep(), duration.getStart()) / 100;
         long end = DurationUtils.INSTANCE.durationToSecondTimeBucket(duration.getStep(), duration.getEnd()) / 100;
 
-        int limit = paging.getPageSize();
-        int from = paging.getPageSize() * paging.getPageNum();
+        PaginationUtils.Page page = PaginationUtils.INSTANCE.exchange(paging);
 
         switch (alarmType) {
             case APPLICATION:
-                return getAlarmService().loadApplicationAlarmList(keyword, start, end, limit, from);
+                return getAlarmService().loadApplicationAlarmList(keyword, start, end, page.getLimit(), page.getFrom());
             case SERVER:
-                return getAlarmService().loadInstanceAlarmList(keyword, start, end, limit, from);
+                return getAlarmService().loadInstanceAlarmList(keyword, start, end, page.getLimit(), page.getFrom());
             case SERVICE:
-                return getAlarmService().loadServiceAlarmList(keyword, start, end, limit, from);
+                return getAlarmService().loadServiceAlarmList(keyword, start, end, page.getLimit(), page.getFrom());
             default:
                 return new Alarm();
         }

apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/main/java/org/apache/skywalking/apm/collector/ui/utils/PaginationUtils.java

+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package org.apache.skywalking.apm.collector.ui.utils;
+
+import org.apache.skywalking.apm.collector.storage.ui.common.Pagination;
+
+/**
+ * @author peng-yongsheng
+ */
+public enum PaginationUtils {
+    INSTANCE;
+
+    public Page exchange(Pagination paging) {
+        int limit = paging.getPageSize();
+        int from = paging.getPageSize() * (paging.getPageNum() - 1);
+
+        return new Page(from, limit);
+    }
+
+    public class Page {
+        private int from;
+        private int limit;
+
+        Page(int from, int limit) {
+            this.from = from;
+            this.limit = limit;
+        }
+
+        public int getFrom() {
+            return from;
+        }
+
+        public int getLimit() {
+            return limit;
+        }
+    }
+}

apm-collector/apm-collector-ui/collector-ui-jetty-provider/src/test/java/org/apache/skywalking/apm/collector/ui/utils/PaginationUtilsTestCase.java

+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package org.apache.skywalking.apm.collector.ui.utils;
+
+import org.apache.skywalking.apm.collector.storage.ui.common.Pagination;
+import org.junit.Assert;
+import org.junit.Test;
+
+/**
+ * @author peng-yongsheng
+ */
+public class PaginationUtilsTestCase {
+
+    @Test
+    public void test() {
+        Pagination pagination = new Pagination();
+        pagination.setPageSize(10);
+        pagination.setPageNum(1);
+
+        PaginationUtils.Page page = PaginationUtils.INSTANCE.exchange(pagination);
+        Assert.assertEquals(0, page.getFrom());
+        Assert.assertEquals(10, page.getLimit());
+
+        pagination = new Pagination();
+        pagination.setPageSize(10);
+        pagination.setPageNum(2);
+
+        page = PaginationUtils.INSTANCE.exchange(pagination);
+        Assert.assertEquals(10, page.getFrom());
+        Assert.assertEquals(10, page.getLimit());
+    }
+}