UnboundID Server SDK

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UnboundID Server SDK Documentation

ExampleLogFileRotationListener.java

/*
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 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at
 * docs/licenses/cddl.txt
 * or http://www.opensource.org/licenses/cddl1.php.
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 *      Copyright 2016 UnboundID Corp.
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package com.unboundid.directory.sdk.examples;



import java.io.File;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import com.unboundid.directory.sdk.common.api.LogFileRotationListener;
import com.unboundid.directory.sdk.common.config.LogFileRotationListenerConfig;
import com.unboundid.directory.sdk.common.types.ServerContext;
import com.unboundid.ldap.sdk.LDAPException;
import com.unboundid.ldap.sdk.ResultCode;
import com.unboundid.util.StaticUtils;
import com.unboundid.util.args.ArgumentException;
import com.unboundid.util.args.ArgumentParser;
import com.unboundid.util.args.FileArgument;



/**
 * This class provides a simple example of a log file rotation listener that
 * will just write a record of each log rotation to a specified file.  It has
 * one configuration argument:
 * <UL>
 *   <LI>output-file -- The path to the file that should be updated
 *       whenever a log file is rotated.</LI>
 * </UL>
 */
public final class ExampleLogFileRotationListener
       extends LogFileRotationListener
{
  /**
   * The name of the argument that will be used to specify the path to the file
   * to be updated whenever a log file is rotated.
   */
  private static final String ARG_NAME_OUTPUT_FILE = "output-file";



  // The output file to be written.
  private volatile File outputFile;



  /**
   * Creates a new instance of this log file rotation listener.  All log file
   * rotation listener implementations must include a default constructor, but
   * any initialization should generally be done in the
   * {@code initializeLogFileRotationListener} method.
   */
  public ExampleLogFileRotationListener()
  {
    // No implementation required.
  }



  /**
   * Retrieves a human-readable name for this extension.
   *
   * @return  A human-readable name for this extension.
   */
  @Override()
  public String getExtensionName()
  {
    return "Example Log File Rotation Listener";
  }



  /**
   * Retrieves a human-readable description for this extension.  Each element
   * of the array that is returned will be considered a separate paragraph in
   * generated documentation.
   *
   * @return  A human-readable description for this extension, or {@code null}
   *          or an empty array if no description should be available.
   */
  @Override()
  public String[] getExtensionDescription()
  {
    return new String[]
    {
      "This log file rotation listener serves an example that may be used to " +
           "demonstrate the process for creating a third-party log file " +
           "rotation listener.  It simply records a message in a specified " +
           "output file whenever a log file is rotated."
    };
  }



  /**
   * Updates the provided argument parser to define any configuration arguments
   * which may be used by this log file rotation listener.  The argument parser
   * may also be updated to define relationships between arguments (e.g., to
   * specify required, exclusive, or dependent argument sets).
   *
   * @param  parser  The argument parser to be updated with the configuration
   *                 arguments which may be used by this log file rotation
   *                 listener.
   *
   * @throws  ArgumentException  If a problem is encountered while updating the
   *                             provided argument parser.
   */
  @Override()
  public void defineConfigArguments(final ArgumentParser parser)
         throws ArgumentException
  {
    // Add an argument that allows you to specify the output file.
    final Character shortIdentifier = null;
    final String    longIdentifier  = ARG_NAME_OUTPUT_FILE;
    final boolean   required        = true;
    final int       maxOccurrences  = 1;
    final String    placeholder     = "{path}";
    final String    description     =
         "The output file to update whenever a log file is rotated.";
    final boolean   fileMustExist   = false;
    final boolean   parentMustExist = true;
    final boolean   mustBeFile      = true;
    final boolean   mustBeDirectory = false;

    parser.addArgument(new FileArgument(shortIdentifier, longIdentifier,
         required, maxOccurrences, placeholder, description, fileMustExist,
         parentMustExist, mustBeFile, mustBeDirectory));
  }



  /**
   * Initializes this log file rotation listener.
   *
   * @param  serverContext  A handle to the server context for the server in
   *                        which this extension is running.
   * @param  config         The general configuration for this log file rotation
   *                        listener.
   * @param  parser         The argument parser which has been initialized from
   *                        the configuration for this log file rotation
   *                        listener.
   *
   * @throws  LDAPException  If a problem occurs while initializing this log
   *                         file rotation listener.
   */
  @Override()
  public void initializeLogFileRotationListener(
                   final ServerContext serverContext,
                   final LogFileRotationListenerConfig config,
                   final ArgumentParser parser)
         throws LDAPException
  {
    serverContext.debugInfo(
         "Beginning log file rotation listener initialization");

