use innerEvent to encapsulate user data only when the tracing is enabled

[tpiperatgod]

this PR also supports allowing the user to decide whether to use the raw data to send.

example:

func Pub(ctx ofctx.Context, in []byte) (ofctx.Out, error) {
	msg := map[string]string{
		"hello": "world",
	}

	msgBytes, _ := json.Marshal(msg)

	// This setting allows Send() to send the raw user data, even when the Tracing is enabled
	ctx.ContextOptions().SetRawData(true)

	res, err := ctx.Send("subscriber", msgBytes)
	if err != nil {
		klog.Error(err)
		return ctx.ReturnOnInternalError(), err
	}
	klog.Infof("send msg and receive result: %s", string(res))

	return ctx.ReturnOnSuccess(), nil
}

Signed-off-by: laminar fangtian@kubesphere.io

[benjaminhuo]

What happens if tracing is enabled and the user chooses to send with raw data?

[tpiperatgod]

I see, let me define the priority as follows:

the user decides whether to send raw data > tracing is enabled > target is traceable

Does this make sense?

[benjaminhuo]

I think the logic is added specially for SkyWalking. Can we replace the !GetSendWithRawData with something like IsTracingProviderSkyWalking?

If user enables skywalking tracing, it has to be cloud events, else keep the original data.
Does this make sense?

[tpiperatgod]

done

[tpiperatgod]

innerEvent will be enabled when all of the following conditions are met:

• Tracing is enabled
• Tracing provider is "skywalking"
• The output target is a traceable component
• RawData is set to false(default) in ContextOption

[lizzzcai]

innerEvent will be enabled when all of the following conditions are met:

• Tracing is enabled
• Tracing provider is "skywalking"
• The output target is a traceable component
• RawData is set to false(default) in ContextOption

If skywalking is enabled for tracing but innerEvent is disabled (for example RawData is set to true), what will happen to the skywalking tracing?

[benjaminhuo]

That's a nice move.
We have metadata added by introducing options.

[benjaminhuo]

innerEvent will be enabled when all of the following conditions are met:

• Tracing is enabled
• Tracing provider is "skywalking"
• The output target is a traceable component
• RawData is set to false(default) in ContextOption

If skywalking is enabled for tracing but innerEvent is disabled (for example RawData is set to true), what will happen to the skywalking tracing?

The sync function tracing still works while the async function tracing doesn't, is that right?

[tpiperatgod]

If skywalking is enabled for tracing but innerEvent is disabled (for example RawData is set to true), what will happen to the skywalking tracing?

the tracing will be broken in this case.

[tpiperatgod]

The sync function tracing still works while the async function tracing doesn't, is that right?

yes, the sync function can carry the tracing metadata through HTTP headers.