org.redisson.client.redisexception: err unknown command PEXPIRETIME问题处理

在获取redis中key的过期时间时，发现并没有如期获取到过期时间，程序抛出了如下的异常

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org.redisson.client.RedisException: ERR unknown command 'PEXPIRETIME'. channel: [id: 0x08706bdb, L:/127.0.0.1:64540 - R:127.0.0.1/127.0.0.1:6379] command: (PEXPIRETIME), promise: java.util.concurrent.CompletableFuture@70c7b9a[Not completed, 1 dependents], params: [sys:token:1848366052968607746]
	at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:380) ~[redisson-3.22.1.jar:3.22.1]
	at org.redisson.client.handler.CommandDecoder.decodeCommand(CommandDecoder.java:205) ~[redisson-3.22.1.jar:3.22.1]
	at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:144) ~[redisson-3.22.1.jar:3.22.1]
	at org.redisson.client.handler.CommandDecoder.decode(CommandDecoder.java:120) ~[redisson-3.22.1.jar:3.22.1]
	at io.netty.handler.codec.ByteToMessageDecoder.decodeRemovalReentryProtection(ByteToMessageDecoder.java:519) ~[netty-codec-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.handler.codec.ReplayingDecoder.callDecode(ReplayingDecoder.java:366) ~[netty-codec-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:280) ~[netty-codec-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:444) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:412) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:440) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:420) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:166) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:788) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:724) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:650) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:562) ~[netty-transport-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:997) ~[netty-common-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74) ~[netty-common-4.1.84.Final.jar:4.1.84.Final]
	at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30) ~[netty-common-4.1.84.Final.jar:4.1.84.Final]
	at java.lang.Thread.run(Thread.java:750) [na:1.8.0_421]

后续debug跟踪调试，发现问题出现在如下代码：

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@Override
public <T> Long getCacheTTL(String key) {
    RBucket<T> bucket = redissonClient.getBucket(key);
    return bucket.getExpireTime();
}

执行到 bucket.getExpireTime()时发生了异常。点进这个函数发现：

image-20241027094313746

getExpireTime()方法需要redis7以上才支持。我用的redis没到那么高的版本。

可以切换成上面的remainTimeToLive方法，解决问题。