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Return watch AbortController immediately to enable cancellation before first event #2877

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Return watch AbortController immediately to enable cancellation before first event #2877

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68afa9d
Initial plan
Copilot May 26, 2026
612eda9
Return watch abort controller before network response
Copilot May 26, 2026
e785fa2
Make watch return abort controller immediately
Copilot May 26, 2026
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76 changes: 40 additions & 36 deletions src/watch.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,6 @@ export class Watch {
const signal = AbortSignal.any([controller.signal, timeoutSignal]);

const ctx = new RequestContext(watchURL.toString(), HttpMethod.GET);
await this.config.applySecurityAuthentication(ctx);

let doneCalled: boolean = false;
const doneCallOnce = (err: any) => {
Expand All @@ -59,45 +58,50 @@ export class Watch {
}
};

try {
const response = await fetch(watchURL, {
method: 'GET',
headers: ctx.getHeaders(),
dispatcher: ctx.getDispatcher(),
signal,
});
const startWatch = async (): Promise<void> => {
try {
await this.config.applySecurityAuthentication(ctx);

if (response.status === 200) {
const body = Readable.fromWeb(response.body! as any);
const response = await fetch(watchURL, {
method: 'GET',
headers: ctx.getHeaders(),
dispatcher: ctx.getDispatcher(),
signal,
});

body.on('error', doneCallOnce);
body.on('close', () => doneCallOnce(null));
body.on('finish', () => doneCallOnce(null));
if (response.status === 200) {
const body = Readable.fromWeb(response.body! as any);

const lines = createInterface(body);
lines.on('error', doneCallOnce);
lines.on('close', () => doneCallOnce(null));
lines.on('finish', () => doneCallOnce(null));
lines.on('line', (line) => {
try {
const data = JSON.parse(line.toString());
callback(data.type, data.object, data);
} catch {
// ignore parse errors
}
});
} else {
const statusText =
response.statusText || STATUS_CODES[response.status] || 'Internal Server Error';
const error = new Error(statusText) as Error & {
statusCode: number | undefined;
};
error.statusCode = response.status;
throw error;
body.on('error', doneCallOnce);
body.on('close', () => doneCallOnce(null));
body.on('finish', () => doneCallOnce(null));

const lines = createInterface(body);
lines.on('error', doneCallOnce);
lines.on('close', () => doneCallOnce(null));
lines.on('finish', () => doneCallOnce(null));
lines.on('line', (line) => {
try {
const data = JSON.parse(line.toString());
callback(data.type, data.object, data);
} catch {
// ignore parse errors
}
});
} else {
const statusText =
response.statusText || STATUS_CODES[response.status] || 'Internal Server Error';
const error = new Error(statusText) as Error & {
statusCode: number | undefined;
};
error.statusCode = response.status;
throw error;
}
} catch (err) {
doneCallOnce(err);
}
} catch (err) {
doneCallOnce(err);
}
};
startWatch().catch(doneCallOnce);

return controller;
}
Expand Down
49 changes: 47 additions & 2 deletions src/watch_test.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -65,6 +65,10 @@ describe('Watch', () => {

let doneCalled = false;
let doneErr: any;
let doneResolve!: () => void;
const donePromise = new Promise<void>((resolve) => {
doneResolve = resolve;
});

await watch.watch(
path,
Expand All @@ -73,8 +77,10 @@ describe('Watch', () => {
(err: any) => {
doneCalled = true;
doneErr = err;
doneResolve();
},
);
await donePromise;
strictEqual(doneCalled, true);
strictEqual(doneErr.toString(), 'Error: Internal Server Error');
mockAgent.assertNoPendingInterceptors();
Expand Down Expand Up @@ -170,7 +176,7 @@ describe('Watch', () => {
const watch = new Watch(kc);

let doneCalled = 0;
let doneResolve: () => void;
let doneResolve!: () => void;

const donePromise = new Promise<void>((resolve) => {
doneResolve = resolve;
Expand Down Expand Up @@ -364,7 +370,7 @@ describe('Watch', () => {

let doneErr: any;

let doneResolve: () => void;
let doneResolve!: () => void;
const donePromise = new Promise<void>((resolve) => {
doneResolve = resolve;
});
Expand All @@ -386,6 +392,45 @@ describe('Watch', () => {
strictEqual(doneErr.name, 'TimeoutError');
});

it('should return abort controller before receiving response data', async (t) => {
const kc = await setupMockSystem(t, (_req: any, _res: any) => {
// Intentionally do not write headers/body so fetch stays pending.
});
const watch = new Watch(kc);

let doneErr: any;

let doneResolve!: () => void;
const donePromise = new Promise<void>((resolve) => {
doneResolve = resolve;
});

const controllerPromise = watch.watch(
'/some/path/to/object',
{},
() => {
throw new Error('Unexpected data received');
},
(err: any) => {
doneErr = err;
doneResolve();
},
);

const controller = await Promise.race([
controllerPromise,
new Promise<AbortController>((_, reject) => {
setTimeout(() => {
reject(new Error('watch() did not return AbortController in time'));
}, 100);
}),
]);

controller.abort();
await donePromise;
strictEqual(doneErr?.name, 'AbortError');
});

it('should throw on empty config', async () => {
const kc = new KubeConfig();
const watch = new Watch(kc);
Expand Down