WIP: core

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

@@ -35,12 +35,14 @@
 import org.apache.calcite.rex.RexNode;
 import org.apache.calcite.util.BuiltInMethod;
 
+import org.checkerframework.checker.nullness.qual.Nullable;
+
 import java.util.List;
 
 /** Relational expression that applies a limit and/or offset to its input. */
 public class EnumerableLimit extends SingleRel implements EnumerableRel {
-  public final RexNode offset;
-  public final RexNode fetch;
+  public final @Nullable RexNode offset;
+  public final @Nullable RexNode fetch;
 
   /** Creates an EnumerableLimit.
    *
@@ -49,8 +51,8 @@ public EnumerableLimit(
       RelOptCluster cluster,
       RelTraitSet traitSet,
       RelNode input,
-      RexNode offset,
-      RexNode fetch) {
+      @Nullable RexNode offset,
+      @Nullable RexNode fetch) {
     super(cluster, traitSet, input);
     this.offset = offset;
     this.fetch = fetch;
@@ -59,8 +61,8 @@ public EnumerableLimit(
   }
 
   /** Creates an EnumerableLimit. */
-  public static EnumerableLimit create(final RelNode input, RexNode offset,
-      RexNode fetch) {
+  public static EnumerableLimit create(final RelNode input, @Nullable RexNode offset,
+      @Nullable RexNode fetch) {
     final RelOptCluster cluster = input.getCluster();
     final RelMetadataQuery mq = cluster.getMetadataQuery();
     final RelTraitSet traitSet =

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

@@ -50,7 +50,7 @@ public class EnumerableTableFunctionScan extends TableFunctionScan
 
   public EnumerableTableFunctionScan(RelOptCluster cluster,
       RelTraitSet traits, List<RelNode> inputs, @Nullable Type elementType,
-      @Nullable RelDataType rowType, RexNode call,
+      RelDataType rowType, RexNode call,
       @Nullable Set<RelColumnMapping> columnMappings) {
     super(cluster, traits, inputs, call, elementType, rowType,
         columnMappings);
@@ -61,7 +61,7 @@ public EnumerableTableFunctionScan(RelOptCluster cluster,
       List<RelNode> inputs,
       RexNode rexCall,
       @Nullable Type elementType,
-      @Nullable RelDataType rowType,
+      RelDataType rowType,
       @Nullable Set<RelColumnMapping> columnMappings) {
     return new EnumerableTableFunctionScan(getCluster(), traitSet, inputs,
         elementType, rowType, rexCall, columnMappings);

core/src/main/java/org/apache/calcite/adapter/jdbc/JdbcSchema.java

@@ -19,7 +19,6 @@
 import org.apache.calcite.avatica.AvaticaUtils;
 import org.apache.calcite.avatica.MetaImpl;
 import org.apache.calcite.avatica.SqlType;
-import org.apache.calcite.linq4j.Nullness;
 import org.apache.calcite.linq4j.function.Experimental;
 import org.apache.calcite.linq4j.tree.Expression;
 import org.apache.calcite.rel.type.RelDataType;
@@ -85,7 +84,7 @@ public class JdbcSchema implements Schema {
   private final boolean snapshot;
 
   @Experimental
-  public static final ThreadLocal<Foo> THREAD_METADATA = new ThreadLocal<>();
+  public static final ThreadLocal<@Nullable Foo> THREAD_METADATA = new ThreadLocal<>();
 
   private static final Ordering<Iterable<Integer>> VERSION_ORDERING =
       Ordering.<Integer>natural().lexicographical();

core/src/main/java/org/apache/calcite/adapter/jdbc/JdbcToEnumerableConverter.java

@@ -24,7 +24,6 @@
 import org.apache.calcite.adapter.enumerable.PhysTypeImpl;
 import org.apache.calcite.adapter.java.JavaTypeFactory;
 import org.apache.calcite.config.CalciteSystemProperty;
-import org.apache.calcite.linq4j.Nullness;
 import org.apache.calcite.linq4j.tree.BlockBuilder;
 import org.apache.calcite.linq4j.tree.ConstantExpression;
 import org.apache.calcite.linq4j.tree.Expression;
@@ -41,7 +40,6 @@
 import org.apache.calcite.rel.convert.ConverterImpl;
 import org.apache.calcite.rel.metadata.RelMetadataQuery;
 import org.apache.calcite.rel.type.RelDataType;
-import org.apache.calcite.rex.RexLiteral;
 import org.apache.calcite.runtime.Hook;
 import org.apache.calcite.runtime.SqlFunctions;
 import org.apache.calcite.schema.Schemas;

