AbstractBlockBasedDataStore (FFMQ Core 4.0.9 API)

java.lang.Object
- net.timewalker.ffmq4.storage.data.impl.AbstractDataStore
- - net.timewalker.ffmq4.storage.data.impl.AbstractBlockBasedDataStore

All Implemented Interfaces:: DataStore, LinkedDataStore

Direct Known Subclasses:: BlockBasedDataStore, JournalingBlockBasedDataStore

public abstract class AbstractBlockBasedDataStore
extends AbstractDataStore

Block-based data store with journal support

Implements a mix between a block-based file system structure and a doubly-linked list.

Disk layout of the allocation table :

  blockCount               | 4 bytes (int)     | Number of blocks in store
  blockSize                | 4 bytes (int)     | Size of a storage block
  firstClusterIndex        | 4 bytes (int)     | Index of the first block
  allocationTable  (*blockCount allocation entries)
      flags                | 1 byte            | Flags indicating the block usage
      allocatedSize        | 4 bytes (int)     | Size of the actual data stored in this block
      previousClusterIndex | 4 bytes (int)     | Index of the previous block
      nextClusterIndex     | 4 bytes (int)     | Index of the next block

Disk layout of the data store :

  blocks (*blockCount blocks of size blockSize)

Computing a block offset from its index :
blockOffset = blockIndex*blockSize

Field Summary

Fields
Modifier and Type	Field and Description
`protected static int`	`AB_ALLOCSIZE_OFFSET`
`protected static int`	`AB_FLAGS_OFFSET`
`protected static int`	`AB_NEXTBLOCK_OFFSET`
`protected static int`	`AB_PREVBLOCK_OFFSET`
`protected int[]`	`allocatedSize`
`static String`	`ALLOCATION_TABLE_SUFFIX`
`protected File`	`allocationTableFile`
`protected RandomAccessFile`	`allocationTableRandomAccessFile`
`static int`	`AT_BLOCK_SIZE`
`static int`	`AT_HEADER_BLOCKCOUNT_OFFSET`
`protected static int`	`AT_HEADER_FIRSTBLOCK_OFFSET`
`static int`	`AT_HEADER_SIZE`
`protected int`	`blockCount`
`protected int`	`blockSize`
`static String`	`DATA_FILE_SUFFIX`
`protected File`	`dataFile`
`protected RandomAccessFile`	`dataRandomAccessFile`
`protected AbstractDestinationDescriptor`	`descriptor`
`protected int`	`firstBlock`
`protected byte[]`	`flags`
`protected int[]`	`nextBlock`
`protected int[]`	`previousBlock`

Fields inherited from class net.timewalker.ffmq4.storage.data.impl.AbstractDataStore
locks, SAFE_MODE

Constructor Summary

Constructors
Constructor and Description

AbstractBlockBasedDataStore(AbstractDestinationDescriptor descriptor)
Constructor

Constructors
Constructor and Description
`AbstractBlockBasedDataStore(AbstractDestinationDescriptor descriptor)` Constructor

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`protected void`	`checkHandle(int handle)` Check handle validity
`void`	`close()` Close the store releasing associated system resources
`int`	`delete(int handle)` Delete data associated to the given handle from the store
`protected abstract void`	`extendStoreFiles(int oldBlockCount, int newBlockCount)` Extend the store files to newBlockCount
`int`	`first()` Get the first data handle stored
`protected abstract void`	`flush()` Flush internal buffers
`int`	`getAbsoluteStoreUsage()` Get the absolute store usage amount (%) (Ratio of used space over maximum allocatable space)
`int`	`getBlockSize()`
`int`	`getStoreUsage()` Get the store usage amount (%) (Ratio of used space over currently allocated space)
`void`	`init()` Initialize the data store
`protected void`	`initFilesystem()`
`protected void`	`integrityCheck()` Run an integrity check on the store files and fix them as necessary
`int`	`next(int handle)` Get the next data handle after the given one
`int`	`previous(int handle)` Get the previous data handle after the given one
`protected abstract void`	`readDataBlock(byte[] data, int offset, int len, int blockHandle)` Read a data block to disk
`int`	`replace(int handle, Object obj)` Replace data in the store at the given position
`Object`	`retrieve(int handle)` Retrieve the data associated to a given handle
`byte[]`	`retrieveHeader(int handle, int headerSize)`
`protected byte[]`	`serializeAllocationBlock(int blockIndex)` Serialize allocation block at index blockIndex
`int`	`size()` Get the number of entries in the store
`int`	`store(Object obj, int previousHandle)` Put some data under in the store after the previous handle data
`String`	`toString()`
`protected abstract void`	`writeAllocationBlock(int blockIndex)` Write an allocation block to disk
`protected abstract void`	`writeDataBlock(byte[] data, int offset, int len, int blockHandle)` Write a data block to disk
`protected abstract void`	`writeFirstBlock()` Write the first block index to disk

Methods inherited from class net.timewalker.ffmq4.storage.data.impl.AbstractDataStore
isLocked, lock, unlock

