Commit Graph

58 Commits

Author SHA1 Message Date
George Kalpakas 2156beed0c fix(service-worker): correctly serve `ngsw/state` with a non-root SW scope (#37922)
The Angular ServiceWorker can serve requests to a special virtual path,
`ngsw/state`, showing [information about its internal state][1], which
can be useful for debugging.

Previously, this would only work if the ServiceWorker's [scope][2] was
the root directory (`/`). Otherwise, (e.g. when building the app with
`--baseHref=/some/path/`), the ServiceWorker would fail to detect a
request to `/some/path/ngsw/state` as matching `ngsw/state` and would
not serve it with the debugging information.

This commit fixes it by ensuring that the ServiceWorker's scope is taken
into account when detecting a request to `ngsw/state`.

[1]: https://angular.io/guide/service-worker-devops#locating-and-analyzing-debugging-information
[2]: https://developer.mozilla.org/en-US/docs/Web/API/ServiceWorkerRegistration/scope

Fixes #30505

PR Close #37922
2020-07-09 09:44:56 -07:00
Adrien Vergé d63ecf4c5f fix(service-worker): Don't stay locked in EXISTING_CLIENTS_ONLY if corrupted data (#37453)
**Problem**

After #31109 and #31865, it's still possible to get locked in state
`EXISTING_CLIENTS_ONLY`, without any possibility to get out (even by
pushing new updates on the server).
More specifically, if control doc `/latest` of `ngsw:/:db:control` once
gets a bad value, then the service worker will fail early, and won't be
able to overwrite `/latest` with new, valid values (the ones from future
updates).

For example, once in this state, URL `/ngsw/state` will show:

    NGSW Debug Info:
    Driver state: EXISTING_CLIENTS_ONLY (Degraded due to failed initialization: Invariant violated (initialize): latest hash 8b75… has no known manifest
    Error: Invariant violated (initialize): latest hash 8b75… has no known manifest
        at Driver.<anonymous> (https://my.app/ngsw-worker.js:2302:27)
        at Generator.next (<anonymous>)
        at fulfilled (https://my.app/ngsw-worker.js:175:62))
    Latest manifest hash: 8b75…
    Last update check: 22s971u

... with hash `8b75…` corresponding to no installed version.

**Solution**

Currently, when such a case happens, the service worker [simply fails
with an assertion][1]. Because this failure happens early, and is not
handled, the service worker is not able to update `/latest` to new
installed app versions.

I propose to detect this corrupted case (a `latest` hash that doesn't
match any installed version) a few lines above, so that the service
worker can correctly call its [already existing cleaning code][2].

[1]: https://github.com/angular/angular/blob/3569fdf/packages/service-worker/worker/src/driver.ts#L559-L563
[2]: https://github.com/angular/angular/blob/3569fdf/packages/service-worker/worker/src/driver.ts#L505-L519

This change successfully fixes the problem described above.

Unit test written with the help of George Kalpakas. Thank you!

PR Close #37453
2020-06-08 09:31:34 -07:00
Joey Perrott d1ea1f4c7f build: update license headers to reference Google LLC (#37205)
Update the license headers throughout the repository to reference Google LLC
rather than Google Inc, for the required license headers.

PR Close #37205
2020-05-26 14:26:58 -04:00
Maximilian Koeller ee35e223a7 feat(service-worker): use `ignoreVary: true` when retrieving responses from cache (#34663)
The Angular ServiceWorker always uses a copy of the request without
headers for caching assets (in order to avoid issues with opaque
responses). Therefore, it was previously not possible to retrieve
resources from the cache if the response contained [Vary](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Vary) headers.

In addition to that, `Vary` headers do not work in all browsers (or work
differently) and may not work as intended with ServiceWorker caches. See
[this article](https://www.smashingmagazine.com/2017/11/understanding-vary-header) and the linked resources for more info.

This commit avoids the aforementioned issues by making sure the Angular
ServiceWorker always sets the `ignoreVary` option passed to
[Cache#match()](https://developer.mozilla.org/en-US/docs/Web/API/Cache/match) to `true`. This allows the ServiceWorker to correctly
retrieve cached responses with `Vary` headers, which was previously not
possible.

Fixes #36638

BREAKING CHANGE:

Previously, [Vary](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Vary)
headers would be taken into account when retrieving resources from the
cache, completely preventing the retrieval of cached assets (due to
ServiceWorker implementation details) and leading to unpredictable
behavior due to inconsistent/buggy implementations in different
browsers.

