Updates to address comments, add javadocs

core/src/main/java/org/apache/accumulo/core/client/admin/TabletMergeability.java

@@ -24,30 +24,62 @@
 
 import com.google.common.base.Preconditions;
 
+/**
+ * @since 4.0.0
+ */
 public class TabletMergeability implements Serializable {
   private static final long serialVersionUID = 1L;
 
-  public static final TabletMergeability NEVER = new TabletMergeability(Duration.ofNanos(-1));
-  public static final TabletMergeability NOW = new TabletMergeability(Duration.ZERO);
+  private static final TabletMergeability NEVER = new TabletMergeability(Duration.ofNanos(-1));
+  private static final TabletMergeability NOW = new TabletMergeability(Duration.ZERO);
 
   private final Duration delay;
 
   private TabletMergeability(Duration delay) {
     this.delay = Objects.requireNonNull(delay);
   }
 
+  /**
+   * Determines if the configured delay signals a tablet is never eligible to be automatically
+   * merged. (Has a delay of -1)
+   *
+   * @return true if never mergeable, else false
+   */
   public boolean isNever() {
     return this.delay.isNegative();
   }
 
+  /**
+   * Determines if the configured delay signals a tablet is always eligible to be automatically
+   * merged now. (Has a delay of 0)
+   *
+   * @return true if always mergeable now, else false
+   */
   public boolean isNow() {
     return this.delay.isZero();
   }
 
-  public boolean isFuture() {
+  /**
+   * Determines if the configured delay signals a tablet has a configured delay before being
+   * eligible to be automatically merged. (Has a positive delay)
+   *
+   * @return true if there is a configured delay, else false
+   */
+  public boolean isDelayed() {
     return delay.toNanos() > 0;
   }
 
+  /**
+   * Returns the duration of the delay which is one of:
+   *
+   * <ul>
+   * <li>-1 (never)</li>
+   * <li>0 (now)</li>
+   * <li>positive delay</li>
+   * </ul>
+   *
+   * @return the configured mergeability delay
+   */
   public Duration getDelay() {
     return delay;
   }
@@ -73,15 +105,53 @@ public String toString() {
     } else if (isNever()) {
       return "TabletMergeability=NEVER";
     }
-    return "TabletMergeability=AFTER:" + delay.toNanos();
+    return "TabletMergeability=AFTER:" + delay.toMillis() + "ms";
+  }
+
+  /**
+   * Signifies that a tablet is never eligible to be automatically merged.
+   *
+   * @return a {@link TabletMergeability} with a delay of -1 signaling never merge
+   */
+  public static TabletMergeability never() {
+    return NEVER;
+  }
+
+  /**
+   * Signifies that a tablet is eligible now to be automatically merged
+   *
+   * @return a {@link TabletMergeability} with a delay of 0 signaling never merge
+   */
+  public static TabletMergeability now() {
+    return NOW;
   }
 
+  /**
+   * Creates a {@link TabletMergeability} from the given delay. The duration must be one of
+   * <ul>
+   * <li>-1 (never)</li>
+   * <li>0 (now)</li>
+   * <li>positive delay</li>
+   * </ul>
+   *
+   * @param delay the duration of the delay
+   *
+   * @return a {@link TabletMergeability} from the given delay.
+   */
   public static TabletMergeability from(Duration delay) {
     Preconditions.checkArgument(delay.toNanos() >= -1,
-        "Duration of delay must be -1, 0, or a positive offset.");
+        "Duration of delay must be -1, 0, or a positive delay.");
     return new TabletMergeability(delay);
   }
 
+  /**
+   * Creates a {@link TabletMergeability} that signals a tablet has a delay to a point in the future
+   * before it is automatically eligible to be merged. The duration must be positive value.
+   *
+   * @param delay the duration of the delay
+   *
+   * @return a {@link TabletMergeability} from the given delay.
+   */
   public static TabletMergeability after(Duration delay) {
     Preconditions.checkArgument(delay.toNanos() > 0, "Duration of delay must be greater than 0.");
     return new TabletMergeability(delay);

core/src/main/java/org/apache/accumulo/core/metadata/schema/TabletMergeabilityMetadata.java

@@ -35,18 +35,18 @@
 public class TabletMergeabilityMetadata implements Serializable {
   private static final long serialVersionUID = 1L;
 
