y9hYxTRq

1import java.util.UUID;
2import java.util.concurrent.TimeUnit;
3
4/**
5 * Created by huangxx on 2017/6/27.
6 */
7@Service
8@Log4j2
9public class LockKeyService {
10
11    @Autowired
12    private RedisTemplate<String, String> redisTemplate;
13
14    private static final String LOCK_NAME = "LOCK_NAMKE:%s";
15
16    @Override
17    public String getKeyByrequestId(String requestId) {
18        String identifier = acquireLockAndWait(requestId, 2, 5);
19        if (StringUtils.isNotBlank(identifier)) {
20            try {
21                secretKey = generateKey(requestId);
22                dosomething(secretKey);
23            } catch (Exception e) {
24               ......
25            } finally {
26                releaseLock(requestId, identifier);
27            }
28        }
29        return secretKey;
30    }
31
32    /**
33     * @param requestId
34     * @param acquireLockTimeout 获取锁超时时间 单位：s
35     * @param lockTimeout        锁过期时间 单位：s
36     * @return
37     */
38    private String acquireLockWithTimeout(String requestId, long acquireLockTimeout, long lockTimeout) {
39        String identifier = UUID.randomUUID().toString();
40        String lockName = String.format(LOCK_NAME, requestId);
41        long end = System.currentTimeMillis() + acquireLockTimeout * 1000;
42        while (System.currentTimeMillis() < end) {
43            if (redisTemplate.opsForValue().setIfAbsent(lockName, identifier)) {
44                expire(lockName, lockTimeout, TimeUnit.SECONDS);
45                return identifier;
46            }
47            if (redisTemplate.getExpire(lockName) == -1) {
48                expire(lockName, lockTimeout, TimeUnit.SECONDS);
49            }
50            try {
51                Thread.sleep(500);
52            } catch (InterruptedException ie) {
53                log.error("acquireLockWithTimeout thread sleep error!", ie);
54            }
55        }
56        return null;
57    }
58
59    /**
60     * @param requestId
61     * @param waitTime    等待时间 单位：s
62     * @param lockTimeout 锁过期时间 单位：s
63     * @return
64     */
65    private String acquireLockAndWait(String requestId, long waitTime, long lockTimeout) {
66        String identifier = UUID.randomUUID().toString();
67        String lockName = String.format(LOCK_NAME, requestId);
68        if (redisTemplate.opsForValue().setIfAbsent(lockName, identifier)) {
69            expire(lockName, lockTimeout, TimeUnit.SECONDS);
70            return identifier;
71        }
72        if (redisTemplate.getExpire(lockName) == -1) {
73            expire(lockName, lockTimeout, TimeUnit.SECONDS);
74        }
75        try {
76            Thread.sleep(waitTime * 1000);
77        } catch (InterruptedException ie) {
78            log.error("acquireLockAndWait thread sleep error!", ie);
79        }
80        return null;
81    }
82
83    /**
84     * 释放锁，只有锁内容符合时才会释放
85     *
86     * @param requestId     用户id
87     * @param identifier 锁内容
88     * @return
89     */
90    private boolean releaseLock(String requestId, String identifier) {
91        String lockName = String.format(LOCK_NAME, requestId);
92        while (true) {
93            if (identifier.equals(redisTemplate.opsForValue().get(lockName))) {
94                redisTemplate.delete(lockName);
95                return true;
96            }
97            break;
98        }
99        return false;
100    }
101
102    private String dosomething(String requestId) {
103        ......
104    }
105
106    private void expire(String key, long time, TimeUnit timeUnit) {
107        boolean success = redisTemplate.expire(key, time, timeUnit);
108        while(!success){
109            success = redisTemplate.expire(key, time, timeUnit);
110        }
111    }
112
113}