core/src/main/java/org/apache/calcite/jdbc/CalcitePrepare.java

@@ -68,7 +68,7 @@
  */
 public interface CalcitePrepare {
   Function0<CalcitePrepare> DEFAULT_FACTORY = CalcitePrepareImpl::new;
-  ThreadLocal<Deque<Context>> THREAD_CONTEXT_STACK =
+  ThreadLocal<@Nullable Deque<Context>> THREAD_CONTEXT_STACK =
       ThreadLocal.withInitial(ArrayDeque::new);
 
   ParseResult parse(Context context, String sql);
@@ -189,7 +189,7 @@ private static SparkHandler createHandler() {
     }
 
     public static void push(Context context) {
-      final Deque<Context> stack = THREAD_CONTEXT_STACK.get();
+      final Deque<Context> stack = castNonNull(THREAD_CONTEXT_STACK.get());
       final List<String> path = context.getObjectPath();
       if (path != null) {
         for (Context context1 : stack) {
@@ -203,11 +203,11 @@ public static void push(Context context) {
     }
 
     public static Context peek() {
-      return castNonNull(THREAD_CONTEXT_STACK.get().peek());
+      return castNonNull(castNonNull(THREAD_CONTEXT_STACK.get()).peek());
     }
 
     public static void pop(Context context) {
-      Context x = THREAD_CONTEXT_STACK.get().pop();
+      Context x = castNonNull(THREAD_CONTEXT_STACK.get()).pop();
       assert x == context;
     }
 
@@ -333,7 +333,7 @@ public CalciteSignature(String sql, List<AvaticaParameter> parameterList,
         long maxRowCount, Bindable<T> bindable) {
       this(sql, parameterList, internalParameters, rowType, columns,
           cursorFactory, rootSchema, collationList, maxRowCount, bindable,
-          null);
+          castNonNull(null));
     }
 
     public CalciteSignature(String sql,
@@ -346,7 +346,7 @@ public CalciteSignature(String sql,
         List<RelCollation> collationList,
         long maxRowCount,
         @Nullable Bindable<T> bindable,
-        Meta.@Nullable StatementType statementType) {
+        Meta.StatementType statementType) {
       super(columns, sql, parameterList, internalParameters, cursorFactory,
           statementType);
       this.rowType = rowType;

core/src/main/java/org/apache/calcite/jdbc/CalciteSchema.java

@@ -692,7 +692,8 @@ public NavigableSet<String> getFunctionNames() {
     }
 
     public Set<String> getSubSchemaNames() {
-      return CalciteSchema.this.getSubSchemaMap().keySet();
+      //noinspection RedundantCast
+      return (Set<String>) CalciteSchema.this.getSubSchemaMap().keySet();
     }
 
     public SchemaPlus add(String name, Schema schema) {

core/src/main/java/org/apache/calcite/materialize/Lattice.java

@@ -66,6 +66,11 @@
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Ordering;
 
+import org.checkerframework.checker.initialization.qual.UnknownInitialization;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
+import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.checker.nullness.qual.RequiresNonNull;
+
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashSet;
@@ -82,9 +87,11 @@
 import java.util.function.IntFunction;
 import java.util.stream.Collectors;
 import javax.annotation.Nonnull;
-import javax.annotation.Nullable;
 import javax.annotation.ParametersAreNonnullByDefault;
 
+import static org.apache.calcite.linq4j.Nullness.assertNonNull;
+import static org.apache.calcite.linq4j.Nullness.castNonNull;
+
 /**
  * Structure that allows materialized views based upon a star schema to be
  * recognized and recommended.
@@ -128,16 +135,21 @@ private Lattice(CalciteSchema rootSchema, LatticeRootNode rootNode,
     }
     Preconditions.checkArgument(rowCountEstimate > 0d);
     this.rowCountEstimate = rowCountEstimate;
-    this.statisticProvider =
+    @SuppressWarnings("argument.type.incompatible")
+    LatticeStatisticProvider statisticProvider =
         Objects.requireNonNull(statisticProviderFactory.apply(this));
+    this.statisticProvider = statisticProvider;
   }
 
   /** Creates a Lattice. */
   public static Lattice create(CalciteSchema schema, String sql, boolean auto) {
     return builder(schema, sql).auto(auto).build();
   }
 
