Prevent infinite recursion on unbindAndTeardown when Observe's _bindings is undefined and Observe is self-referential

[bmomberger-reciprocity]

Previously in util/bind/bind.js

                this._bindings--;
                // If there are no longer any bindings and
                // there is a bindteardown method, call it.
                if(!this._bindings){

If _bindings was undefined, this sets it to NaN and then does the teardown. If in the teardown this object is touched again, having NaN for bindings will decrement to NaN again, still be falsy, and run the teardown again (eventually leading to a stack fault).

The code in this pull request sets _bindings to 0 if it is undefined. Any subsequent visit to unbindAndTeardown will then decrement it to -1 or less, which is okay because we've already started the teardown process.

[justinbmeyer]

Thanks brad!

Justin Meyer
847-924-6039

On Fri, Aug 16, 2013 at 3:03 PM, Brad (Bradley) Momberger <
notifications@github.com> wrote:

Previously in util/bind/bind.js

            this._bindings--;
            // If there are no longer any bindings and
            // there is a bindteardown method, call it.
            if(!this._bindings){

If _bindings was undefined, this sets it to NaN and then does the
teardown. If in the teardown this object is touched again, having NaN for
bindings will decrement to NaN again, still be falsy, and run the teardown
again (eventually leading to a stack fault).

The code in this pull request sets _bindings to 0 if it is undefined. Any
subsequent visit to unbindAndTeardown will then decrement it to -1 or less,

which is okay because we've already started the teardown process.

You can merge this Pull Request by running

git pull https://github.com/bmomberger-reciprocity/canjs self-limiting-unbind

Or view, comment on, or merge it at:

#461
Commit Summary

• Preventing infinite recursion on unbindAndTeardown by ensuring that
  _bindings is always a number when incremented/decremented

File Changes

• M util/bind/bind.jshttps://github.com/Prevent infinite recursion on unbindAndTeardown when Observe's _bindings is undefined and Observe is self-referential #461/files#diff-0(8)

Patch Links:

• https://github.com/bitovi/canjs/pull/461.patch
• https://github.com/bitovi/canjs/pull/461.diff

[daffl]

Looks good to me. What was the case when this is happening? Should we add a test for it?

[airhadoken]

It was happening in /reciprocity/ggrc-core until we applied the fix, but I am having trouble distilling the problem down into a simple fiddle. I think it might be in part due to us overriding can.Model.model.

[daffl]

Ok. Merging this in since it doesn't seem to break any of the existing tests.

[justinbmeyer]

I bet calling unbind without calling bind might do it.

Sent from my iPhone

On Sep 19, 2013, at 4:24 PM, David Luecke notifications@github.com wrote:

Ok. Merging this in since it doesn't seem to break any of the existing tests.

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