Now, `Vary` headers are ignored when retrieving resources from the
ServiceWorker caches, which can result in resources being retrieved even
when their headers are different. If your application needs to
differentiate its responses based on request headers, please make sure
the Angular ServiceWorker is [configured](https://angular.io/guide/service-worker-config)
to avoid caching the affected resources.

PR Close #34663
2020-05-01 09:44:07 -07:00
Maximilian Koeller dc9f4b994e feat(service-worker): include `CacheQueryOptions` options in ngsw-config (#34663)
Previously it was not possible to provide `CacheQueryOptions` ([MDN](https://developer.mozilla.org/en-US/docs/Web/API/Cache)) for querying the Cache.
This commit introduces a new parameter called `cacheQueryOptions` for `DataGroup` and `AssetGroup`.
Currently only `ignoreSearch` is supported as `ignoreVary` and `ignoreMethod` would require using
the complete Request object for matching which is not possible with the current implementation.

Closes #28443

PR Close #34663
2020-05-01 09:44:07 -07:00
Joey Perrott 698b0288be build: reformat repo to new clang@1.4.0 (#36613)
PR Close #36613
2020-04-14 12:08:36 -07:00
JiaLiPassion 41667de778 fix(zone.js): add issue numbers of `@types/jasmine` to the test cases (#34625)
Some cases will still need to use `spy as any` cast, because `@types/jasmine` have some issues,
1. The issue jasmine doesn't handle optional method properties, https://github.com/DefinitelyTyped/DefinitelyTyped/issues/43486
2. The issue jasmine doesn't handle overload method correctly, https://github.com/DefinitelyTyped/DefinitelyTyped/issues/42455

PR Close #34625
2020-04-08 12:10:34 -07:00
JiaLiPassion ef4736d052 build: update jasmine to 3.5 (#34625)
1. update jasmine to 3.5
2. update @types/jasmine to 3.5
3. update @types/jasminewd2 to 2.0.8

Also fix several cases, the new jasmine 3 will help to create test cases correctly,
such as in the `jasmine 2.x` version, the following case will pass

```
expect(1 == 2);
```

But in jsamine 3, the case will need to be

```
expect(1 == 2).toBeTrue();
```

PR Close #34625
2020-04-08 12:10:34 -07:00
Alex Wiese 96cdf035d8 fix(service-worker): treat 503 as offline (#35595)
Prior to this commit the service worker only treated 504 errors as "effectively offline".
This commit changes the behaviour to treat both 503 (Service Unavailable) and 504 as "offline".

Fixes #35571

PR Close #35595
2020-02-25 13:10:10 -08:00
Paul Gschwendtner 970b22f98e test: setup circular dependency tests for all entry points (#34774)
Sets up circular dependency tests for all entry-points in the
project (except for the ones part of a deprecated package).

PR Close #34774
2020-01-23 11:36:40 -08:00
Denis Omelkov 621b659aa9 fix(service-worker): allow creating post api requests after cache failure (#33930)
Before creating a mutating http request, service-worker
invalidates lru cache entry and writes to cache storage.
Therefore, cache storage failure can prevent making post requests.
Fix this by catching and logging cache error, add a test case.

Fixes #33793

PR Close #33930
2019-11-22 13:15:56 -05:00
Miško Hevery 7a29b24720 style: Remove use of `String` as type and use `string` instead. (#33763)
PR Close #33763
2019-11-12 13:59:16 -08:00
Michael Prentice 72eba7745f fix(service-worker): ensure initialization before handling messages (#32525)
- resolves "Invariant violated (initialize): latest hash null has no known manifest"
- Thanks to @gkalpak and @hsta for helping test and investigate this fix

Fixes #25611

PR Close #32525
2019-10-31 22:55:35 +00:00
Denis Omelkov 52483bf680 fix(service-worker): continue serving api requests on cache failure (#32996)
When responses are cached ok during sw initialization,
but caching throws an error when handling api response,
this response never gets to client. Fix response
delivery by catching errors, add logging and 2 test cases.

