Package db.buffers

Class LocalBufferFile

  • All Implemented Interfaces:
    BufferFile
    Direct Known Subclasses:
    LocalManagedBufferFile
    public class LocalBufferFile
extends java.lang.Object
implements BufferFile
    LocalBufferFile implements a BufferFile as block-oriented random-access file. This type of buffer file supports save-as but does not support the save operation.

    • Constructor Summary

      Constructors 
      Constructor Description
      LocalBufferFile​(java.io.File file, boolean readOnly)
      Open an existing block file.
      LocalBufferFile​(java.io.File file, int bufferSize)
      Create a new buffer file for writing.

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      static void cleanupOldPreSaveFiles​(java.io.File dir, long beforeNow)
      Attempt to remove all pre-save files.
      void clearParameters()
      Deletes all parameters
      void clone​(java.io.File destinationFile, TaskMonitor monitor)
      Clone this buffer file to the specified file.
      void close()
      Close the buffer file.
      static void copyFile​(BufferFile srcFile, BufferFile destFile, ChangeMap changeMap, TaskMonitor monitor)
      Copy the complete content of a specfied srcFile into a destFile excluding file ID.
      boolean delete()
      Delete this buffer file if writable.
      void dispose()
      Dispose of this buffer file object.
      protected void finalize()  
      DataBuffer get​(DataBuffer buf, int index)
      Get the specified buffer.
      static BufferFileBlock getBufferFileBlock​(DataBuffer buf, int bufferSize)
      Generate a BufferFileBlock instance which corresponds to the specified DataBuffer based upon LocalBufferFile block usage.
      int getBufferSize()
      Return the actual size of a user data buffer.
      static DataBuffer getDataBuffer​(BufferFileBlock block)
      Generate a DataBuffer instance which corresponds to the specified block based upon LocalBufferFile block usage.
      java.io.File getFile()
      Returns the physical file associated with this BufferFile.
      int[] getFreeIndexes()
      Returns the list of free indexes sorted by value.
      int getIndexCount()
      Returns the number of allocated buffer indexes.
      InputBlockStream getInputBlockStream()
      Obtain a direct stream to read all blocks of this buffer file
      OutputBlockStream getOutputBlockStream​(int blockCount)
      Obtain a direct stream to write blocks to this buffer file
      int getParameter​(java.lang.String name)
      Get a the stored value for a named parameter.
      java.lang.String[] getParameterNames()
      Returns a list of all parameter names.
      boolean isReadOnly()
      Returns true if this file may not be modified via the buffer put method.
      static DataBuffer peek​(java.io.File file, int bufferIndex)
      Read a buffer from an existing buffer file.
      static void poke​(java.io.File file, int bufferIndex, DataBuffer buf)
      Modify an existing buffer file.
      void put​(DataBuffer buf, int index)
      Store a data buffer at the specified block index.
      void setFreeIndexes​(int[] indexes)
      Sets the list of free buffer indexes.
      void setParameter​(java.lang.String name, int value)
      Set the integer value for a named parameter.
      boolean setReadOnly()
      If file is open read-write, the modified contents are flushed and the file re-opened as read-only.
      java.lang.String toString()  

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • LocalBufferFile

        public LocalBufferFile​(java.io.File file,
                       int bufferSize)
                throws java.io.IOException
        Create a new buffer file for writing. If the file does not exist and create is true, a new buffer file will be created. The file will be saved when closed.
        Parameters:
        file - buffer file
        bufferSize - user buffer size
        Throws:
        DuplicateFileException - if file already exists
        java.io.IOException - if an I/O error occurs during file creation

      • LocalBufferFile

        public LocalBufferFile​(java.io.File file,
                       boolean readOnly)
                throws java.io.IOException
        Open an existing block file.
        Parameters:
        file - block file
        readOnly - if true the file will be opened read-only
        Throws:
        java.io.IOException - if an IO error occurs or the incorrect magicNumber was read from the file.

