WIP: nullness

core/src/main/java/org/apache/calcite/adapter/clone/ColumnLoader.java

@@ -64,6 +64,7 @@ class ColumnLoader<T> {
    * @param sourceTable Source data
    * @param protoRowType Logical row type
    * @param repList Physical row types, or null if not known */
+  @SuppressWarnings("method.invocation.invalid")
   ColumnLoader(JavaTypeFactory typeFactory,
       Enumerable<T> sourceTable,
       RelProtoDataType protoRowType,
@@ -239,8 +240,9 @@ private void load(final RelDataType elementType,
       switch (rep) {
       case OBJECT:
       case JAVA_SQL_TIMESTAMP:
-        return Util.transform((List<@Nullable Timestamp>) list,
+        final List<@Nullable Long> longs = Util.transform((List<@Nullable Timestamp>) list,
             (Timestamp t) -> t == null ? null : t.getTime());
+        return longs;
       default:
         break;
       }

core/src/main/java/org/apache/calcite/adapter/enumerable/EnumerableTableScan.java

@@ -104,7 +104,7 @@ assert canHandle(table)
   /** Creates an EnumerableTableScan. */
   public static EnumerableTableScan create(RelOptCluster cluster,
       RelOptTable relOptTable) {
-    final Table table = relOptTable.unwrapOrThrow(Table.class);
+    final Table table = relOptTable.unwrap(Table.class);
     Class elementType = EnumerableTableScan.deduceElementType(table);
     final RelTraitSet traitSet =
         cluster.traitSetOf(EnumerableConvention.INSTANCE)
@@ -171,7 +171,7 @@ public static boolean canHandle(RelOptTable relOptTable) {
     return true;
   }
 
-  public static Class deduceElementType(Table table) {
+  public static Class deduceElementType(@Nullable Table table) {
     if (table instanceof QueryableTable) {
       final QueryableTable queryableTable = (QueryableTable) table;
       final Type type = queryableTable.getElementType();

core/src/main/java/org/apache/calcite/plan/volcano/RelSubset.java

@@ -62,7 +62,6 @@
 
 import static org.apache.calcite.linq4j.Nullness.castNonNull;
 
-import static java.util.Objects.requireNonNull;
 
 /**
  * Subset of an equivalence class where all relational expressions have the

core/src/main/java/org/apache/calcite/plan/volcano/VolcanoPlanner.java

@@ -79,8 +79,8 @@
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
-import java.util.PriorityQueue;
 import java.util.Objects;
+import java.util.PriorityQueue;
 import java.util.Set;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;

core/src/main/java/org/apache/calcite/rel/externalize/RelEnumTypes.java

@@ -33,6 +33,8 @@
 
 import com.google.common.collect.ImmutableMap;
 
+import static org.apache.calcite.linq4j.Nullness.castNonNull;
+
 /** Registry of {@link Enum} classes that can be serialized to JSON.
  *
  * <p>Suppose you want to serialize the value
@@ -76,7 +78,7 @@ private RelEnumTypes() {}
 
   private static void register(ImmutableMap.Builder<String, Enum<?>> builder,
       Class<? extends Enum> aClass) {
-    for (Enum enumConstant : aClass.getEnumConstants()) {
+    for (Enum enumConstant : castNonNull(aClass.getEnumConstants())) {
       builder.put(enumConstant.name(), enumConstant);
     }
   }

core/src/main/java/org/apache/calcite/rel/externalize/RelJsonReader.java

@@ -85,7 +85,7 @@ public RelNode read(String s) throws IOException {
         .configure(DeserializationFeature.USE_BIG_DECIMAL_FOR_FLOATS, true)
         .readValue(s, TYPE_REF);
     @SuppressWarnings("unchecked")
-    final List<Map<String, Object>> rels = (List) o.get("rels");
+    final List<Map<String, Object>> rels = (List) requireNonNull(o.get("rels"), "rels");
     readRels(rels);
     return requireNonNull(lastRel, "lastRel");
   }
@@ -97,7 +97,7 @@ private void readRels(List<Map<String, Object>> jsonRels) {
   }
 
   private void readRel(final Map<String, Object> jsonRel) {
-    String id = (String) jsonRel.get("id");
+    String id = (String) requireNonNull(jsonRel.get("id"), "jsonRel.id");
     String type = (String) jsonRel.get("relOp");
     Constructor constructor = relJson.getConstructor(type);
     RelInput input = new RelInput() {
@@ -174,7 +174,7 @@ private void readRel(final Map<String, Object> jsonRel) {
 