Fixes #21412

PR Close #32996
2019-10-14 20:21:41 +00:00
George Kalpakas 094538c0ce feat(service-worker): recover from `EXISTING_CLIENTS_ONLY` mode when there is a valid update (#31865)
Previously, when the ServiceWorker entered a degraded mode
(`EXISTING_CLIENTS_ONLY` or `SAFE_MODE`) it would remain in that mode
for the rest of the lifetime of ServiceWorker instance. Note that
ServiceWorkers are stopped by the browser after a certain period of
inactivity and a new instance is created as soon as the ServiceWorker
needs to handle an event (such as a request from the page). Those new
instances would start from the `NORMAL` mode.

The reason for this behavior is to err on the side of caution: If we
can't be sure why the ServiceWorker entered the degraded mode, it is
risky to try recovering on the same instance and might lead to
unexpected behavior.

However, it turns out that the `EXISTING_CLIENTS_ONLY` mode can only be
a result of some error happening with the latest version (e.g. a hash
mismatch in the manifest). Therefore, it is safe to recover from that
mode once a new, valid update is successfully installed and to start
accepting new clients.

This commit ensures that the mode is set back to `NORMAL`, when (a) an
update is successfully installed and (b) the current mode is
`EXISTING_CLIENTS_ONLY`.

Besides making the behavior more predictable (instead of relying on the
browser to decide when to terminate the current ServiceWorker instance
and create a new one), this change can also improve the developer
experience:
When people notice the error during debugging and fix it by deploying a
new version (either to production or locally), it is confusing that the
ServiceWorker will fetch and install the update (as seen by the requests
in the Network panel in DevTools) but not serve it to clients. With this
change, the update will be served to new clients as soon as it is
installed.

Fixes #31109

PR Close #31865
2019-09-04 15:41:04 -07:00
George Kalpakas bda2b4ebb6 fix(service-worker): keep serving clients on older versions if latest is invalidated (#31865)
Previously, when the latest version was invalidated (e.g. due to a hash
mismatch), the SW entered a degraded `EXISTING_CLIENTS_ONLY` mode and
removed _all_ clients from its client-version map (essentially stopping
to serve any clients). Based on the code and surrounding comments, the
intention seems to have been to only remove clients that were on the
invalidated version, but keep other clients on older versions.

This commit fixes it by only unassigning clients what were on the latest
version and keep clients assigned to older versions.

PR Close #31865
2019-09-04 15:41:04 -07:00
George Kalpakas 20dc5e83ee test(service-worker): add helper function for making navigation requests (#31865)
Helper functions for making navigation requests were created in several
places inside the test suite, so this commit creates a top-level such
helper and uses that in all tests that need it.

PR Close #31865
2019-09-04 15:41:04 -07:00
George Kalpakas 93abc35213 fix(service-worker): cache opaque responses when requests exceeds timeout threshold (#30977)
PR Close #30977
2019-06-27 09:52:29 -07:00
George Kalpakas d7be38f84b fix(service-worker): cache opaque responses in data groups with `freshness` strategy (#30977)
Previously, (presummably due to a typo) the `okToCacheOpaque` argument
of `DataGroup#cacheResponse()` was essentially never taken into account
(since opaque responses have a non-200 status code and thus `res.ok` is
always false).

This commit fixes the typo, which allows opaque responses to be cached
when `okToCacheOpaque` is true (i.e. in data groups using the
`freshness` strategy).

Fixes #30968

PR Close #30977
2019-06-27 09:52:29 -07:00
George Kalpakas c150354464 test(service-worker): properly reset mock server state for each test (#30977)
PR Close #30977
2019-06-27 09:52:28 -07:00
George Kalpakas 7217525da4 test(service-worker): simplify test helpers (#30977)
PR Close #30977
2019-06-27 09:52:28 -07:00
George Kalpakas b6e8d19313 test(service-worker): remove obsolete async test helpers (#30977)
Jasmine natively supports returning promises from spec functions for
quite some time now. We don't need special async helpers.

PR Close #30977
2019-06-27 09:52:28 -07:00
Peter Johan Salomonsen 6200732e23 feat(service-worker): support bypassing SW with specific header/query param (#30010)
Add support for bypassing the ServiceWorker for a request by using the
ngsw-bypass header or query parameter.

Fixes #21191

PR Close #30010
2019-04-25 13:09:44 -07:00
George Kalpakas a24f4b51b3 test(service-worker): test support for multiple apps on different subpaths of a domain (#27080)
PR Close #27080
2019-03-21 12:07:56 -04:00
Sheik Althaf e721c08c7f feat(service-worker): support multiple apps on different subpaths of a domain (#27080)
Previously, it was not possible to have multiple apps (using
`@angular/service-worker`) on different subpaths of the same domain,
because each SW would overwrite the caches of the others (even though
their scope was different).

