diff --git a/Documentation/config-gerrit.txt b/Documentation/config-gerrit.txt
index 098bfff..2fbe58c 100644
--- a/Documentation/config-gerrit.txt
+++ b/Documentation/config-gerrit.txt
@@ -397,6 +397,35 @@
 [[cache_options]]Cache Options
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+cache.diff_intraline.maxIdleWorkers::
++
+Number of idle worker threads to maintain for the intraline difference
+computations.  There is no upper bound on how many concurrent requests
+can occur at once, if additional threads are started to handle a peak
+load, only this many will remaining idle afterwards.
++
+Default is 1.5x number of available CPUs.
+
+cache.diff_intraline.timeout::
++
+Maximum number of milliseconds to wait for intraline difference data
+before giving up and disabling it for a particular file pair.  This is
+a work around for an infinite loop bug in the intraline difference
+implementation.  If computation takes longer than the timeout the
+worker thread is terminated and no intraline difference is displayed.
++
+Values should use common unit suffixes to express their setting:
++
+* ms, milliseconds
+* s, sec, second, seconds
+* m, min, minute, minutes
+* h, hr, hour, hours
+
++
+If a unit suffix is not specified, `milliseconds` is assumed.
++
+Default is 5 seconds.
+
 cache.diff_intraline.enabled::
 +
 Boolean to enable or disable the computation of intraline differences
diff --git a/gerrit-common/src/main/java/com/google/gerrit/common/data/PatchScript.java b/gerrit-common/src/main/java/com/google/gerrit/common/data/PatchScript.java
index e24405f..24cdee4 100644
--- a/gerrit-common/src/main/java/com/google/gerrit/common/data/PatchScript.java
+++ b/gerrit-common/src/main/java/com/google/gerrit/common/data/PatchScript.java
@@ -55,6 +55,7 @@
   protected List<Patch> history;
   protected boolean hugeFile;
   protected boolean intralineDifference;
+  protected boolean intralineFailure;
 
   public PatchScript(final Change.Key ck, final ChangeType ct, final String on,
       final String nn, final FileMode om, final FileMode nm,
@@ -62,7 +63,7 @@
       final SparseFileContent ca, final SparseFileContent cb,
       final List<Edit> e, final DisplayMethod ma, final DisplayMethod mb,
       final CommentDetail cd, final List<Patch> hist, final boolean hf,
-      final boolean id) {
+      final boolean id, final boolean idf) {
     changeId = ck;
     changeType = ct;
     oldName = on;
@@ -80,6 +81,7 @@
     history = hist;
     hugeFile = hf;
     intralineDifference = id;
+    intralineFailure = idf;
   }
 
   protected PatchScript() {
@@ -149,6 +151,10 @@
     return intralineDifference;
   }
 
+  public boolean hasIntralineFailure() {
+    return intralineFailure;
+  }
+
   public SparseFileContent getA() {
     return a;
   }
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchConstants.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchConstants.java
index 93e8deb..dbbc9c3 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchConstants.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchConstants.java
@@ -31,6 +31,7 @@
 
   String patchHistoryTitle();
   String disabledOnLargeFiles();
+  String intralineFailure();
 
   String upToChange();
   String linePrev();
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchConstants.properties b/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchConstants.properties
index 90def1d..590007d 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchConstants.properties
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchConstants.properties
@@ -13,6 +13,7 @@
 patchHeaderNew = New Version
 patchHistoryTitle = Patch History
 disabledOnLargeFiles = Disabled on very large source files.
+intralineFailure = Intraline difference not available due to server error.
 
