HBASE-21874 Bucket cache on Persistent memory

Signed-off-by: Anoop John <anoop.hbase@gmail.com>, Sean Busbey
<busbey@apache.org>

hbase-common/src/main/resources/hbase-default.xml

@@ -925,8 +925,10 @@ possible configurations would overwhelm and obscure the important.
     <name>hbase.bucketcache.ioengine</name>
     <value></value>
     <description>Where to store the contents of the bucketcache. One of: offheap,
-    file, files or mmap. If a file or files, set it to file(s):PATH_TO_FILE.
-    mmap means the content will be in an mmaped file. Use mmap:PATH_TO_FILE.
+    file, files, mmap or pmem. If a file or files, set it to file(s):PATH_TO_FILE.
+    mmap means the content will be in an mmaped file. Use mmap:PATH_TO_FILE. 'pmem'
+    is bucket cache over a file on the persistent memory device.
+    Use pmem:PATH_TO_FILE.
     See http://hbase.apache.org/book.html#offheap.blockcache for more information.
     </description>
   </property>

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/BucketCache.java

@@ -379,7 +379,15 @@ public class BucketCache implements BlockCache, HeapSize {
     } else if (ioEngineName.startsWith("offheap")) {
       return new ByteBufferIOEngine(capacity);
     } else if (ioEngineName.startsWith("mmap:")) {
-      return new FileMmapEngine(ioEngineName.substring(5), capacity);
+      return new ExclusiveMemoryMmapIOEngine(ioEngineName.substring(5), capacity);
+    } else if (ioEngineName.startsWith("pmem:")) {
+      // This mode of bucket cache creates an IOEngine over a file on the persistent memory
+      // device. Since the persistent memory device has its own address space the contents
+      // mapped to this address space does not get swapped out like in the case of mmapping
+      // on to DRAM. Hence the cells created out of the hfile blocks in the pmem bucket cache
+      // can be directly referred to without having to copy them onheap. Once the RPC is done,
+      // the blocks can be returned back as in case of ByteBufferIOEngine.
+      return new SharedMemoryMmapIOEngine(ioEngineName.substring(5), capacity);
     } else {
       throw new IllegalArgumentException(
           "Don't understand io engine name for cache- prefix with file:, files:, mmap: or offheap");

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/ExclusiveMemoryMmapIOEngine.java

@@ -0,0 +1,50 @@
+/**
+ * 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.hadoop.hbase.io.hfile.bucket;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+
+import org.apache.hadoop.hbase.io.hfile.Cacheable;
+import org.apache.hadoop.hbase.io.hfile.Cacheable.MemoryType;
+import org.apache.hadoop.hbase.io.hfile.CacheableDeserializer;
+import org.apache.hadoop.hbase.nio.SingleByteBuff;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * IO engine that stores data to a file on the local block device using memory mapping
+ * mechanism
+ */
+@InterfaceAudience.Private
+public class ExclusiveMemoryMmapIOEngine extends FileMmapIOEngine {
+  static final Logger LOG = LoggerFactory.getLogger(ExclusiveMemoryMmapIOEngine.class);
+
+  public ExclusiveMemoryMmapIOEngine(String filePath, long capacity) throws IOException {
+    super(filePath, capacity);
+  }
+
+  @Override
+  public Cacheable read(long offset, int length, CacheableDeserializer<Cacheable> deserializer)
+      throws IOException {
+    byte[] dst = new byte[length];
+    bufferArray.getMultiple(offset, length, dst);
+    return deserializer.deserialize(new SingleByteBuff(ByteBuffer.wrap(dst)), true,
+      MemoryType.EXCLUSIVE);
+  }
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/FileMmapIOEngine.java

@@ -1,20 +1,19 @@
 /**
- * Copyright The Apache Software Foundation
+ * 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
  *
- * 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
+ *     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.
+ * 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.hadoop.hbase.io.hfile.bucket;
 
@@ -24,33 +23,31 @@ import java.nio.ByteBuffer;
 import java.nio.channels.FileChannel;
 import java.util.concurrent.atomic.AtomicInteger;
 
-import org.apache.yetus.audience.InterfaceAudience;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
 import org.apache.hadoop.hbase.io.hfile.Cacheable;
-import org.apache.hadoop.hbase.io.hfile.Cacheable.MemoryType;
 import org.apache.hadoop.hbase.io.hfile.CacheableDeserializer;
 import org.apache.hadoop.hbase.nio.ByteBuff;
-import org.apache.hadoop.hbase.nio.SingleByteBuff;
 import org.apache.hadoop.hbase.util.ByteBufferAllocator;
 import org.apache.hadoop.hbase.util.ByteBufferArray;
 import org.apache.hadoop.util.StringUtils;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 /**
- * IO engine that stores data to a file on the local file system using memory mapping
+ * IO engine that stores data to a file on the specified file system using memory mapping
  * mechanism
  */
 @InterfaceAudience.Private
-public class FileMmapEngine implements IOEngine {
-  static final Logger LOG = LoggerFactory.getLogger(FileMmapEngine.class);
+public abstract class FileMmapIOEngine implements IOEngine {
+  static final Logger LOG = LoggerFactory.getLogger(FileMmapIOEngine.class);
 
