Merge pull request #13357 from vector-im/foldleft/decoder-ring

Developer tool: convert rageshake error locations back to sourcecode locations
pull/13486/head
Zoe 2020-05-01 09:37:51 +01:00 committed by GitHub
commit 0e75b1b0db
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/*
* Quick-n-dirty algebraic datatypes.
*
* These let us handle the possibility of failure without having to constantly write code to check for it.
* We can apply all of the transformations we need as if the data is present using `map`.
* If there's a None, or a FetchError, or a Pending, those are left untouched.
*
* I've used perhaps an odd bit of terminology from scalaz in `fold`. This is basically a `switch` statement:
* You pass it a set of functions to handle the various different states of the datatype, and if it finds the
* function it'll call it on its value.
*
* It's handy to have this in functional style when dealing with React as we can dispatch different ways of rendering
* really simply:
* ```
* bundleFetchStatus.fold({
* some: (fetchStatus) => <ProgressBar fetchsStatus={fetchStatus} />,
* }),
* ```
*/
class Optional {
static from(value) {
return value && Some.of(value) || None;
}
map(f) {
return this;
}
flatMap(f) {
return this;
}
fold({ none }) {
return none && none();
}
}
class Some extends Optional {
constructor(value) {
super();
this.value = value;
}
map(f) {
return Some.of(f(this.value));
}
flatMap(f) {
return f(this.value);
}
fold({ some }) {
return some && some(this.value);
}
static of(value) {
return new Some(value);
}
}
const None = new Optional();
class FetchStatus {
constructor(opt = {}) {
this.opt = { at: Date.now(), ...opt };
}
map(f) {
return this;
}
flatMap(f) {
return this;
}
}
class Success extends FetchStatus {
static of(value) {
return new Success(value);
}
constructor(value, opt) {
super(opt);
this.value = value;
}
map(f) {
return new Success(f(this.value), this.opt);
}
flatMap(f) {
return f(this.value, this.opt);
}
fold({ success }) {
return success instanceof Function ? success(this.value, this.opt) : undefined;
}
}
class Pending extends FetchStatus {
static of(opt) {
return new Pending(opt);
}
constructor(opt) {
super(opt);
}
fold({ pending }) {
return pending instanceof Function ? pending(this.opt) : undefined;
}
}
class FetchError extends FetchStatus {
static of(reason, opt) {
return new FetchError(reason, opt);
}
constructor(reason, opt) {
super(opt);
this.reason = reason;
}
fold({ error }) {
return error instanceof Function ? error(this.reason, this.opt) : undefined;
}
}

319
res/decoder-ring/decoder.js Normal file
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class StartupError extends Error {}
/*
* We need to know the bundle path before we can fetch the sourcemap files. In a production environment, we can guess
* it using this.
*/
async function getBundleName() {
const res = await fetch("../index.html");
if (!res.ok) {
throw new StartupError(`Couldn't fetch index.html to prefill bundle; ${res.status} ${res.statusText}`);
}
const index = await res.text();
return index.split("\n").map((line) =>
line.match(/<script src="bundles\/([^/]+)\/bundle.js"/),
)
.filter((result) => result)
.map((result) => result[1])[0];
}
function validateBundle(value) {
return value.match(/^[0-9a-f]{20}$/) ? Some.of(value) : None;
}
/* A custom fetcher that abandons immediately upon getting a response.
* The purpose of this is just to validate that the user entered a real bundle, and provide feedback.