 upToChange = Up to change
 linePrev = Previous line
diff --git a/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchScreen.java b/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchScreen.java
index 812a74e..cbe037b 100644
--- a/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchScreen.java
+++ b/gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchScreen.java
@@ -15,6 +15,7 @@
 package com.google.gerrit.client.patches;
 
 import com.google.gerrit.client.Dispatcher;
+import com.google.gerrit.client.ErrorDialog;
 import com.google.gerrit.client.Gerrit;
 import com.google.gerrit.client.RpcStatus;
 import com.google.gerrit.client.changes.CommitMessageBlock;
@@ -140,6 +141,7 @@
   /** Keys that cause an action on this screen */
   private KeyCommandSet keysNavigation;
   private HandlerRegistration regNavigation;
+  private boolean intralineFailure;
 
   /**
    * How this patch should be displayed in the patch screen.
@@ -461,6 +463,17 @@
       settingsPanel.getReviewedCheckBox().setValue(true);
       setReviewedByCurrentUser(true /* reviewed */);
     }
+
+    intralineFailure = isFirst && script.hasIntralineFailure();
+  }
+
+  @Override
+  public void onShowView() {
+    super.onShowView();
+    if (intralineFailure) {
+      intralineFailure = false;
+      new ErrorDialog(PatchUtil.C.intralineFailure()).show();
+    }
   }
 
   private void showPatch(final boolean showPatch) {
diff --git a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/patch/PatchScriptBuilder.java b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/patch/PatchScriptBuilder.java
index 2604d92..b7b3dd2 100644
--- a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/patch/PatchScriptBuilder.java
+++ b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/patch/PatchScriptBuilder.java
@@ -20,12 +20,14 @@
 import com.google.gerrit.prettify.common.EditList;
 import com.google.gerrit.prettify.common.SparseFileContent;
 import com.google.gerrit.reviewdb.AccountDiffPreference;
+import com.google.gerrit.reviewdb.AccountDiffPreference.Whitespace;
 import com.google.gerrit.reviewdb.Change;
 import com.google.gerrit.reviewdb.Patch;
 import com.google.gerrit.reviewdb.PatchLineComment;
-import com.google.gerrit.reviewdb.AccountDiffPreference.Whitespace;
+import com.google.gerrit.reviewdb.Project;
 import com.google.gerrit.server.FileTypeRegistry;
 import com.google.gerrit.server.patch.IntraLineDiff;
+import com.google.gerrit.server.patch.IntraLineDiffKey;
 import com.google.gerrit.server.patch.PatchListCache;
 import com.google.gerrit.server.patch.PatchListEntry;
 import com.google.gerrit.server.patch.Text;
@@ -65,6 +67,7 @@
   };
 
   private Repository db;
+  private Project.NameKey projectKey;
   private ObjectReader reader;
   private Change change;
   private AccountDiffPreference diffPrefs;
@@ -88,8 +91,9 @@
     patchListCache = plc;
   }
 
-  void setRepository(final Repository r) {
-    db = r;
+  void setRepository(Repository r, Project.NameKey projectKey) {
+    this.db = r;
+    this.projectKey = projectKey;
   }
 
   void setChange(final Change c) {
@@ -128,6 +132,7 @@
       final CommentDetail comments, final List<Patch> history)
       throws IOException {
     boolean intralineDifference = diffPrefs.isIntralineDifference();
+    boolean intralineFailure = false;
 
     a.path = oldName(content);
     b.path = newName(content);
@@ -137,17 +142,29 @@
 
     edits = new ArrayList<Edit>(content.getEdits());
 
-    if (intralineDifference) {
-      if (isModify(content)) {
-        IntraLineDiff d =
-            patchListCache.getIntraLineDiff(a.id, a.src, b.id, b.src, edits);
-        if (d != null) {
-          edits = new ArrayList<Edit>(d.getEdits());
-        } else {
-          intralineDifference = false;
+    if (intralineDifference && isModify(content)) {
+      IntraLineDiff d =
+          patchListCache.getIntraLineDiff(new IntraLineDiffKey(a.id, a.src,
+              b.id, b.src, edits, projectKey, bId, b.path));
+      if (d != null) {
+        switch (d.getStatus()) {
+          case EDIT_LIST:
+            edits = new ArrayList<Edit>(d.getEdits());
+            break;
+
+          case DISABLED:
+            intralineDifference = false;
+            break;
+
+          case ERROR:
+          case TIMEOUT:
+            intralineDifference = false;
+            intralineFailure = true;
+            break;
         }
       } else {
         intralineDifference = false;
+        intralineFailure = true;
       }
     }
 
