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From "Sean Nikolai Fridman (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CB-1462) False logic for native watchPosition/clearWatch
Date Fri, 14 Sep 2012 09:50:07 GMT
Sean Nikolai Fridman created CB-1462:
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             Summary: False logic for native watchPosition/clearWatch
                 Key: CB-1462
                 URL: https://issues.apache.org/jira/browse/CB-1462
             Project: Apache Cordova
          Issue Type: Bug
          Components: Android, CordovaJS
    Affects Versions: 2.0.0
            Reporter: Sean Nikolai Fridman
            Assignee: Joe Bowser


Note: This is a bug in Android's native geolocation implementation. I can't speak to what
happens on other platforms. However, I get the feeling that the bug is symptomatic of the
JS implementation so it might very well exist not only on Android.

Description: When watchPosition is called, it first calls getCurrentLocation (resulting in
a native call to getLocation), then makes a native call to addWatch. In Android, addWatch
callback ids and getLocation callback ids are stored in separate data structures. The bug
I'm seeing is, when I call clearWatch before the watch operation's implicit getCurrentLocation
callback is invoked, the watch operation is removed/stopped in native, but the corresponding
getCurrentLocation operation is not.  This is not compliant with the W3C spec, which states
that that no further callbacks for the watch operation should be invoked. Worse, this causes
a bug on Android where GPS is never shut off! clearWatch stops the location listener *iff*
{{callbacks.size + watches.size == 0}}, and so if the callback hadn't been invoked yet...

_(Actually, skimming back through the code, I'm not seeing anywhere where the location listener
is stopped after a getCurrentPosition. Which may be another issue... not sure.)_

And the potential issue in Javascript is this: if native has no knowledge of which getCurrentLocation
callbacks are part of a watch operation and which are just normal independent ones, how can
it possibly remove the callback id for the implicit getCurrentLocation operation on clearWatch?
And how can it possibly know if it can really stop listening for location updates?

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