-  private boolean isValid(Litmus litmus) {
+  @RequiresNonNull({"rootNode", "defaultMeasures", "columns"})
+  private boolean isValid(
+      @UnknownInitialization Lattice this,
+      Litmus litmus) {
     if (!rootNode.isValid(litmus)) {
       return false;
     }
@@ -152,7 +164,7 @@ private boolean isValid(Litmus litmus) {
     return litmus.succeed();
   }
 
-  private static void populateAliases(SqlNode from, List<String> aliases,
+  private static void populateAliases(SqlNode from, List<@Nullable String> aliases,
       @Nullable String current) {
     if (from instanceof SqlJoin) {
       SqlJoin join = (SqlJoin) from;
@@ -375,7 +387,10 @@ public String countSql(ImmutableBitSet groupSet) {
   public StarTable createStarTable() {
     final List<Table> tables = new ArrayList<>();
     for (LatticeNode node : rootNode.descendants) {
-      tables.add(node.table.t.unwrap(Table.class));
+      tables.add(
+          assertNonNull(
+              node.table.t.unwrap(Table.class),
+              () -> "can't get table for " + node.table.t));
     }
     return StarTable.of(this, tables);
   }
@@ -524,9 +539,9 @@ Vertex getSource() {
   /** Vertex in the temporary graph. */
   private static class Vertex {
     final LatticeTable table;
-    final String alias;
+    final @Nullable String alias;
 
-    private Vertex(LatticeTable table, String alias) {
+    private Vertex(LatticeTable table, @Nullable String alias) {
       this.table = table;
       this.alias = alias;
     }
@@ -542,7 +557,7 @@ private Vertex(LatticeTable table, String alias) {
   public static class Measure implements Comparable<Measure> {
     public final SqlAggFunction agg;
     public final boolean distinct;
-    @Nullable public final String name;
+    public final @Nullable String name;
     public final ImmutableList<Column> args;
     public final String digest;
 
@@ -673,7 +688,7 @@ public int compareTo(Column column) {
     public abstract void toSql(SqlWriter writer);
 
     /** The alias that SQL would give to this expression. */
-    public abstract String defaultAlias();
+    public abstract @Nullable String defaultAlias();
   }
 
   /** Column in a lattice. Columns are identified by table alias and
@@ -730,7 +745,7 @@ public void toSql(SqlWriter writer) {
       writer.write(e);
     }
 
-    public String defaultAlias() {
+    public @Nullable String defaultAlias() {
       // there is no default alias for an expression
       return null;
     }
@@ -779,9 +794,9 @@ public static class Builder {
     private boolean algorithm = false;
     private long algorithmMaxMillis = -1;
     private boolean auto = true;
-    private Double rowCountEstimate;
-    private String statisticProvider;
-    private Map<String, DerivedColumn> derivedColumnsByName =
+    private @MonotonicNonNull Double rowCountEstimate;
+    private @Nullable String statisticProvider;
+    private final Map<String, DerivedColumn> derivedColumnsByName =
         new LinkedHashMap<>();
 
     public Builder(LatticeSpace space, CalciteSchema schema, String sql) {
@@ -797,15 +812,18 @@ public Builder(LatticeSpace space, CalciteSchema schema, String sql) {
       populate(relNodes, tempLinks, parsed.root.rel);
 
       // Get aliases.
-      List<String> aliases = new ArrayList<>();
-      populateAliases(((SqlSelect) parsed.sqlNode).getFrom(), aliases, null);
+      List<@Nullable String> aliases = new ArrayList<>();
+      SqlNode from = ((SqlSelect) parsed.sqlNode).getFrom();
+      assert from != null : "from must not be null";
+      populateAliases(from, aliases, null);
 
