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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/17228/
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(Updated Jan. 28, 2014, 2:10 a.m.)
Review request for shindig, Dan Dumont, Ryan Baxter, Rich Thompson, Stanton
Sievers, and Zhi Hong Yang.
Changes
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Add Shindig to the groups for the review
Bugs: SHINDIG-1893
https://issues.apache.org/jira/browse/SHINDIG-1893
Repository: shindig
Description
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During our gadget development, several gadgets are referring to the same gadget
template. The rendering of those gadgets is problematic sometimes.
When the problem occur, the Java stack trace look like this:
Stack Dump = java.lang.NullPointerException
at org.apache.xerces.dom.ParentNode.nodeListItem(Unknown Source)
at org.apache.xerces.dom.ParentNode.item(Unknown Source)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processChildNodes(DefaultTemplateProcessor.java:134)
at
org.apache.shindig.gadgets.templates.tags.TemplateBasedTagHandler.processTemplate(TemplateBasedTagHandler.java:68)
at
org.apache.shindig.gadgets.templates.tags.TemplateBasedTagHandler.process(TemplateBasedTagHandler.java:58)
at
org.apache.shindig.gadgets.templates.XmlTemplateLibrary$LibraryTagHandler.process(XmlTemplateLibrary.java:305)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processElementInner(DefaultTemplateProcessor.java:341)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processElement(DefaultTemplateProcessor.java:246)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processNode(DefaultTemplateProcessor.java:154)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processChildNodes(DefaultTemplateProcessor.java:134)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processTemplate(DefaultTemplateProcessor.java:126)
at
org.apache.shindig.gadgets.rewrite.TemplateRewriter.executeTemplates(TemplateRewriter.java:357)
at
org.apache.shindig.gadgets.rewrite.TemplateRewriter.rewriteImpl(TemplateRewriter.java:177)
at
org.apache.shindig.gadgets.rewrite.TemplateRewriter.rewrite(TemplateRewriter.java:129)
at
org.apache.shindig.gadgets.render.HtmlRenderer.render(HtmlRenderer.java:88)
at org.apache.shindig.gadgets.render.Renderer.render(Renderer.java:101)
at
org.apache.shindig.gadgets.servlet.GadgetRenderingServlet.render(GadgetRenderingServlet.java:112)
at
org.apache.shindig.gadgets.servlet.GadgetRenderingServlet.doGet(GadgetRenderingServlet.java:90)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:575)
Stack Dump2 = java.lang.NullPointerException
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processText(DefaultTemplateProcessor.java:174)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processNode(DefaultTemplateProcessor.java:151)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processChildNodes(DefaultTemplateProcessor.java:134)
at
org.apache.shindig.gadgets.templates.tags.TemplateBasedTagHandler.processTemplate(TemplateBasedTagHandler.java:68)
at
org.apache.shindig.gadgets.templates.tags.TemplateBasedTagHandler.process(TemplateBasedTagHandler.java:58)
at
org.apache.shindig.gadgets.templates.XmlTemplateLibrary$LibraryTagHandler.process(XmlTemplateLibrary.java:305)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processElementInner(DefaultTemplateProcess"
severity="50" version="1.0.1">
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processElement(DefaultTemplateProcessor.java:247)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processNode(DefaultTemplateProcessor.java:154)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processChildNodes(DefaultTemplateProcessor.java:134)
at
org.apache.shindig.gadgets.templates.DefaultTemplateProcessor.processTemplate(DefaultTemplateProcessor.java:126)
at
org.apache.shindig.gadgets.rewrite.TemplateRewriter.executeTemplates(TemplateRewriter.java:358)
at
org.apache.shindig.gadgets.rewrite.TemplateRewriter.rewriteImpl(TemplateRewriter.java:178)
at
org.apache.shindig.gadgets.rewrite.TemplateRewriter.rewrite(TemplateRewriter.java:130)
at
org.apache.shindig.gadgets.render.HtmlRenderer.render(HtmlRenderer.java:88)
at org.apache.shindig.gadgets.render.Renderer.render(Renderer.java:101)
at
org.apache.shindig.gadgets.servlet.GadgetRenderingServlet.render(GadgetRenderingServlet.java:107)
at
org.apache.shindig.gadgets.servlet.GadgetRenderingServlet.doGet(GadgetRenderingServlet.java:85)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:693)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:806)
The Xerces implementation is not thread safe and when we are caching the
template we can potentially have multiple threads manipulating the same Element
object. This results in random null pointer exceptions as well as other odd
exceptions in the code. The solution is to add synchronized to the key XML
element.
Diffs
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/trunk/java/gadgets/src/main/java/org/apache/shindig/gadgets/templates/DefaultTemplateProcessor.java
1560262
/trunk/java/gadgets/src/main/java/org/apache/shindig/gadgets/templates/TemplateLibraryFactory.java
1560262
/trunk/java/gadgets/src/main/java/org/apache/shindig/gadgets/templates/XmlTemplateLibrary.java
1560262
/trunk/java/gadgets/src/main/java/org/apache/shindig/gadgets/templates/tags/FlashTagHandler.java
1560262
/trunk/java/gadgets/src/main/java/org/apache/shindig/gadgets/templates/tags/TemplateBasedTagHandler.java
1560262
Diff: https://reviews.apache.org/r/17228/diff/
Testing
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Thanks,
ChunYan Zhang
