技術共有

キャッシュ分散ロックの原理と基本的な使用法

2024-07-12

한어Русский языкEnglishFrançaisIndonesianSanskrit日本語DeutschPortuguêsΕλληνικάespañolItalianoSuomalainenLatina

分散ロックの原理と使用法

 

スピン

  1.  public Map<String, List<Catelog2Vo>> getCatalogJsonFromDBWithRedisLock() {
  2.  
  3.         Boolean b = redisTemplate.opsForValue().setIfAbsent(Lock, Lock, Duration.ofMinutes(1));
  4.         if (!b) {
  5.             int i = 10;
  6.             while (i > 0) {
  7.                 Object result = redisTemplate.opsForValue().get(CATALOG_JSON);
  8.                 try {
  9.                     TimeUnit.MILLISECONDS.sleep(100);
  10.                 } catch (InterruptedException e) {
  11.                     throw new RuntimeException(e);
  12.                 }
  13.                 if (result != null) {
  14.                     System.out.println("命中缓存 db lock");
  15.                     return (Map<String, List<Catelog2Vo>>) result;
  16.                 }
  17.                 i--;
  18.             }
  19.             throw new RuntimeException("系统繁忙，请重新访问");
  20.         }
  21.  
  22.  
  23.         //1.查出所有1级分类
  24.         List<CategoryEntity> selectList = baseMapper.selectList(null);
  25.         /**
  26.          * 将数据库的多次查询变成一次
  27.          */
  28.         System.out.println("查询了数据库");
  29.  
  30.         //2. 封装数据
  31.         List<CategoryEntity> level1Category = selectList.stream().filter(s -> s.getParentCid().equals(0L)).collect(Collectors.toList());
  32.         Map<String, List<Catelog2Vo>> map = level1Category.stream().collect(Collectors.toMap(k -> k.getCatId().toString(), v -> {
  33.             //1.每一个的一级分类,查到1级分类的所有二级分类
  34.             List<CategoryEntity> categoryEntities = selectList.stream().filter(s -> s.getParentCid().equals(v.getCatId())).collect(Collectors.toList());
  35.  
  36.             List<Catelog2Vo> catelog2VoList = categoryEntities.stream().map(c -> {
  37.                 Catelog2Vo catelog2Vo = new Catelog2Vo();
  38.                 catelog2Vo.setId(c.getCatId().toString());
  39.                 catelog2Vo.setName(c.getName());
  40.                 catelog2Vo.setCatalog1Id(v.getCatId().toString());
  41.  
  42.                 List<CategoryEntity> categoryEntities1 = selectList.stream().filter(s -> s.getParentCid().equals(c.getCatId())).collect(Collectors.toList());
  43.                 List<Catelog2Vo.Catelog3Vo> collect = categoryEntities1.stream().map(c3 -> {
  44.                     Catelog2Vo.Catelog3Vo catelog3Vo = new Catelog2Vo.Catelog3Vo();
  45.                     catelog3Vo.setId(c3.getCatId().toString());
  46.                     catelog3Vo.setName(c3.getName());
  47.                     catelog3Vo.setCatalog2Id(c.getCatId().toString());
  48.                     return catelog3Vo;
  49.                 }).collect(Collectors.toList());
  50.  
  51.                 catelog2Vo.setCatalog3List(collect);
  52.  
  53.                 return catelog2Vo;
  54.             }).collect(Collectors.toList());
  55.  
  56.  
  57.             return catelog2VoList;
  58.         }));
  59.         if (map == null) {
  60.             /**
  61.              * 解决缓存穿透
  62.              */
  63.             map = new HashMap<>();
  64.         }
  65.         redisTemplate.opsForValue().set(CATALOG_JSON, map, Duration.ofDays(1));
  66.         redisTemplate.delete(Lock);
  67.         return map;
  68.     }

