write cookie_jar, hsts_list, auth_cache to file if profile_dir option is present

[DDEFISHER]

For Persistent sessions student project

"if the profile directory command-line option is present when the ResourceThread is instructed to exit, serialize the data contained in cookie_storage, hsts_list, and the new HTTP authorization cache, and write the serialized data in separate files inside the profile directory."

and

"perform the same serialization on shutdown for local_data in storage_thread.rs, which represents the LocalStorage API."

---

This change is

[highfive]

Heads up! This PR modifies the following files:

• @KiChjang: components/net/resource_thread.rs, components/net/cookie_storage.rs, components/net/cookie.rs

[highfive]

Warning

• These commits modify net code, but no tests are modified. Please consider adding a test!

[jdm]

Good start!
-S-awaiting-review +S-needs-code-changes

---

Reviewed 3 of 3 files at r1.
Review status: all files reviewed at latest revision, 6 unresolved discussions.

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components/net/cookie_storage.rs, line 16 [r1] (raw file):
Let's add a u32 version field as well and start with 1.

---

components/net/cookie_storage.rs, line 19 [r1] (raw file):
We should be able to derive RustcEncodable on CookieStorage like HSTSList.

---

components/net/resource_thread.rs, line 222 [r1] (raw file):
There's a lot of duplicated code in these new functions. We can make this more general, like so:

fn write_json_to_file<T: Encodable>(data: &T, profile_dir: &str, filename: &str) {
    ...
}

---

components/net/resource_thread.rs, line 223 [r1] (raw file):
Let's make the final structure look like:

{
    "version": 1,
    "entries": {
        ...
    },
}

---

components/net/resource_thread.rs, line 230 [r1] (raw file):
Path::new(profile_dir).join("auth_cache") will properly support other operating systems like Windows.

---

components/net/resource_thread.rs, line 364 [r1] (raw file):
We should be derive RustcEncodable on AuthCacheEntry instead, like HSTSEntry.

---

Comments from Reviewable

[DDEFISHER]

Should I change the auth_cache type in ResourceManager from auth_cache: Arc<RwLock<HashMap<Url, AuthCacheEntry>>>, to auth_cache: AuthCache and then create AuthCache with the following fields?

AuthCache { version: u32, entries: Arc<RwLock<HashMap<Url, AuthCacheEntry>>>, }

[jdm]

Sure, that seems like a useful change.

[jdm]

Almost there!
-S-awaiting-review +S-needs-code-changes

---

Reviewed 5 of 5 files at r2.
Review status: all files reviewed at latest revision, 8 unresolved discussions.

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components/net/cookie.rs, line 207 [r2] (raw file):
The string still says tm_mon.

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components/net/resource_thread.rs, line 210 [r2] (raw file):
Why is the clone necessary here (and subsequent lines)?

---

components/net/resource_thread.rs, line 211 [r2] (raw file):
Let's add warn!("Error writing auth cache to disk")

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components/net/resource_thread.rs, line 214 [r2] (raw file):
Let's add .json to the filenames here.

---

components/net/resource_thread.rs, line 215 [r2] (raw file):
Let's add a warn! here.

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components/net/resource_thread.rs, line 219 [r2] (raw file):
Let's add a warn! here.

---

components/net/resource_thread.rs, line 234 [r2] (raw file):
We probably shouldn't silently write an empty payload if we have a problem encoding. Let's just return here.

---

components/net/resource_thread.rs, line 330 [r2] (raw file):
nit: space after :

---

Comments from Reviewable

[DDEFISHER]

Went ahead and added the part to serialize local data as well for the next step
"perform the same serialization on shutdown for local_data in storage_thread.rs, which represents the LocalStorage API."

[jdm]

@bors-servo: r+
Thanks!

---

Reviewed 3 of 3 files at r3.
Review status: all files reviewed at latest revision, all discussions resolved.

---

Comments from Reviewable

[bors-servo]

📌 Commit b12594a has been approved by jdm

[bors-servo]

☔ The latest upstream changes (presumably #9942) made this pull request unmergeable. Please resolve the merge conflicts.

[jdm]

@bors-servo: r+

[bors-servo]

📌 Commit d4f63cd has been approved by jdm

[bors-servo]

⌛ Testing commit d4f63cd with merge 75d99ee...

[bors-servo]

💔 Test failed - linux-rel

[jdm]

@bors-servo: retry

• #10753

[bors-servo]

⚡ Previous build results for android, arm32, arm64, linux-dev, mac-dev-unit, mac-rel-css, mac-rel-wpt are reusable. Rebuilding only linux-rel...

[bors-servo]

☀️ Test successful - android, arm32, arm64, linux-dev, linux-rel, mac-dev-unit, mac-rel-css, mac-rel-wpt