    • Method Detail

      • poke

        public static void poke​(java.io.File file,
                        int bufferIndex,
                        DataBuffer buf)
                 throws java.io.IOException
        Modify an existing buffer file. WARNING! Use with extreme caution since this modifies the original file and could destroy data if used improperly.
        Parameters:
        file -
        bufferIndex -
        buf -
        Throws:
        java.io.IOException

      • peek

        public static DataBuffer peek​(java.io.File file,
                              int bufferIndex)
                       throws java.io.IOException
        Read a buffer from an existing buffer file.
        Parameters:
        file -
        bufferIndex -
        Returns:
        Throws:
        java.io.IOException

      • getFile

        public java.io.File getFile()
        Returns the physical file associated with this BufferFile.

      • isReadOnly

        public boolean isReadOnly()
        Description copied from interface: BufferFile
        Returns true if this file may not be modified via the buffer put method. A read-only file may be considered "updateable" if the canSave method returns true. The term "updateable" means that a Save file can be obtained via the getSaveFile method.
        Specified by:
        isReadOnly in interface BufferFile

      • getParameter

        public int getParameter​(java.lang.String name)
                 throws java.util.NoSuchElementException
        Description copied from interface: BufferFile
        Get a the stored value for a named parameter.
        Specified by:
        getParameter in interface BufferFile
        Parameters:
        name - parameter name
        Returns:
        integer value
        Throws:
        java.util.NoSuchElementException - thrown if parameter not found

      • setParameter

        public void setParameter​(java.lang.String name,
                         int value)
        Description copied from interface: BufferFile
        Set the integer value for a named parameter.
        Specified by:
        setParameter in interface BufferFile
        Parameters:
        name - parameter name
        value - parameter value

      • clearParameters

        public void clearParameters()
        Description copied from interface: BufferFile
        Deletes all parameters
        Specified by:
        clearParameters in interface BufferFile

      • getParameterNames

        public java.lang.String[] getParameterNames()
        Description copied from interface: BufferFile
        Returns a list of all parameter names.
        Specified by:
        getParameterNames in interface BufferFile

      • getFreeIndexes

        public int[] getFreeIndexes()
        Description copied from interface: BufferFile
        Returns the list of free indexes sorted by value. The management of the free-index-list is implementation specific.
        Specified by:
        getFreeIndexes in interface BufferFile

      • setFreeIndexes

        public void setFreeIndexes​(int[] indexes)
        Description copied from interface: BufferFile
        Sets the list of free buffer indexes. The management of the free-index-list is implementation specific.
        Specified by:
        setFreeIndexes in interface BufferFile

      • getDataBuffer

        public static DataBuffer getDataBuffer​(BufferFileBlock block)
        Generate a DataBuffer instance which corresponds to the specified block based upon LocalBufferFile block usage.
        Parameters:
        block - the buffer file block to be converted
        Returns:
        DataBuffer instance or null if head block. If empty block DataBuffer will have null data

      • getBufferFileBlock

        public static BufferFileBlock getBufferFileBlock​(DataBuffer buf,
                                                 int bufferSize)
        Generate a BufferFileBlock instance which corresponds to the specified DataBuffer based upon LocalBufferFile block usage. This should generally not be used for writing empty blocks since they will not be properly linked which is normally handled during header flush which is performed by BufferFile close on files being written.
        Parameters:
        buf - the data buffer to be converted
        bufferSize - data buffer size used for integrity check and generating empty buffer
        Returns:
        BufferFileBlock instance.

      • get

        public DataBuffer get​(DataBuffer buf,
                      int index)
               throws java.io.IOException
        Description copied from interface: BufferFile
        Get the specified buffer. DataBuffer data and flags are read from the file at index and stored within the supplied DataBuffer object. If the read buffer is empty, the DataBuffer's data field will remain unchanged (which could be null).
        Specified by:
        get in interface BufferFile
        Parameters:
        buf - a buffer whose data array will be filled-in or replaced.
        index - index of buffer to be read. First user buffer is at index 0.
        Throws:
        java.io.EOFException - if the requested buffer index is greater than the number of available buffers of the end-of-file was encountered while reading the buffer.
        java.io.IOException - if an I/O error occurs

      • put

        public void put​(DataBuffer buf,
                int index)
         throws java.io.IOException
        Description copied from interface: BufferFile
        Store a data buffer at the specified block index.
        Specified by:
        put in interface BufferFile
        Parameters:
        buf - data buffer
        index - block index
        Throws:
        java.io.IOException - thrown if an IO error occurs