This commit fixes it by ensuring that the cache names created by the SW
are different for each scope.

Fixes #21388

PR Close #27080
2019-03-21 12:07:56 -04:00
George Kalpakas 37a154e4e6 test(service-worker): do not create testing artifacts on environments that do not support SW (#27080)
The tests will not be run anyway, so the artifacts are never used and
there might be errors if creating the testing artifacts relies on APIs
that are not available in that environment (e.g. `URL`).

PR Close #27080
2019-03-21 12:07:56 -04:00
George Kalpakas 586234bb01 fix(service-worker): detect new version even if files are identical to an old one (#26006)
Previously, if an app version contained the same files as an older
version (e.g. making a change, then rolling it back), the SW would not
detect it as the latest version (and update clients).

This commit fixes it by adding a `timestamp` field in `ngsw.json`, which
makes each build unique (with sufficiently high probability).

Fixes #24338

PR Close #26006
2019-03-05 09:41:44 -08:00
George Kalpakas 48214e2a05 fix(service-worker): ignore passive mixed content requests (#25994)
Although [passive mixed content][1] requests (like images) only produce
a warning without a ServiceWorker, fetching it via a ServiceWorker
results in an error. See
https://github.com/angular/angular/issues/23012#issuecomment-376430187
for more details.

This commit makes the ServiceWorker ignore such requests and let them be
handled by the browser directly to avoid breaking apps that would work
without the ServiceWorker.

[1]: https://developers.google.com/web/fundamentals/security/prevent-mixed-content/what-is-mixed-content#passive_mixed_content

Fixes #23012

PR Close #25994
2019-03-04 11:51:05 -08:00
Serginho d49d1e7d73 fix(service-worker): navigation urls backwards compatibility (#27244)
PR Close #27244
2019-01-15 09:50:31 -08:00
joostme aca8ea9c0b refactor(service-worker): Format comments and add additional test (#25860)
- Format JSDoc for notificationClicks
- Add comment on why handleClick does not use hasOwnProperty
- Add additional test that uses handleClick without action

PR Close #25860
2018-11-01 15:13:33 -07:00
Joost Zöllner 4a01ada291 fix(service-worker): Fix public api guard typing (#25860)
PR Close #25860
2018-11-01 15:13:33 -07:00
Joost Zöllner f017b26e5d refactor(service-worker): update tests based of review feedback (#25860)
- Rename invalid click event name
- Make test expects more explicit
- Remove NotificationClickEvent in favor of NotificationEvent

PR Close #25860
2018-11-01 15:13:32 -07:00
Joost Zoellner cf6ea283bb feat(service-worker): handle 'notificationclick' events (#25860)
The previous version did not support the 'notificationclick' event.
Add event handler for the event and provide an observable of
clicked notifications in the SwPush service.

Closes #20956, #22311

PR Close #25860
2018-11-01 15:13:32 -07:00
Igor Minar 4237c34c78 test(ivy): mark failing test targets with fixme-ivy-jit and fixme-ivy-local tags (#26471)
We are close enough to blacklist a few test targets, rather than whitelist targets to run...

Because bazel rules can be composed of other rules that don't inherit tags automatically,
I had to explicitly mark all of our ts_library and ng_module targes with "ivy-local" and
"ivy-jit" tags so that we can create a query that excludes all fixme- tagged targets even
if those targets are composed of other targets that don't inherit this tag.

This is the updated overview of ivy related bazel tags:

- ivy-only: target that builds or runs only under ivy
- fixme-ivy-jit: target that doesn't yet build or run under ivy with --compile=jit
- fixme-ivy-local: target that doesn't yet build or run under ivy with --compile=local
- no-ivy-jit: target that is not intended to build or run under ivy with --compile=jit
- no-ivy-local: target that is not intended to build or run under ivy with --compile=local

PR Close #26471
2018-10-23 08:57:42 -07:00
George Kalpakas 2326b9c294 fix(service-worker): clean up caches from old SW versions (#26319)
Since the SW immediately takes over all clients, it is safe to delete
caches used by older (e.g. beta) `@angular/service-worker` versions to
avoid running into browser storage quota limitations.

