fix: prevent memory leak on macOS, closes #536

[keiya01]

What kind of change does this PR introduce?

• Bugfix
• Feature
• Docs
• New Binding issue #___
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change?

• Yes, and the changes were approved in issue #___
• No

Checklist

• When resolving issues, they are referenced in the PR's title (e.g fix: remove a typo, closes #___, #___)
• A change file is added if any packages will require a version bump due to this PR per the instructions in the readme.
• I have added a convincing reason for adding this feature, if necessary

Other information

[lucasfernog]

I think you meant removing the script message handler for the IPC?

wry/src/webview/wkwebview/mod.rs

Line 307 in 494a110

let _: () = msg_send![manager, addScriptMessageHandler:handler name:ipc];

[keiya01]

This PR is based on https://stackoverflow.com/questions/58454042/wkwebview-instances-and-memory-leak.
I'm sorry I don't know detail about this solution but we need to attach webview to scriptMessageHandler. And we can reduce memory usage when I add and remove window(webview).
But maybe this improvement is occurred only on my macOS environment, so please check it on your environment.

[keiya01]

Maybe we can also use removeAllScriptMessageHandlers.

[lucasfernog]

Sounds like exactly what we need :)

[keiya01]

I changed all of commit because I found new solution 🙇

[keiya01]

I found the Id::from_ptr is not working well, so id object is not dropped.
I fixed these code to use Id::from_retained_ptr with reference to rust-objc-id example.
If we use Id::from_retained_ptr, navigation to about:blank is not needed :)

[FabianLars]

Yep, tested it and it indeed cleans up the process we were talking about correctly! nice 🥳

What it still doesn''t cleanup is the Networking process, but since it does the same on Linux it looks like a webkit problem 🤔

[keiya01]

I think network connection is closed but network memory is still remained. I think this is because networking process is single process, networking memory is shared between multiple webview 👀

[keiya01]

This process is responsible for handling network requests as well as storage management. All WebContent processes in a single session (default vs. private browsing) share a single networking session in the networking process.
https://github.com/WebKit/WebKit/blob/main/Introduction.md

This is webkit description.
I think we can remove cache but all of webview cache will be removed. It will bring to bad page loading performance.

[keiya01]

I will try to use this gist to remove cache in another PR.

[wusyong]

@keiya01 LGTM. Do you want to merge this now?
I suppose networking process will be another PR right? Could you choose an issue and make it the main tracking issue?
Also you can just add a branch in this repo next time.

[keiya01]

Yes, I want to merge this PR now.
I will try to resolve #590 in another PR.