Support in-place feature JS updates

Updates FeatureResourceLoader to optionally support reloading JS referenced by a feature on disk when the resource has changed.

The polling rate for changes is configurable, in millis. A polling approach is used for simplicity (no need for event mechanism) and to avoid slamming disk.

[Paul Lindner, 2010-06-21 20:53:18]

Seems okay -- does not account for new files or changes to the dependency
graph..  Might be interesting if we support jndi resources in the future..

http://codereview.appspot.com/1732044/diff/1/2
File
java/gadgets/src/main/java/org/apache/shindig/gadgets/features/FeatureResourceLoader.java
(right):

http://codereview.appspot.com/1732044/diff/1/2#newcode174
java/gadgets/src/main/java/org/apache/shindig/gadgets/features/FeatureResourceLoader.java:174:
// Only check for file updates at preconfigured intervals. This prevents
truncated comment?

http://codereview.appspot.com/1732044/diff/1/2#newcode175
java/gadgets/src/main/java/org/apache/shindig/gadgets/features/FeatureResourceLoader.java:175:
lastUpdateCheckTime = timeSource.currentTimeMillis();
DRY - calculate this once before the if statement?

[johnfargo, 2010-06-21 21:57:03]

On Mon, Jun 21, 2010 at 1:53 PM, <lindner@inuus.com> wrote:

> Seems okay -- does not account for new files or changes to the
> dependency graph..  Might be interesting if we support jndi resources in
> the future..
>

This change is irrelevant to the dependency graph, or to new files -- a
follow-up will account for those, loading the actual *.xml files (more of a
Registry thing). Much hairier issue IMO, and doesn't account for the
majority of use cases I've seen (in which a small bug etc is found or a new
augmentation is desired).

Re: JNDI et al, agreed. This change really only is for File resources. We'll
have to generalize this if we want general-purpose updatable stuff, yes?


>
>
> http://codereview.appspot.com/1732044/diff/1/2
> File
>
>
>
java/gadgets/src/main/java/org/apache/shindig/gadgets/features/FeatureResourceLoader.java
> (right):
>
> http://codereview.appspot.com/1732044/diff/1/2#newcode174
>
>
java/gadgets/src/main/java/org/apache/shindig/gadgets/features/FeatureResourceLoader.java:174:
> // Only check for file updates at preconfigured intervals. This prevents
> truncated comment?
>

Oops, fixed.


>
> http://codereview.appspot.com/1732044/diff/1/2#newcode175
>
>
java/gadgets/src/main/java/org/apache/shindig/gadgets/features/FeatureResourceLoader.java:175:
> lastUpdateCheckTime = timeSource.currentTimeMillis();
> DRY - calculate this once before the if statement?


Fixed.

Patch in a second.


>
>
> http://codereview.appspot.com/1732044/show
>

[johnfargo, 2010-06-21 21:57:45]

Patch Set #2: Accounting for Paul's comments.

[Paul Lindner, 2010-06-21 23:04:41]

lgtm