add MutableMeasureComputersHolder

to remove dependency on a concrete class holder

server/sonar-server/src/main/java/org/sonar/server/computation/measure/MeasureComputersHolderImpl.java

@@ -28,7 +28,7 @@ import static com.google.common.base.Preconditions.checkState;
 import static com.google.common.collect.FluentIterable.from;
 import static java.util.Objects.requireNonNull;
 
-public class MeasureComputersHolderImpl implements MeasureComputersHolder {
+public class MeasureComputersHolderImpl implements MutableMeasureComputersHolder {
 
   @CheckForNull
   private Iterable<MeasureComputer> measureComputers;
@@ -39,12 +39,7 @@ public class MeasureComputersHolderImpl implements MeasureComputersHolder {
     return measureComputers;
   }
 
-  /**
-   * Initializes the measure computers in the holder.
-   *
-   * @throws NullPointerException if the specified List is {@code null}
-   * @throws IllegalStateException if the holder has already been initialized
-   */
+  @Override
   public void setMeasureComputers(Iterable<MeasureComputer> measureComputers) {
     requireNonNull(measureComputers, "Measure computers cannot be null");
     checkState(this.measureComputers == null, "Measure computers have already been initialized");

server/sonar-server/src/main/java/org/sonar/server/computation/measure/MutableMeasureComputersHolder.java

@@ -0,0 +1,36 @@
+/*
+ * SonarQube, open source software quality management tool.
+ * Copyright (C) 2008-2014 SonarSource
+ * mailto:contact AT sonarsource DOT com
+ *
+ * SonarQube is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * SonarQube is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.server.computation.measure;
+
+import org.sonar.api.ce.measure.MeasureComputer;
+
+/**
+ * A {@link MeasureComputersHolder} which value can be set only once.
+ */
+public interface MutableMeasureComputersHolder extends MeasureComputersHolder {
+
+  /**
+   * Initializes the measure computers in the holder.
+   *
+   * @throws NullPointerException if the specified Iterable is {@code null}
+   * @throws IllegalStateException if the holder has already been initialized
+   */
+  void setMeasureComputers(Iterable<MeasureComputer> measureComputers);
+}

server/sonar-server/src/main/java/org/sonar/server/computation/step/FeedMeasureComputers.java

@@ -36,18 +36,18 @@ import org.sonar.api.measures.CoreMetrics;
 import org.sonar.api.measures.Metric;
 import org.sonar.api.measures.Metrics;
 import org.sonar.api.utils.dag.DirectAcyclicGraph;
-import org.sonar.server.computation.measure.MeasureComputersHolderImpl;
+import org.sonar.server.computation.measure.MutableMeasureComputersHolder;
 import org.sonar.server.computation.measure.api.MeasureComputerProviderContext;
 
 public class FeedMeasureComputers implements ComputationStep {
 
   private static final Set<String> CORE_METRIC_KEYS = FluentIterable.from(CoreMetrics.getMetrics()).transform(MetricToKey.INSTANCE).toSet();
 
-  private final MeasureComputersHolderImpl measureComputersHolder;
+  private final MutableMeasureComputersHolder measureComputersHolder;
   private final Metrics[] metricsRepositories;
   private final MeasureComputerProvider[] measureComputerProviders;
 
-  public FeedMeasureComputers(MeasureComputersHolderImpl measureComputersHolder, Metrics[] metricsRepositories, MeasureComputerProvider[] measureComputerProviders) {
+  public FeedMeasureComputers(MutableMeasureComputersHolder measureComputersHolder, Metrics[] metricsRepositories, MeasureComputerProvider[] measureComputerProviders) {
     this.measureComputersHolder = measureComputersHolder;
     this.measureComputerProviders = measureComputerProviders;
     this.metricsRepositories = metricsRepositories;
@@ -56,21 +56,21 @@ public class FeedMeasureComputers implements ComputationStep {
   /**
    * Constructor override used by Pico to instantiate the class when no plugin is defining metrics
    */
-  public FeedMeasureComputers(MeasureComputersHolderImpl measureComputersHolder, MeasureComputerProvider[] measureComputerProviders) {
+  public FeedMeasureComputers(MutableMeasureComputersHolder measureComputersHolder, MeasureComputerProvider[] measureComputerProviders) {
     this(measureComputersHolder, new Metrics[] {}, measureComputerProviders);
   }
 
   /**
    * Constructor override used by Pico to instantiate the class when no plugin is defining measure computers
    */
-  public FeedMeasureComputers(MeasureComputersHolderImpl measureComputersHolder, Metrics[] metricsRepositories) {
+  public FeedMeasureComputers(MutableMeasureComputersHolder measureComputersHolder, Metrics[] metricsRepositories) {
     this(measureComputersHolder, metricsRepositories, new MeasureComputerProvider[] {});
   }
 
   /**
    * Constructor override used by Pico to instantiate the class when no plugin is defining metrics neither measure computers
    */
-  public FeedMeasureComputers(MeasureComputersHolderImpl measureComputersHolder) {
+  public FeedMeasureComputers(MutableMeasureComputersHolder measureComputersHolder) {
     this(measureComputersHolder, new Metrics[] {}, new MeasureComputerProvider[] {});
   }
 
@@ -108,7 +108,7 @@ public class FeedMeasureComputers implements ComputationStep {
         dag.add(generates, computer);
       }
     }
-    return FluentIterable.from(dag.sort());
+    return dag.sort();
   }
 
   private void validateInputMetrics(List<MeasureComputer> computers) {