Switch to DivSuffixSort and fix patchgen bug.

Credit to admo@google.com for investigating DivsuffixSort and making it
work well with the existing framework.

This speeds up patch generation by up to 50%. It also fixes issue 7,
which could cause bad patches to be generated when multiple entries in
the "new" archive were matches for an entry in the "old" archive (e.g.,
a file copied to two paths in the "new" archive).

LICENSE

@@ -200,3 +200,27 @@
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
+
+===========================================================================
+
+The following applies to DivSuffixSorter.java:
+
+MIT License:
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.

generator/src/main/java/com/google/archivepatcher/generator/PreDiffPlanner.java

@@ -24,8 +24,10 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 /**
  * Plans archive transformations to be made prior to differencing.
@@ -86,8 +88,8 @@ class PreDiffPlanner {
    * @throws IOException if there are any problems reading the input files
    */
   PreDiffPlan generatePreDiffPlan() throws IOException {
-    List<TypedRange<Void>> oldFilePlan = new ArrayList<>();
-    List<TypedRange<JreDeflateParameters>> newFilePlan = new ArrayList<>();
+    Set<TypedRange<Void>> oldFilePlan = new HashSet<>();
+    Set<TypedRange<JreDeflateParameters>> newFilePlan = new HashSet<>();
     List<QualifiedRecommendation> qualifiedRecommendations = new ArrayList<>();
 
     // This will be used to find files that have been renamed, but not modified. This is relatively
@@ -148,12 +150,14 @@ PreDiffPlan generatePreDiffPlan() throws IOException {
       }
     }
 
-    Collections.sort(oldFilePlan);
-    Collections.sort(newFilePlan);
+    List<TypedRange<Void>> oldFilePlanList = new ArrayList<>(oldFilePlan);
+    Collections.sort(oldFilePlanList);
+    List<TypedRange<JreDeflateParameters>> newFilePlanList = new ArrayList<>(newFilePlan);
+    Collections.sort(newFilePlanList);
     return new PreDiffPlan(
         Collections.unmodifiableList(qualifiedRecommendations),
-        Collections.unmodifiableList(oldFilePlan),
-        Collections.unmodifiableList(newFilePlan));
+        Collections.unmodifiableList(oldFilePlanList),
+        Collections.unmodifiableList(newFilePlanList));
   }
 
   /**

generator/src/main/java/com/google/archivepatcher/generator/bsdiff/BsDiffPatchWriter.java

@@ -362,7 +362,7 @@ public static void generatePatch(
 
     // Do the suffix search.
     try (final RandomAccessObject groupArray =
-        new QuickSuffixSorter(randomAccessObjectFactory).suffixSort(oldData)) {
+        new DivSuffixSorter(randomAccessObjectFactory).suffixSort(oldData)) {
       BsDiffMatcher matcher = new BsDiffMatcher(oldData, newData, groupArray, minimumMatchLength);
       generatePatchWithMatcher(oldData, newData, matcher, outputStream);
     }