@@ -188,10 +205,11 @@
       packContent(diffPrefs.getIgnoreWhitespace() != Whitespace.IGNORE_NONE);
     }
 
-    return new PatchScript(change.getKey(), content.getChangeType(), content
-        .getOldName(), content.getNewName(), a.fileMode, b.fileMode, content
-        .getHeaderLines(), diffPrefs, a.dst, b.dst, edits, a.displayMethod,
-        b.displayMethod, comments, history, hugeFile, intralineDifference);
+    return new PatchScript(change.getKey(), content.getChangeType(),
+        content.getOldName(), content.getNewName(), a.fileMode, b.fileMode,
+        content.getHeaderLines(), diffPrefs, a.dst, b.dst, edits,
+        a.displayMethod, b.displayMethod, comments, history, hugeFile,
+        intralineDifference, intralineFailure);
   }
 
   private static boolean isModify(PatchListEntry content) {
diff --git a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/patch/PatchScriptFactory.java b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/patch/PatchScriptFactory.java
index 377cf49..fcaa0c5 100644
--- a/gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/patch/PatchScriptFactory.java
+++ b/gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/patch/PatchScriptFactory.java
@@ -173,7 +173,7 @@
   private PatchScriptBuilder newBuilder(final PatchList list, Repository git) {
     final AccountDiffPreference dp = new AccountDiffPreference(diffPrefs);
     final PatchScriptBuilder b = builderFactory.get();
-    b.setRepository(git);
+    b.setRepository(git, projectKey);
     b.setChange(change);
     b.setDiffPrefs(dp);
     b.setTrees(list.isAgainstParent(), list.getOldId(), list.getNewId());
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineDiff.java b/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineDiff.java
index d694724..3805f8f 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineDiff.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineDiff.java
@@ -14,9 +14,13 @@
 
 package com.google.gerrit.server.patch;
 
+import static com.google.gerrit.server.ioutil.BasicSerialization.readEnum;
 import static com.google.gerrit.server.ioutil.BasicSerialization.readVarInt32;
+import static com.google.gerrit.server.ioutil.BasicSerialization.writeEnum;
 import static com.google.gerrit.server.ioutil.BasicSerialization.writeVarInt32;
 
+import com.google.gerrit.reviewdb.CodedEnum;
+
 import org.eclipse.jgit.diff.Edit;
 import org.eclipse.jgit.diff.ReplaceEdit;
 
@@ -33,17 +37,44 @@
 public class IntraLineDiff implements Serializable {
   static final long serialVersionUID = IntraLineDiffKey.serialVersionUID;
 
+  public static enum Status implements CodedEnum {
+    EDIT_LIST('e'), DISABLED('D'), TIMEOUT('T'), ERROR('E');
+
+    private final char code;
+
+    Status(char code) {
+      this.code = code;
+    }
+
+    @Override
+    public char getCode() {
+      return code;
+    }
+  }
+
+  private transient Status status;
   private transient List<Edit> edits;
 
+  IntraLineDiff(Status status) {
+    this.status = status;
+    this.edits = Collections.emptyList();
+  }
+
   IntraLineDiff(List<Edit> edits) {
+    this.status = Status.EDIT_LIST;
     this.edits = Collections.unmodifiableList(edits);
   }
 
