Avro Connectors

/**
 * Input format for reading Avro files in Flink batch jobs
 * @param <E> The type of records to read
 */
public class AvroInputFormat<E> extends FileInputFormat<E>
        implements ResultTypeQueryable<E>, CheckpointableInputFormat<FileInputSplit, Tuple2<Long, Long>> {
    
    /**
     * Creates an AvroInputFormat for reading Avro files
     * @param filePath Path to the Avro file or directory
     * @param type Class representing the record type to read
     */
    public AvroInputFormat(Path filePath, Class<E> type);
    
    /**
     * Sets whether to reuse Avro value instances for better performance
     * @param reuseAvroValue true to reuse instances, false to create new ones
     */
    public void setReuseAvroValue(boolean reuseAvroValue);
    
    /**
     * Sets whether files should be read as whole (non-splittable)
     * @param unsplittable true to read files as whole, false to allow splitting
     */
    public void setUnsplittable(boolean unsplittable);
    
    /**
     * Returns the type information for the records produced by this format
     * @return TypeInformation describing the output type
     */
    public TypeInformation<E> getProducedType();
    
    /**
     * Opens the input split for reading
     * @param split The file input split to read from
     */
    public void open(FileInputSplit split) throws IOException;
    
    /**
     * Checks if the end of the input has been reached
     * @return true if no more records are available
     */
    public boolean reachedEnd() throws IOException;
    
    /**
     * Reads the next record from the input
     * @param reuseValue Record instance to reuse (may be null)
     * @return The next record
     */
    public E nextRecord(E reuseValue) throws IOException;
    
    /**
     * Returns the number of records read from the current block
     * @return Number of records read
     */
    public long getRecordsReadFromBlock();
    
    /**
     * Gets the current checkpoint state for fault tolerance
     * @return Checkpoint state as (position, recordsRead) tuple
     */
    public Tuple2<Long, Long> getCurrentState();
    
    /**
     * Reopens the format with a previous checkpoint state
     * @param split The file input split to read
     * @param state The checkpoint state to restore
     */
    public void reopen(FileInputSplit split, Tuple2<Long, Long> state) throws IOException;
}

import org.apache.flink.api.java.ExecutionEnvironment;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.io.AvroInputFormat;
import org.apache.flink.core.fs.Path;

// Define your Avro record class
public class User {
    public String name;
    public int age;
    public String email;
}

ExecutionEnvironment env = ExecutionEnvironment.getExecutionEnvironment();

// Create AvroInputFormat
AvroInputFormat<User> avroInput = new AvroInputFormat<>(
    new Path("hdfs://path/to/users.avro"),
    User.class
);

// Configure for better performance
avroInput.setReuseAvroValue(true);

// Read the data
DataSet<User> users = env.createInput(avroInput);
users.print();

/**
 * Output format for writing Avro files in Flink batch jobs
 * @param <E> The type of records to write
 */
public class AvroOutputFormat<E> extends FileOutputFormat<E> implements Serializable {
    
    /**
     * Creates an AvroOutputFormat with file path and record type
     * @param filePath Path where the Avro file will be written
     * @param type Class representing the record type to write
     */
    public AvroOutputFormat(Path filePath, Class<E> type);
    
    /**
     * Creates an AvroOutputFormat with only record type (path set later)
     * @param type Class representing the record type to write
     */
    public AvroOutputFormat(Class<E> type);
    
    /**
     * Sets a custom Avro schema to use for writing
     * @param schema The Avro schema to use
     */
    public void setSchema(Schema schema);
    
    /**
     * Writes a record to the output
     * @param record The record to write
     */
    public void writeRecord(E record) throws IOException;
    
    /**
     * Opens the output format for writing
     * @param taskNumber The number of the parallel task
     * @param numTasks The total number of parallel tasks
     */
    public void open(int taskNumber, int numTasks) throws IOException;
    
    /**
     * Closes the output format and flushes any remaining data
     */
    public void close() throws IOException;
}

import org.apache.flink.api.java.io.AvroOutputFormat;
import org.apache.avro.Schema;
import org.apache.avro.SchemaBuilder;

// Create output format
AvroOutputFormat<User> avroOutput = new AvroOutputFormat<>(
    new Path("hdfs://path/to/output.avro"),
    User.class
);

