"res.(http.Flusher).Flush()" not work #4

xiongsongsong · 2021-08-06T07:52:40Z

when use golang direct run,it's perfect:
https://user-images.githubusercontent.com/342509/128476357-3f6f97de-7f09-4b16-97b7-39571450390c.mov

package main

import (
	"fmt"
	"net/http"
	"time"
)

func main() {
http.HandleFunc("/wawawa",  func(res http.ResponseWriter, req *http.Request) {
	flusher := res.(http.Flusher)
	res.Header().Set("Content-Type", "text/html")
	fmt.Fprintf(res, "<!doctype html>\n<html><head><title>test</title></head><body>")
	for i := 1; i <= 50; i++ {
		fmt.Fprintf(res, "<p>Chunk #%d</p>\n<script>console.log(new Date())</script>\n", i)
		// perfect
		flusher.Flush()
		time.Sleep(500 * time.Millisecond)
	}
	fmt.Fprintf(res, "</body>\n</html>")
})

	http.ListenAndServe(":8080", nil)

	select {}
}

but with wasm, it's not work:
https://user-images.githubusercontent.com/342509/128476360-f9d80484-c6e4-4bb8-805d-5fc4273727e2.mov

package main

import (
	"fmt"
	"net/http"
	"time"
	wasmhttp "github.com/nlepage/go-wasm-http-server"
)

func main() {
	http.HandleFunc("/wawawa",  func(res http.ResponseWriter, req *http.Request) {
		flusher := res.(http.Flusher)
		res.Header().Set("Content-Type", "text/html")
		fmt.Fprintf(res, "<!doctype html>\n<html><head><title>test</title></head><body>")
		for i := 1; i <= 50; i++ {
			fmt.Fprintf(res, "<p>Chunk #%d</p>\n<script>console.log(new Date())</script>\n", i)
			// not work, 25 s later
			flusher.Flush()
			time.Sleep(500 * time.Millisecond)
		}
		fmt.Fprintf(res, "</body>\n</html>")
	})

	wasmhttp.Serve(nil)

	select {}
}

nlepage · 2021-08-07T18:58:38Z

Hi @xiongsongsong
Yes this is an expected behavior.
go-wasm-http-server first records the entire response then sends it in one piece to the browser.
So in your case the first 25 seconds are spent recording the response, then all the html content is sent in a whole chunk to the browser.
For now this kind of response "streaming" isn't possible.
There is a related issue #2, about using a ReadableStream for the response body, which should allow this kind of streaming.
I'm going to try using ReadableStream, I'll keep you updated.

xiongsongsong added the enhancement New feature or request label Aug 6, 2021

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"res.(http.Flusher).Flush()" not work #4

"res.(http.Flusher).Flush()" not work #4

xiongsongsong commented Aug 6, 2021 •

edited

nlepage commented Aug 7, 2021

"res.(http.Flusher).Flush()" not work #4

"res.(http.Flusher).Flush()" not work #4

Comments

xiongsongsong commented Aug 6, 2021 • edited

nlepage commented Aug 7, 2021

xiongsongsong commented Aug 6, 2021 •

edited