[GitHub] [incubator-ratis] ankitsinghal commented on a change in pull request #25: RATIS-588 LogStream StateMachine export

[GitBox <gi...@apache.org>]

ankitsinghal commented on a change in pull request #25: RATIS-588 LogStream StateMachine export
URL: https://github.com/apache/incubator-ratis/pull/25#discussion_r295016811
 
 

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 File path: ratis-logservice/src/main/java/org/apache/ratis/logservice/impl/ArchiveHdfsLogReader.java
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+/**
+ * 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 org.apache.ratis.logservice.impl;
+
+import java.io.EOFException;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+import java.util.NoSuchElementException;
+
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.fs.FSDataInputStream;
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.ratis.logservice.api.ArchiveLogReader;
+import org.apache.ratis.logservice.api.LogName;
+import org.apache.ratis.thirdparty.com.google.common.base.Preconditions;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Archive Log Reader implementation. This class is not thread-safe
+ *
+ */
+
+public class ArchiveHdfsLogReader implements ArchiveLogReader {
+  public static final Logger LOG = LoggerFactory.getLogger(ArchiveHdfsLogReader.class);
+  private long fileLength;
+  private List<FileStatus> files;
+  private FileSystem hdfs;
+  private FSDataInputStream is;
+  private ByteBuffer currentRecord;
+  private int fileCounter=0;
+  private int currentRecordId = -1;
+
+  public ArchiveHdfsLogReader(String archiveLocation) throws IOException {
+    Configuration configuration = new Configuration();
+    this.hdfs = FileSystem.get(configuration);
+    Path archiveLocationPath=new Path(archiveLocation);
+    if (!hdfs.exists(archiveLocationPath)) {
+      throw new FileNotFoundException(archiveLocation);
+    }
+    files = Arrays.asList(hdfs.listStatus(archiveLocationPath));
+    Collections.sort(files, new Comparator<FileStatus>() {
+      @Override public int compare(FileStatus o1, FileStatus o2) {
+        //ascending order
+        return o1.getPath().getName().compareTo(o2.getPath().getName());
+      }
+    });
+    openNextFilePath();
+    loadNext();
+  }
+
+  public Path openNextFilePath() throws IOException {
+    Path filePath = files.get(fileCounter).getPath();
+    this.is = this.hdfs.open(filePath);
+    this.fileLength = this.hdfs.getFileStatus(filePath).getLen();
+    fileCounter++;
+    return filePath;
+
+  }
+
+  @Override public void seek(long recordId) throws IOException {
+    while (currentRecordId < recordId && hasNext()) {
+      next();
+    }
+  }
+
+  @Override public boolean hasNext() throws IOException {
+    return currentRecord != null;
+  }
+
+  @Override public byte[] next() throws IOException {
+    return readNext().array();
+  }
+
+  @Override public long getCurrentRaftIndex() {
+    return 0;
+  }
+
+  @Override public ByteBuffer readNext() throws IOException {
+    if (currentRecord == null) {
+      throw new NoSuchElementException();
+    }
+    ByteBuffer current = currentRecord;
+    currentRecord = null;
+    loadNext();
+    return current;
+  }
+
+  private int readLength() throws IOException {
+    int length;
+    try {
+      length = is.readInt();
+    }catch (EOFException e){
+      if (files.size()==fileCounter) {
+        throw e;
+      }else {
+        openNextFilePath();
+        length = is.readInt();
+      }
+    }
+    return length;
+  }
+
+  @Override public void readNext(ByteBuffer buffer) throws IOException {
+    Preconditions.checkNotNull(buffer, "buffer is NULL");
+    buffer.put(readNext().array());
+  }
+
+  @Override public List<ByteBuffer> readBulk(int numRecords) throws IOException {
+    Preconditions.checkArgument(numRecords > 0, "number of records must be greater than 0");
+    List<ByteBuffer> ret = new ArrayList<ByteBuffer>();
+    try {
+
+      for (int i = 0; i < numRecords; i++) {
+        ByteBuffer buffer = readNext();
+        ret.add(buffer);
+      }
+
+    } catch (EOFException eof) {
+    } catch (Exception e) {
+      throw new IOException(e);
+    } finally {
+      return ret;
+    }
+  }
+
+  @Override public int readBulk(ByteBuffer[] buffers) throws IOException {
+    Preconditions.checkNotNull(buffers, "list of buffers is NULL");
+    Preconditions.checkArgument(buffers.length > 0, "list of buffers is empty");
+    int count = 0;
+    try {
+      for (int i = 0; i < buffers.length; i++) {
+        buffers[i] = readNext();
+        count++;
+      }
+    } catch (EOFException eof) {
+
+    }
+    return count;
+  }
+
+  @Override public long getPosition() throws IOException {
+    return currentRecordId;
+  }
+
+  @Override public void close() throws IOException {
+    if (this.is != null) {
+      this.is.close();
+      this.is = null;
+    }
+  }
+
+  private void loadNext() throws IOException {
+    try {
+      ByteBuffer buff = ByteBuffer.allocate(readLength());
+      is.read(buff.array());
+      currentRecordId++;
+      currentRecord = buff;
+    } catch (EOFException e) {
+      currentRecord = null;
 
 Review comment:
   A good catch.. thanks 

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