From 9db28c74a4e901a3be01116c23c169d06b1192a0 Mon Sep 17 00:00:00 2001
From: fit2cloud-chenyw <yawen.chen@fit2cloud.com>
Date: Tue, 29 Jun 2021 17:34:58 +0800
Subject: [PATCH] =?UTF-8?q?feat:=20=E8=A7=86=E5=9B=BE=E7=BC=93=E5=AD=98=20?=
 =?UTF-8?q?=E5=A2=9E=E5=8A=A0=E4=BA=92=E6=96=A5=E9=94=81=20=E9=81=BF?=
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MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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---
 .../service/chart/ChartViewService.java       | 40 +++++++++++++++++--
 1 file changed, 37 insertions(+), 3 deletions(-)

diff --git a/backend/src/main/java/io/dataease/service/chart/ChartViewService.java b/backend/src/main/java/io/dataease/service/chart/ChartViewService.java
index 256a96f3ec..7f233d6fa5 100644
--- a/backend/src/main/java/io/dataease/service/chart/ChartViewService.java
+++ b/backend/src/main/java/io/dataease/service/chart/ChartViewService.java
@@ -34,6 +34,7 @@ import javax.annotation.Resource;
 import java.math.BigDecimal;
 import java.math.RoundingMode;
 import java.util.*;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.stream.Collectors;
 
 /**
@@ -55,6 +56,9 @@ public class ChartViewService {
     @Resource
     private ExtChartGroupMapper extChartGroupMapper;
 
+    //默认使用非公平
+    private ReentrantLock lock = new ReentrantLock();
+
     public ChartViewWithBLOBs save(ChartViewWithBLOBs chartView) {
         checkName(chartView);
         long timestamp = System.currentTimeMillis();
@@ -219,8 +223,7 @@ public class ChartViewService {
             } else {
                 datasourceRequest.setQuery(qp.getSQL(tableName, xAxis, yAxis, customFilter, extFilterList));
             }
-            // String key = "provider_sql_"+datasourceRequest.getDatasource().getId() + "_" + datasourceRequest.getTable() + "_" +datasourceRequest.getQuery();
-            // 定时抽取使用缓存
+            /*// 定时抽取使用缓存
             Object cache;
             // 仪表板有参数不实用缓存
             if (CollectionUtils.isNotEmpty(requestList.getFilter())) {
@@ -228,13 +231,15 @@ public class ChartViewService {
             }
             // 仪表板无参数 且 未缓存过该视图 则查询后缓存
             else if ((cache = CacheUtils.get(JdbcConstants.VIEW_CACHE_KEY, id)) == null) {
+                lock.lock();
                 data = datasourceProvider.getData(datasourceRequest);
                 CacheUtils.put(JdbcConstants.VIEW_CACHE_KEY, id, data, null, null);
             }
             // 仪表板有缓存 使用缓存
             else {
                 data = (List<String[]>) cache;
-            }
+            }*/
+            data = cacheViewData(datasourceProvider, datasourceRequest, id);
         }
         if (StringUtils.containsIgnoreCase(view.getType(), "pie") && data.size() > 1000) {
             data = data.subList(0, 1000);
@@ -301,6 +306,35 @@ public class ChartViewService {
         return dto;
     }
 
+    /**
+     * 避免缓存击穿
+     * 虽然流量不一定能够达到击穿的水平
+     * @param datasourceProvider
+     * @param datasourceRequest
+     * @param viewId
+     * @return
+     * @throws Exception
+     */
+    public List<String[]> cacheViewData(DatasourceProvider datasourceProvider, DatasourceRequest datasourceRequest, String viewId) throws Exception{
+        List<String[]> result ;
+        Object cache = CacheUtils.get(JdbcConstants.VIEW_CACHE_KEY, viewId);
+        if (cache == null) {
+            if (lock.tryLock()) {// 获取锁成功
+                result = datasourceProvider.getData(datasourceRequest);
+                if (result != null) {
+                    CacheUtils.put(JdbcConstants.VIEW_CACHE_KEY, viewId, result, null, null);
+                }
+                lock.unlock();
+            }else {//获取锁失败
+                Thread.sleep(100);//避免CAS自旋频率过大 占用cpu资源过高
+                result = cacheViewData(datasourceProvider, datasourceRequest, viewId);
+            }
+        }else {
+            result = (List<String[]>)cache;
+        }
+        return result;
+    }
+
     private void checkName(ChartViewWithBLOBs chartView) {
 //        if (StringUtils.isEmpty(chartView.getId())) {
 //            return;