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https://issues.apache.org/jira/browse/CB-3927?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13690265#comment-13690265
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Andrew Grieve commented on CB-3927:
-----------------------------------
Fix from Jeff in review: https://reviews.apache.org/r/12013/
Jeff has a patch that he'll upload which shows how to repro the bug on every
start-up by disabling exec chaining and adding a sleep after the call to
loadUrl().
Pretty crazy that this bug has been around ever since the switch to a JS
Object-based bridge!
> Exec Can Fail to Issue Callback Immediately After onCordovaReady
> ----------------------------------------------------------------
>
> Key: CB-3927
> URL: https://issues.apache.org/jira/browse/CB-3927
> Project: Apache Cordova
> Issue Type: Bug
> Components: Android, CordovaJS
> Reporter: Jeffrey Willms
> Assignee: Andrew Grieve
>
> If javascript issues an exec to native after waiting for onCordovaReady the
> exec can possibly fail to issue any callback. The bug is caused when
> CordovaWebViewClient.onPageStarted, which resets the NativeToJsMessageQueue,
> is called between native queuing the response message and the javascript
> polling for that response. While webView.loadUrl is called near the entry
> point of the app, the onPageStarted event can happen very far in the future,
> after cordova-ready.
> These are the order of events that typically need to happen for this bug to
> manifest:
> - webView.loadUrl is called near entry point of app
> - At some point in the future after cordova-ready, exec is called by
> javascript
> - Native handler processes exec but gets blocked before the response message
> can be added to the queue because another thread is currently accessing the
> queue
> - Native exec returns without response
> - Handler gets unblocked and adds the response message to the queue and
> signals to javascript that there are messages to be read
> - CordovaWebViewClient.onPageStarted is called which resets the message queue
> - javascript receives signal from native and polls for messages, but gets
> none in response because the queue was reset
> The end result is that neither the success or failure callback of the exec
> ever gets issued.
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