-  public static final TabletMergeabilityMetadata NEVER =
-      new TabletMergeabilityMetadata(TabletMergeability.NEVER);
-  public static final TabletMergeabilityMetadata NOW =
-      new TabletMergeabilityMetadata(TabletMergeability.NOW);
+  private static final TabletMergeabilityMetadata NEVER =
+      new TabletMergeabilityMetadata(TabletMergeability.never());
+  private static final TabletMergeabilityMetadata NOW =
+      new TabletMergeabilityMetadata(TabletMergeability.now());
 
   private final TabletMergeability tabletMergeability;
   private final SteadyTime steadyTime;
 
   private TabletMergeabilityMetadata(TabletMergeability tabletMergeability, SteadyTime steadyTime) {
     this.tabletMergeability = Objects.requireNonNull(tabletMergeability);
     this.steadyTime = steadyTime;
-    Preconditions.checkArgument(tabletMergeability.isFuture() == (steadyTime != null),
+    Preconditions.checkArgument(tabletMergeability.isDelayed() == (steadyTime != null),
         "SteadyTime must be set if and only if TabletMergeability delay is greater than 0.");
   }
 
@@ -114,6 +114,14 @@ public String toString() {
     return "TabletMergeabilityMetadata{" + tabletMergeability + ", " + steadyTime + '}';
   }
 
+  public static TabletMergeabilityMetadata now() {
+    return NOW;
+  }
+
+  public static TabletMergeabilityMetadata never() {
+    return NEVER;
+  }
+
   public static TabletMergeabilityMetadata after(Duration delay, SteadyTime currentTime) {
     return from(TabletMergeability.after(delay), currentTime);
   }

core/src/main/java/org/apache/accumulo/core/metadata/schema/TabletMetadata.java

@@ -702,7 +702,7 @@ static class Builder {
     private final ImmutableSet.Builder<FateId> compacted = ImmutableSet.builder();
     private final ImmutableSet.Builder<FateId> userCompactionsRequested = ImmutableSet.builder();
     private UnSplittableMetadata unSplittableMetadata;
-    private TabletMergeabilityMetadata mergeability = TabletMergeabilityMetadata.NEVER;
+    private TabletMergeabilityMetadata mergeability = TabletMergeabilityMetadata.never();
 
     void table(TableId tableId) {
       this.tableId = tableId;

core/src/test/java/org/apache/accumulo/core/metadata/schema/TabletMetadataTest.java

@@ -644,7 +644,7 @@ public void testBuilder() {
         .putFile(sf1, dfv1).putFile(sf2, dfv2).putBulkFile(rf1, loadedFateId1)
         .putBulkFile(rf2, loadedFateId2).putFlushId(27).putDirName("dir1").putScan(sf3).putScan(sf4)
         .putCompacted(compactFateId1).putCompacted(compactFateId2).putCloned()
-        .putTabletMergeability(TabletMergeabilityMetadata.NOW)
+        .putTabletMergeability(TabletMergeabilityMetadata.now())
         .build(ECOMP, HOSTING_REQUESTED, MERGED, USER_COMPACTION_REQUESTED, UNSPLITTABLE);
 
     assertEquals(extent, tm.getExtent());
@@ -664,7 +664,7 @@ public void testBuilder() {
     assertFalse(tm.hasMerged());
     assertNull(tm.getUnSplittable());
     assertEquals("OK", tm.getCloned());
-    assertEquals(TabletMergeabilityMetadata.NOW, tm.getTabletMergeability());
+    assertEquals(TabletMergeabilityMetadata.now(), tm.getTabletMergeability());
     assertThrows(IllegalStateException.class, tm::getOperationId);
     assertThrows(IllegalStateException.class, tm::getSuspend);
     assertThrows(IllegalStateException.class, tm::getTime);

server/base/src/main/java/org/apache/accumulo/server/init/FileSystemInitializer.java

@@ -95,7 +95,7 @@ private Map<Key,Value> createEntries() {
       var builder = TabletMetadata.builder(keyExtent).putDirName(dirName)
           .putTime(new MetadataTime(0, TimeType.LOGICAL))
           .putTabletAvailability(TabletAvailability.HOSTED)
-          .putTabletMergeability(TabletMergeabilityMetadata.NEVER).putPrevEndRow(prevEndRow);
+          .putTabletMergeability(TabletMergeabilityMetadata.never()).putPrevEndRow(prevEndRow);
       for (String file : files) {
         builder.putFile(new ReferencedTabletFile(new Path(file)).insert(), new DataFileValue(0, 0));
       }

server/base/src/test/java/org/apache/accumulo/server/constraints/MetadataConstraintsTest.java