+  public Status getStatus() {
+    return status;
+  }
+
   public List<Edit> getEdits() {
     return edits;
   }
 
   private void writeObject(final ObjectOutputStream out) throws IOException {
+    writeEnum(out, status);
     writeVarInt32(out, edits.size());
     for (Edit e : edits) {
       writeEdit(out, e);
@@ -61,6 +92,7 @@
   }
 
   private void readObject(final ObjectInputStream in) throws IOException {
+    status = readEnum(in, Status.values());
     int editCount = readVarInt32(in);
     Edit[] editArray = new Edit[editCount];
     for (int i = 0; i < editCount; i++) {
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineDiffKey.java b/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineDiffKey.java
index 61004dd..a8d62fc 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineDiffKey.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineDiffKey.java
@@ -17,6 +17,8 @@
 import static org.eclipse.jgit.lib.ObjectIdSerialization.readNotNull;
 import static org.eclipse.jgit.lib.ObjectIdSerialization.writeNotNull;
 
+import com.google.gerrit.reviewdb.Project;
+
 import org.eclipse.jgit.diff.Edit;
 import org.eclipse.jgit.lib.ObjectId;
 
@@ -27,7 +29,7 @@
 import java.util.List;
 
 public class IntraLineDiffKey implements Serializable {
-  static final long serialVersionUID = 2L;
+  static final long serialVersionUID = 3L;
 
   private transient ObjectId aId;
   private transient ObjectId bId;
@@ -38,14 +40,22 @@
   private transient Text bText;
   private transient List<Edit> edits;
 
-  IntraLineDiffKey(ObjectId aId, Text aText, ObjectId bId, Text bText,
-      List<Edit> edits) {
+  private transient Project.NameKey projectKey;
+  private transient ObjectId commit;
+  private transient String path;
+
+  public IntraLineDiffKey(ObjectId aId, Text aText, ObjectId bId, Text bText,
+      List<Edit> edits, Project.NameKey projectKey, ObjectId commit, String path) {
     this.aId = aId;
     this.bId = bId;
 
     this.aText = aText;
     this.bText = bText;
     this.edits = edits;
+
+    this.projectKey = projectKey;
+    this.commit = commit;
+    this.path = path;
   }
 
   Text getTextA() {
@@ -60,6 +70,26 @@
     return edits;
   }
 
+  ObjectId getBlobA() {
+    return aId;
+  }
+
+  ObjectId getBlobB() {
+    return bId;
+  }
+
+  Project.NameKey getProject() {
+    return projectKey;
+  }
+
+  ObjectId getCommit() {
+    return commit;
+  }
+
+  String getPath() {
+    return path;
+  }
+
   @Override
   public int hashCode() {
     int h = 0;
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineLoader.java b/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineLoader.java
index 0d3afde..0ac1af2 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineLoader.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/patch/IntraLineLoader.java
@@ -16,24 +16,200 @@
 package com.google.gerrit.server.patch;
 
 import com.google.gerrit.server.cache.EntryCreator;
+import com.google.gerrit.server.config.ConfigUtil;
+import com.google.gerrit.server.config.GerritServerConfig;
+import com.google.inject.Inject;
 
 import org.eclipse.jgit.diff.Edit;
 import org.eclipse.jgit.diff.MyersDiff;
 import org.eclipse.jgit.diff.ReplaceEdit;
+import org.eclipse.jgit.lib.Config;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.regex.Pattern;
 
 class IntraLineLoader extends EntryCreator<IntraLineDiffKey, IntraLineDiff> {
+  private static final Logger log = LoggerFactory
+      .getLogger(IntraLineLoader.class);
+
   private static final Pattern BLANK_LINE_RE = Pattern
       .compile("^[ \\t]*(|[{}]|/\\*\\*?|\\*)[ \\t]*$");
 
   private static final Pattern CONTROL_BLOCK_START_RE = Pattern
       .compile("[{:][ \\t]*$");
 
