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fix(service-worker): freshness strategy should clone response for cac…

…he (#19764)

When Cache.put() is called with a Response, it consumes the response. If
the Response is used for any other purpose (such as satisfying the
original FetchEvent) it must be cloned first.

A bug exists in the mocks used for SW tests, where this condition is not
validated. The bodies of MockResponses can be utilized repeatedly without
erroring in the same way that a real browser would. This bug is fixed by
this commit, which causes tests for the freshness strategy of data caching
to start failing.

The cause of this failure is a second bug in the data caching code, where
the Response is not cloned prior to being passed to Cache.put(). This is
also fixed.

PR Close #19764
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alxhub authored and tbosch committed Oct 10, 2017
1 parent fcfb154 commit 396c2417d95639e858f6e11970ded09817e9e01c
@@ -370,8 +370,7 @@ export class DataGroup {
}
// The request completed in time, so cache it inline with the response flow.
// Make sure to clone it so the real response can still be returned to the user.
await this.cacheResponse(req, res.clone(), lru);
await this.cacheResponse(req, res, lru);
return res;
}
@@ -409,7 +408,7 @@ export class DataGroup {
// No response in the cache. No choice but to fall back on the full network fetch.
res = await networkFetch;
await this.cacheResponse(req, res.clone(), lru, true);
await this.cacheResponse(req, res, lru, true);
return res;
}
@@ -517,8 +516,9 @@ export class DataGroup {
// until enough other resources are requested that it falls off the end of the LRU chain.
lru.accessed(req.url);
// Store the response in the cache.
await(await this.cache).put(req, res);
// Store the response in the cache (cloning because the browser will consume
// the body during the caching operation).
await(await this.cache).put(req, res.clone());
// Store the age of the cache.
const ageTable = await this.ageTable;
@@ -138,6 +138,11 @@ export class MockCache implements Cache {
async put(request: RequestInfo, response: Response): Promise<void> {
const url = (typeof request === 'string' ? request : request.url);
this.cache.set(url, response.clone());
// Even though the body above is cloned, consume it here because the
// real cache consumes the body.
await response.text();
return;
}
@@ -12,7 +12,7 @@ export class MockBody implements Body {
constructor(public _body: string|null) {}
async arrayBuffer(): Promise<ArrayBuffer> {
this.bodyUsed = true;
this.markBodyUsed();
if (this._body !== null) {
const buffer = new ArrayBuffer(this._body.length);
const access = new Uint8Array(buffer);
@@ -28,7 +28,7 @@ export class MockBody implements Body {
async blob(): Promise<Blob> { throw 'Not implemented'; }
async json(): Promise<any> {
this.bodyUsed = true;
this.markBodyUsed();
if (this._body !== null) {
return JSON.parse(this._body);
} else {
@@ -37,7 +37,7 @@ export class MockBody implements Body {
}
async text(): Promise<string> {
this.bodyUsed = true;
this.markBodyUsed();
if (this._body !== null) {
return this._body;
} else {
@@ -46,6 +46,13 @@ export class MockBody implements Body {
}
async formData(): Promise<FormData> { throw 'Not implemented'; }
private markBodyUsed(): void {
if (this.bodyUsed === true) {
throw new Error('Cannot reuse body without cloning.');
}
this.bodyUsed = true;
}
}
export class MockHeaders implements Headers {

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