@@ -664,13 +664,13 @@ public void testMergeabilityColumn() {
 
     m = new Mutation(new Text("0;foo"));
     TabletColumnFamily.MERGEABILITY_COLUMN.put(m,
-        TabletMergeabilityMetadata.toValue(TabletMergeabilityMetadata.NEVER));
+        TabletMergeabilityMetadata.toValue(TabletMergeabilityMetadata.never()));
     violations = mc.check(createEnv(), m);
     assertTrue(violations.isEmpty());
 
     m = new Mutation(new Text("0;foo"));
     TabletColumnFamily.MERGEABILITY_COLUMN.put(m,
-        TabletMergeabilityMetadata.toValue(TabletMergeabilityMetadata.NOW));
+        TabletMergeabilityMetadata.toValue(TabletMergeabilityMetadata.now()));
     violations = mc.check(createEnv(), m);
     assertTrue(violations.isEmpty());
 

server/manager/src/main/java/org/apache/accumulo/manager/FateServiceHandler.java

@@ -257,7 +257,7 @@ public void executeFateOperation(TInfo tinfo, TCredentials c, TFateId opid, TFat
         manager.fate(type).seedTransaction(op, fateId,
             new TraceRepo<>(new CreateTable(c.getPrincipal(), tableName, timeType, options,
                 splitsPath, splitCount, splitsDirsPath, initialTableState,
-                initialTabletAvailability, namespaceId, TabletMergeabilityMetadata.NEVER)),
+                initialTabletAvailability, namespaceId, TabletMergeabilityMetadata.never())),
             autoCleanup, goalMessage);
 
         break;

server/manager/src/main/java/org/apache/accumulo/manager/tableOps/split/UpdateTablets.java

@@ -219,8 +219,8 @@ private void addNewTablets(FateId fateId, Manager manager, TabletMetadata tablet
             .debug("{} copying compacted marker to new child tablet {}", fateId, compactedFateId));
 
         mutator.putTabletAvailability(tabletMetadata.getTabletAvailability());
-        mutator.putTabletMergeability(splitInfo.isSystemCreated() ? TabletMergeabilityMetadata.NOW
-            : TabletMergeabilityMetadata.NEVER);
+        mutator.putTabletMergeability(splitInfo.isSystemCreated() ? TabletMergeabilityMetadata.now()
+            : TabletMergeabilityMetadata.never());
         tabletMetadata.getLoaded().forEach((k, v) -> mutator.putBulkFile(k.getTabletFile(), v));
 
         newTabletsFiles.get(newExtent).forEach(mutator::putFile);

server/manager/src/test/java/org/apache/accumulo/manager/tableOps/merge/MergeTabletsTest.java

@@ -152,7 +152,7 @@ public void testManyColumns() throws Exception {
     var availability = TabletAvailability.HOSTED;
     var lastLocation = TabletMetadata.Location.last("1.2.3.4:1234", "123456789");
     var suspendingTServer = SuspendingTServer.fromValue(new Value("1.2.3.4:5|56"));
-    var mergeability = TabletMergeabilityMetadata.NOW;
+    var mergeability = TabletMergeabilityMetadata.now();
 
     var tablet1 =
         TabletMetadata.builder(ke1).putOperation(opid).putDirName("td1").putFile(file3, dfv3)
@@ -234,7 +234,7 @@ public void testManyColumns() throws Exception {
       EasyMock.expect(tabletMutator.deleteSuspension()).andReturn(tabletMutator);
       EasyMock.expect(tabletMutator.deleteLocation(lastLocation)).andReturn(tabletMutator);
       EasyMock.expect(tabletMutator.deleteUnSplittable()).andReturn(tabletMutator);
-      EasyMock.expect(tabletMutator.putTabletMergeability(TabletMergeabilityMetadata.NOW))
+      EasyMock.expect(tabletMutator.putTabletMergeability(TabletMergeabilityMetadata.now()))
           .andReturn(tabletMutator).once();
 
     });
@@ -405,7 +405,7 @@ public void testTime() throws Exception {
             .once();
         EasyMock.expect(tabletMutator.setMerged()).andReturn(tabletMutator).once();
         // Current default if not set is NEVER
-        EasyMock.expect(tabletMutator.putTabletMergeability(TabletMergeabilityMetadata.NEVER))
+        EasyMock.expect(tabletMutator.putTabletMergeability(TabletMergeabilityMetadata.never()))
             .andReturn(tabletMutator).once();
       });
     }

server/manager/src/test/java/org/apache/accumulo/manager/tableOps/split/UpdateTabletsTest.java