+  private final BlockingQueue<Worker> workerPool;
+  private final long timeoutMillis;
+
+  @Inject
+  IntraLineLoader(final @GerritServerConfig Config cfg) {
+    final int workers =
+        cfg.getInt("cache", PatchListCacheImpl.INTRA_NAME, "maxIdleWorkers",
+            Runtime.getRuntime().availableProcessors() * 3 / 2);
+    workerPool = new ArrayBlockingQueue<Worker>(workers, true /* fair */);
+
+    timeoutMillis =
+        ConfigUtil.getTimeUnit(cfg, "cache", PatchListCacheImpl.INTRA_NAME,
+            "timeout", TimeUnit.MILLISECONDS.convert(5, TimeUnit.SECONDS),
+            TimeUnit.MILLISECONDS);
+  }
+
   @Override
   public IntraLineDiff createEntry(IntraLineDiffKey key) throws Exception {
+    Worker w = workerPool.poll();
+    if (w == null) {
+      w = new Worker();
+    }
+
+    Worker.Result r = w.computeWithTimeout(key, timeoutMillis);
+
+    if (r == Worker.Result.TIMEOUT) {
+      // Don't keep this thread. We have to murder it unsafely, which
+      // means its unable to be reused in the future. Return back a
+      // null result, indicating the cache cannot load this key.
+      //
+      return new IntraLineDiff(IntraLineDiff.Status.TIMEOUT);
+    }
+
+    if (!workerPool.offer(w)) {
+      // If the idle worker pool is full, terminate this thread.
+      //
+      w.end();
+    }
+
+    if (r.error != null) {
+      // If there was an error computing the result, carry it
+      // up to the caller so the cache knows this key is invalid.
+      //
+      throw r.error;
+    }
+
+    return r.diff;
+  }
+
+  private static class Worker {
+    private static final AtomicInteger count = new AtomicInteger(1);
+
+    private final ArrayBlockingQueue<Input> input;
+    private final ArrayBlockingQueue<Result> result;
+    private final Thread thread;
+
+    Worker() {
+      input = new ArrayBlockingQueue<Input>(1);
+      result = new ArrayBlockingQueue<Result>(1);
+
+      thread = new Thread(new Runnable() {
+        public void run() {
+          workerLoop();
+        }
+      });
+      thread.setName("IntraLineDiff-" + count.getAndIncrement());
+      thread.setDaemon(true);
+      thread.start();
+    }
+
+    Result computeWithTimeout(IntraLineDiffKey key, long timeoutMillis)
+        throws Exception {
+      if (!input.offer(new Input(key))) {
+        log.error("Cannot enqueue task to thread " + thread.getName());
+        return null;
+      }
+
+      Result r = result.poll(timeoutMillis, TimeUnit.MILLISECONDS);
+      if (r != null) {
+        return r;
+      } else {
+        log.warn(timeoutMillis + " ms timeout reached for IntraLineDiff"
+            + " in project " + key.getProject().get() //
+            + " on commit " + key.getCommit().name() //
+            + " for path " + key.getPath() //
+            + " comparing " + key.getBlobA().name() //
+            + ".." + key.getBlobB().name() //
+            + ".  Killing " + thread.getName());
+        try {
+          thread.stop();
+        } catch (Throwable error) {
+          // Ignore any reason the thread won't stop.
+          log.error("Cannot stop runaway thread " + thread.getName(), error);
+        }
+        return Result.TIMEOUT;
+      }
+    }
+
+    void end() {
+      if (!input.offer(Input.END_THREAD)) {
+        log.error("Cannot gracefully stop thread " + thread.getName());
+      }
+    }
+
+    private void workerLoop() {
+      try {
+        for (;;) {
+          Input in;
+          try {
+            in = input.take();
+          } catch (InterruptedException e) {
+            log.error("Unexpected interrupt on " + thread.getName());
+            continue;
+          }
+
+          if (in == Input.END_THREAD) {
+            return;
+          }
+
+          Result r;
+          try {
+            r = new Result(IntraLineLoader.compute(in.key));
+          } catch (Exception error) {
+            r = new Result(error);
+          }
+
+          if (!result.offer(r)) {
+            log.error("Cannot return result from " + thread.getName());
+          }
+        }
+      } catch (ThreadDeath iHaveBeenShot) {
+        // Handle thread death by gracefully returning to the caller,
+        // allowing the thread to be destroyed.
+      }
+    }
+
+    private static class Input {
+      static final Input END_THREAD = new Input(null);
+
+      final IntraLineDiffKey key;
+
+      Input(IntraLineDiffKey key) {
+        this.key = key;
+      }
+    }
+
+    static class Result {
+      static final Result TIMEOUT = new Result((IntraLineDiff) null);
+
+      final IntraLineDiff diff;
+      final Exception error;
+
+      Result(IntraLineDiff diff) {
+        this.diff = diff;
+        this.error = null;
+      }
+
+      Result(Exception error) {
+        this.diff = null;
+        this.error = error;
+      }
+    }
+  }
+
+  private static IntraLineDiff compute(IntraLineDiffKey key) throws Exception {
     List<Edit> edits = new ArrayList<Edit>(key.getEdits());
     Text aContent = key.getTextA();
     Text bContent = key.getTextB();
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListCache.java b/gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListCache.java
index c7bb08b..a7cf10a 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListCache.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListCache.java
@@ -17,17 +17,11 @@
 import com.google.gerrit.reviewdb.Change;
 import com.google.gerrit.reviewdb.PatchSet;
 