-  private final String path;
-  private long size;
-  private ByteBufferArray bufferArray;
+  protected final String path;
+  protected long size;
+  protected ByteBufferArray bufferArray;
   private final FileChannel fileChannel;
   private RandomAccessFile raf = null;
 
-  public FileMmapEngine(String filePath, long capacity) throws IOException {
+  public FileMmapIOEngine(String filePath, long capacity) throws IOException {
     this.path = filePath;
     this.size = capacity;
     long fileSize = 0;
@@ -64,13 +61,15 @@ public class FileMmapEngine implements IOEngine {
       LOG.error("Can't create bucket cache file " + filePath, fex);
       throw fex;
     } catch (IOException ioex) {
-      LOG.error("Can't extend bucket cache file; insufficient space for "
-          + StringUtils.byteDesc(fileSize), ioex);
+      LOG.error(
+        "Can't extend bucket cache file; insufficient space for " + StringUtils.byteDesc(fileSize),
+        ioex);
       shutdown();
       throw ioex;
     }
     ByteBufferAllocator allocator = new ByteBufferAllocator() {
       AtomicInteger pos = new AtomicInteger(0);
+
       @Override
       public ByteBuffer allocate(long size) throws IOException {
         ByteBuffer buffer = fileChannel.map(java.nio.channels.FileChannel.MapMode.READ_WRITE,
@@ -87,8 +86,8 @@ public class FileMmapEngine implements IOEngine {
 
   @Override
   public String toString() {
-    return "ioengine=" + this.getClass().getSimpleName() + ", path=" + this.path +
-      ", size=" + String.format("%,d", this.size);
+    return "ioengine=" + this.getClass().getSimpleName() + ", path=" + this.path + ", size="
+        + String.format("%,d", this.size);
   }
 
   /**
@@ -97,17 +96,13 @@ public class FileMmapEngine implements IOEngine {
    */
   @Override
   public boolean isPersistent() {
+    // TODO : HBASE-21981 needed for persistence to really work
     return true;
   }
 
   @Override
-  public Cacheable read(long offset, int length, CacheableDeserializer<Cacheable> deserializer)
-      throws IOException {
-    byte[] dst = new byte[length];
-    bufferArray.getMultiple(offset, length, dst);
-    return deserializer.deserialize(new SingleByteBuff(ByteBuffer.wrap(dst)), true,
-      MemoryType.EXCLUSIVE);
-  }
+  public abstract Cacheable read(long offset, int length,
+      CacheableDeserializer<Cacheable> deserializer) throws IOException;
 
   /**
    * Transfers data from the given byte buffer to file
@@ -119,7 +114,7 @@ public class FileMmapEngine implements IOEngine {
   public void write(ByteBuffer srcBuffer, long offset) throws IOException {
     assert srcBuffer.hasArray();
     bufferArray.putMultiple(offset, srcBuffer.remaining(), srcBuffer.array(),
-        srcBuffer.arrayOffset());
+      srcBuffer.arrayOffset());
   }
 
   @Override
@@ -127,9 +122,9 @@ public class FileMmapEngine implements IOEngine {
     // This singleByteBuff can be considered to be array backed
     assert srcBuffer.hasArray();
     bufferArray.putMultiple(offset, srcBuffer.remaining(), srcBuffer.array(),
-        srcBuffer.arrayOffset());
-
+      srcBuffer.arrayOffset());
   }
+
   /**
    * Sync the data to file after writing
    * @throws IOException

hbase-server/src/main/java/org/apache/hadoop/hbase/io/hfile/bucket/SharedMemoryMmapIOEngine.java