       @Override public List<AggregateCall> getAggregateCalls(String tag) {
         @SuppressWarnings("unchecked")
-        final List<Map<String, Object>> jsonAggs = (List) jsonRel.get(tag);
+        final List<Map<String, Object>> jsonAggs = (List) getNonNull(tag);
         final List<AggregateCall> inputs = new ArrayList<>();
         for (Map<String, Object> jsonAggCall : jsonAggs) {
           inputs.add(toAggCall(jsonAggCall));
@@ -298,10 +298,13 @@ private AggregateCall toAggCall(Map<String, Object> jsonAggCall) {
         () -> "relJson.toAggregation output for " + aggMap);
     final Boolean distinct = (Boolean) jsonAggCall.get("distinct");
     @SuppressWarnings("unchecked")
-    final List<Integer> operands = (List<Integer>) jsonAggCall.get("operands");
+    final List<Integer> operands = (List<Integer>) requireNonNull(
+        jsonAggCall.get("operands"),
+        "jsonAggCall.operands");
     final Integer filterOperand = (Integer) jsonAggCall.get("filter");
+    final Object jsonAggType = requireNonNull(jsonAggCall.get("type"), "jsonAggCall.type");
     final RelDataType type =
-        relJson.toType(cluster.getTypeFactory(), jsonAggCall.get("type"));
+        relJson.toType(cluster.getTypeFactory(), jsonAggType);
     final String name = (String) jsonAggCall.get("name");
     return AggregateCall.create(aggregation, distinct, false, false, operands,
         filterOperand == null ? -1 : filterOperand,

core/src/main/java/org/apache/calcite/rel/externalize/RelJsonWriter.java

@@ -30,6 +30,7 @@
 import java.util.IdentityHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 
 /**
  * Callback for a relational expression to dump itself as JSON.
@@ -42,7 +43,7 @@ public class RelJsonWriter implements RelWriter {
   protected final JsonBuilder jsonBuilder;
   protected final RelJson relJson;
   private final Map<RelNode, String> relIdMap = new IdentityHashMap<>();
-  protected final List<Object> relList;
+  protected final List<@Nullable Object> relList;
   private final List<Pair<String, @Nullable Object>> values = new ArrayList<>();
   private @Nullable String previousId;
 
@@ -68,8 +69,8 @@ protected void explain_(RelNode rel, List<Pair<String, @Nullable Object>> values
       put(map, value.left, value.right);
     }
     // omit 'inputs: ["3"]' if "3" is the preceding rel
-    final List<Object> list = explainInputs(rel.getInputs());
-    if (list.size() != 1 || !list.get(0).equals(previousId)) {
+    final List<@Nullable Object> list = explainInputs(rel.getInputs());
+    if (list.size() != 1 || !Objects.equals(list.get(0), previousId)) {
       map.put("inputs", list);
     }
 
@@ -81,12 +82,12 @@ protected void explain_(RelNode rel, List<Pair<String, @Nullable Object>> values
     previousId = id;
   }
 
-  private void put(Map<String, Object> map, String name, Object value) {
+  private void put(Map<String, @Nullable Object> map, String name, @Nullable Object value) {
     map.put(name, relJson.toJson(value));
   }
 
-  private List<Object> explainInputs(List<RelNode> inputs) {
-    final List<Object> list = jsonBuilder.list();
+  private List<@Nullable Object> explainInputs(List<RelNode> inputs) {
+    final List<@Nullable Object> list = jsonBuilder.list();
     for (RelNode input : inputs) {
       String id = relIdMap.get(input);
       if (id == null) {
@@ -128,7 +129,7 @@ private List<Object> explainInputs(List<RelNode> inputs) {
    * explained.
    */
   public String asString() {
-    final Map<String, Object> map = jsonBuilder.map();
+    final Map<String, @Nullable Object> map = jsonBuilder.map();
     map.put("rels", relList);
     return jsonBuilder.toJsonString(map);
   }

core/src/main/java/org/apache/calcite/rel/rules/AggregateExpandDistinctAggregatesRule.java

