Make span tag key/value pairs to be utf-8 encoded

[buxingzhe]

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Our application shows the log like below due to the URL path contain non utf-8 encoded characters.
"go2sky-gRPC2020/12/28 18:49:46 send segment error rpc error: code = Internal desc = grpc: error while marshaling: proto: field "KeyStringValuePair.Value" contains invalid UTF-8"
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The sdk should always encode the key/value string for tags with utf-8.

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[wu-sheng]

the URL path contain non utf-8 encoded characters.

Why is that? If it is URL encoded, it should have UTF-8 encoded already.

[buxingzhe]

As the log doesn't output the real string value, so I'm not sure why this happened.
I think it's probably related to the setting of "span.Tag(go2sky.TagURL, req.URL.String()). As the URL may have query parameters that contain characters like Chinese.

[wu-sheng]

URL includes parameters? Which framework having this feature? URL should be encoded even for Chinese.

[buxingzhe]

Here is a URL that with query parameters. Query parameters are the key value pairs after '?'.
https://www.baidu.com/s?wd=中文&rsv_spt=1&rsv_iqid=0xee4f0d5400029778

[wu-sheng]

OK, we should use uri#encoding before put it into the tags.

[rainbend]

Hi @buxingzhe Can you give me more information? I didn't come across proto: field "KeyStringValuePair.Value" contains invalid UTF-8 :)

[buxingzhe]

I just found such errors in our log, but I don't figure out how it happens.
Here are some links related to this issue, hope to help you.
golang/protobuf#1228
https://stackoverflow.com/questions/15139449/google-protocol-buffer-error-encountered-string-containing-invalid-utf-8-data