PrimitiveGenericRecord interface and implementation

N.B.: This is still a work in progress. There are some build issues
that I need to debug. And the code overall is untested.

avro-fastserde/src/main/java/com/linkedin/avro/api/PrimitiveGenericRecord.java

@@ -0,0 +1,103 @@
+package com.linkedin.avro.api;
+
+import java.nio.ByteBuffer;
+import org.apache.avro.AvroRuntimeException;
+import org.apache.avro.generic.GenericData;
+import org.apache.avro.generic.GenericRecord;
+import org.apache.avro.util.Utf8;
+
+
+/**
+ * An extension to the {@link GenericRecord} API that includes utility functions for
+ * casting fields to the right type, including both boxed and unboxed. The following
+ * is worth keeping in mind:
+ *
+ * - All getter and setter functions can throw {@link ClassCastException} if used on
+ *   the wrong type.
+ * - All setter functions can throw {@link AvroRuntimeException} if used on a field
+ *   which doesn't exist in the schema, which is the same behavior as
+ *   {@link GenericData.Record}.
+ * - All primitive getter functions likewise can throw {@link AvroRuntimeException}
+ *   if used on a field which doesn't exist in the schema.
+ * - All object getter functions can return null if used on a field which doesn't
+ *   exist in the schema, which is the same behavior as {@link GenericData.Record#get()}
+ * - All primitive getter functions can throw a {@link NullPointerException} if used to
+ *   retrieved an optional field for which the value has been set to null. In order
+ *   to avoid this, one can use the {@link #isNotNull(String)} function before calling
+ *   a primitive getter.
+ */
+public interface PrimitiveGenericRecord extends GenericRecord {
+  /**
+   * A function to check if a given field contains a non-null value. This can be used
+   * in conjunction with the primitive getters to avoid boxing. For example, with the
+   * regular {@link GenericRecord} API, it is common to do the following:
+   *
+   * Float myField = record.get("myField");
+   * if (myField != null) {
+   *   doSomething(myField);
+   * }
+   *
+   * Instead, with the {@link PrimitiveGenericRecord} API, the above pattern would be
+   * refactored into:
+   *
+   * if (record.isNotNull("myField")) {
+   *   doSomething(record.getPrimitiveFloat("myField"));
+   * }
+   *
+   * This allows optional fields to be handled as primitives and thus avoid the boxing
+   * overhead.
+   *
+   * @param key the field name
+   * @return true if the field has a value defined, or false if it is null
+   * @throws AvroRuntimeException
+   */
+  boolean isNotNull(String key) throws AvroRuntimeException;
+
+  // Boolean getter/setters
+  Boolean getBoolean(String key) throws ClassCastException;
+  boolean getPrimitiveBoolean(String key) throws AvroRuntimeException, ClassCastException, NullPointerException;
+  void putBoolean(String key, Boolean value) throws AvroRuntimeException, ClassCastException;
+  void putPrimitiveBoolean(String key, boolean value) throws AvroRuntimeException, ClassCastException;
+
+  // Bytes getter/setter
+  ByteBuffer getBytes(String key) throws ClassCastException;
+  void putByteBuffer(String key, ByteBuffer value) throws AvroRuntimeException, ClassCastException;
+
+  // Double getter/setters
+  Double getDouble(String key) throws ClassCastException;
+  double getPrimitiveDouble(String key) throws AvroRuntimeException, ClassCastException, NullPointerException;
+  void putDouble(String key, Double value) throws AvroRuntimeException, ClassCastException;
+  void putPrimitiveDouble(String key, double value) throws AvroRuntimeException, ClassCastException;
+
+  // Float getter/setters
+  Float getFloat(String key) throws ClassCastException;
+  float getPrimitiveFloat(String key) throws AvroRuntimeException, ClassCastException, NullPointerException;
+  void putFloat(String key, Float value) throws AvroRuntimeException, ClassCastException;
+  void putPrimitiveFloat(String key, float value) throws AvroRuntimeException, ClassCastException;
+
+  // Integer getter/setters
+  Integer getInteger(String key) throws ClassCastException;
+  int getPrimitiveInteger(String key) throws AvroRuntimeException, ClassCastException, NullPointerException;
+  void putInteger(String key, Integer value) throws AvroRuntimeException, ClassCastException;
+  void putPrimitiveInteger(String key, int value) throws AvroRuntimeException, ClassCastException;
+
+  // Long getter/setters
+  Long getLong(String key) throws ClassCastException;
+  long getPrimitiveLong(String key) throws AvroRuntimeException, ClassCastException, NullPointerException;
+  void putLong(String key, Long value) throws AvroRuntimeException, ClassCastException;
+  void putPrimitiveLong(String key, long value) throws AvroRuntimeException, ClassCastException;
+
+  // String getter/setters
+  CharSequence getCharSequence(String key) throws ClassCastException;
+  void putCharSequence(String key, CharSequence value) throws AvroRuntimeException, ClassCastException;
+  String getString(String key) throws ClassCastException;
+  void putString(String key, String value) throws AvroRuntimeException, ClassCastException;
+  Utf8 getUtf8(String key) throws ClassCastException;
+  void putUtf8(String key, Utf8 value) throws AvroRuntimeException, ClassCastException;
+
+  // Record getter/setters
+  PrimitiveGenericRecord getRecord(String key) throws ClassCastException;
+  void putRecord(String key, PrimitiveGenericRecord value) throws AvroRuntimeException, ClassCastException;
+
+  // TODO: Add getter/setters for maps and arrays of all the above types...?
+}

avro-fastserde/src/main/java/com/linkedin/avro/api/impl/PrimitiveField.java

@@ -0,0 +1,17 @@
+package com.linkedin.avro.api.impl;
+
+import org.apache.avro.Schema;
+
+
+public class PrimitiveField extends Schema.Field {
+  private final int primitivePosition;
+
+  public PrimitiveField(String name, Schema schema, String doc, Object defaultValue, Order order, int primitivePosition) {
+    super(name, schema, doc, defaultValue, order);
+    this.primitivePosition = primitivePosition;
+  }
+
+  public int getPrimitivePosition() {
+    return primitivePosition;
+  }
+}