Use Messenger for executeInTarget

[fregante]

• Includes Preserve trace when forwarding webext-messenger#55

Tests done

200 Successful

1. brick: open tab
2. brick: alert in Target:target

404 Missing target

1. brick: alert in Target:target
   • it doesn't exist, so it will receive BusinessError("Sender tab has no target")

410 Outdated target

1. brick: open tab
2. brick: wait 2000 ms
3. manually close tab
4. brick: alert in Target:target
   • it no longer exists exist, so it will receive BusinessError("Sender tab has no target")

[fregante]

This specific error no longer exists because the retries are handled automatically by webext-messenger when forwarding it. The max retry time is fixed/global to around 5s, but it only applies "per hop", i.e. the background can take 4s to answer, then the content script can wait 4s more, etc.

I suppose this is an issue on large pages that have document_idle late.

If you think this is an issue, I could add an option¹ for this or increase the default timeout.

¹ options are kind of difficult at the moment, 🤭 which is why I split getMethod from getNotifier instead of using isNotification: true

[fregante]

Since I'm bringing the handler back to this context, I will restore this function 🎉

[fregante]

The target was previous stored in the background page and the messaging solution expected the background page to match "sender" with "target".

With the messenger we can message the tab "directly" (i.e. the messenger takes care of forwarding) so we can store it locally (which is where the tab is created anyway).

This might not be the best solution but it's clean-ish (when messaging the target, you'll have to import this block, which shows the direct dependency between the two)

[twschiller]

The target was previous stored in the background page and the messaging solution expected the background page to match "sender" with "target".

This change actually changes the behavior. The old code also tracked if a normal link opened up a new tab. With this new code the "target" relationship will only be tracked through this block?

• Check impact on tabs opened through 'a'

See the bookkeeping via browser.tabs.onCreated at initExecutor: http://github.com/pixiebrix/pixiebrix-extension/blob/main/src/background/executor.ts#L300-L300

[fregante]

Indeed. In that case we can exclusively send messages via the background page because that's the only context that can know that information. I'll have to restore the previous manual forwarding

[fregante]

A note about the other targets:

• opener can probably be handled by the messenger by using runBlock({tabId: "opener"})
• broadcast likely similar implementation to Replace notifyContentScripts with Messenger #1329
• frame_nonce I haven't looked at it yet, but maybe via {tabId: "this", page: "?nonce=ABC"}. Related: How can a content script target a frame? webext-messenger#41

[twschiller]

Broadcast likely similar implementation to Replace notifyContentScripts with Messenger #1329

Unlike notifications, broadcast actually returns the results as the array. You mean in terms of how it notifies all the tabs?

frame_nonce I haven't looked at it yet, but maybe via {tabId: "this", page: "?nonce=ABC"}

I think using the more general page matching capability here to support our nonce based frame approach makes sense here

[fregante]

I think using the more general page matching capability here to support our nonce based frame approach makes sense here

I'm starting to think that all of these methods will continue existing in the background page because that's the only context that can do this.

[twschiller]

See comment about the "target" book keeping. How does the target in redirectPage file relate to tabToTarget in the executor?

I might be missing something?

[fregante]

You're right, I left a comment in the review. I'll preserve the background-based manual forwarding as before, except with the messenger instead of sendMessage

[fregante]

None of this is useful unfortunately, I'll reopen a PR with new code that only replaces the sendMessage with the messenger.