redission 序列化问题追踪

背景

项目原本是用jedis连接redis,但考虑到需要用redis锁,因此替换为方便快捷的redisson,但是使用redisson之后会报decode error,具体信息如下:

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2019-05-15 13:39:59.973 [redisson-netty-2-3] ERROR o.r.c.h.CommandDecoder [decodeCommand:203]     - Unable to decode data. channel: [id: 0x477c5ced, L:/192.168.4.94:57423 - R:10.10.10.43/10.10.10.43:6379], reply: ReplayingDecoderByteBuf(ridx=102, widx=102), command: (GET), params: [Geek:xxxxx:xxxx]
java.io.IOException: java.lang.NullPointerException
at org.nustaq.serialization.FSTObjectInput.readObject(FSTObjectInput.java:247)
at org.redisson.codec.FstCodec$1.decode(FstCodec.java:228)
at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:368)
at org.redisson.client.handler.CommandDecoder.decodeCommand(CommandDecoder.java:200)
at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:140)
at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:115)
at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:502)
at io.netty.handler.codec.ReplayingDecoder.callDecode(ReplayingDecoder.java:366)
at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:278)

测试代码

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RBucket ste = redissonClient.getBucket("Geek:add:ddd");
Object re = ste.get();

考虑可能是由于序列化产生的问题,查到[NullPointer 3.10.6][NullPointer 3.10.6],设置codec为StringCodec,即

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redissonClient.getConfig().setCodec(new StringCodec());

但是并未解决问题,redisson仍然使用默认的FstCodec,通过idea强大的提示功能可以看到 getBucket接受一个codec参数

idea.png

修改代码为

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RBucket ste = redissonClient.getBucket("Geek:add:ddd", new StringCodec());
String re = ste.get();

完美解决

问题

为什么直接设置redisson config 不生效呢,一步步查源码 RedissonObject#RedissonObject

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public RedissonObject(CommandAsyncExecutor commandExecutor, String name) {
this(commandExecutor.getConnectionManager().getCodec(), commandExecutor, name);
}

可以看出redisson 默认从ConnectionManager里获取codec方式,继续看,以 SingleConnectionManager 为例,SingleConnectionManagerMasterSlaveConnectionManager的子类,具体的类图关系

connectionManage.png

config.java

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public Config(Config oldConf) {
setExecutor(oldConf.getExecutor());
if (oldConf.getCodec() == null) {
// use it by default
oldConf.setCodec(new FstCodec());
}
......
}

即检测到原有codec为空时,则设置为FstCodec

看一下 Redisson.java 配置关键部分代码

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protected Redisson(Config config) {
this.config = config;
Config configCopy = new Config(config);

connectionManager = ConfigSupport.createConnectionManager(configCopy);
evictionScheduler = new EvictionScheduler(connectionManager.getCommandExecutor());
writeBehindService = new WriteBehindService(connectionManager.getCommandExecutor());
}

public static RedissonClient create(Config config) {
Redisson redisson = new Redisson(config);
if (config.isReferenceEnabled()) {
redisson.enableRedissonReferenceSupport();
}
return redisson;
}

可以看出, config是在redisson初始化的时候传入的

因为我用的是redisson-spring-boot-starter,看一下这个starter里面,是如何初始化的,redisson starter 默认使用 spring-data-redis 配置。

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@Bean(destroyMethod = "shutdown")
@ConditionalOnMissingBean(RedissonClient.class)
public RedissonClient redisson() throws IOException {
Config config = null;
....

if (redissonProperties.getConfig() != null) {
....
} else {
config = new Config();
String prefix = "redis://";
Method method = ReflectionUtils.findMethod(RedisProperties.class, "isSsl");
if (method != null && (Boolean)ReflectionUtils.invokeMethod(method, redisProperties)) {
prefix = "rediss://";
}

config.useSingleServer()
.setAddress(prefix + redisProperties.getHost() + ":" + redisProperties.getPort())
.setConnectTimeout(timeout)
.setDatabase(redisProperties.getDatabase())
.setPassword(redisProperties.getPassword());
}

return Redisson.create(config);

回到一开始的问题,直接设置redisson codec为什么不生效?仔细以上分析可以知道,redisson统一设置codec主要是通过初始化的时候传入ConnectionManager使 codec生效,而通过 redissonClient.getConfig().setCodec(...)的方式并不能改变ConnectionManager中的编码方式。

结论:

  1. 如果想自定义codec,需要自己初始化redissonClient[调用Redisson.create(config)], 或者重写redisson-starter
  2. 在定制化程度不高时,可直接使用默认codec,或者把特定的codec传入方法体内

Reference

[NullPointer 3.10.6]: https://github.com/redisson/redisson/issues/2032 “Issue”