Line data    Source code

       1             : // Copyright (C) 2014 The Android Open Source Project
       2             : //
       3             : // Licensed under the Apache License, Version 2.0 (the "License");
       4             : // you may not use this file except in compliance with the License.
       5             : // You may obtain a copy of the License at
       6             : //
       7             : // http://www.apache.org/licenses/LICENSE-2.0
       8             : //
       9             : // Unless required by applicable law or agreed to in writing, software
      10             : // distributed under the License is distributed on an "AS IS" BASIS,
      11             : // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
      12             : // See the License for the specific language governing permissions and
      13             : // limitations under the License.
      14             : 
      15             : package com.google.gerrit.server.git;
      16             : 
      17             : import static com.google.common.base.Preconditions.checkArgument;
      18             : import static java.util.Objects.requireNonNull;
      19             : 
      20             : import com.google.gerrit.common.Nullable;
      21             : import java.util.Collection;
      22             : import java.util.HashMap;
      23             : import java.util.Map;
      24             : import org.eclipse.jgit.lib.ObjectId;
      25             : 
      26             : /**
      27             :  * Class describing a merge tip during merge operation.
      28             :  *
      29             :  * <p>The current tip of a {@link MergeTip} may be null if the merge operation is against an unborn
      30             :  * branch, and has not yet been attempted. This is distinct from a null {@link MergeTip} instance,
      31             :  * which may be used to indicate that a merge failed or another error state.
      32             :  */
      33             : public class MergeTip {
      34             :   private CodeReviewCommit initialTip;
      35             :   private CodeReviewCommit branchTip;
      36             :   private Map<ObjectId, ObjectId> mergeResults;
      37             : 
      38             :   /**
      39             :    * @param initialTip tip before the merge operation; may be null, indicating an unborn branch.
      40             :    * @param toMerge list of commits to be merged in merge operation; may not be null or empty.
      41             :    */
      42          53 :   public MergeTip(@Nullable CodeReviewCommit initialTip, Collection<CodeReviewCommit> toMerge) {
      43          53 :     requireNonNull(toMerge, "toMerge may not be null");
      44          53 :     checkArgument(!toMerge.isEmpty(), "toMerge may not be empty");
      45          53 :     this.initialTip = initialTip;
      46          53 :     this.branchTip = initialTip;
      47          53 :     this.mergeResults = new HashMap<>();
      48             :     // Assume fast-forward merge until opposite is proven.
      49          53 :     for (CodeReviewCommit commit : toMerge) {
      50          53 :       mergeResults.put(commit.copy(), commit.copy());
      51          53 :     }
      52          53 :   }
      53             : 
      54             :   /**
      55             :    * Returns the initial tip of the branch before the merge operation started; may be null,
      56             :    * indicating a previously unborn branch.
      57             :    */
      58             :   public CodeReviewCommit getInitialTip() {
      59          53 :     return initialTip;
      60             :   }
      61             : 
      62             :   /**
      63             :    * Moves this MergeTip to newTip and appends mergeResult.
      64             :    *
      65             :    * @param newTip The new tip; may not be null.
      66             :    * @param mergedFrom The result of the merge of {@code newTip}.
      67             :    */
      68             :   public void moveTipTo(CodeReviewCommit newTip, ObjectId mergedFrom) {
      69          53 :     checkArgument(newTip != null);
      70          53 :     branchTip = newTip;
      71          53 :     mergeResults.put(mergedFrom, newTip.copy());
      72          53 :   }
      73             : 
      74             :   /**
      75             :    * The merge results of all the merges of this merge operation.
      76             :    *
      77             :    * @return The merge results of the merge operation as a map of SHA-1 to be merged to SHA-1 of the
      78             :    *     merge result.
      79             :    */
      80             :   public Map<ObjectId, ObjectId> getMergeResults() {
      81          53 :     return mergeResults;
      82             :   }
      83             : 
      84             :   /**
      85             :    * Returns The current tip of the current merge operation; may be null, indicating an unborn
      86             :    * branch.
      87             :    */
      88             :   @Nullable
      89             :   public CodeReviewCommit getCurrentTip() {
      90          53 :     return branchTip;
      91             :   }
      92             : }