*/
const bundleCache = new Map();
function bundleSubject(bundle) {
if (!bundle.match(/^[0-9a-f]{20}$/)) throw new Error("Bad input");
if (bundleCache.has(bundle)) {
return bundleCache.get(bundle);
}
const fetcher = new rxjs.BehaviorSubject(Pending.of());
bundleCache.set(bundle, fetcher);
fetch(`/bundles/${bundle}/bundle.js.map`).then((res) => {
res.body.cancel(); /* Bail on the download immediately - it could be big! */
const status = res.ok;
if (status) {
fetcher.next(Success.of());
} else {
fetcher.next(FetchError.of(`Failed to fetch: ${res.status} ${res.statusText}`));
}
});
return fetcher;
}
/*
* Convert a ReadableStream of bytes into an Observable of a string
* The observable will emit a stream of Pending objects and will concatenate
* the number of bytes received with whatever pendingContext has been supplied.
* Finally, it will emit a Success containing the result.
* You'd use this on a Response.body.
*/
function observeReadableStream(readableStream, pendingContext = {}) {
let bytesReceived = 0;
let buffer = "";
const pendingSubject = new rxjs.BehaviorSubject(Pending.of({ ...pendingContext, bytesReceived }));
const throttledPending = pendingSubject.pipe(rxjs.operators.throttleTime(100));
const resultObservable = new rxjs.Subject();
const reader = readableStream.getReader();
const utf8Decoder = new TextDecoder("utf-8");
function readNextChunk() {
reader.read().then(({ done, value }) => {
if (done) {
pendingSubject.complete();
resultObservable.next(Success.of(buffer));
return;
}
bytesReceived += value.length;
pendingSubject.next(Pending.of({...pendingContext, bytesReceived }));
/* string concatenation is apparently the most performant way to do this */
buffer += utf8Decoder.decode(value);
readNextChunk();
});
}
readNextChunk();
return rxjs.concat(throttledPending, resultObservable);
}
/*
* A wrapper which converts the browser's `fetch()` mechanism into an Observable. The Observable then provides us with
* a stream of datatype values: first, a sequence of Pending objects that keep us up to date with the download progress,
* finally followed by either a Success or Failure object. React then just has to render each of these appropriately.
*/
const fetchCache = new Map();
function fetchAsSubject(endpoint) {
if (fetchCache.has(endpoint)) {
// TODO: expiry/retry logic here?
return fetchCache.get(endpoint);
}
const fetcher = new rxjs.BehaviorSubject(Pending.of());
fetchCache.set(endpoint, fetcher);
fetch(endpoint).then((res) => {
if (!res.ok) {
fetcher.next(FetchError.of(`Failed to fetch endpoint ${endpoint}: ${res.status} ${res.statusText}`));
return;
}
const contentLength = res.headers.get("content-length");
const context = contentLength ? { length: parseInt(contentLength) } : {};
const streamer = observeReadableStream(res.body, context, endpoint);
streamer.subscribe((value) => {
fetcher.next(value);
});
});
return fetcher;
}
/* ===================== */
/* ==== React stuff ==== */
/* ===================== */
/* Rather than importing an entire build infrastructure, for now we just use React without JSX */
const e = React.createElement;
/*
* Provides user feedback given a FetchStatus object.
*/
function ProgressBar({ fetchStatus }) {
return e('span', { className: "progress "},
fetchStatus.fold({
pending: ({ bytesReceived, length }) => {
if (!bytesReceived) {
return e('span', { className: "spinner" }, "\u29b5");
}
const kB = Math.floor(10 * bytesReceived / 1024) / 10;
if (!length) {
return e('span', null, `Fetching (${kB}kB)`);
}
const percent = Math.floor(100 * bytesReceived / length);
return e('span', null, `Fetching (${kB}kB) ${percent}%`);
},
success: () => e('span', null, "\u2713"),
error: (reason) => {
return e('span', { className: 'error'}, `\u2717 ${reason}`);
},
},
));
}
/*
* The main component.
