Package db.buffers
Class LocalBufferFile
- java.lang.Object
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- db.buffers.LocalBufferFile
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- 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.
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Field Summary
Fields Modifier and Type Field Description static java.lang.String
BUFFER_FILE_EXTENSION
static java.lang.String
PRESAVE_FILE_EXT
static java.lang.String
PRESAVE_FILE_PREFIX
static java.lang.String
TEMP_FILE_EXT
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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.
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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 parametersvoid
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 fileOutputBlockStream
getOutputBlockStream(int blockCount)
Obtain a direct stream to write blocks to this buffer fileint
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()
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Field Detail
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BUFFER_FILE_EXTENSION
public static final java.lang.String BUFFER_FILE_EXTENSION
- See Also:
- Constant Field Values
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PRESAVE_FILE_EXT
public static final java.lang.String PRESAVE_FILE_EXT
- See Also:
- Constant Field Values
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PRESAVE_FILE_PREFIX
public static final java.lang.String PRESAVE_FILE_PREFIX
- See Also:
- Constant Field Values
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TEMP_FILE_EXT
public static final java.lang.String TEMP_FILE_EXT
- See Also:
- Constant Field Values
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Constructor Detail
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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 filebufferSize
- user buffer size- Throws:
DuplicateFileException
- if file already existsjava.io.IOException
- if an I/O error occurs during file creation
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LocalBufferFile
public LocalBufferFile(java.io.File file, boolean readOnly) throws java.io.IOException
Open an existing block file.- Parameters:
file
- block filereadOnly
- 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.
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Method Detail
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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
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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
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getFile
public java.io.File getFile()
Returns the physical file associated with this BufferFile.
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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 interfaceBufferFile
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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 interfaceBufferFile
- Parameters:
name
- parameter name- Returns:
- integer value
- Throws:
java.util.NoSuchElementException
- thrown if parameter not found
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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 interfaceBufferFile
- Parameters:
name
- parameter namevalue
- parameter value
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clearParameters
public void clearParameters()
Description copied from interface:BufferFile
Deletes all parameters- Specified by:
clearParameters
in interfaceBufferFile
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getParameterNames
public java.lang.String[] getParameterNames()
Description copied from interface:BufferFile
Returns a list of all parameter names.- Specified by:
getParameterNames
in interfaceBufferFile
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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 interfaceBufferFile
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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 interfaceBufferFile
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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
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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 convertedbufferSize
- data buffer size used for integrity check and generating empty buffer- Returns:
- BufferFileBlock instance.
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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 interfaceBufferFile
- 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
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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 interfaceBufferFile
- Parameters:
buf
- data bufferindex
- block index- Throws:
java.io.IOException
- thrown if an IO error occurs
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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 interfaceBufferFile
- Returns:
- DataBuffer data size as a number of bytes
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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 interfaceBufferFile
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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 interfaceBufferFile
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finalize
protected void finalize() throws java.lang.Throwable
- Overrides:
finalize
in classjava.lang.Object
- Throws:
java.lang.Throwable
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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 interfaceBufferFile
- Returns:
- true if successfully transitioned from read-write to read-only
- Throws:
java.io.IOException
- if an I/O error occurs
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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 interfaceBufferFile
- Throws:
java.io.IOException
- if an I/O error occurs
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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 interfaceBufferFile
- Returns:
- true if deleted, false if the file is read-only
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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 filemonitor
- progress monitor- Throws:
java.io.IOException
- if IO error occurs.CancelledException
- if the monitor cancels the operation.
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toString
public java.lang.String toString()
- Overrides:
toString
in classjava.lang.Object
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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
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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
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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 filedestFile
- 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.
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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 filesbeforeNow
- if not 0, file mod time must be less than the specified time
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