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fix(H2 Client): bind stream 'data' listener only after received 'response' event #2985

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merged 6 commits into from
Mar 25, 2024
Merged

fix(H2 Client): bind stream 'data' listener only after received 'response' event #2985

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cd2eaf4
fix(fetch): pause stream if data is received before headers in HTTP/2
stefanoaga Mar 22, 2024
cf6a5ea
Revert "fix(fetch): pause stream if data is received before headers i…
st3ffgv4 Mar 23, 2024
9219ee3
fix(H2 Client): pause stream if response data is sent before response…
st3ffgv4 Mar 23, 2024
fb8d568
Revert "fix(H2 Client): pause stream if response data is sent before …
st3ffgv4 Mar 24, 2024
6c661b3
fix(H2 Client): bind stream 'data' listener once 'response' is triggered
st3ffgv4 Mar 24, 2024
54cd840
Merge branch 'nodejs:main' into main
st3ffgv4 Mar 24, 2024
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4 changes: 3 additions & 1 deletion lib/dispatcher/client-h2.js
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Original file line number Diff line number Diff line change
Expand Up @@ -253,6 +253,7 @@ function writeH2 (client, request) {

/** @type {import('node:http2').ClientHttp2Stream} */
let stream
let isStreamResponseStarted = false

const { hostname, port } = client[kUrl]

Expand Down Expand Up @@ -388,6 +389,7 @@ function writeH2 (client, request) {
++session[kOpenStreams]

stream.once('response', headers => {
isStreamResponseStarted = true
const { [HTTP2_HEADER_STATUS]: statusCode, ...realHeaders } = headers
request.onResponseStarted()

Expand Down Expand Up @@ -419,7 +421,7 @@ function writeH2 (client, request) {
})

stream.on('data', (chunk) => {
if (request.onData(chunk) === false) {
if (!isStreamResponseStarted || request.onData(chunk) === false) {
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this will throw away the first chunk?

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@ronag thaks, good point, I was focused on seeing that the error no longer occurs.

Is it ok to declare a temp chunks array and if isStreamResponseStarted is false in 'data' event push the chunk and then in 'response' event if the temp chunks array has length > 0 call the request.onData method after the request.onHeaders?

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This does kind of feel like an error in node core http, it doesn't make sense to me that data is emitted before response. Do you think you could report it in the node core repo in addition to this workaround PR.

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@ronag before report,
i was checking nodejs documentation about http2

there's one example here: https://nodejs.org/api/http2.html#clienthttp2sessionrequestheaders-options

const http2 = require('node:http2');
const clientSession = http2.connect('https://localhost:1234');
const {
  HTTP2_HEADER_PATH,
  HTTP2_HEADER_STATUS,
} = http2.constants;

const req = clientSession.request({ [HTTP2_HEADER_PATH]: '/' });
req.on('response', (headers) => {
  console.log(headers[HTTP2_HEADER_STATUS]);
  req.on('data', (chunk) => { /* .. */ });
  req.on('end', () => { /* .. */ });
});

the data event listener is binded inside the response listener callback.
So i have moved client-h2.js stream on data event inside stream on response (at the and of the callback) and it seems to be ok now

 stream.once('response', headers => {
    const { [HTTP2_HEADER_STATUS]: statusCode, ...realHeaders } = headers
    request.onResponseStarted()

    if (request.onHeaders(Number(statusCode), realHeaders, stream.resume.bind(stream), '') === false) {
      stream.pause()
    }

    stream.on('data', (chunk) => {
      if (request.onData(chunk) === false) {
        stream.pause()
      }
    })
  })

my test script is:

const Agent = require("./lib/dispatcher/agent");
const { fetch } = require("./lib/web/fetch");

const dispatcher = new Agent({ allowH2: true });

(async () => {
  while (true) {
    //console.log("fetching 1000 requests");
    //console.time();
    await Promise.all(
      Array.from({ length: 1000 }).map(async () => {
        try {
          const response = await fetch("https://http2.pro/api/v1", {
            dispatcher,
          });
          const text = await response.text();
          //console.log(text);
          if(!text) throw new Error("NOT GOOD")
        } catch (e) {
          console.error(e);
        }
      }),
    );
    //console.timeEnd();
  }
})();

This make more sense to you?
Thanks

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Make sense, but yea, please open an issue because this seems wrong.

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Issue opened

stream.pause()
}
})
Expand Down