  1.  public Map<String, List<Catelog2Vo>> getCatalogJsonFromDBWithRedisLock() {
  2.         String uuid = UUID.randomUUID().toString();
  3.         Boolean b = redisTemplate.opsForValue().setIfAbsent(Lock, uuid, Duration.ofMinutes(1));
  4.         if (!b) {
  5.             int i = 10;
  6.             while (i > 0) {
  7.                 Object result = redisTemplate.opsForValue().get(CATALOG_JSON);
  8.                 try {
  9.                     TimeUnit.MILLISECONDS.sleep(100);
  10.                 } catch (InterruptedException e) {
  11.                     throw new RuntimeException(e);
  12.                 }
  13.                 if (result != null) {
  14.                     System.out.println("命中缓存 db lock");
  15.                     return (Map<String, List<Catelog2Vo>>) result;
  16.                 }
  17.                 i--;
  18.             }
  19.             throw new RuntimeException("系统繁忙，请重新访问");
  20.         }
  21.  
  22.  
  23.         //1.查出所有1级分类
  24.         List<CategoryEntity> selectList = baseMapper.selectList(null);
  25.         /**
  26.          * 将数据库的多次查询变成一次
  27.          */
  28.         System.out.println("查询了数据库");
  29.  
  30.         //2. 封装数据
  31.         List<CategoryEntity> level1Category = selectList.stream().filter(s -> s.getParentCid().equals(0L)).collect(Collectors.toList());
  32.         Map<String, List<Catelog2Vo>> map = level1Category.stream().collect(Collectors.toMap(k -> k.getCatId().toString(), v -> {
  33.             //1.每一个的一级分类,查到1级分类的所有二级分类
  34.             List<CategoryEntity> categoryEntities = selectList.stream().filter(s -> s.getParentCid().equals(v.getCatId())).collect(Collectors.toList());
  35.  
  36.             List<Catelog2Vo> catelog2VoList = categoryEntities.stream().map(c -> {
  37.                 Catelog2Vo catelog2Vo = new Catelog2Vo();
  38.                 catelog2Vo.setId(c.getCatId().toString());
  39.                 catelog2Vo.setName(c.getName());
  40.                 catelog2Vo.setCatalog1Id(v.getCatId().toString());
  41.  
  42.                 List<CategoryEntity> categoryEntities1 = selectList.stream().filter(s -> s.getParentCid().equals(c.getCatId())).collect(Collectors.toList());
  43.                 List<Catelog2Vo.Catelog3Vo> collect = categoryEntities1.stream().map(c3 -> {
  44.                     Catelog2Vo.Catelog3Vo catelog3Vo = new Catelog2Vo.Catelog3Vo();
  45.                     catelog3Vo.setId(c3.getCatId().toString());
  46.                     catelog3Vo.setName(c3.getName());
  47.                     catelog3Vo.setCatalog2Id(c.getCatId().toString());
  48.                     return catelog3Vo;
  49.                 }).collect(Collectors.toList());
  50.  
  51.                 catelog2Vo.setCatalog3List(collect);
  52.  
  53.                 return catelog2Vo;
  54.             }).collect(Collectors.toList());
  55.  
  56.  
  57.             return catelog2VoList;
  58.         }));
  59.         if (map == null) {
  60.             /**
  61.              * 解决缓存穿透
  62.              */
  63.             map = new HashMap<>();
  64.         }
  65.         redisTemplate.opsForValue().set(CATALOG_JSON, map, Duration.ofDays(1));
  66.         Object o = redisTemplate.opsForValue().get(Lock);
  67.         if (o != null && o.equals(uuid)) {
  68.             redisTemplate.delete(Lock);
  69.         }
  70.  
  71.         return map;
  72.     }

まだ問題があります

送信処理に時間がかかるため、この時点で KEY の有効期限が切れた場合は、他のスレッドに KEY を作成させてから、前のスレッドにデータを返します。KEY が削除されると、他の人が新たに追加したキーが削除されます。削除されました。