*/
function BundlePicker() {
const [bundle, setBundle] = React.useState("");
const [file, setFile] = React.useState("");
const [line, setLine] = React.useState("1");
const [column, setColumn] = React.useState("");
const [result, setResult] = React.useState(None);
const [bundleFetchStatus, setBundleFetchStatus] = React.useState(None);
const [fileFetchStatus, setFileFetchStatus] = React.useState(None);
/* At startup, try to fill in the bundle name for the user */
React.useEffect(() => {
getBundleName().then((name) => {
if (bundle === "" && validateBundle(name) !== None) {
setBundle(name);
}
}, console.log.bind(console));
}, []);
/* ------------------------- */
/* Follow user state changes */
/* ------------------------- */
const onBundleChange = React.useCallback((event) => {
const value = event.target.value;
setBundle(value);
}, []);
const onFileChange = React.useCallback((event) => {
const value = event.target.value;
setFile(value);
}, []);
const onLineChange = React.useCallback((event) => {
const value = event.target.value;
setLine(value);
}, []);
const onColumnChange = React.useCallback((event) => {
const value = event.target.value;
setColumn(value);
}, []);
/* ------------------------------------------------ */
/* Plumb data-fetching observables through to React */
/* ------------------------------------------------ */
/* Whenever a valid bundle name is input, go see if it's a real bundle on the server */
React.useEffect(() =>
validateBundle(bundle).fold({
some: (value) => {
const subscription = bundleSubject(value)
.pipe(rxjs.operators.map(Some.of))
.subscribe(setBundleFetchStatus);
return () => subscription.unsubscribe();
},
none: () => setBundleFetchStatus(None),
}),
[bundle]);
/* Whenever a valid javascript file is input, see if it corresponds to a sourcemap file and initiate a fetch
* if so. */
React.useEffect(() => {
if (!file.match(/.\.js$/) || validateBundle(bundle) === None) {
setFileFetchStatus(None);
return;
}
const observable = fetchAsSubject(`/bundles/${bundle}/${file}.map`)
.pipe(
rxjs.operators.map((fetchStatus) => fetchStatus.flatMap(value => {
try {
return Success.of(JSON.parse(value));
} catch (e) {
return FetchError.of(e);
}
})),
rxjs.operators.map(Some.of),
);
const subscription = observable.subscribe(setFileFetchStatus);
return () => subscription.unsubscribe();
}, [bundle, file]);
/*
* Whenever we have a valid fetched sourcemap, and a valid line, attempt to find the original position from the
* sourcemap.
*/
React.useEffect(() => {
// `fold` dispatches on the datatype, like a switch statement
fileFetchStatus.fold({
some: (fetchStatus) =>
// `fold` just returns null for all of the cases that aren't `Success` objects here
fetchStatus.fold({
success: (value) => {
if (!line) return setResult(None);
const pLine = parseInt(line);
const pCol = parseInt(column);
sourceMap.SourceMapConsumer.with(value, undefined, (consumer) =>
consumer.originalPositionFor({ line: pLine, column: pCol }),
).then((result) => setResult(Some.of(JSON.stringify(result))));
},
}),
none: () => setResult(None),
});
}, [fileFetchStatus, line, column]);
/* ------ */
/* Render */
/* ------ */
return e('div', {},
e('div', { className: 'inputs' },
e('div', { className: 'bundle' },
e('label', { htmlFor: 'bundle'}, 'Bundle'),
e('input', {
name: 'bundle',
required: true,
pattern: "[0-9a-f]{20}",
onChange: onBundleChange,
value: bundle,
}),
bundleFetchStatus.fold({
some: (fetchStatus) => e(ProgressBar, { fetchStatus }),
none: () => null,
}),
),
e('div', { className: 'file' },
e('label', { htmlFor: 'file' }, 'File'),
e('input', {
name: 'file',
required: true,
pattern: ".+\\.js",
onChange: onFileChange,
value: file,
}),
fileFetchStatus.fold({
some: (fetchStatus) => e(ProgressBar, { fetchStatus }),
none: () => null,
}),
),
e('div', { className: 'line' },
