Don't RPC to load the full file if we already have it

If the user is toggling the "Show full file" flag and we already
were given the full file contents just so we can do proper syntax
highlighting, don't RPC to load the same script again.  Instead just
reformat the UI and update it.

Because this can take a bit of local CPU time, we don't do it on
the event handler but instead display the "Loading" box and run it
after the current event finishes.  This way the checkbox can update
and the user can see that we are working.

Change-Id: I70d16803c61f91f7060b7f8c91b766f3437b8d1f
Signed-off-by: Shawn O. Pearce <sop@google.com>

gerrit-common/src/main/java/com/google/gerrit/common/data/PatchScript.java

@@ -87,8 +87,8 @@ public class PatchScript {
     return history;
   }
 
-  public int getContext() {
+  public PatchScriptSettings getSettings() {
-    return settings.getContext();
+    return settings;
   }
 
   public boolean isIgnoreWhitespace() {
@@ -138,6 +138,7 @@ public class PatchScript {
   }
 
   public Iterable<EditList.Hunk> getHunks() {
-    return new EditList(edits, getContext(), a.size(), b.size()).getHunks();
+    final int ctx = settings.getContext();
+    return new EditList(edits, ctx, a.size(), b.size()).getHunks();
   }
 }

gerrit-gwtui/src/main/java/com/google/gerrit/client/Gerrit.java

@@ -273,9 +273,9 @@ public class Gerrit implements EntryPoint {
     };
     gBody.add(body);
 
-    final RpcStatus rpcStatus = new RpcStatus(gTopMenu);
+    RpcStatus.INSTANCE = new RpcStatus(gTopMenu);
-    JsonUtil.addRpcStartHandler(rpcStatus);
+    JsonUtil.addRpcStartHandler(RpcStatus.INSTANCE);
-    JsonUtil.addRpcCompleteHandler(rpcStatus);
+    JsonUtil.addRpcCompleteHandler(RpcStatus.INSTANCE);
     JsonUtil.setDefaultXsrfManager(new XsrfManager() {
       @Override
       public String getToken(JsonDefTarget proxy) {

gerrit-gwtui/src/main/java/com/google/gerrit/client/RpcStatus.java

@@ -24,6 +24,8 @@ import com.google.gwtjsonrpc.client.event.RpcStartEvent;
 import com.google.gwtjsonrpc.client.event.RpcStartHandler;
 
 public class RpcStatus implements RpcStartHandler, RpcCompleteHandler {
+  public static RpcStatus INSTANCE;
+
   private static int hideDepth;
 
   /** Execute code, hiding the RPCs they execute from being shown visually. */

gerrit-gwtui/src/main/java/com/google/gerrit/client/patches/PatchScreen.java

@@ -19,6 +19,7 @@ import static com.google.gerrit.reviewdb.AccountGeneralPreferences.WHOLE_FILE_CO
 
 import com.google.gerrit.client.Dispatcher;
 import com.google.gerrit.client.Gerrit;
+import com.google.gerrit.client.RpcStatus;
 import com.google.gerrit.client.changes.ChangeScreen;
 import com.google.gerrit.client.changes.PatchTable;
 import com.google.gerrit.client.changes.Util;
@@ -48,6 +49,8 @@ import com.google.gwt.event.logical.shared.OpenHandler;
 import com.google.gwt.event.logical.shared.ValueChangeEvent;
 import com.google.gwt.event.logical.shared.ValueChangeHandler;
 import com.google.gwt.event.shared.HandlerRegistration;
+import com.google.gwt.user.client.Command;
+import com.google.gwt.user.client.DeferredCommand;
 import com.google.gwt.user.client.rpc.AsyncCallback;
 import com.google.gwt.user.client.ui.CheckBox;
 import com.google.gwt.user.client.ui.DisclosurePanel;
@@ -138,6 +141,7 @@ public abstract class PatchScreen extends Screen {
   private AbstractPatchContentTable contentTable;
 
   private int rpcSequence;
+  private PatchScript lastScript;
 
   /** The index of the file we are currently looking at among the fileList */
   private int patchIndex;
@@ -229,7 +233,8 @@ public abstract class PatchScreen extends Screen {
 
     add(createNextPrevLinks());
     contentPanel = new FlowPanel();
-    contentPanel.setStyleName(Gerrit.RESOURCES.css().sideBySideScreenSideBySideTable());
+    contentPanel.setStyleName(Gerrit.RESOURCES.css()
+        .sideBySideScreenSideBySideTable());
     contentPanel.add(noDifference);
     contentPanel.add(contentTable);
     add(contentPanel);
@@ -259,7 +264,8 @@ public abstract class PatchScreen extends Screen {
 
   private void initDisplayControls() {
     final Grid displayControls = new Grid(0, 5);
-    displayControls.setStyleName(Gerrit.RESOURCES.css().patchScreenDisplayControls());
+    displayControls.setStyleName(Gerrit.RESOURCES.css()
+        .patchScreenDisplayControls());
     add(displayControls);
 
     createIgnoreWhitespace(displayControls, 0, 0);
@@ -278,15 +284,41 @@ public abstract class PatchScreen extends Screen {
     cb.addValueChangeHandler(new ValueChangeHandler<Boolean>() {
       @Override
       public void onValueChange(ValueChangeEvent<Boolean> event) {
+        final PatchScript last = lastScript;
         if (event.getValue()) {
-          // Show a diff of the full files
           scriptSettings.setContext(WHOLE_FILE_CONTEXT);
+          if (last != null && last.getA().isWholeFile()) {
+            final int max = Math.max(last.getA().size(), last.getB().size());
+            last.getSettings().setContext(max);
+            updateNoRpc(last);
+            return;
+          }
         } else {
           // Restore the context lines to the user's preference
           initContextLines();
+          final int n = scriptSettings.getContext();
+          if (last != null && n <= last.getSettings().getContext()) {
+            last.getSettings().setContext(n);
+            updateNoRpc(last);
+            return;
+          }
         }
         refresh(false /* not the first time */);
       }
+
+      private void updateNoRpc(final PatchScript last) {
+        RpcStatus.INSTANCE.onRpcStart(null);
+        DeferredCommand.addCommand(new Command() {
+          @Override
+          public void execute() {
+            try {
+              onResult(last, false /* not the first time */);
+            } finally {
+              RpcStatus.INSTANCE.onRpcComplete(null);
+            }
+          }
+        });
+      }
     });
     parent.setWidget(row, col + 1, cb);
 
@@ -403,6 +435,7 @@ public abstract class PatchScreen extends Screen {
 
   protected void refresh(final boolean isFirst) {
     final int rpcseq = ++rpcSequence;
+    lastScript = null;
     PatchUtil.DETAIL_SVC.patchScript(patchKey, idSideA, idSideB,
         scriptSettings, new ScreenLoadCallback<PatchScript>(this) {
           @Override
@@ -462,6 +495,7 @@ public abstract class PatchScreen extends Screen {
       contentTable.finishDisplay();
     }
     showPatch(hasDifferences);
+    lastScript = script;
 
     // Mark this file reviewed as soon we display the diff screen
     if (Gerrit.isSignedIn() && isFirst) {