add missing file for HDFS-5096

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/HDFS-4949@1532925 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/CachedBlock.java

@@ -0,0 +1,249 @@
+/**
+ * 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.hdfs.server.namenode;
+
+import java.util.Arrays;
+import java.util.LinkedList;
+import java.util.List;
+
+import org.apache.hadoop.classification.InterfaceAudience;
+import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor;
+import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor.CachedBlocksList;
+import org.apache.hadoop.hdfs.server.blockmanagement.DatanodeDescriptor.CachedBlocksList.Type;
+import org.apache.hadoop.util.IntrusiveCollection;
+import org.apache.hadoop.util.LightWeightGSet;
+import org.apache.hadoop.util.IntrusiveCollection.Element;
+import org.apache.hadoop.util.LightWeightGSet.LinkedElement;
+
+/**
+ * Represents a cached block.
+ */
+@InterfaceAudience.LimitedPrivate({"HDFS"})
+public final class CachedBlock implements Element, 
+    LightWeightGSet.LinkedElement {
+  private static final Object[] EMPTY_ARRAY = new Object[0];
+
+  /**
+   * Block id.
+   */
+  private final long blockId;
+
+  /**
+   * Used to implement #{LightWeightGSet.LinkedElement}
+   */
+  private LinkedElement nextElement;
+
+  /**
+   * Bit 15: Mark
+   * Bit 0-14: cache replication factor.
+   */
+  private short replicationAndMark;
+
+  /**
+   * Used to implement the CachedBlocksList.
+   *
+   * Since this CachedBlock can be in multiple CachedBlocksList objects,
+   * we need to be able to store multiple 'prev' and 'next' pointers.
+   * The triplets array does this.
+   *
+   * Each triplet contains a CachedBlockList object followed by a
+   * prev pointer, followed by a next pointer.
+   */
+  private Object[] triplets;
+
+  public CachedBlock(long blockId, short replication, boolean mark) {
+    this.blockId = blockId;
+    this.triplets = EMPTY_ARRAY;
+    setReplicationAndMark(replication, mark);
+  }
+
+  public long getBlockId() {
+    return blockId;
+  }
+
+  @Override
+  public int hashCode() {
+    return (int)(blockId^(blockId>>>32));
+  }
+
+  @Override
+  public boolean equals(Object o) {
+    if (o.getClass() != this.getClass()) {
+      return false;
+    }
+    CachedBlock other = (CachedBlock)o;
+    return other.blockId == blockId;
+  }
+
+  public void setReplicationAndMark(short replication, boolean mark) {
+    assert replication >= 0;
+    replicationAndMark = (short)((replication << 1) | (mark ? 0x1 : 0x0));
+  }
+
+  public boolean getMark() {
+    return ((replicationAndMark & 0x1) != 0);
+  }
+
+  public short getReplication() {
+    return (short)(replicationAndMark >>> 1);
+  }
+
+  /**
+   * Return true if this CachedBlock is present on the given list.
+   */
+  public boolean isPresent(CachedBlocksList cachedBlocksList) {
+    for (int i = 0; i < triplets.length; i += 3) {
+      CachedBlocksList list = (CachedBlocksList)triplets[i];
+      if (list == cachedBlocksList) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  /**
+   * Get a list of the datanodes which this block is cached,
+   * planned to be cached, or planned to be uncached on.
+   *
+   * @param type      If null, this parameter is ignored.
+   *                  If it is non-null, we match only datanodes which
+   *                  have it on this list.
+   *                  See {@link DatanodeDescriptor#CachedBlocksList#Type}
+   *                  for a description of all the lists.
+   *                  
+   * @return          The list of datanodes.  Modifying this list does not
+   *                  alter the state of the CachedBlock.
+   */
+  public List<DatanodeDescriptor> getDatanodes(Type type) {
+    List<DatanodeDescriptor> nodes = new LinkedList<DatanodeDescriptor>();
+    for (int i = 0; i < triplets.length; i += 3) {
+      CachedBlocksList list = (CachedBlocksList)triplets[i];
+      if ((type == null) || (list.getType() == type)) {
+        nodes.add(list.getDatanode());
+      }
+    }
+    return nodes;
+  }
+
+  @Override
+  public void insertInternal(IntrusiveCollection<? extends Element> list, Element prev,
+      Element next) {
+    for (int i = 0; i < triplets.length; i += 3) {
+      if (triplets[i] == list) {
+        throw new RuntimeException("Trying to re-insert an element that " +
+            "is already in the list.");
+      }
+    }
+    Object newTriplets[] = Arrays.copyOf(triplets, triplets.length + 3);
+    newTriplets[triplets.length] = list;
+    newTriplets[triplets.length + 1] = prev;
+    newTriplets[triplets.length + 2] = next;
+    triplets = newTriplets;
+  }
+  
+  @Override
+  public void setPrev(IntrusiveCollection<? extends Element> list, Element prev) {
+    for (int i = 0; i < triplets.length; i += 3) {
+      if (triplets[i] == list) {
+        triplets[i + 1] = prev;
+        return;
+      }
+    }
+    throw new RuntimeException("Called setPrev on an element that wasn't " +
+        "in the list.");
+  }
+
+  @Override
+  public void setNext(IntrusiveCollection<? extends Element> list, Element next) {
+    for (int i = 0; i < triplets.length; i += 3) {
+      if (triplets[i] == list) {
+        triplets[i + 2] = next;
+        return;
+      }
+    }
+    throw new RuntimeException("Called setNext on an element that wasn't " +
+        "in the list.");
+  }
+
+  @Override
+  public void removeInternal(IntrusiveCollection<? extends Element> list) {
+    for (int i = 0; i < triplets.length; i += 3) {
+      if (triplets[i] == list) {
+        Object[] newTriplets = new Object[triplets.length - 3];
+        System.arraycopy(triplets, 0, newTriplets, 0, i);
+        System.arraycopy(triplets, i + 3, newTriplets, i,
+            triplets.length - (i + 3));
+        triplets = newTriplets;
+        return;
+      }
+    }
+    throw new RuntimeException("Called remove on an element that wasn't " +
+        "in the list.");
+  }
+
+  @Override
+  public Element getPrev(IntrusiveCollection<? extends Element> list) {
+    for (int i = 0; i < triplets.length; i += 3) {
+      if (triplets[i] == list) {
+        return (Element)triplets[i + 1];
+      }
+    }
+    throw new RuntimeException("Called getPrev on an element that wasn't " +
+        "in the list.");
+  }
+
+  @Override
+  public Element getNext(IntrusiveCollection<? extends Element> list) {
+    for (int i = 0; i < triplets.length; i += 3) {
+      if (triplets[i] == list) {
+        return (Element)triplets[i + 2];
+      }
+    }
+    throw new RuntimeException("Called getNext on an element that wasn't " +
+        "in the list.");
+  }
+
+  @Override
+  public boolean isInList(IntrusiveCollection<? extends Element> list) {
+    for (int i = 0; i < triplets.length; i += 3) {
+      if (triplets[i] == list) {
+        return true;
+      }
+    }
+    return false;
+  }
+  
+  @Override
+  public String toString() {
+    return new StringBuilder().append("{").
+        append("blockId=").append(blockId).append(", ").
+        append("replication=").append(getReplication()).append(", ").
+        append("mark=").append(getMark()).append("}").
+        toString();
+  }
+
+  @Override // LightWeightGSet.LinkedElement 
+  public void setNext(LinkedElement next) {
+    this.nextElement = next;
+  }
+
+  @Override // LightWeightGSet.LinkedElement 
+  public LinkedElement getNext() {
+    return nextElement;
+  }
+}