org.jclouds.glacier.util.TreeHash Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of glacier Show documentation
jclouds components to access an implementation of glacier
There is a newer version: 2.4.0
/*
 * 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.jclouds.glacier.util;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static org.jclouds.util.Closeables2.closeQuietly;

import java.io.IOException;
import java.io.InputStream;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;

import org.jclouds.io.Payload;

import com.google.common.base.Objects;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableList.Builder;
import com.google.common.collect.ImmutableSortedMap;
import com.google.common.hash.HashCode;
import com.google.common.hash.Hashing;
import com.google.common.hash.HashingInputStream;
import com.google.common.io.ByteStreams;

public final class TreeHash {
   private static final int CHUNK_SIZE = 1024 * 1024;

   private final HashCode treeHash;
   private final HashCode linearHash;

   private TreeHash(HashCode treeHash, HashCode linearHash) {
      this.treeHash = checkNotNull(treeHash, "treeHash");
      this.linearHash = checkNotNull(linearHash, "linearHash");
   }

   public HashCode getLinearHash() {
      return linearHash;
   }

   public HashCode getTreeHash() {
      return treeHash;
   }

   @Override
   public int hashCode() {
      return Objects.hashCode(this.treeHash, this.linearHash);
   }

   @Override
   public boolean equals(Object obj) {
      if (obj == null)
         return false;
      if (getClass() != obj.getClass())
         return false;
      TreeHash other = (TreeHash) obj;
      return Objects.equal(this.treeHash, other.treeHash) && Objects.equal(this.linearHash, other.linearHash);
   }

   @Override
   public String toString() {
      return "TreeHash [treeHash=" + treeHash + ", linearHash=" + linearHash + "]";
   }

   private static HashCode hashList(Collection hashList) {
      Builder result = ImmutableList.builder();
      while (hashList.size() > 1) {
         //Hash pairs of values and add them to the result list.
         for (Iterator it = hashList.iterator(); it.hasNext();) {
            HashCode hc1 = it.next();
            if (it.hasNext()) {
                HashCode hc2 = it.next();
                result.add(Hashing.sha256().newHasher()
                      .putBytes(hc1.asBytes())
                      .putBytes(hc2.asBytes())
                      .hash());
            } else {
               result.add(hc1);
            }
         }
         hashList = result.build();
         result = ImmutableList.builder();
      }
      return hashList.iterator().next();
   }

   /**
    * Builds the Hash and the TreeHash values of the payload.
    *
    * @return The calculated TreeHash.
    * @see 
    */
   public static TreeHash buildTreeHashFromPayload(Payload payload) throws IOException {
      InputStream is = null;
      try {
         is = checkNotNull(payload, "payload").openStream();
         Builder list = ImmutableList.builder();
         HashingInputStream linearHis = new HashingInputStream(Hashing.sha256(), is);
         while (true) {
             HashingInputStream chunkedHis = new HashingInputStream(
                     Hashing.sha256(), ByteStreams.limit(linearHis, CHUNK_SIZE));
             long count = ByteStreams.copy(chunkedHis, ByteStreams.nullOutputStream());
             if (count == 0) {
                 break;
             }
             list.add(chunkedHis.hash());
         }
         //The result list contains exactly one element now.
         return new TreeHash(hashList(list.build()), linearHis.hash());
      } finally {
         closeQuietly(is);
      }
   }

   /**
    * Builds a TreeHash based on a map of hashed chunks.
    *
    * @return The calculated TreeHash.
    * @see 
    */
   public static HashCode buildTreeHashFromMap(Map map) {
      checkArgument(!map.isEmpty(), "The map cannot be empty.");
      return hashList(ImmutableSortedMap.copyOf(map).values());
   }
}