DON'T change the format otherwise it is hard to review.
And please explain your design in detail and show benchmark improvement

Reverted gofmt.

For the design, the issue of #835 was caused by:

• HTMLEscape call inside encodeFinish (internal/encoder/encoder.go:238) was passed nil.
• Because we did not pass any preallocated bytes, the implementation always allocated to grow the dst bytes to fit the result.

To make the change to reduce this allocation:

• We get a preallocated bytes from vars.NewBytes to be passed to HTMLEscape
• We store the result in buf, and we put back the old content of buf to vars.FreeBytes as it is not used anymore
• We can remove the free logic in Encode as encodeFinish already put back any unused bytes
• Similar for utf8.CorrectWith

For the benchmark, check out the following benchmark code based on the payload in the linked issue:

func BenchmarkSonicEscapeHTML(b *testing.B) {
	payload := new(infobipResponse)
	err := json.Unmarshal([]byte(data), payload)
	require.NoError(b, err)

	api := sonic.Config{EscapeHTML: true}.Froze()
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_, _ = api.Marshal(payload)
	}
}

Here is the result from the old code (48ba40b):

BenchmarkSonicEscapeHTML-8       1976474               603.1 ns/op          2354 B/op          3 allocs/op

Here is the result from the new code (fedc295):

BenchmarkSonicEscapeHTML-8       2506180               502.3 ns/op           924 B/op          2 allocs/op

See the decrease in allocation count and allocated bytes per operation.

how about the performace of JSON without HTLM chars? Including both CPU and MEM

how about the performace of JSON without HTLM chars? Including both CPU and MEM

The previous result payload does not contain any HTML chars. From my understanding, currently the EscapeHTML logic will be executed with the allocation, regardless whether the payload contain any HTML chars or not.

Here is another result I got when running the experiment using sensitive payload:

• from the old code:

BenchmarkSonicEscapeHTML-8       1877959               639.2 ns/op          2484 B/op          3 allocs/op

• from the new code:

BenchmarkSonicEscapeHTML-8       2222899               545.5 ns/op          1054 B/op          2 allocs/op