@@ -296,7 +296,7 @@ public void testManyColumns() throws Exception {
         .andReturn(tablet1Mutator);
     EasyMock.expect(tablet1Mutator.putFile(file2, dfv2)).andReturn(tablet1Mutator);
     // SplitInfo marked as system generated so should be set to NOW
-    EasyMock.expect(tablet1Mutator.putTabletMergeability(TabletMergeabilityMetadata.NOW))
+    EasyMock.expect(tablet1Mutator.putTabletMergeability(TabletMergeabilityMetadata.now()))
         .andReturn(tablet1Mutator);
     tablet1Mutator.submit(EasyMock.anyObject());
     EasyMock.expectLastCall().once();
@@ -315,7 +315,7 @@ public void testManyColumns() throws Exception {
     EasyMock.expect(tablet2Mutator.putCompacted(ucfid3)).andReturn(tablet2Mutator);
     EasyMock.expect(tablet2Mutator.putTabletAvailability(availability)).andReturn(tablet2Mutator);
     // SplitInfo marked as system generated so should be set to NOW
-    EasyMock.expect(tablet2Mutator.putTabletMergeability(TabletMergeabilityMetadata.NOW))
+    EasyMock.expect(tablet2Mutator.putTabletMergeability(TabletMergeabilityMetadata.now()))
         .andReturn(tablet2Mutator);
     EasyMock.expect(tablet2Mutator.putBulkFile(loaded1.getTabletFile(), flid1))
         .andReturn(tablet2Mutator);

test/src/main/java/org/apache/accumulo/test/ample/metadata/TestAmple.java

@@ -150,7 +150,7 @@ public void createMetadata(TableId tableId) {
         tabletMutator.putDirName(dirName);
         tabletMutator.putTime(new MetadataTime(0, TimeType.MILLIS));
         tabletMutator.putTabletAvailability(TabletAvailability.HOSTED);
-        tabletMutator.putTabletMergeability(TabletMergeabilityMetadata.NEVER);
+        tabletMutator.putTabletMergeability(TabletMergeabilityMetadata.never());
         tabletMutator.mutate();
       } catch (Exception e) {
         throw new IllegalStateException(e);

test/src/main/java/org/apache/accumulo/test/functional/AddSplitIT.java

@@ -96,7 +96,7 @@ public void addSplitTest() throws Exception {
       TableId id = TableId.of(c.tableOperations().tableIdMap().get(tableName));
       try (TabletsMetadata tm = getServerContext().getAmple().readTablets().forTable(id).build()) {
         // Default for user created tablets should be mergeability set to NEVER
-        tm.stream().forEach(tablet -> assertEquals(TabletMergeabilityMetadata.NEVER,
+        tm.stream().forEach(tablet -> assertEquals(TabletMergeabilityMetadata.never(),
             tablet.getTabletMergeability()));
       }
     }

test/src/main/java/org/apache/accumulo/test/functional/MetadataIT.java

@@ -290,7 +290,7 @@ private void testCommonSystemTableConfig(ClientContext client, TableId tableId,
       assertTrue(
           tablets.stream().allMatch(tm -> tm.getTabletAvailability() == TabletAvailability.HOSTED));
       assertTrue(tablets.stream()
-          .allMatch(tm -> tm.getTabletMergeability().equals(TabletMergeabilityMetadata.NEVER)));
+          .allMatch(tm -> tm.getTabletMergeability().equals(TabletMergeabilityMetadata.never())));
     }
   }
 }

test/src/main/java/org/apache/accumulo/test/functional/SplitIT.java

@@ -263,8 +263,8 @@ public void tabletShouldSplit() throws Exception {
               .equals(entry.getKey().getColumnQualifier())) {
             // Default tablet should be set to NEVER, all newly generated system splits should be
             // set to NOW
-            var mergeability = extent.endRow() == null ? TabletMergeabilityMetadata.NEVER
-                : TabletMergeabilityMetadata.NOW;
+            var mergeability = extent.endRow() == null ? TabletMergeabilityMetadata.never()
+                : TabletMergeabilityMetadata.now();
             assertEquals(mergeability, TabletMergeabilityMetadata.fromValue(entry.getValue()));
           }
           count++;