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Simplify string concatenation in log #1378

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Feb 24, 2018
Merged

Simplify string concatenation in log #1378

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9 changes: 2 additions & 7 deletions .../dubbo-remoting-api/src/main/java/com/alibaba/dubbo/remoting/transport/DecodeHandler.java
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Original file line number Diff line number Diff line change
Expand Up @@ -55,16 +55,11 @@ private void decode(Object message) {
try {
((Decodeable) message).decode();
if (log.isDebugEnabled()) {
log.debug(new StringBuilder(32).append("Decode decodeable message ")
.append(message.getClass().getName()).toString());
log.debug("Decode decodeable message " + message.getClass().getName());
}
} catch (Throwable e) {
if (log.isWarnEnabled()) {
log.warn(
new StringBuilder(32)
.append("Call Decodeable.decode failed: ")
.append(e.getMessage()).toString(),
e);
log.warn("Call Decodeable.decode failed: " + e.getMessage(), e);
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the capacity of StringBuilder in modified statement is 16, not equals with 32 in the original one

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Thanks @kimmking , what do you think about this change?

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remain original codes

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I think this is a good optimization, let's wait for other suggestions before merge.

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@liketic liketic Feb 23, 2018 •
edited
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Thanks @chickenlj . For those cases, the naive summation will be much faster than StringBuilder. I made a simple test:

public static void main(String[] args) {

        for (int t = 0; t < 10; t++) {
            long st = System.currentTimeMillis();

            for (int i = 0; i < 100000; i++) {
                String s = "Decode decodeable message " + "xxx";
            }

            long e = System.currentTimeMillis();
            System.out.print(e - st);
            System.out.print(" ");
            
            st = System.currentTimeMillis();

            for (int i = 0; i < 100000; i++) {
                new StringBuilder(32).append("Decode decodeable message ").append("xxx").toString();
            }
            e = System.currentTimeMillis();
            System.out.println(e - st);
        }
    }

and I got output:

1 13
0 11
0 4
0 3
0 4
0 4
0 4
0 1
0 1
0 1

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this is not an equivalent comparison. the compiler may optimize "Decode decodeable message " + "xxx" into "Decode decodeable message xxx" directly.

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Thanks @beiwei30 ! That's my mistake. The test is uncorrect. The two strings cannot both be constants. 👍

}
} // ~ end of catch
} // ~ end of if
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