[GitHub] [pulsar] jiazhai commented on a change in pull request #4403: File system offload

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

jiazhai commented on a change in pull request #4403: File system offload
URL: https://github.com/apache/pulsar/pull/4403#discussion_r293339119
 
 

 ##########
 File path: tiered-storage/file-system/src/main/java/org/apache/bookkeeper/mledger/offload/filesystem/impl/FileStoreBackedReadHandleImpl.java
 ##########
 @@ -0,0 +1,321 @@
+/**
+ * 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.bookkeeper.mledger.offload.filesystem.impl;
+
+import com.google.common.collect.Maps;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.PooledByteBufAllocator;
+import org.apache.bookkeeper.client.BKException;
+import org.apache.bookkeeper.client.api.DigestType;
+import org.apache.bookkeeper.client.api.LastConfirmedAndEntry;
+import org.apache.bookkeeper.client.api.LedgerEntries;
+import org.apache.bookkeeper.client.api.LedgerEntry;
+import org.apache.bookkeeper.client.api.LedgerMetadata;
+import org.apache.bookkeeper.client.api.ReadHandle;
+import org.apache.bookkeeper.client.impl.LedgerEntriesImpl;
+import org.apache.bookkeeper.client.impl.LedgerEntryImpl;
+
+import org.apache.bookkeeper.net.BookieSocketAddress;
+import org.apache.bookkeeper.proto.DataFormats;
+import org.apache.hadoop.io.BytesWritable;
+import org.apache.hadoop.io.LongWritable;
+import org.apache.hadoop.io.MapFile;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+import java.util.NavigableMap;
+import java.util.TreeMap;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.ScheduledExecutorService;
+
+public class FileStoreBackedReadHandleImpl implements ReadHandle {
+    private static final Logger log = LoggerFactory.getLogger(FileStoreBackedReadHandleImpl.class);
+    private final ExecutorService executor;
+    private final MapFile.Reader reader;
+    private final long ledgerId;
+    private final LedgerMetadata ledgerMetadata;
+
+    private FileStoreBackedReadHandleImpl(ExecutorService executor, MapFile.Reader reader, long ledgerId) throws IOException {
+        this.ledgerId = ledgerId;
+        this.executor = executor;
+        this.reader = reader;
+        LongWritable key = new LongWritable();
+        BytesWritable value = new BytesWritable();
+        try {
+            key.set(-1);
+            reader.get(key, value);
+            this.ledgerMetadata = parseLedgerMetadata(value.copyBytes());
+        } catch (IOException e) {
+            log.error("Fail to read LedgerMetadata for key {}",
 
 Review comment:
   Maybe we could define a static var for -1? 
   e.g.
   `public static final  METADATA_KEY_INDEX = -1` ? 

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