PR Close #26319
2018-10-16 14:12:07 -07:00
George Kalpakas 2bd767c4a6 fix(service-worker): do not blow up when caches are unwritable (#26042)
In some cases, example when the user clears the caches in DevTools but
the SW remains active on another tab and keeps references to the deleted
caches, trying to write to the cache throws errors (e.g.
`Entry was not found`).

When this happens, the SW can no longer work correctly and should enter
a degraded mode allowing requests to be served from the network.

Possibly related:
- https://github.com/GoogleChrome/workbox/issues/792
- https://bugs.chromium.org/p/chromium/issues/detail?id=639034

This commits remedies this situation, by ensuring the SW can enter the
degraded `EXISTING_CLIENTS_ONLY` mode and forward requests to the
network.

PR Close #26042
2018-09-24 09:53:39 -07:00
Greg Magolan b99d7ed5bf build(bazel): update to rules_typescript 0.17.0 & rules_nodejs 0.13.4 (#25920)
PR Close #25920
2018-09-18 13:05:38 -07:00
Alan Agius 01ec5fd6b0 fix(service-worker): `Cache-Control: no-cache` on assets breaks service worker (#25408)
At the moment `cacheAge` can we undefined when having `Cache-Control` set to `no-cache` due the mapping method in `needToRevalidate`

Closes #25442

PR Close #25408
2018-08-14 16:40:15 -07:00
George Kalpakas 52d43a99ef fix(service-worker): avoid network requests when looking up hashed resources in cache (#24127)
PR Close #24127
2018-07-06 13:50:37 -07:00
George Kalpakas e0ed59e55f fix(service-worker): correctly handle requests with empty `clientId` (#23625)
Requests from clients that are not assigned a client ID by the browser
will produce `fetch` events with `null` or empty (`''`) `clientId`s.

Previously, the ServiceWorker only handled `null` values correctly. Yet
empty strings are also valid (see for example [here][1] and [there][2]).
With this commit, the SW will interpret _all_ falsy `clientId` values
the same (i.e. "no client ID assigned") and handle them appropriately.

Related Chromium issue/discussion: [#832105][3]

[1]: 4cc72bd0f1/docs/index.bs (L1392)
[2]: https://w3c.github.io/ServiceWorker/#fetchevent-interface
[3]: https://bugs.chromium.org/p/chromium/issues/detail?id=832105

Fixes #23526

PR Close #23625
2018-05-09 11:50:02 -07:00
George Kalpakas d6b1466c81 test(service-worker): support mock requests with null/empty client ID (#23625)
PR Close #23625
2018-05-09 11:50:02 -07:00
George Kalpakas d1abf4e897 test(service-worker): improve adding clients in `SwTestHarness` (#23625)
This commits changes how clients are added in `SwTestHarness`, so that
the behavior in tests closer mimics what would happen in an actual
ServiceWorker.
It also removes auto-adding clients when calling `clients.get()`, which
could hide bugs related to non-existing clients.

PR Close #23625
2018-05-09 11:50:02 -07:00
George Kalpakas 6c2c95851a fix(service-worker): let `*` match 0 characters in globs (#23339)
In [glob patterns][1], the `*` wildcard is supposed to match 0 or more
characters.

For reference:
- This is also how `*` works in other implementations, such as
  `.gitignore` files or Firebase hosting config.
- Some popular JS implementations (e.g. [minimatch][2], [micromatch][3])
  work differently, matching 1 or more character (but not 0).

This commit "fixes" the minimal glob support in
`@angular/service-worker` to allow `*` to also match 0 characters.

[1]: https://en.wikipedia.org/wiki/Glob_%28programming%29
[2]: https://www.npmjs.com/package/minimatch
[3]: https://www.npmjs.com/package/micromatch

PR Close #23339
2018-04-13 13:13:36 -07:00
George Kalpakas 08325aaffc feat(service-worker): add support for configuring navigations URLs (#23339)
The ServiceWorker will redirect navigation requests that don't match any
`asset` or `data` group to the specified index file. The rules for a
request to be classified as a navigation request are as follows:
1. Its `mode` must be `navigation`.
2. It must accept a `text/html` response.
3. Its URL must match certain criteria (see below).

By default, a navigation request can have any URL except for:
1. URLs containing `__`.
2. URLs to files (i.e. containing a file extension in the last path
   segment).

While these rules are fine in many cases, sometimes it is desirable to
configure different rules for the URLs of navigation requests (e.g.
ignore specific URLs and pass them through to the server).