値の比較を取得 + 比較が成功した場合は削除 = アトミック操作

redis+luaスクリプトの実装

 public static final String Lock = "Lock";
  1.   public Map<String, List<Catelog2Vo>> getCatalogJsonFromDBWithRedisLock() {
  2.         String uuid = UUID.randomUUID().toString();
  3.         Boolean b = redisTemplate.opsForValue().setIfAbsent(Lock, uuid, Duration.ofMinutes(5));
  4.         if (!b) {
  5.             System.out.println("获取分布式锁失败，等待重试");
  6.             int i = 10;
  7.             while (i > 0) {
  8.                 Object result = redisTemplate.opsForValue().get(CATALOG_JSON);
  9.                 try {
  10.                     TimeUnit.MILLISECONDS.sleep(100);
  11.                 } catch (InterruptedException e) {
  12.                    e.printStackTrace();
  13.                 }
  14.                 if (result != null) {
  15.                     System.out.println("命中缓存 db lock");
  16.                     return (Map<String, List<Catelog2Vo>>) result;
  17.                 }
  18.                 i--;
  19.             }
  20.             throw new RuntimeException("系统繁忙，请重新访问");
  21.         }
  22.  
  23.  
  24.         //1.查出所有1级分类
  25.         /**
  26.          * 将数据库的多次查询变成一次
  27.          */
  28.         System.out.println("获取分布式锁成功");
  29.  
  30.         //2. 封装数据
  31.         Map<String, List<Catelog2Vo>> map = null;
  32.         try {
  33.             System.out.println("查询了数据库");
  34.             List<CategoryEntity> selectList = baseMapper.selectList(null);
  35.             List<CategoryEntity> level1Category = selectList.stream().filter(s -> s.getParentCid().equals(0L)).collect(Collectors.toList());
  36.             map = level1Category.stream().collect(Collectors.toMap(k -> k.getCatId().toString(), v -> {
  37.                 //1.每一个的一级分类,查到1级分类的所有二级分类
  38.                 List<CategoryEntity> categoryEntities = selectList.stream().filter(s -> s.getParentCid().equals(v.getCatId())).collect(Collectors.toList());
  39.  
  40.                 List<Catelog2Vo> catelog2VoList = categoryEntities.stream().map(c -> {
  41.                     Catelog2Vo catelog2Vo = new Catelog2Vo();
  42.                     catelog2Vo.setId(c.getCatId().toString());
  43.                     catelog2Vo.setName(c.getName());
  44.                     catelog2Vo.setCatalog1Id(v.getCatId().toString());
  45.  
  46.                     List<CategoryEntity> categoryEntities1 = selectList.stream().filter(s -> s.getParentCid().equals(c.getCatId())).collect(Collectors.toList());
  47.                     List<Catelog2Vo.Catelog3Vo> collect = categoryEntities1.stream().map(c3 -> {
  48.                         Catelog2Vo.Catelog3Vo catelog3Vo = new Catelog2Vo.Catelog3Vo();
  49.                         catelog3Vo.setId(c3.getCatId().toString());
  50.                         catelog3Vo.setName(c3.getName());
  51.                         catelog3Vo.setCatalog2Id(c.getCatId().toString());
  52.                         return catelog3Vo;
  53.                     }).collect(Collectors.toList());
  54.  
  55.                     catelog2Vo.setCatalog3List(collect);
  56.  
  57.                     return catelog2Vo;
  58.                 }).collect(Collectors.toList());
  59.  
  60.  
  61.                 return catelog2VoList;
  62.             }));
  63.             if (map == null) {
  64.                 /**
  65.                  * 解决缓存穿透
  66.                  */
  67.                 map = new HashMap<>();
  68.             }
  69.             redisTemplate.opsForValue().set(CATALOG_JSON, map, Duration.ofDays(1));
  70.  
  71.  
  72.         } catch (Exception e) {
  73.             e.printStackTrace();
  74.         } finally {
  75.             //lua脚本解锁
  76.             //如果获取key等于传过来的值，就执行删除操作,否则就不执行
  77.             String script="if redis.call('get',KEYS[1])==ARGV[1] then return redis.call('del',KEYS[1]) else return 0 end";
  78.             Long execute = redisTemplate.execute(new DefaultRedisScript<Long>(script, Long.class), Arrays.asList(Lock), uuid);
  79.             if (execute==1){
  80.                 System.out.println("原子删锁成功");
  81.             }else {
  82.                 System.out.println("原子删锁失败");
  83.             }
  84.         }
  85.  
  86.         return map;
  87.     }

データベースにクエリを実行したのは 1 つだけです

個人プロフィール

彼は 30 年以上テクノロジーの研究に専念しており、java、linux、javascript、php、css などのさまざまな言語に堪能であり、オープンソース分野で多くの貢献を行っています。将来の参考のために技術開発におけるいくつかの問題を共有する開発者ドキュメント ステーション。

私の連絡先情報

郵便