@@ -0,0 +1,64 @@
+/**
+ * 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.hadoop.hbase.io.hfile.bucket;
+
+import java.io.IOException;
+
+import org.apache.hadoop.hbase.io.hfile.Cacheable;
+import org.apache.hadoop.hbase.io.hfile.Cacheable.MemoryType;
+import org.apache.hadoop.hbase.io.hfile.CacheableDeserializer;
+import org.apache.hadoop.hbase.nio.ByteBuff;
+import org.apache.yetus.audience.InterfaceAudience;
+
+/**
+ * IO engine that stores data in pmem devices such as DCPMM. This engine also mmaps the file from
+ * the given path. But note that this path has to be a path on the pmem device so that when mmapped
+ * the file's address is mapped to the Pmem's address space and not in the DRAM. Since this address
+ * space is exclusive for the Pmem device there is no swapping out of the mmapped contents that
+ * generally happens when DRAM's free space is not enough to hold the specified file's mmapped
+ * contents. This gives us the option of using the {@code MemoryType#SHARED} type when serving the
+ * data from this pmem address space. We need not copy the blocks to the onheap space as we need to
+ * do for the case of {@code ExclusiveMemoryMmapIOEngine}.
+ */
+@InterfaceAudience.Private
+public class SharedMemoryMmapIOEngine extends FileMmapIOEngine {
+
+  // TODO this will support only one path over Pmem. To make use of multiple Pmem devices mounted,
+  // we need to support multiple paths like files IOEngine. Support later.
+  public SharedMemoryMmapIOEngine(String filePath, long capacity) throws IOException {
+    super(filePath, capacity);
+  }
+
+  @Override
+  public boolean usesSharedMemory() {
+    return true;
+  }
+
+  @Override
+  public Cacheable read(long offset, int length, CacheableDeserializer<Cacheable> deserializer)
+      throws IOException {
+    ByteBuff dstBuffer = bufferArray.asSubByteBuff(offset, length);
+    // Here the buffer that is created directly refers to the buffer in the actual buckets.
+    // When any cell is referring to the blocks created out of these buckets then it means that
+    // those cells are referring to a shared memory area which if evicted by the BucketCache would
+    // lead to corruption of results. Hence we set the type of the buffer as SHARED_MEMORY
+    // so that the readers using this block are aware of this fact and do the necessary action
+    // to prevent eviction till the results are either consumed or copied
+    return deserializer.deserialize(dstBuffer, true, MemoryType.SHARED);
+  }
+}

hbase-server/src/test/java/org/apache/hadoop/hbase/io/hfile/bucket/TestExclusiveMemoryMmapEngine.java

@@ -32,21 +32,21 @@ import org.junit.Test;
 import org.junit.experimental.categories.Category;
 
 /**
- * Basic test for {@link FileMmapEngine}
+ * Basic test for {@link ExclusiveMemoryMmapIOEngine}
  */
 @Category({IOTests.class, SmallTests.class})
-public class TestFileMmapEngine {
+public class TestExclusiveMemoryMmapEngine {
 
   @ClassRule
   public static final HBaseClassTestRule CLASS_RULE =
-      HBaseClassTestRule.forClass(TestFileMmapEngine.class);
+      HBaseClassTestRule.forClass(TestExclusiveMemoryMmapEngine.class);
 
   @Test
   public void testFileMmapEngine() throws IOException {
     int size = 2 * 1024 * 1024; // 2 MB
     String filePath = "testFileMmapEngine";
     try {
-      FileMmapEngine fileMmapEngine = new FileMmapEngine(filePath, size);
+      ExclusiveMemoryMmapIOEngine fileMmapEngine = new ExclusiveMemoryMmapIOEngine(filePath, size);
       for (int i = 0; i < 50; i++) {
         int len = (int) Math.floor(Math.random() * 100);
         long offset = (long) Math.floor(Math.random() * size % (size - len));

src/main/asciidoc/_chapters/architecture.adoc

@@ -733,6 +733,8 @@ See configurations, sizings, current usage, time-in-the-cache, and even detail o
 
 `LruBlockCache` is the original implementation, and is entirely within the Java heap.
 `BucketCache` is optional and mainly intended for keeping block cache data off-heap, although `BucketCache` can also be a file-backed cache.
+ In file-backed we can either use it in the file mode or the mmaped mode.
+ We also have pmem mode where the bucket cache resides on the persistent memory device.
 
 When you enable BucketCache, you are enabling a two tier caching system. We used to describe the
 tiers as "L1" and "L2" but have deprecated this terminology as of hbase-2.0.0. The "L1" cache referred to an

src/main/asciidoc/_chapters/hbase-default.adoc

@@ -1197,10 +1197,13 @@ When the size of a leaf-level, intermediate-level, or root-level
 *`hbase.bucketcache.ioengine`*::
 +
 .Description
-Where to store the contents of the bucketcache. One of: onheap,
-      offheap, or file. If a file, set it to file:PATH_TO_FILE.
-      See https://hbase.apache.org/devapidocs/org/apache/hadoop/hbase/io/hfile/CacheConfig.html
-      for more information.
+Where to store the contents of the bucketcache. One of: offheap,
+    file, files, mmap or pmem. If a file or files, set it to file(s):PATH_TO_FILE.
+    mmap means the content will be in an mmaped file. Use mmap:PATH_TO_FILE.
+    'pmem' is bucket cache over a file on the persistent memory device.
+    Use pmem:PATH_TO_FILE.
+    See https://hbase.apache.org/devapidocs/org/apache/hadoop/hbase/io/hfile/CacheConfig.html
+    for more information.
 
 +
 .Default