content: /*
   * The Alluxio Open Foundation licenses this work under the Apache License, version 2.0
   * (the "License"). You may not use this work except in compliance with the License, which is
   * available at www.apache.org/licenses/LICENSE-2.0
   *
   * This software is distributed on an "AS IS" basis, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
   * either express or implied, as more fully set forth in the License.
   *
   * See the NOTICE file distributed with this work for information regarding copyright ownership.
   */
  
  package alluxio.master.file;
  
  import alluxio.master.file.meta.MutableInodeDirectory;
  import alluxio.master.file.meta.MutableInodeFile;
  import alluxio.master.journal.JournalEntryMerger;
  import alluxio.proto.journal.Journal;
  
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  import javax.annotation.concurrent.ThreadSafe;
  
  /**
   * A file system journal entry merger which merges inode creation and inode update journals
   * on the same inode object into one.
   * This class is not thread-safe and should not be shared across threads.
   */
  @ThreadSafe
  public class FileSystemJournalEntryMerger implements JournalEntryMerger {
    /** Persists merged journal entries. */
    private final List<Journal.JournalEntry> mJournalEntries = new ArrayList<>();
    /** A map whose key is the inode id and value is the journal index in the mJournalEntries list.*/
    private final Map<Long, Integer> mEntriesMap = new HashMap<>();
  
    /**
     * Adds a new journal entry and merges it on the fly.
     * @param entry the new journal entry to add
     */
    @Override
    public synchronized void add(Journal.JournalEntry entry) {
      if (entry.hasInodeFile() || entry.hasInodeDirectory()) {
        mJournalEntries.add(entry);
        mEntriesMap.put(getInodeId(entry), mJournalEntries.size() - 1);
      }
      else if (
          entry.hasUpdateInode() || entry.hasUpdateInodeFile() || entry.hasUpdateInodeDirectory()
      ) {
        if (!mEntriesMap.containsKey(getInodeId(entry))) {
          mJournalEntries.add(entry);
          return;
        }
        int index = mEntriesMap.get(getInodeId(entry));
        Journal.JournalEntry existingEntry = mJournalEntries.get(index);
        if (existingEntry.hasInodeFile()) {
          MutableInodeFile inodeFile =
              MutableInodeFile.fromJournalEntry(existingEntry.getInodeFile());
          if (entry.hasUpdateInode()) {
            inodeFile.updateFromEntry(entry.getUpdateInode());
          } else if (entry.hasUpdateInodeFile()) {
            inodeFile.updateFromEntry(entry.getUpdateInodeFile());
          }
          mJournalEntries.set(index,
              inodeFile.toJournalEntry(existingEntry.getInodeFile().getPath()));
        }
        if (existingEntry.hasInodeDirectory()) {
          MutableInodeDirectory inodeDirectory =
              MutableInodeDirectory.fromJournalEntry(existingEntry.getInodeDirectory());
          if (entry.hasUpdateInode()) {
            inodeDirectory.updateFromEntry(entry.getUpdateInode());
            // Update Inode directory does not contain directory fingerprint,
            // so we still need to add the new inode journal entry to the list to keep the
            // fingerprint update,
            // while we still merge it with the existing inode directory on as best efforts.
            if (entry.getUpdateInode().hasUfsFingerprint()
                && !entry.getUpdateInode().getUfsFingerprint().equals("")) {
              mJournalEntries.add(entry);
            }
          } else if (entry.hasUpdateInodeDirectory()) {
            inodeDirectory.updateFromEntry(entry.getUpdateInodeDirectory());
          }
          mJournalEntries.set(index,
              inodeDirectory.toJournalEntry(existingEntry.getInodeDirectory().getPath()));
        }
      } else {
        mJournalEntries.add(entry);
      }
    }
  
    @Override
    public synchronized List<Journal.JournalEntry> getMergedJournalEntries() {
      return Collections.unmodifiableList(mJournalEntries);
    }
  
    @Override
    public synchronized void clear() {
      mEntriesMap.clear();
      mJournalEntries.clear();
    }
  
    private long getInodeId(Journal.JournalEntry entry) {
      if (entry.hasInodeDirectory()) {
        return entry.getInodeDirectory().getId();
      }
      if (entry.hasInodeFile()) {
        return entry.getInodeFile().getId();
      }
      if (entry.hasUpdateInode()) {
        return entry.getUpdateInode().getId();
      }
      if (entry.hasUpdateInodeFile()) {
        return entry.getUpdateInodeFile().getId();
      }
      if (entry.hasUpdateInodeDirectory()) {
        return entry.getUpdateInodeDirectory().getId();
      }
      throw new RuntimeException("Unsupported JournalEntry type. The following entries are supported:"
          + "InodeDirectory/InodeFile/UpdateInode/UpdateInodeFile/UpdateInodeDirectory");
    }
  }
  