      • getBufferSize

        public int getBufferSize()
        Description copied from interface: BufferFile
        Return the actual size of a user data buffer. This value should be used when constructing DataBuffer objects.
        Specified by:
        getBufferSize in interface BufferFile
        Returns:
        DataBuffer data size as a number of bytes

      • getIndexCount

        public int getIndexCount()
        Description copied from interface: BufferFile
        Returns the number of allocated buffer indexes. When a new buffer is allocated, and the file size grows, the buffer will remain allocated although it may be added to the list of free-indexes. A file will never shrink in size due to this permanent allocation.
        Specified by:
        getIndexCount in interface BufferFile

      • dispose

        public void dispose()
        Description copied from interface: BufferFile
        Dispose of this buffer file object. If file is not readOnly and has not been closed, an attempt will be made to delete the associated file(s). Once disposed, it may no longer be used.
        Specified by:
        dispose in interface BufferFile

      • finalize

        protected void finalize()
                 throws java.lang.Throwable
        Overrides:
        finalize in class java.lang.Object
        Throws:
        java.lang.Throwable

      • setReadOnly

        public boolean setReadOnly()
                    throws java.io.IOException
        Description copied from interface: BufferFile
        If file is open read-write, the modified contents are flushed and the file re-opened as read-only. This is also used to commit a new version if the file had been modified for update.
        Specified by:
        setReadOnly in interface BufferFile
        Returns:
        true if successfully transitioned from read-write to read-only
        Throws:
        java.io.IOException - if an I/O error occurs

      • close

        public void close()
           throws java.io.IOException
        Description copied from interface: BufferFile
        Close the buffer file. If the file was open for write access, all buffers are flushed and the file header updated. Once closed, this object is immediately disposed and may no longer be used.
        Specified by:
        close in interface BufferFile
        Throws:
        java.io.IOException - if an I/O error occurs

      • delete

        public boolean delete()
        Description copied from interface: BufferFile
        Delete this buffer file if writable. Once deleted, this object is immediately disposed and may no longer be used.
        Specified by:
        delete in interface BufferFile
        Returns:
        true if deleted, false if the file is read-only

      • clone

        public void clone​(java.io.File destinationFile,
                  TaskMonitor monitor)
           throws java.io.IOException,
                  CancelledException
        Clone this buffer file to the specified file. The file must not already exist. If the operation is cancelled or an error occurs the file is not created.
        Parameters:
        destinationFile - destination file
        monitor - progress monitor
        Throws:
        java.io.IOException - if IO error occurs.
        CancelledException - if the monitor cancels the operation.

      • toString

        public java.lang.String toString()
        Overrides:
        toString in class java.lang.Object

      • getInputBlockStream

        public InputBlockStream getInputBlockStream()
                                     throws java.io.IOException
        Obtain a direct stream to read all blocks of this buffer file
        Returns:
        input block stream
        Throws:
        java.io.IOException

      • getOutputBlockStream

        public OutputBlockStream getOutputBlockStream​(int blockCount)
                                       throws java.io.IOException
        Obtain a direct stream to write blocks to this buffer file
        Parameters:
        blockCount - number of blocks to be transferred
        Returns:
        output block stream
        Throws:
        java.io.IOException

      • copyFile

        public static void copyFile​(BufferFile srcFile,
                            BufferFile destFile,
                            ChangeMap changeMap,
                            TaskMonitor monitor)
                     throws java.io.IOException,
                            CancelledException
        Copy the complete content of a specfied srcFile into a destFile excluding file ID. Both files remain open.
        Parameters:
        srcFile - open buffer file
        destFile - empty buffer file which is open for writing.
        changeMap - optional change map which indicates those buffers which must be copied. Any buffer index outside the range of the change map will also be copied.
        monitor - progress monitor
        Throws:
        java.io.IOException - if IO error occurs.
        CancelledException - if the monitor cancels the operation.

      • cleanupOldPreSaveFiles

        public static void cleanupOldPreSaveFiles​(java.io.File dir,
                                          long beforeNow)
        Attempt to remove all pre-save files. Those still open by an existing process should not be removed by the operating system.
        Parameters:
        dir - data directory containing presave files
        beforeNow - if not 0, file mod time must be less than the specified time