[FOP-1594] Synchronization fault in FontCache

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 0.95
• Component/s: font/unqualified
• Environment: Operating System: Linux; Platform: PC
• External issue ID: 46211
• Assignee: fop-dev
• Reporter: ilj
• Created: 14/Nov/08 05:12
• Updated: 14/Nov/08 12:06
• Resolved: 01/Apr/12 06:43

Description

I have an application which renders a lot of PDFs using several threads. We had an issue recently, concerning font loading. While investigating this stack trace:

java.lang.NullPointerException
at org.apache.fop.fonts.FontCache.isFailedFont(FontCache.java:294)
at org.apache.fop.fonts.autodetect.FontInfoFinder.find(FontInfoFinder.java:179)
at org.apache.fop.render.PrintRendererConfigurator.addFontInfoListFromFileList(PrintRendererConfigurator.java:233)
at org.apache.fop.render.PrintRendererConfigurator.buildFontListFromConfiguration(PrintRendererConfigurator.java:140)
at org.apache.fop.render.PrintRendererConfigurator.configure(PrintRendererConfigurator.java:95)
at org.apache.fop.render.pdf.PDFRendererConfigurator.configure(PDFRendererConfigurator.java:71)
at org.apache.fop.render.RendererFactory.createRenderer(RendererFactory.java:187)
at org.apache.fop.area.RenderPagesModel.<init>(RenderPagesModel.java:68)
at org.apache.fop.area.AreaTreeHandler.setupModel(AreaTreeHandler.java:127)
at org.apache.fop.area.AreaTreeHandler.<init>(AreaTreeHandler.java:102)
at org.apache.fop.render.RendererFactory.createFOEventHandler(RendererFactory.java:224)
at org.apache.fop.fo.FOTreeBuilder.<init>(FOTreeBuilder.java:100)
at org.apache.fop.apps.Fop.createDefaultHandler(Fop.java:100)
at org.apache.fop.apps.Fop.<init>(Fop.java:78)
at org.apache.fop.apps.FopFactory.newFop(FopFactory.java:247)

I have found a possible synchronization fault in FontCache method:

== Java code ==
public boolean isFailedFont(String embedUrl, long lastModified) {
if (failedFontMap.containsKey(embedUrl)) {
synchronized (changeLock) {
long failedLastModified = ((Long)failedFontMap.get(embedUrl)).longValue();
if (lastModified != failedLastModified)

{ // this font has been changed so lets remove it // from failed font map for now failedFontMap.remove(embedUrl); changed = true; }
}
return true;
}
return false;
}
== end Java code ==

to my opinion, it shall be like this:

== Java code ==
public boolean isFailedFont(String embedUrl, long lastModified) {
synchronized (changeLock) {
if (failedFontMap.containsKey(embedUrl)) {

long failedLastModified = ((Long)failedFontMap.get(embedUrl)).longValue();
if (lastModified != failedLastModified) { // this font has been changed so lets remove it // from failed font map for now failedFontMap.remove(embedUrl); changed = true; }

return true;
}
return false;
}
}
== end Java code ==