// Optional: Set custom schema
Schema customSchema = SchemaBuilder.record("User")
    .fields()
    .name("name").type().stringType().noDefault()
    .name("age").type().intType().noDefault()
    .name("email").type().stringType().noDefault()
    .endRecord();
avroOutput.setSchema(customSchema);

// Write data
DataSet<User> users = // ... your data
users.output(avroOutput);

/**
 * Avro decoder that reads from Java DataInput streams
 */
public class DataInputDecoder extends org.apache.avro.io.Decoder {
    
    // Note: Uses package-level constructor in actual implementation
    
    /**
     * Sets the input data source
     * @param in DataInput stream to read from
     */
    public void setIn(DataInput in);
    
    /**
     * Reads null value
     */
    public void readNull() throws IOException;
    
    /**
     * Reads a boolean value
     * @return The boolean value
     */
    public boolean readBoolean() throws IOException;
    
    /**
     * Reads an integer value
     * @return The integer value
     */
    public int readInt() throws IOException;
    
    /**
     * Reads a long value
     * @return The long value
     */
    public long readLong() throws IOException;
    
    /**
     * Reads a float value
     * @return The float value
     */
    public float readFloat() throws IOException;
    
    /**
     * Reads a double value
     * @return The double value
     */
    public double readDouble() throws IOException;
    
    /**
     * Reads variable-length bytes
     * @param old ByteBuffer to reuse (may be null)
     * @return ByteBuffer containing the bytes
     */
    public ByteBuffer readBytes(ByteBuffer old) throws IOException;
    
    /**
     * Reads an enum value
     * @return The enum ordinal
     */
    public int readEnum() throws IOException;
    
    /**
     * Reads fixed-length bytes
     * @param bytes Destination byte array
     * @param start Starting offset in the array
     * @param length Number of bytes to read
     */
    public void readFixed(byte[] bytes, int start, int length) throws IOException;
    
    /**
     * Skips fixed-length bytes
     * @param length Number of bytes to skip
     */
    public void skipFixed(int length) throws IOException;
    
    /**
     * Skips variable-length bytes
     */
    public void skipBytes() throws IOException;
    
    /**
     * Reads UTF-8 string
     * @param old Utf8 object to reuse (may be null)
     * @return UTF-8 string
     */
    public Utf8 readString(Utf8 old) throws IOException;
    
    /**
     * Reads a string value
     * @return The string value
     */
    public String readString() throws IOException;
    
    /**
     * Skips string value
     */
    public void skipString() throws IOException;
    
    /**
     * Starts reading an array
     * @return Number of elements in the array
     */
    public long readArrayStart() throws IOException;
    
    /**
     * Reads next array element count
     * @return Number of remaining elements
     */
    public long arrayNext() throws IOException;
    
    /**
     * Skips entire array
     * @return Number of elements skipped
     */
    public long skipArray() throws IOException;
    
    /**
     * Starts reading a map
     * @return Number of entries in the map
     */
    public long readMapStart() throws IOException;
    
    /**
     * Reads next map element count
     * @return Number of remaining entries
     */
    public long mapNext() throws IOException;
    
    /**
     * Skips entire map
     * @return Number of entries skipped
     */
    public long skipMap() throws IOException;
    
    /**
     * Reads union index
     * @return Union branch index
     */
    public int readIndex() throws IOException;
    
    /**
     * Utility method for reading variable-length long count
     * @param in DataInput stream to read from
     * @return Variable-length long value
     */
    public static long readVarLongCount(DataInput in) throws IOException;
}

/**
 * Avro encoder that writes to Java DataOutput streams
 */
public class DataOutputEncoder extends org.apache.avro.io.Encoder implements Serializable {
    
    // Note: Uses package-level constructor in actual implementation
    
    /**
     * Sets the output data destination
     * @param out DataOutput stream to write to
     */
    public void setOut(DataOutput out);
    
    /**
     * Writes a boolean value
     * @param b The boolean value to write
     */
    public void writeBoolean(boolean b) throws IOException;
    
    /**
     * Writes an integer value
     * @param n The integer value to write
     */
    public void writeInt(int n) throws IOException;
    
    /**
     * Writes a long value
     * @param n The long value to write
     */
    public void writeLong(long n) throws IOException;
    
    /**
     * Flushes the output (no-op implementation)
     */
    public void flush() throws IOException;
    