       // Build a graph.
       final DirectedGraph<Vertex, Edge> graph =
           DefaultDirectedGraph.create(Edge.FACTORY);
       final List<Vertex> vertices = new ArrayList<>();
-      for (Pair<RelNode, String> p : Pair.zip(relNodes, aliases)) {
-        final LatticeTable table = space.register(p.left.getTable());
+      for (Pair<RelNode, @Nullable String> p : Pair.zip(relNodes, aliases)) {
+        final LatticeTable table = space.register(
+            assertNonNull(p.left.getTable(), () -> "no table for " + p.left));
         final Vertex vertex = new Vertex(table, p.right);
         graph.addVertex(vertex);
         vertices.add(vertex);
@@ -815,7 +833,7 @@ public Builder(LatticeSpace space, CalciteSchema schema, String sql) {
         final Vertex target = vertices.get(tempLink[1][0]);
         Edge edge = graph.getEdge(source, target);
         if (edge == null) {
-          edge = graph.addEdge(source, target);
+          edge = castNonNull(graph.addEdge(source, target));
         }
         edge.pairs.add(IntPair.of(tempLink[0][1], tempLink[1][1]));
       }
@@ -907,7 +925,7 @@ public Builder rowCountEstimate(double rowCountEstimate) {
     /** Sets the "statisticProvider" attribute.
      *
      * <p>If not set, the lattice will use {@link Lattices#CACHED_SQL}. */
-    public Builder statisticProvider(String statisticProvider) {
+    public Builder statisticProvider(@Nullable String statisticProvider) {
       this.statisticProvider = statisticProvider;
       return this;
     }
@@ -1108,7 +1126,7 @@ void fixUp(MutableNode node) {
           final String alias = SqlValidatorUtil.uniquify(name,
               columnAliases, SqlValidatorUtil.ATTEMPT_SUGGESTER);
           final BaseColumn column =
-              new BaseColumn(c++, node.alias, name, alias);
+              new BaseColumn(c++, castNonNull(node.alias), name, alias);
           columnList.add(column);
           columnAliasList.put(name, column); // name before it is made unique
         }

core/src/main/java/org/apache/calcite/materialize/MaterializationService.java

@@ -64,7 +64,7 @@ public class MaterializationService {
       new MaterializationService();
 
   /** For testing. */
-  private static final ThreadLocal<MaterializationService> THREAD_INSTANCE =
+  private static final ThreadLocal<@Nullable MaterializationService> THREAD_INSTANCE =
       ThreadLocal.withInitial(MaterializationService::new);
 
   private static final Comparator<Pair<CalciteSchema.TableEntry, TileKey>> C =

core/src/main/java/org/apache/calcite/plan/AbstractRelOptPlanner.java

@@ -28,7 +28,10 @@
 
 import com.google.common.collect.ImmutableList;
 
+import org.checkerframework.checker.initialization.qual.UnknownInitialization;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 import org.checkerframework.checker.nullness.qual.Nullable;
+import org.checkerframework.dataflow.qual.Pure;
 import org.slf4j.Logger;
 
 import java.text.NumberFormat;
@@ -66,9 +69,9 @@ public abstract class AbstractRelOptPlanner implements RelOptPlanner {
 
   protected final RelOptCostFactory costFactory;
 
-  private @Nullable MulticastRelOptListener listener;
+  private @MonotonicNonNull MulticastRelOptListener listener;
 
-  private @Nullable RuleAttemptsListener ruleAttemptsListener;
+  private @MonotonicNonNull RuleAttemptsListener ruleAttemptsListener;
 
   private @Nullable Pattern ruleDescExclusionFilter;
 
@@ -175,11 +178,11 @@ public boolean removeRule(RelOptRule rule) {
    * @param description Description
    * @return Rule with given description, or null if not found
    */
-  protected RelOptRule getRuleByDescription(String description) {
+  protected @Nullable RelOptRule getRuleByDescription(String description) {
     return mapDescToRule.get(description);
   }
 
-  public void setRuleDescExclusionFilter(Pattern exclusionFilter) {
+  public void setRuleDescExclusionFilter(@Nullable Pattern exclusionFilter) {
     ruleDescExclusionFilter = exclusionFilter;
   }
 
@@ -255,7 +258,9 @@ public RelTraitSet emptyTraitSet() {
     return getCost(rel, mq);
   }
 
-  public void addListener(RelOptListener newListener) {
+  public void addListener(
+      @UnknownInitialization AbstractRelOptPlanner this,
+      RelOptListener newListener) {
     if (listener == null) {
       listener = new MulticastRelOptListener();
     }
@@ -427,6 +432,7 @@ protected void notifyDiscard(RelNode rel) {
     }
   }
 
+  @Pure
   public @Nullable RelOptListener getListener() {
     return listener;
   }

core/src/main/java/org/apache/calcite/plan/Convention.java

@@ -124,7 +124,7 @@ public RelTraitDef getTraitDef() {
       return ConventionTraitDef.INSTANCE;
     }
 
-    @Override public RelNode enforce(final RelNode input,
+    @Override public @Nullable RelNode enforce(final RelNode input,
         final RelTraitSet required) {
       return null;
     }