Simplify code a little

zanata-model/src/main/java/org/zanata/model/SimpleSourceContents.java

@@ -42,12 +42,12 @@ public class SimpleSourceContents implements SourceContents
 {
    private final String qualifiedId;
    private final Map<LocaleId, TargetContents> targets;
-   private final LocaleId locale;
+   private final @Nonnull LocaleId locale;
    private List<String> contents;
 
    public SimpleSourceContents(String qualifiedId,
          Map<LocaleId, TargetContents> targets,
-         LocaleId locale,
+         @Nonnull LocaleId locale,
          List<String> contents)
    {
       this.qualifiedId = qualifiedId;
@@ -57,7 +57,7 @@ public SimpleSourceContents(String qualifiedId,
    }
 
    public SimpleSourceContents(String qualifiedId,
-         LocaleId locale,
+         @Nonnull LocaleId locale,
          @Nonnull String content0,
          Map<LocaleId, TargetContents> targets)
    {
@@ -66,7 +66,7 @@ public SimpleSourceContents(String qualifiedId,
 
    public SimpleSourceContents(String qualifiedId,
          Map<LocaleId, TargetContents> targets,
-         LocaleId locale,
+         @Nonnull LocaleId locale,
          @Nonnull String... contents)
    {
       this(qualifiedId, targets, locale, ImmutableList.copyOf(contents));

zanata-model/src/main/java/org/zanata/model/SourceContents.java

@@ -21,6 +21,9 @@
 
 package org.zanata.model;
 
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+
 import org.zanata.common.HasContents;
 import org.zanata.common.LocaleId;
 
@@ -30,18 +33,18 @@
  */
 public interface SourceContents extends HasContents
 {
-   public LocaleId getLocale();
-   public String getQualifiedId();
+   public @Nonnull LocaleId getLocale();
+   public @Nonnull String getQualifiedId();
    /**
     * Gets the TargetContents for a single locale.
     * Note that default implementation in HTextFlow requires a lot of database I/O
     * @param localeId
     * @return
     */
-   public TargetContents getTargetContents(LocaleId localeId);
+   public @Nullable TargetContents getTargetContents(@Nonnull LocaleId localeId);
    /**
     * Gets the TargetContents for all available locales.
     * @return
     */
-   public Iterable<TargetContents> getAllTargetContents();
+   public @Nonnull Iterable<TargetContents> getAllTargetContents();
 }

zanata-war/src/main/java/org/zanata/rest/service/TMXStreamingOutput.java

@@ -38,9 +38,13 @@
 
 import org.zanata.common.LocaleId;
 import org.zanata.model.SourceContents;
+import org.zanata.util.NullCloseable;
 import org.zanata.util.OkapiUtil;
 import org.zanata.util.VersionUtility;
 
+import com.google.common.collect.Iterators;
+import com.google.common.collect.PeekingIterator;
+
 /**
  * Exports a collection of NamedDocument (ie a project iteration) to an
  * OutputStream in TMX format.
@@ -53,65 +57,53 @@ public class TMXStreamingOutput implements StreamingOutput
    private static final String creationToolVersion =
          VersionUtility.getVersionInfo(TMXStreamingOutput.class).getVersionNo();
    private final @Nonnull Iterator<? extends SourceContents> tuIter;
-   private final @Nullable LocaleId targetLocale;
    private final ExportTUStrategy exportTUStrategy;
 
    public TMXStreamingOutput(@Nonnull Iterator<? extends SourceContents> tuIter,
          @Nullable LocaleId targetLocale)
    {
       this.tuIter = tuIter;
-      this.targetLocale = targetLocale;
       this.exportTUStrategy = new ExportTUStrategy(targetLocale);
    }
 
-   @SuppressWarnings("null")
-   private @Nonnull net.sf.okapi.common.LocaleId toOkapiLocaleOrEmpty(@Nullable LocaleId locale)
-   {
-      if (locale == null)
-      {
-         // TMXWriter demands a non-null target locale, but if you write
-         // your TUs with writeTUFull(), it is never actually used.
-         return net.sf.okapi.common.LocaleId.EMPTY;
-      }
-      return OkapiUtil.toOkapiLocale(locale);
-   }
-
    @Override
    public void write(OutputStream output) throws IOException, WebApplicationException
    {
-      try
-      {
-         @Cleanup
-         Writer writer = new PrintWriter(output);
-         @Cleanup
-         XMLWriter xmlWriter = new XMLWriter(writer);
-         @Cleanup
-         ZanataTMXWriter tmxWriter = new ZanataTMXWriter(xmlWriter);
-         String segType = "block"; // TODO other segmentation types
-         String dataType = "unknown"; // TODO track data type metadata throughout the system
-
-         net.sf.okapi.common.LocaleId allLocale = new net.sf.okapi.common.LocaleId("*all*", false);
-
-         tmxWriter.writeStartDocument(
-               allLocale,
-               toOkapiLocaleOrEmpty(targetLocale),
-               creationTool, creationToolVersion,
-               segType, null, dataType);
-
-         while (tuIter.hasNext())
-         {
-            SourceContents tu = tuIter.next();
-            exportTUStrategy.exportTranslationUnit(tmxWriter, tu, toOkapiLocaleOrEmpty(tu.getLocale()));
-         }
-         tmxWriter.writeEndDocument();
-      }
-      finally
+      @Cleanup
+      Closeable closeable = (Closeable) (tuIter instanceof Closeable ? tuIter : NullCloseable.INSTANCE);
+      @SuppressWarnings("null")
+      PeekingIterator<SourceContents> iter = Iterators.peekingIterator(tuIter);
+      // Fetch the first result, so that we can fail fast, before
+      // writing any output. This should enable RESTEasy to return an
+      // error instead of simply aborting the output stream.
+      if (iter.hasNext()) iter.peek();
+
+      @Cleanup
+      Writer writer = new PrintWriter(output);
+      @Cleanup
+      XMLWriter xmlWriter = new XMLWriter(writer);
+      @Cleanup
+      ZanataTMXWriter tmxWriter = new ZanataTMXWriter(xmlWriter);
+      String segType = "block"; // TODO other segmentation types
+      String dataType = "unknown"; // TODO track data type metadata throughout the system
+
+      net.sf.okapi.common.LocaleId allLocale = new net.sf.okapi.common.LocaleId("*all*", false);
+
+      tmxWriter.writeStartDocument(
+            allLocale,
+            // TMXWriter demands a non-null target locale, but if you write
+            // your TUs with writeTUFull(), it is never used.
+            net.sf.okapi.common.LocaleId.EMPTY,
+            creationTool, creationToolVersion,
+            segType, null, dataType);
+
+      while (iter.hasNext())
       {
-         if (tuIter instanceof Closeable)
-         {
-            ((Closeable) tuIter).close();
-         }
+         SourceContents tu = iter.next();
+         net.sf.okapi.common.LocaleId sourceLocale = OkapiUtil.toOkapiLocale(tu.getLocale());
+         exportTUStrategy.exportTranslationUnit(tmxWriter, tu, sourceLocale);
       }
+      tmxWriter.writeEndDocument();
    }
 
 }

zanata-war/src/main/java/org/zanata/util/NullCloseable.java

@@ -0,0 +1,13 @@
+package org.zanata.util;
+
+import java.io.Closeable;
+import java.io.IOException;
+
+public class NullCloseable implements Closeable
+{
+   public static NullCloseable INSTANCE = new NullCloseable();
+   @Override
+   public void close() throws IOException
+   {
+   }
+}