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https://issues.apache.org/jira/browse/CB-1318?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13449375#comment-13449375
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Jimmy Jarvis edited comment on CB-1318 at 9/6/12 2:03 PM:
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JSON-P uses a unique callback identifier, similar to the proposed fix above,
and is far more reliable and easier to debug than reset with repeating IDs. It
would be unfortunate overhead to have to reinitialize our native logic every
time a page reloads. The app would be come far less responsive, at least for
us. If a plugin is a bunch of stubs, it's not an big deal as you say --
however, if it is a longer running setup process ---- I'd prefer ignoring
unmatched callbacks. I agree sending the plugin a Reset or Terminate message
would enable the plugin authors an opportunity to do proper cleanup on pending
requests, but even if they do not, unique ID's (like JSON-P) are a better
solution than repeating IDs.
was (Author: jiminyjarvis):
JSON-P uses a unique callback identifier, similar to the proposed fix
above, and is far more reliable and easier to debug than reset with repeating
IDs. It would be unfortunate overhead to have to reinitialize our native logic
every time a page reloads. The app would be come far less responsive, at least
for us. If a plugin is a bunch of stubs, it's not an big deal as you say --
however, if it is a longer running setup process ---- I'd prefer ignoring
unmatched callbacks. I agree seeing the plugin a Reset or Terminate message
would enable the plugin authors an opportunity to do proper cleanup on pending
requests, but even if they do not, unique ID's (like JSON-P) are a better
solution than repeating IDs.
> Cordova Callback Logic Not Implemented Correctly - Native Asynchronous
> Completion Can Call Wrong Logic in Javascript - Requires Non-recurring Unique
> ID as Outlined
> --------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> Key: CB-1318
> URL: https://issues.apache.org/jira/browse/CB-1318
> Project: Apache Cordova
> Issue Type: Bug
> Components: Android, iOS
> Affects Versions: 2.0.0
> Reporter: Jimmy Jarvis
> Assignee: Shazron Abdullah
> Priority: Critical
> Fix For: 2.2.0
>
>
> This bug creates very difficult to find execution anomalies for any
> asynchronous callback that occurs when the calling context has changed.
> PROBLEM: Cordova callback logic can trigger the callback function of an
> unrelated call from a different context. When a call from Javascript is made,
> Cordova generates a new callbackId, adds it to the cordova.callbacks array,
> and passes it along to the native code. Some time later, when the native code
> completes the request, it injects javascript to call the callbackSuccess or
> callbackError function. The respective callback handler looks up the callback
> attributes from the cordova.callbacks array and executes the original
> caller's completion function. The problem is each page, or reload of a page,
> resets the callbackId counter to zero and new calls end up reusing the same
> callbackId, even though the native code haS not yet completed the prior
> request. This can occur upon a new page load or reload upon an empty href in
> an anchor tag. A call to native code from page1.html could trigger the
> completion routine on page2.html because the native code has no context of
> the change on the other side of the bridge.
> SOLUTION: Replace the incrementing callbackId with a unique identifier to
> insure only the caller's completion logic will be called. I have done this
> with a Pseudo-GUID generator. Fix outlined below:
> // REPLACE THIS LINE in both cordova.2.0.0.js and cordova.ios.js
> callbackId = service + cordova.callbackId++; // BUG: incrementing
> Id's can call unrelated callback logic
> // WITH THIS LINE
> callbackId = service + ":" +
> 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function(c) {var r =
> Math.random()*16|0,v=c=='x'?r:r&0x3|0x8;return v.toString(16);}); // Generate
> unique callbackID with Pseudo-GUID
> This fix insures no code will execute if the caller's context has changed and
> is a more well formatted callbackId.
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