write part files directly into the target directory on S3 file systems

Author: martin-boettcher

calvalus-processing/src/main/java/com/bc/calvalus/processing/beam/S3aCompatibleSequenceFileOutputFormat.java

@@ -0,0 +1,118 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 com.bc.calvalus.processing.beam;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.classification.InterfaceStability;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.io.SequenceFile;
+import org.apache.hadoop.io.SequenceFile.CompressionType;
+import org.apache.hadoop.io.compress.CompressionCodec;
+import org.apache.hadoop.io.compress.DefaultCodec;
+import org.apache.hadoop.mapreduce.Job;
+import org.apache.hadoop.mapreduce.JobContext;
+import org.apache.hadoop.mapreduce.OutputFormat;
+import org.apache.hadoop.mapreduce.RecordWriter;
+import org.apache.hadoop.mapreduce.TaskAttemptContext;
+import org.apache.hadoop.mapreduce.lib.output.FileOutputFormat;
+import org.apache.hadoop.util.ReflectionUtils;
+
+import java.io.IOException;
+
+/** An {@link OutputFormat} that writes {@link SequenceFile}s. */
+@InterfaceAudience.Public
+@InterfaceStability.Stable
+public class S3aCompatibleSequenceFileOutputFormat<K,V> extends S3aCompatibleOutputFormat<K, V> {
+
+  protected SequenceFile.Writer getSequenceWriter(TaskAttemptContext context,
+      Class<?> keyClass, Class<?> valueClass) 
+      throws IOException {
+    Configuration conf = context.getConfiguration();
+	    
+    CompressionCodec codec = null;
+    CompressionType compressionType = CompressionType.NONE;
+    if (getCompressOutput(context)) {
+      // find the kind of compression to do
+      compressionType = getOutputCompressionType(context);
+      // find the right codec
+      Class<?> codecClass = getOutputCompressorClass(context, 
+                                                     DefaultCodec.class);
+      codec = (CompressionCodec) 
+        ReflectionUtils.newInstance(codecClass, conf);
+    }
+    // get the path of the temporary output file 
+    Path file = getDefaultWorkFile(context, "");
+    FileSystem fs = file.getFileSystem(conf);
+    return SequenceFile.createWriter(fs, conf, file,
+             keyClass,
+             valueClass,
+             compressionType,
+             codec,
+             context);
+  }
+  
+  public RecordWriter<K, V> 
+         getRecordWriter(TaskAttemptContext context
+                         ) throws IOException, InterruptedException {
+    final SequenceFile.Writer out = getSequenceWriter(context,
+      context.getOutputKeyClass(), context.getOutputValueClass());
+
+    return new RecordWriter<K, V>() {
+
+        public void write(K key, V value)
+          throws IOException {
+
+          out.append(key, value);
+        }
+
+        public void close(TaskAttemptContext context) throws IOException { 
+          out.close();
+        }
+      };
+  }
+
+  /**
+   * Get the {@link CompressionType} for the output {@link SequenceFile}.
+   * @param job the {@link Job}
+   * @return the {@link CompressionType} for the output {@link SequenceFile}, 
+   *         defaulting to {@link CompressionType#RECORD}
+   */
+  public static CompressionType getOutputCompressionType(JobContext job) {
+    String val = job.getConfiguration().get(FileOutputFormat.COMPRESS_TYPE, 
+                                            CompressionType.RECORD.toString());
+    return CompressionType.valueOf(val);
+  }
+  
+  /**
+   * Set the {@link CompressionType} for the output {@link SequenceFile}.
+   * @param job the {@link Job} to modify
+   * @param style the {@link CompressionType} for the output
+   *              {@link SequenceFile} 
+   */
+  public static void setOutputCompressionType(Job job, 
+		                                          CompressionType style) {
+    setCompressOutput(job, true);
+    job.getConfiguration().set(FileOutputFormat.COMPRESS_TYPE, 
+                               style.toString());
+  }
+
+}
+