    /**
     * Writes null value
     */
    public void writeNull() throws IOException;
    
    /**
     * Writes a float value
     * @param f The float value to write
     */
    public void writeFloat(float f) throws IOException;
    
    /**
     * Writes a double value
     * @param d The double value to write
     */
    public void writeDouble(double d) throws IOException;
    
    /**
     * Writes an enum value
     * @param e The enum ordinal to write
     */
    public void writeEnum(int e) throws IOException;
    
    /**
     * Writes fixed-length bytes
     * @param bytes Byte array containing data
     * @param start Starting offset in the array
     * @param len Number of bytes to write
     */
    public void writeFixed(byte[] bytes, int start, int len) throws IOException;
    
    /**
     * Writes variable-length bytes from ByteBuffer
     * @param bytes ByteBuffer containing data
     */
    public void writeBytes(ByteBuffer bytes) throws IOException;
    
    /**
     * Writes UTF-8 string
     * @param utf8 The UTF-8 string to write
     */
    public void writeString(Utf8 utf8) throws IOException;
    
    /**
     * Writes a string value
     * @param str The string to write
     */
    public void writeString(String str) throws IOException;
    
    /**
     * Writes variable-length bytes
     * @param bytes Byte array containing data
     * @param start Starting offset in the array
     * @param len Number of bytes to write
     */
    public void writeBytes(byte[] bytes, int start, int len) throws IOException;
    
    /**
     * Starts writing an array
     */
    public void writeArrayStart() throws IOException;
    
    /**
     * Sets the item count for arrays and maps
     * @param itemCount Number of items to write
     */
    public void setItemCount(long itemCount) throws IOException;
    
    /**
     * Starts writing an individual item
     */
    public void startItem() throws IOException;
    
    /**
     * Ends writing an array
     */
    public void writeArrayEnd() throws IOException;
    
    /**
     * Starts writing a map
     */
    public void writeMapStart() throws IOException;
    
    /**
     * Ends writing a map
     */
    public void writeMapEnd() throws IOException;
    
    /**
     * Writes union index
     * @param unionIndex The union branch index
     */
    public void writeIndex(int unionIndex) throws IOException;
    
    /**
     * Utility method for writing variable-length long count
     * @param out DataOutput stream to write to
     * @param val Variable-length long value to write
     */
    public static void writeVarLongCount(DataOutput out, long val) throws IOException;
}

/**
 * Wrapper for Flink FSDataInputStream to make it compatible with Avro SeekableInput
 */
public class FSDataInputStreamWrapper implements Closeable, SeekableInput {
    
    /**
     * Creates a wrapper around a Flink FSDataInputStream
     * @param stream The FSDataInputStream to wrap
     * @param len Length of the stream in bytes
     */
    public FSDataInputStreamWrapper(FSDataInputStream stream, long len);
    
    /**
     * Returns the length of the stream
     * @return Stream length in bytes
     */
    public long length();
    
    /**
     * Reads data into a byte array
     * @param b Destination byte array
     * @param off Offset in the destination array
     * @param len Maximum number of bytes to read
     * @return Number of bytes actually read
     */
    public int read(byte[] b, int off, int len) throws IOException;
    
    /**
     * Seeks to a specific position in the stream
     * @param p Position to seek to
     */
    public void seek(long p) throws IOException;
    
    /**
     * Returns the current position in the stream
     * @return Current position
     */
    public long tell() throws IOException;
    
    /**
     * Closes the underlying stream
     */
    public void close() throws IOException;
}

// Avro types
import org.apache.avro.Schema;
import org.apache.avro.io.Decoder;
import org.apache.avro.io.Encoder;
import org.apache.avro.file.SeekableInput;
import org.apache.avro.util.Utf8;

// Flink types
import org.apache.flink.api.common.io.FileInputFormat;
import org.apache.flink.api.common.io.FileOutputFormat;
import org.apache.flink.api.common.io.CheckpointableInputFormat;
import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.java.tuple.Tuple2;
import org.apache.flink.core.io.InputSplit;
import org.apache.flink.core.fs.FSDataInputStream;
import org.apache.flink.core.fs.Path;

// Java types
import java.io.DataInput;
import java.io.DataOutput;
import java.io.Closeable;
import java.io.Serializable;
import java.io.IOException;
import java.nio.ByteBuffer;