Class FileMessageFactory

java.lang.Object
org.apache.catalina.ha.deploy.FileMessageFactory
public class FileMessageFactory extends Object
This factory is used to read files and write files by splitting them up into smaller messages. So that entire files don't have to be read into memory.
The factory can be used as a reader or writer but not both at the same time. When done reading or writing the factory will close the input or output streams and mark the factory as closed. It is not possible to use it after that.
To force a cleanup, call cleanup() from the calling object.
This class is not thread safe.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected boolean
    closed
    Once the factory is used, it cannot be reused.
    protected long
    creationTime
    Deprecated.
    Unused.
    protected byte[]
    data
    The bytes that we hold the data in, not thread safe.
    protected final File
    file
    The file that we are reading/writing
    protected FileInputStream
    in
    When openForWrite=false, the input stream is held by this variable
    protected boolean
    isWriting
    Flag that indicates if a thread is writing messages to disk.
    protected AtomicLong
    lastMessageProcessed
    The number of the last message processed.
    protected long
    lastModified
    The time this instance was last modified.
    protected int
    maxValidTime
    The maximum time (in seconds) this instance will be allowed to exist from lastModifiedTime.
    protected final Map<Long,FileMessage>
    msgBuffer
    Messages received out of order are held in the buffer until required.
    protected int
    nrOfMessagesProcessed
    The number of messages we have written
    protected final boolean
    openForWrite
    True means that we are writing with this factory.
    protected FileOutputStream
    out
    When openForWrite=true, the output stream is held by this variable
    static final int
    READ_SIZE
    The number of bytes that we read from file
    protected long
    size
    The total size of the file
    protected long
    totalNrOfMessages
    The total number of packets that we split this file into

  • Method Summary

    Modifier and Type
    Method
    Description
    protected void
    checkState(boolean openForWrite)
    Check to make sure the factory is able to perform the function it is asked to do.
    void
    cleanup()
    Closes the factory, its streams and sets all its references to null
    File
    getFile()
     
    static FileMessageFactory
    getInstance(File f, boolean openForWrite)
    Creates a factory to read or write from a file.
    int
    getMaxValidTime()
     
    boolean
    isValid()
     
    FileMessage
    readMessage(FileMessage f)
    Reads file data into the file message and sets the size, totalLength, totalNrOfMsgs and the message number
    If EOF is reached, the factory returns null, and closes itself, otherwise the same message is returned as was passed in.
    void
    setMaxValidTime(int maxValidTime)
     
    boolean
    writeMessage(FileMessage msg)
    Writes a message to file.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • READ_SIZE

      public static final int READ_SIZE
      The number of bytes that we read from file
      See Also:

    • file

      protected final File file
      The file that we are reading/writing

    • openForWrite

      protected final boolean openForWrite
      True means that we are writing with this factory. False means that we are reading with this factory

    • closed

      protected boolean closed
      Once the factory is used, it cannot be reused.

    • in

      protected FileInputStream in
      When openForWrite=false, the input stream is held by this variable

    • out

      protected FileOutputStream out
      When openForWrite=true, the output stream is held by this variable

    • nrOfMessagesProcessed

      protected int nrOfMessagesProcessed
      The number of messages we have written

    • size

      protected long size
      The total size of the file

    • totalNrOfMessages

      protected long totalNrOfMessages
      The total number of packets that we split this file into

    • lastMessageProcessed

      protected AtomicLong lastMessageProcessed
      The number of the last message processed. Message IDs are 1 based.

    • msgBuffer

      protected final Map<Long,FileMessage> msgBuffer
      Messages received out of order are held in the buffer until required. If everything is worked as expected, messages will spend very little time in the buffer.

    • data

      protected byte[] data
      The bytes that we hold the data in, not thread safe.

    • isWriting

      protected boolean isWriting
      Flag that indicates if a thread is writing messages to disk. Access to this flag must be synchronised.

    • creationTime

      @Deprecated protected long creationTime
      Deprecated.
      Unused. This will be removed in Tomcat 11.
      The time this instance was created. (in milliseconds)

    • lastModified

      protected long lastModified
      The time this instance was last modified.

    • maxValidTime

      protected int maxValidTime
      The maximum time (in seconds) this instance will be allowed to exist from lastModifiedTime.

  • Method Details

    • getInstance

      public static FileMessageFactory getInstance(File f, boolean openForWrite) throws FileNotFoundException, IOException
      Creates a factory to read or write from a file. When opening for read, the readMessage can be invoked, and when opening for write the writeMessage can be invoked.
      Parameters:
      f - File - the file to be read or written
      openForWrite - boolean - true, means we are writing to the file, false means we are reading from it
      Returns:
      FileMessageFactory
      Throws:
      FileNotFoundException - - if the file to be read doesn't exist
      IOException - - if it fails to create the file that is to be written

    • readMessage

      public FileMessage readMessage(FileMessage f) throws IllegalArgumentException, IOException
      Reads file data into the file message and sets the size, totalLength, totalNrOfMsgs and the message number
      If EOF is reached, the factory returns null, and closes itself, otherwise the same message is returned as was passed in. This makes sure that not more memory is ever used. To remember, neither the file message or the factory are thread safe. Don't hand off the message to one thread and read the same with another.
      Parameters:
      f - FileMessage - the message to be populated with file data
      Returns:
      FileMessage - returns the same message passed in as a parameter, or null if EOF
      Throws:
      IllegalArgumentException - - if the factory is for writing or is closed
      IOException - - if a file read exception occurs

    • writeMessage

      public boolean writeMessage(FileMessage msg) throws IllegalArgumentException, IOException
      Writes a message to file. If (msg.getMessageNumber() == msg.getTotalNrOfMsgs()) the output stream will be closed after writing.
      Parameters:
      msg - FileMessage - message containing data to be written
      Returns:
      returns true if the file is complete and outputstream is closed, false otherwise.
      Throws:
      IllegalArgumentException - - if the factory is opened for read or closed
      IOException - - if a file write error occurs

    • cleanup

      public void cleanup()
      Closes the factory, its streams and sets all its references to null

    • checkState

      protected void checkState(boolean openForWrite) throws IllegalArgumentException
      Check to make sure the factory is able to perform the function it is asked to do. Invoked by readMessage/writeMessage before those methods proceed.
      Parameters:
      openForWrite - The value to check
      Throws:
      IllegalArgumentException - if the state is not the expected one

    • getFile

      public File getFile()

    • isValid

      public boolean isValid()

    • getMaxValidTime

      public int getMaxValidTime()

    • setMaxValidTime

      public void setMaxValidTime(int maxValidTime)