src/java/org/apache/nutch/parse/ParseStatus.java

/*
 * 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.nutch.parse;

import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;

import org.apache.hadoop.io.VersionMismatchException;
import org.apache.hadoop.io.Writable;
import org.apache.hadoop.io.WritableUtils;
import org.apache.hadoop.conf.Configuration;

import org.apache.nutch.metadata.Metadata;

/**
 * @author Andrzej Bialecki <ab@getopt.org>
 */
public class ParseStatus implements Writable {

  private final static byte VERSION = 2;

  // Primary status codes:

  /** Parsing was not performed. */
  public static final byte NOTPARSED = 0;
  /** Parsing succeeded. */
  public static final byte SUCCESS = 1;
  /** General failure. There may be a more specific error message in arguments. */
  public static final byte FAILED = 2;

  public static final String[] majorCodes = { "notparsed", "success", "failed" };

  // Secondary success codes go here:

  /**
   * Parsed content contains a directive to redirect to another URL. The target
   * URL can be retrieved from the arguments.
   */
  public static final short SUCCESS_REDIRECT = 100;

  // Secondary failure codes go here:

  /**
   * Parsing failed. An Exception occured (which may be retrieved from the
   * arguments).
   */
  public static final short FAILED_EXCEPTION = 200;
  /**
   * Parsing failed. Content was truncated, but the parser cannot handle
   * incomplete content.
   */
  public static final short FAILED_TRUNCATED = 202;
  /**
   * Parsing failed. Invalid format - the content may be corrupted or of wrong
   * type.
   */
  public static final short FAILED_INVALID_FORMAT = 203;
  /**
   * Parsing failed. Other related parts of the content are needed to complete
   * parsing. The list of URLs to missing parts may be provided in arguments.
   * The Fetcher may decide to fetch these parts at once, then put them into
   * Content.metadata, and supply them for re-parsing.
   */
  public static final short FAILED_MISSING_PARTS = 204;
  /**
   * Parsing failed. There was no content to be parsed - probably caused by
   * errors at protocol stage.
   */
  public static final short FAILED_MISSING_CONTENT = 205;

  public static final ParseStatus STATUS_NOTPARSED = new ParseStatus(NOTPARSED);
  public static final ParseStatus STATUS_SUCCESS = new ParseStatus(SUCCESS);
  public static final ParseStatus STATUS_FAILURE = new ParseStatus(FAILED);

  private byte majorCode = 0;
  private short minorCode = 0;
  private String[] args = null;

  public byte getVersion() {
    return VERSION;
  }

  public ParseStatus() {

  }

  public ParseStatus(int majorCode, int minorCode, String[] args) {
    this.args = args;
    this.majorCode = (byte) majorCode;
    this.minorCode = (short) minorCode;
  }

  public ParseStatus(int majorCode) {
    this(majorCode, 0, (String[]) null);
  }

  public ParseStatus(int majorCode, String[] args) {
    this(majorCode, 0, args);
  }

  public ParseStatus(int majorCode, int minorCode) {
    this(majorCode, minorCode, (String[]) null);
  }

  /** Simplified constructor for passing just a text message. */
  public ParseStatus(int majorCode, int minorCode, String message) {
    this(majorCode, minorCode, new String[] { message });
  }

  /** Simplified constructor for passing just a text message. */
  public ParseStatus(int majorCode, String message) {
    this(majorCode, 0, new String[] { message });
  }

  public ParseStatus(Throwable t) {
    this(FAILED, FAILED_EXCEPTION, new String[] { t.toString() });
  }

  public static ParseStatus read(DataInput in) throws IOException {
    ParseStatus res = new ParseStatus();
    res.readFields(in);
    return res;
  }

  public void readFields(DataInput in) throws IOException {
    byte version = in.readByte();
    switch (version) {
    case 1:
      majorCode = in.readByte();
      minorCode = in.readShort();
      args = WritableUtils.readCompressedStringArray(in);
      break;
    case 2:
      majorCode = in.readByte();
      minorCode = in.readShort();
      args = WritableUtils.readStringArray(in);
      break;
    default:
      throw new VersionMismatchException(VERSION, version);
    }
  }

  public void write(DataOutput out) throws IOException {
    out.writeByte(VERSION);
    out.writeByte(majorCode);
    out.writeShort(minorCode);
    if (args == null) {
      out.writeInt(-1);
    } else {
      WritableUtils.writeStringArray(out, args);
    }
  }

  /**
   * A convenience method. Returns true if majorCode is SUCCESS, false
   * otherwise.
   */

  public boolean isSuccess() {
    return majorCode == SUCCESS;
  }

  /**
   * A convenience method. Return a String representation of the first argument,
   * or null.
   */
  public String getMessage() {
    if (args != null && args.length > 0 && args[0] != null)
      return args[0];
    return null;
  }

  public String[] getArgs() {
    return args;
  }

  public int getMajorCode() {
    return majorCode;
  }

  public int getMinorCode() {
    return minorCode;
  }

  /**
   * A convenience method. Creates an empty Parse instance, which returns this
   * status.
   */
  public Parse getEmptyParse(Configuration conf) {
    return new EmptyParseImpl(this, conf);
  }

  /**
   * A convenience method. Creates an empty ParseResult, which contains this
   * status.
   */
  public ParseResult getEmptyParseResult(String url, Configuration conf) {
    return ParseResult.createParseResult(url, getEmptyParse(conf));
  }

  public String toString() {
    StringBuffer res = new StringBuffer();
    String name = null;
    if (majorCode >= 0 && majorCode < majorCodes.length)
      name = majorCodes[majorCode];
    else
      name = "UNKNOWN!";
    res.append(name + "(" + majorCode + "," + minorCode + ")");
    if (args != null) {
      if (args.length == 1) {
        res.append(": " + String.valueOf(args[0]));
      } else {
        for (int i = 0; i < args.length; i++) {
          if (args[i] != null)
            res.append(", args[" + i + "]=" + String.valueOf(args[i]));
        }
      }
    }
    return res.toString();
  }

  public void setArgs(String[] args) {
    this.args = args;
  }

  public void setMessage(String msg) {
    if (args == null || args.length == 0) {
      args = new String[1];
    }
    args[0] = msg;
  }

  public void setMajorCode(byte majorCode) {
    this.majorCode = majorCode;
  }

  public void setMinorCode(short minorCode) {
    this.minorCode = minorCode;
  }

  public boolean equals(Object o) {
    if (o == null)
      return false;
    if (!(o instanceof ParseStatus))
      return false;
    boolean res = true;
    ParseStatus other = (ParseStatus) o;
    res = res && (this.majorCode == other.majorCode)
        && (this.minorCode == other.minorCode);
    if (!res)
      return res;
    if (this.args == null) {
      if (other.args == null)
        return true;
      else
        return false;
    } else {
      if (other.args == null)
        return false;
      if (other.args.length != this.args.length)
        return false;
      for (int i = 0; i < this.args.length; i++) {
        if (!this.args[i].equals(other.args[i]))
          return false;
      }
    }
    return true;
  }

  private static class EmptyParseImpl implements Parse {

    private ParseData data = null;

    public EmptyParseImpl(ParseStatus status, Configuration conf) {
      data = new ParseData(status, "", new Outlink[0], new Metadata(),
          new Metadata());
    }

    public ParseData getData() {
      return data;
    }

    public String getText() {
      return "";
    }

    public boolean isCanonical() {
      return true;
    }
  }
}