[#1459] Added data sink/source for Parquet

gradoop-checkstyle/src/main/resources/gradoop/checkstyle-suppressions.xml

@@ -52,4 +52,8 @@
             files="[/\\]src[/\\]test[/\\]java[/\\]"/>
   <suppress checks="StaticVariableName"
             files="[/\\]src[/\\]test[/\\]java[/\\]"/>
+
+  <!-- no checkstyle for auto generated code -->
+  <suppress checks=".*"
+            files="[/\\]target[/\\]generated-sources[/\\]"/>
 </suppressions>

gradoop-flink/pom.xml

@@ -54,6 +54,10 @@
 
     <build>
         <plugins>
+            <plugin>
+                <groupId>com.github.os72</groupId>
+                <artifactId>protoc-jar-maven-plugin</artifactId>
+            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-compiler-plugin</artifactId>
@@ -124,6 +128,12 @@
             <artifactId>flink-shaded-hadoop-2</artifactId>
 	    </dependency>
 
+        <!-- Parquet -->
+        <dependency>
+            <groupId>org.apache.parquet</groupId>
+            <artifactId>parquet-protobuf</artifactId>
+        </dependency>
+
         <!-- Test dependencies -->
 
         <!-- Gradoop -->

gradoop-flink/src/main/java/org/gradoop/flink/io/impl/parquet/common/HadoopValueInputFormat.java

@@ -0,0 +1,77 @@
+/*
+ * Copyright © 2014 - 2021 Leipzig University (Database Research Group)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.gradoop.flink.io.impl.parquet.common;
+
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.api.java.hadoop.mapreduce.HadoopInputFormatBase;
+import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
+import org.apache.hadoop.mapreduce.InputFormat;
+import org.apache.hadoop.mapreduce.Job;
+
+import java.io.IOException;
+
+/**
+ * InputFormat implementation allowing to use Hadoop (mapreduce) InputFormats which don't provide a key with
+ * Flink.
+ *
+ * @param <T> Value Type
+ */
+public class HadoopValueInputFormat<T> extends HadoopInputFormatBase<Void, T, T> implements
+  ResultTypeQueryable<T> {
+
+  /**
+   * Creates a new Flink input format.
+   *
+   * @param mapreduceInputFormat  Hadoop (mapreduce) input format
+   * @param value value type class
+   * @param job job instance for configuration
+   */
+  public HadoopValueInputFormat(InputFormat<Void, T> mapreduceInputFormat, Class<T> value, Job job) {
+    super(mapreduceInputFormat, Void.class, value, job);
+  }
+
+  @Override
+  public T nextRecord(T record) throws IOException {
+    if (!this.fetched) {
+      fetchNext();
+    }
+    if (!this.hasNext) {
+      return null;
+    }
+    try {
+      record = recordReader.getCurrentValue();
+    } catch (InterruptedException e) {
+      throw new IOException("Could not get KeyValue pair.", e);
+    }
+    this.fetched = false;
+
+    return record;
+  }
+
+  @Override
+  public TypeInformation<T> getProducedType() {
+    return TypeInformation.of(this.valueClass);
+  }
+
+  @Override
+  public String toString() {
+    String jobName = this.getConfiguration().get("mapreduce.job.name");
+    if (jobName != null) {
+      return String.format("HadoopValueInputFormat[%s]", jobName);
+    }
+    return super.toString();
+  }
+}