-import org.eclipse.jgit.diff.Edit;
-import org.eclipse.jgit.lib.ObjectId;
-
-import java.util.List;
-
 /** Provides a cached list of {@link PatchListEntry}. */
 public interface PatchListCache {
   public PatchList get(PatchListKey key);
 
   public PatchList get(Change change, PatchSet patchSet);
 
-  public IntraLineDiff getIntraLineDiff(ObjectId aId, Text aText, ObjectId bId,
-      Text bText, List<Edit> edits);
+  public IntraLineDiff getIntraLineDiff(IntraLineDiffKey key);
 }
diff --git a/gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListCacheImpl.java b/gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListCacheImpl.java
index 285420c..e1a0a40 100644
--- a/gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListCacheImpl.java
+++ b/gerrit-server/src/main/java/com/google/gerrit/server/patch/PatchListCacheImpl.java
@@ -30,17 +30,14 @@
 import com.google.inject.TypeLiteral;
 import com.google.inject.name.Named;
 
-import org.eclipse.jgit.diff.Edit;
 import org.eclipse.jgit.lib.Config;
 import org.eclipse.jgit.lib.ObjectId;
 
-import java.util.List;
-
 /** Provides a cached list of {@link PatchListEntry}. */
 @Singleton
 public class PatchListCacheImpl implements PatchListCache {
   private static final String FILE_NAME = "diff";
-  private static final String INTRA_NAME = "diff_intraline";
+  static final String INTRA_NAME = "diff_intraline";
 
   public static Module module() {
     return new CacheModule() {
@@ -98,14 +95,15 @@
   }
 
   @Override
-  public IntraLineDiff getIntraLineDiff(ObjectId aId, Text aText, ObjectId bId,
-      Text bText, List<Edit> edits) {
+  public IntraLineDiff getIntraLineDiff(IntraLineDiffKey key) {
     if (computeIntraline) {
-      IntraLineDiffKey key =
-          new IntraLineDiffKey(aId, aText, bId, bText, edits);
-      return intraCache.get(key);
+      IntraLineDiff d = intraCache.get(key);
+      if (d == null) {
+        d = new IntraLineDiff(IntraLineDiff.Status.ERROR);
+      }
+      return d;
     } else {
-      return null;
+      return new IntraLineDiff(IntraLineDiff.Status.DISABLED);
     }
   }
 }