Parse Change.Ids out of meta refs

This allows visible meta refs in VisibleRefFilter.

Change-Id: Ia7a0a0027109a85204882c8a69b03292a29ece92

gerrit-reviewdb/src/main/java/com/google/gerrit/reviewdb/client/Change.java

@@ -136,11 +136,11 @@ public final class Change {
         return null;
       }
       int ce = nextNonDigit(ref, cs);
-      int patchSetId = PatchSet.Id.fromRef(ref, ce);
+      if (ref.substring(ce).equals(RefNames.META_SUFFIX)
-      if (patchSetId < 0) {
+          || PatchSet.Id.fromRef(ref, ce) >= 0) {
-        return null;
+        return new Change.Id(Integer.parseInt(ref.substring(cs, ce)));
       }
-      return new Change.Id(Integer.parseInt(ref.substring(cs, ce)));
+      return null;
     }
 
     static int startIndex(String ref) {

gerrit-reviewdb/src/main/java/com/google/gerrit/reviewdb/client/RefNames.java

@@ -45,6 +45,9 @@ public class RefNames {
    */
   public static final String REFS_CACHE_AUTOMERGE = "refs/cache-automerge/";
 
+  /** Suffix of a meta ref in the notedb. */
+  public static final String META_SUFFIX = "/meta";
+
   public static String refsUsers(Account.Id accountId) {
     StringBuilder r = new StringBuilder();
     r.append(REFS_USER);

gerrit-reviewdb/src/test/java/com/google/gerrit/reviewdb/client/ChangeTest.java

@@ -21,16 +21,18 @@ import org.junit.Test;
 
 public class ChangeTest {
   @Test
-  public void parseRefNames() {
+  public void parseInvalidRefNames() {
-    assertRef(1, "refs/changes/01/1/1");
-    assertRef(1234, "refs/changes/34/1234/56");
-
-    // Not even close.
     assertNotRef(null);
     assertNotRef("");
     assertNotRef("01/1/1");
     assertNotRef("HEAD");
     assertNotRef("refs/tags/v1");
+  }
+
+  @Test
+  public void parsePatchSetRefNames() {
+    assertRef(1, "refs/changes/01/1/1");
+    assertRef(1234, "refs/changes/34/1234/56");
 
     // Invalid characters.
     assertNotRef("refs/changes/0x/1/1");
@@ -60,6 +62,16 @@ public class ChangeTest {
     assertNotRef("refs/changes/34/1234foo");
   }
 
+  @Test
+  public void parseChangeMetaRefNames() {
+    assertRef(1, "refs/changes/01/1/meta");
+    assertRef(1234, "refs/changes/34/1234/meta");
+
+    assertNotRef("refs/changes/01/1/met");
+    assertNotRef("refs/changes/01/1/META");
+    assertNotRef("refs/changes/01/1/1/meta");
+  }
+
   private static void assertRef(int changeId, String refName) {
     assertEquals(new Change.Id(changeId), Change.Id.fromRef(refName));
   }

gerrit-server/src/main/java/com/google/gerrit/server/notedb/ChangeNoteUtil.java

@@ -39,7 +39,7 @@ public class ChangeNoteUtil {
     r.append(m);
     r.append('/');
     r.append(n);
-    r.append("/meta");
+    r.append(RefNames.META_SUFFIX);
     return r.toString();
   }