ppkarwasz commented on code in PR #4698:
URL: https://github.com/apache/eventmesh/pull/4698#discussion_r1438507616
##########
eventmesh-common/src/main/java/org/apache/eventmesh/common/protocol/tcp/codec/Codec.java:
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@@ -161,7 +159,7 @@ private Header parseHeader(ByteBuf in, int headerLength)
throws JsonProcessingEx
}
final byte[] headerData = new byte[headerLength];
in.readBytes(headerData);
- LogUtils.debug(log, "Decode headerJson={}",
deserializeBytes(headerData));
+ log.atDebug().log("Decode headerJson={}",
deserializeBytes(headerData));
Review Comment:
> True🤣I tested it with the code below, and the timer shows that only
Supplier could avoid executing `formatMsg()`. However the Fluent API said that
`For disabled log levels, the returned LoggingEventBuilder instance does
nothing`. Why is that?
This is due to the order in which Java evaluates methods: it always
evaluates the arguments of a method before the method itself. In this concrete
example:
```java
log.atDebug().log("Decode headerJson={}", deserializeBytes(headerData));
```
Java will:
1. Call `Logger#atDebug()` and obtain a `NOPLoggingEventBuilder`,
2. Call `deserializeBytes` and obtain a string,
3. Call `NOPLoggingEventBuilder#log` which does nothing.
The [Scala
language](https://docs.scala-lang.org/tour/by-name-parameters.html) has
call-by-name arguments that are evaluated only if they are used. In Java
everything is call-by-value and the arguments are computed even if they are not
used.
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