Merge changes from topics "jgit-reachability", "reachability-2"

* changes:
  VisibilityChecker: Remove topoSort argument
  VisibilityCache: Use jgit's ReachabilityChecker

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index 9b003bc..afff638 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -164,7 +164,7 @@
     sha1 = "198ea005f41219f038f4291f0b0e9f3259730e92",
 )
 
-JGIT_VERS = "5.4.3.201909031940-r"
+JGIT_VERS = "5.5.1.201910021850-r"
 
 JGIT_REPO = MAVEN_CENTRAL
 
@@ -172,28 +172,28 @@
     name = "jgit-lib",
     artifact = "org.eclipse.jgit:org.eclipse.jgit:" + JGIT_VERS,
     repository = JGIT_REPO,
-    sha1 = "10322c4e103485f8b4873cbbf982342f9c3d7989",
+    sha1 = "e0ba7a468e8c62da8521ca3a06a061d4dde95223",
 )
 
 maven_jar(
     name = "jgit-servlet",
     artifact = "org.eclipse.jgit:org.eclipse.jgit.http.server:" + JGIT_VERS,
     repository = JGIT_REPO,
-    sha1 = "59d0c943343f30612e4e2a5a3bf1b95b56e00207",
+    sha1 = "dde1857a91504fadda0af4bb8958d11cfb14dcfe",
 )
 
 maven_jar(
     name = "jgit-junit",
     artifact = "org.eclipse.jgit:org.eclipse.jgit.junit:" + JGIT_VERS,
     repository = JGIT_REPO,
-    sha1 = "71659fc1a1729b7c67846dac8cd6a762fa72002a",
+    sha1 = "894f85c1615d1b47def1018bd98ca65dcaf5a8d5",
 )
 
 maven_jar(
     name = "jgit-archive",
     artifact = "org.eclipse.jgit:org.eclipse.jgit.archive:" + JGIT_VERS,
     repository = JGIT_REPO,
-    sha1 = "21dc4a10882dc667c83bf82a563a6fc4d7719456",
+    sha1 = "1dd6de0d52ad3055cee6ba9b34764b08d85a5238",
 )
 
 maven_jar(

java/com/google/gitiles/LogServlet.java

diff --git a/java/com/google/gitiles/LogServlet.java b/java/com/google/gitiles/LogServlet.java
index 4d038ae..c738f0e 100644
--- a/java/com/google/gitiles/LogServlet.java
+++ b/java/com/google/gitiles/LogServlet.java
@@ -71,6 +71,9 @@
   private static final String FOLLOW_PARAM = "follow";
   private static final String NAME_STATUS_PARAM = "name-status";
   private static final String PRETTY_PARAM = "pretty";
+  private static final String TOPO_ORDER_PARAM = "topo-order";
+  private static final String REVERSE_PARAM = "reverse";
+  private static final String FIRST_PARENT_PARAM = "first-parent";
 
   private static final int DEFAULT_LIMIT = 100;
   private static final int MAX_LIMIT = 10000;
@@ -223,6 +226,15 @@
   private static RevWalk newWalk(Repository repo, GitilesView view, GitilesAccess access)
       throws MissingObjectException, IOException {
     RevWalk walk = new RevWalk(repo);
+    if (isTrue(view, FIRST_PARENT_PARAM)) {
+      walk.setFirstParent(true);
+    }
+    if (isTrue(view, TOPO_ORDER_PARAM)) {
+      walk.sort(RevSort.TOPO, true);
+    }
+    if (isTrue(view, REVERSE_PARAM)) {
+      walk.sort(RevSort.REVERSE, true);
+    }
     try {
       walk.markStart(walk.parseCommit(view.getRevision().getId()));
       if (!Revision.isNull(view.getOldRevision())) {
@@ -233,12 +245,6 @@
     }
     setTreeFilter(walk, view, access);
     setRevFilter(walk, view);
-    if (isTrue(view, "topo-order")) {
-      walk.sort(RevSort.TOPO, true);
-    }
-    if (isTrue(view, "reverse")) {
-      walk.sort(RevSort.REVERSE, true);
-    }
     return walk;
   }
 

javatests/com/google/gitiles/LogServletTest.java

diff --git a/javatests/com/google/gitiles/LogServletTest.java b/javatests/com/google/gitiles/LogServletTest.java
index 06ddaf4..7232439 100644
--- a/javatests/com/google/gitiles/LogServletTest.java
+++ b/javatests/com/google/gitiles/LogServletTest.java
@@ -67,6 +67,19 @@
   }
 
   @Test
+  public void firstParentLog() throws Exception {
+    RevCommit p1 = repo.update("master", repo.commit().add("foo", "foo\n"));
+    RevCommit p2 = repo.update("master", repo.commit().add("foo", "foo2\n"));
+    RevCommit c = repo.update("master", repo.commit().parent(p1).parent(p2).add("foo", "foo3\n"));
+
+    Log response = buildJson(LOG, "/repo/+log/master", "first-parent");
+    assertThat(response.log).hasSize(2);
+
+    verifyJsonCommit(response.log.get(0), c);
+    verifyJsonCommit(response.log.get(1), p1);
+  }
+
+  @Test
   public void follow() throws Exception {
     String contents = "contents";
     RevCommit c1 = repo.branch("master").commit().add("foo", contents).create();