e('label', { htmlFor: 'line' }, 'Line'),
e('input', {
name: 'line',
required: true,
pattern: "[0-9]+",
onChange: onLineChange,
value: line,
}),
),
e('div', { className: 'column' },
e('label', { htmlFor: 'column' }, 'Column'),
e('input', {
name: 'column',
required: true,
pattern: "[0-9]+",
onChange: onColumnChange,
value: column,
}),
),
),
e('div', null,
result.fold({
none: () => "Select a bundle, file and line",
some: (value) => e('pre', null, value),
}),
),
);
}
/* Global stuff */
window.Decoder = {
BundlePicker,
};

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<html>
<head>
<title>Rageshake decoder ring</title>
<script crossorigin src="https://unpkg.com/source-map@0.7.3/dist/source-map.js"></script>
<script>
sourceMap.SourceMapConsumer.initialize({
"lib/mappings.wasm": "https://unpkg.com/source-map@0.7.3/lib/mappings.wasm"
});
</script>
<script crossorigin src="https://unpkg.com/react@16/umd/react.production.min.js"></script>
<script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.production.min.js"></script>
<!--<script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script>
<script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script>-->
<script crossorigin src="https://unpkg.com/rxjs/bundles/rxjs.umd.min.js"></script>
<script src="datatypes.js"></script>
<script src="decoder.js"></script>
<style>
@keyframes spin {
from {transform:rotate(0deg);}
to {transform:rotate(359deg);}
}
body {
font-family: sans-serif
}
.spinner {
animation: spin 4s infinite linear;
display: inline-block;
text-align: center;
vertical-align: middle;
font-size: larger;
}
.progress {
padding-left: 0.5em;
padding-right: 0.5em;
}
.bundle input {
width: 24ex;
}
.valid::after {
content: "✓"
}
label {
width: 3em;
margin-right: 1em;
display: inline-block;
}
input:valid {
border: 1px solid green;
}
.inputs > div {
margin-bottom: 0.5em;
}
</style>
</head>
<body>
<header><h2>Decoder ring</h2></header>
<content id="main">Waiting for javascript to run...</content>
<script type="text/javascript">
document.addEventListener("DOMContentLoaded", () => {
try {
ReactDOM.render(React.createElement(Decoder.BundlePicker), document.getElementById("main"))
} catch (e) {
const n = document.createElement("div");
n.innerText = `Error starting: ${e.message}`;
document.getElementById("main").appendChild(n);
}
});
</script>
</body>
</html>

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@ -63,6 +63,7 @@ const COPY_LIST = [
["res/welcome/**", "webapp/welcome"], ["res/welcome/**", "webapp/welcome"],
["res/themes/**", "webapp/themes"], ["res/themes/**", "webapp/themes"],
["res/vector-icons/**", "webapp/vector-icons"], ["res/vector-icons/**", "webapp/vector-icons"],
["res/decoder-ring/**", "webapp/decoder-ring"],
["node_modules/matrix-react-sdk/res/media/**", "webapp/media"], ["node_modules/matrix-react-sdk/res/media/**", "webapp/media"],
["node_modules/olm/olm_legacy.js", "webapp", { directwatch: 1 }], ["node_modules/olm/olm_legacy.js", "webapp", { directwatch: 1 }],
["./config.json", "webapp", { directwatch: 1 }], ["./config.json", "webapp", { directwatch: 1 }],

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@ -19,6 +19,8 @@ module.exports = (env, argv) => {
// This makes the sourcemaps human readable for developers. We use eval-source-map // This makes the sourcemaps human readable for developers. We use eval-source-map
// because the plain source-map devtool ruins the alignment. // because the plain source-map devtool ruins the alignment.
development['devtool'] = 'eval-source-map'; development['devtool'] = 'eval-source-map';
} else {
development['devtool'] = 'nosources-source-map';
} }
// Resolve the directories for the react-sdk and js-sdk for later use. We resolve these early so we // Resolve the directories for the react-sdk and js-sdk for later use. We resolve these early so we