This commit adds support for specifying an optional `navigationUrls`
list in `ngsw-config.json`, which contains URLs or simple globs
(currently only recognizing `!`, `*` and `**`).
Only requests whose URLs match any of the positive URLs/patterns and
none of the negative ones (i.e. URLs/patterns starting with `!`) will be
considered navigation requests (and handled accordingly by the SW).

(This is an alternative implementation to #23025.)

Fixes #20404

PR Close #23339
2018-04-13 13:13:36 -07:00
George Kalpakas d9dc46e651 fix(service-worker): ignore invalid `only-if-cached` requests (#22883)
Under some circumstances (possibly related to opening Chrome DevTools),
requests are made with `cache: 'only-if-cached'` and `mode: 'no-cors'`.
These request will eventually fail, because `only-if-cached` is only
allowed to be used with `mode: 'same-origin'`.
This is likely a bug in Chrome DevTools.

This commit avoids errors related to such requests by not handling them.

Fixes #22362

PR Close #22883
2018-03-28 10:02:16 -07:00
George Kalpakas 9e9b8dd494 fix(service-worker): do not enter degraded mode when offline (#22883)
Previously, when trying to fetch `ngsw.json` (e.g. during
`checkForUpdate()`) while either the client or the server were offline,
the ServiceWorker would enter a degrade mode, where only existing
clients would be served. This essentially meant that the ServiceWorker
didn't work offline.
This commit fixes it by differentiating offline errors and not entering
degraded mode. The ServiceWorker will remain in the current mode until
connectivity to the server is restored.

Fixes #21636

PR Close #22883
2018-03-28 10:02:16 -07:00
George Kalpakas 12665a749c test(service-worker): minor test fixes and refactorings (#22883)
PR Close #22883
2018-03-28 10:02:16 -07:00
Alex Eagle ba8df8a3f1 build: update to latest bazel rules (#22558)
PR Close #22558
2018-03-02 13:27:25 -08:00
Alex Eagle c4f02e21dd build: move repeated tsconfig attributes to a macro (#20964)
This helps ensure we use the same tsconfig.json file for all compilations.
Next steps are to make it the same tsconfig.json file used by the editor

PR Close #20964
2018-01-10 12:30:19 -08:00
Alex Rickabaugh 395109817b fix(service-worker): properly handle invalid hashes in all scenarios (#21288)
When the SW fetches URLs listed in a manifest with hashes, it checks
the content hash against the manifest to make sure it has the correct
version of the URL. In the event of a mismatch, the SW is supposed to
consider the manifest invalid, and avoid using it. There are 3 cases
to consider by which this can happen.

Case 1: during the initial SW installation, a manifest is activated
without waiting for every URL to be fully loaded. In the background,
every prefetch URL listed by the manifest is requested and cached.
One such prefetch request could fail the hash test, and cause the
manifest to be treated as invalid. In such a case, the SW should
enter a state of EXISTING_CLIENTS_ONLY, as the latest manifest is
invalid.

This case works today.

Case 2: during the initial SW installation, as in Case 1, a manifest
is activated without waiting for each URL to fully load. However,
it's possible that the application could request a URL with a bad
hash before background initialization tries to load that URL. This
happens if, for example, the application has a broken index.html.

In this case, the SW should enter a state of EXISTING_CLIENTS_ONLY,
and serve the request from the network instead.

What happens today is that the internal error escapes the SW and
is returned as a rejected Promise to respondWith(), causing a
browser-level error that the site cannot be loaded, breaking the
site.

This change allows the SW to detect the error and enter the correct
state, falling back on the network if needed.

Case 3: during checkForUpdate(), the SW will try to fully cache the
new update before making it the latest version. Failure here is
complicated - if the page fails to load due to transient network
conditions (timeouts, 500s, etc), then it makes sense to continue
serving the existing cached version, and attempt to activate the
update on the next cycle.

If the page fails due to non-transient conditions though (400 error,
hash mismatch, etc), then the SW should consider the updated
manifest invalid, and enter a state of EXISTING_CLIENTS_ONLY.

Currently, all errors are treated as transient.

This change causes the SW to treat all errors during updates as
non-transient, which can cause the SW to unnecessarily enter a
safe mode. A future change can allow the SW to remain in normal mode
if the error is provably transient.

PR Close #21288
2018-01-10 12:18:24 -08:00