gradoop-flink/src/main/java/org/gradoop/flink/io/impl/parquet/common/HadoopValueOutputFormat.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright © 2014 - 2021 Leipzig University (Database Research Group)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.gradoop.flink.io.impl.parquet.common;
+
+import org.apache.flink.api.java.hadoop.mapreduce.HadoopOutputFormatBase;
+import org.apache.hadoop.mapreduce.Job;
+import org.apache.hadoop.mapreduce.OutputFormat;
+
+import java.io.IOException;
+
+/**
+ * OutputFormat implementation allowing to use Hadoop (mapreduce) OutputFormats which don't provide a key
+ * with Flink.
+ *
+ * @param <T> Value Type
+ */
+public class HadoopValueOutputFormat<T> extends HadoopOutputFormatBase<Void, T, T> {
+
+  /**
+   * Creates a new Flink output format.
+   *
+   * @param mapreduceOutputFormat Hadoop (mapreduce) output format
+   * @param job job instance for configuration
+   */
+  public HadoopValueOutputFormat(OutputFormat<Void, T> mapreduceOutputFormat, Job job) {
+    super(mapreduceOutputFormat, job);
+  }
+
+  @Override
+  public void writeRecord(T record) throws IOException {
+    try {
+      this.recordWriter.write(null, record);
+    } catch (InterruptedException e) {
+      throw new IOException("Could not write Record.", e);
+    }
+  }
+
+  @Override
+  public String toString() {
+    String jobName = this.getConfiguration().get("mapreduce.job.name");
+    if (jobName != null) {
+      return String.format("HadoopValueOutputFormat[%s]", jobName);
+    }
+    return super.toString();
+  }
+}

gradoop-flink/src/main/java/org/gradoop/flink/io/impl/parquet/common/ParquetOutputFormatWithMode.java

@@ -0,0 +1,64 @@
+/*
+ * Copyright © 2014 - 2021 Leipzig University (Database Research Group)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.gradoop.flink.io.impl.parquet.common;
+
+import org.apache.hadoop.mapreduce.JobContext;
+import org.apache.hadoop.mapreduce.RecordWriter;
+import org.apache.hadoop.mapreduce.TaskAttemptContext;
+import org.apache.parquet.hadoop.ParquetFileWriter;
+import org.apache.parquet.hadoop.ParquetOutputFormat;
+import org.apache.parquet.hadoop.util.ContextUtil;
+
+import java.io.IOException;
+
+/**
+ * Extension of the {@link ParquetOutputFormat<T>} that allows specifying a file creation mode.
+ *
+ * @param <T> the type of the materialized records
+ */
+public class ParquetOutputFormatWithMode<T> extends ParquetOutputFormat<T> {
+
+  /**
+   * File creation mode configuration key
+   */
+  private static final String PARQUET_WRITER_MODE = "parquet.writer.mode";
+
+  /**
+   * Sets the file creation mode of a {@link JobContext}.
+   *
+   * @param context the job's context
+   * @param mode the file creation mode
+   */
+  public static void setFileCreationMode(JobContext context, ParquetFileWriter.Mode mode) {
+    ContextUtil.getConfiguration(context).setEnum(PARQUET_WRITER_MODE, mode);
+  }
+
+  /**
+   * Gets the file creation mode of a {@link JobContext}.
+   *
+   * @param context the job's context
+   * @return the specified mode or defaults to {@link ParquetFileWriter.Mode#CREATE} if not found
+   */
+  public static ParquetFileWriter.Mode getFileCreationMode(JobContext context) {
+    return ContextUtil.getConfiguration(context).getEnum(PARQUET_WRITER_MODE, ParquetFileWriter.Mode.CREATE);
+  }
+
+  @Override
+  public RecordWriter<Void, T> getRecordWriter(TaskAttemptContext taskAttemptContext) throws IOException,
+    InterruptedException {
+    return super.getRecordWriter(taskAttemptContext, getFileCreationMode(taskAttemptContext));
+  }
+}

gradoop-flink/src/main/java/org/gradoop/flink/io/impl/parquet/common/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright © 2014 - 2021 Leipzig University (Database Research Group)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/**
+ * Contains all commonly used classes related to parquet input and output to Flink.
+ */
+package org.gradoop.flink.io.impl.parquet.common;

gradoop-flink/src/main/java/org/gradoop/flink/io/impl/parquet/package-info.java

@@ -0,0 +1,19 @@
+/*
+ * Copyright © 2014 - 2021 Leipzig University (Database Research Group)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/**
+ * Contains all classes related to parquet input and output to Flink.
+ */
+package org.gradoop.flink.io.impl.parquet;