@@ -631,7 +631,7 @@ private RelBuilder convertMonopole(RelBuilder relBuilder, Aggregate aggregate,
    *                  be modified  @return Relational expression
    */
   private void doRewrite(RelBuilder relBuilder, Aggregate aggregate, int n,
-      List<Integer> argList, int filterArg, List<RexInputRef> refs) {
+      List<Integer> argList, int filterArg, List<@Nullable RexInputRef> refs) {
     final RexBuilder rexBuilder = aggregate.getCluster().getRexBuilder();
     final List<RelDataTypeField> leftFields;
     if (n == 0) {

core/src/main/java/org/apache/calcite/rel/rules/AggregateJoinTransposeRule.java

@@ -48,6 +48,8 @@
 
 import com.google.common.collect.ImmutableList;
 
+import org.checkerframework.checker.nullness.qual.Nullable;
+
 import java.util.ArrayList;
 import java.util.BitSet;
 import java.util.HashMap;
@@ -449,7 +451,7 @@ private static <E> SqlSplittableAggFunction.Registry<E> registry(
   /** Work space for an input to a join. */
   private static class Side {
     final Map<Integer, Integer> split = new HashMap<>();
-    RelNode newInput;
+    @Nullable RelNode newInput;
     boolean aggregate;
   }
 

core/src/main/java/org/apache/calcite/rel/rules/CalcRelSplitter.java

@@ -973,7 +973,8 @@ private static class HighestUsageFinder extends RexVisitorImpl<Void> {
           continue;
         }
         currentLevel = exprLevels[i];
-        exprs[i].accept(this);
+        @SuppressWarnings("argument.type.incompatible")
+        final Void unused = exprs[i].accept(this);
       }
     }
 

core/src/main/java/org/apache/calcite/rel/rules/JoinToMultiJoinRule.java

@@ -43,6 +43,8 @@
 import java.util.List;
 import java.util.Map;
 
+import static java.util.Objects.requireNonNull;
+
 /**
  * Planner rule to flatten a tree of
  * {@link org.apache.calcite.rel.logical.LogicalJoin}s
@@ -342,7 +344,7 @@ private void combineOuterJoins(
    */
   private void copyOuterJoinInfo(
       MultiJoin multiJoin,
-      List<Pair<JoinRelType, RexNode>> destJoinSpecs,
+      List<Pair<JoinRelType, @Nullable RexNode>> destJoinSpecs,
       int adjustmentAmount,
       @Nullable List<RelDataTypeField> srcFields,
       @Nullable List<RelDataTypeField> destFields) {
@@ -513,7 +515,9 @@ private ImmutableMap<Integer, ImmutableIntList> addOnJoinFieldRefCounts(
         nFields =
             multiJoinInputs.get(currInput).getRowType().getFieldCount();
       }
-      int[] refCounts = refCountsMap.get(currInput);
+      final int key = currInput;
+      int[] refCounts = requireNonNull(refCountsMap.get(key),
+          () -> "refCountsMap.get(currInput) for " + key);
       refCounts[i - startField] += joinCondRefCounts[i];
     }
 

core/src/main/java/org/apache/calcite/rel/rules/LoptJoinTree.java

@@ -19,6 +19,9 @@
 import org.apache.calcite.rel.RelNode;
 import org.apache.calcite.rel.core.Join;
 
+import org.checkerframework.checker.initialization.qual.NotOnlyInitialized;
+import org.checkerframework.checker.initialization.qual.UnderInitialization;
+
 import java.util.ArrayList;
 import java.util.List;
 import java.util.Objects;
@@ -36,6 +39,7 @@
 public class LoptJoinTree {
   //~ Instance fields --------------------------------------------------------
 
+  @NotOnlyInitialized
   private final BinaryTree factorTree;
   private final RelNode joinTree;
   private final boolean removableSelfJoin;
@@ -154,9 +158,10 @@ public boolean isRemovableSelfJoin() {
    * track of the parent LoptJoinTree object associated with the binary tree.
    */
   protected abstract static class BinaryTree {
+    @NotOnlyInitialized
     private final LoptJoinTree parent;
 
-    protected BinaryTree(LoptJoinTree parent) {
+    protected BinaryTree(@UnderInitialization LoptJoinTree parent) {
       this.parent = Objects.requireNonNull(parent);
     }
 
@@ -191,7 +196,7 @@ protected static class Node extends BinaryTree {
     private final BinaryTree left;
     private final BinaryTree right;
 
-    public Node(BinaryTree left, BinaryTree right, LoptJoinTree parent) {
+    public Node(BinaryTree left, BinaryTree right, @UnderInitialization LoptJoinTree parent) {
       super(parent);
       this.left = Objects.requireNonNull(left);
       this.right = Objects.requireNonNull(right);