    // Get the output file.
    final FileArgument outputFileArg =
         (FileArgument) parser.getNamedArgument(ARG_NAME_OUTPUT_FILE);
    outputFile = outputFileArg.getValue();
  }



  /**
   * Indicates whether the configuration contained in the provided argument
   * parser represents a valid configuration for this extension.
   *
   * @param  config               The general configuration for this log file
   *                              rotation listener.
   * @param  parser               The argument parser which has been initialized
   *                              with the proposed configuration.
   * @param  unacceptableReasons  A list that can be updated with reasons that
   *                              the proposed configuration is not acceptable.
   *
   * @return  {@code true} if the proposed configuration is acceptable, or
   *          {@code false} if not.
   */
  @Override()
  public boolean isConfigurationAcceptable(
                      final LogFileRotationListenerConfig config,
                      final ArgumentParser parser,
                      final List<String> unacceptableReasons)
  {
    // No special validation is required.
    return true;
  }



  /**
   * Attempts to apply the configuration contained in the provided argument
   * parser.
   *
   * @param  config                The general configuration for this log file
   *                               rotation listener.
   * @param  parser                The argument parser which has been
   *                               initialized with the new configuration.
   * @param  adminActionsRequired  A list that can be updated with information
   *                               about any administrative actions that may be
   *                               required before one or more of the
   *                               configuration changes will be applied.
   * @param  messages              A list that can be updated with information
   *                               about the result of applying the new
   *                               configuration.
   *
   * @return  A result code that provides information about the result of
   *          attempting to apply the configuration change.
   */
  @Override()
  public ResultCode applyConfiguration(
                         final LogFileRotationListenerConfig config,
                         final ArgumentParser parser,
                         final List<String> adminActionsRequired,
                         final List<String> messages)
  {
    // Get the new output file.
    final FileArgument outputFileArg =
         (FileArgument) parser.getNamedArgument(ARG_NAME_OUTPUT_FILE);
    outputFile = outputFileArg.getValue();

    return ResultCode.SUCCESS;
  }



  /**
   * Performs any cleanup which may be necessary when this log file rotation
   * listener is to be taken out of service.
   */
  @Override()
  public void finalizeLogFileRotationListener()
  {
    // No finalization is required.
  }



  /**
   * Performs any appropriate processing for a log file that has been rotated.
   *
   * @param  f  The log file that has been rotated.  This file must not be
   *            deleted, moved, renamed, or otherwise altered during processing.
   *
   * @throws  LDAPException  If a problem is encountered during processing.
   */
  @Override()
  public void doPostRotationProcessing(final File f)
         throws LDAPException
  {
    final PrintWriter writer;
    try
    {
      final boolean appendToFile = true;
      writer = new PrintWriter(new FileWriter(outputFile, appendToFile));
    }
    catch (final Exception e)
    {
      throw new LDAPException(ResultCode.LOCAL_ERROR,
           "Unable to open output file " + outputFile.getAbsolutePath() +
                " to record information about newly-rotated log file " +
                f.getAbsolutePath() + ":  " +
                StaticUtils.getExceptionMessage(e),
           e);
    }

    try
    {
      writer.println(
           StaticUtils.encodeGeneralizedTime(System.currentTimeMillis()) +
                '\t' + f.getAbsolutePath());
    }
    catch (final Exception e)
    {
      throw new LDAPException(ResultCode.LOCAL_ERROR,
           "An error occurred while attempting to update output file " +
                outputFile.getAbsolutePath() + " with information about " +
                "newly-rotated log file " + f.getAbsolutePath() + ":  " +
                StaticUtils.getExceptionMessage(e),
           e);
    }
    finally
    {
      writer.close();
    }
  }



  /**
   * Retrieves a map containing examples of configurations that may be used for
   * this extension.  The map key should be a list of sample arguments, and the
   * corresponding value should be a description of the behavior that will be
   * exhibited by the extension when used with that configuration.
   *
   * @return  A map containing examples of configurations that may be used for
   *          this extension.  It may be {@code null} or empty if there should
   *          not be any example argument sets.
   */
  @Override()
  public Map<List<String>,String> getExamplesArgumentSets()
  {
    final LinkedHashMap<List<String>,String> exampleMap =
         new LinkedHashMap<List<String>,String>(1);

    exampleMap.put(
         Arrays.asList(
              ARG_NAME_OUTPUT_FILE + "=logs/rotation.log"),
         "Update the logs/rotation.log file with a message every time a " +
              "log file is rotated.");

    return exampleMap;
  }
}