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface net.timewalker.ffmq4.storage.data.DataStore
commitChanges, commitChanges

- Field Detail
  - DATA_FILE_SUFFIX
```
public static final String DATA_FILE_SUFFIX
```
    See Also:
    
    Constant Field Values
  - ALLOCATION_TABLE_SUFFIX
```
public static final String ALLOCATION_TABLE_SUFFIX
```
    See Also:
    
    Constant Field Values
  - AT_HEADER_SIZE
```
public static final int AT_HEADER_SIZE
```
    See Also:
    
    Constant Field Values
  - AT_BLOCK_SIZE
```
public static final int AT_BLOCK_SIZE
```
    See Also:
    
    Constant Field Values
  - AT_HEADER_BLOCKCOUNT_OFFSET
```
public static final int AT_HEADER_BLOCKCOUNT_OFFSET
```
    See Also:
    
    Constant Field Values
  - AT_HEADER_FIRSTBLOCK_OFFSET
```
protected static final int AT_HEADER_FIRSTBLOCK_OFFSET
```
    See Also:
    
    Constant Field Values
  - AB_FLAGS_OFFSET
```
protected static final int AB_FLAGS_OFFSET
```
    See Also:
    
    Constant Field Values
  - AB_ALLOCSIZE_OFFSET
```
protected static final int AB_ALLOCSIZE_OFFSET
```
    See Also:
    
    Constant Field Values
  - AB_PREVBLOCK_OFFSET
```
protected static final int AB_PREVBLOCK_OFFSET
```
    See Also:
    
    Constant Field Values
  - AB_NEXTBLOCK_OFFSET
```
protected static final int AB_NEXTBLOCK_OFFSET
```
    See Also:
    
    Constant Field Values
  - descriptor
```
protected AbstractDestinationDescriptor descriptor
```
  - blockSize
```
protected int blockSize
```
  - blockCount
```
protected int blockCount
```
  - flags
```
protected byte[] flags
```
  - allocatedSize
```
protected int[] allocatedSize
```
  - nextBlock
```
protected int[] nextBlock
```
  - previousBlock
```
protected int[] previousBlock
```
  - firstBlock
```
protected int firstBlock
```
  - allocationTableFile
```
protected File allocationTableFile
```
  - dataFile
```
protected File dataFile
```
  - allocationTableRandomAccessFile
```
protected RandomAccessFile allocationTableRandomAccessFile
```
  - dataRandomAccessFile
```
protected RandomAccessFile dataRandomAccessFile
```
- Constructor Detail
  - AbstractBlockBasedDataStore
```
public AbstractBlockBasedDataStore(AbstractDestinationDescriptor descriptor)
```
    Constructor
- Method Detail
  - init
```
public final void init()
                throws DataStoreException
```
    Description copied from interface: LinkedDataStore
    
    Initialize the data store
    
    Throws:
    
    DataStoreException
  - initFilesystem
```
protected void initFilesystem()
                       throws DataStoreException
```
    Throws:
    
    DataStoreException
  - checkHandle
```
protected void checkHandle(int handle)
                    throws DataStoreException
```
    Description copied from class: AbstractDataStore
    
    Check handle validity
    
    Specified by:
    
    checkHandle in class AbstractDataStore
    
    Throws:
    
    DataStoreException
  - first
```
public final int first()
                throws DataStoreException
```
    Description copied from interface: LinkedDataStore
    
    Get the first data handle stored
    
    Returns:
    
    the first entry handle or -1 if the store is empty
    
    Throws:
    
    DataStoreException
  - next
```
public final int next(int handle)
               throws DataStoreException
```
    Description copied from interface: LinkedDataStore
    
    Get the next data handle after the given one
    
    Parameters:
    
    handle - block handle
    
    Returns:
    
    the next entry handle or -1 if their is no successor
    
    Throws:
    
    DataStoreException
  - previous
```
public final int previous(int handle)
                   throws DataStoreException
```
    Description copied from interface: LinkedDataStore
    
    Get the previous data handle after the given one
    
    Parameters:
    
    handle - block handle
    
    Returns:
    
    the previous entry handle or -1 if their is no predecessor
    
    Throws:
    
    DataStoreException
  - retrieveHeader
```
public final byte[] retrieveHeader(int handle,
                                   int headerSize)
                            throws DataStoreException
```
    Throws:
    
    DataStoreException
  - retrieve
```
public final Object retrieve(int handle)
                      throws DataStoreException
```
    Description copied from interface: LinkedDataStore
    
    Retrieve the data associated to a given handle
    
    Throws:
    
    DataStoreException - on storage error or invalid handle
  - size
```
public final int size()
```
    Description copied from interface: DataStore
    
    Get the number of entries in the store
  - delete
```
public final int delete(int handle)
                 throws DataStoreException
```
    Description copied from interface: LinkedDataStore
    
    Delete data associated to the given handle from the store
    
    Returns:
    
    the previous handle or -1
    
    Throws:
    
    DataStoreException - on storage error or invalid handle
  - replace
```
public final int replace(int handle,
                         Object obj)
                  throws DataStoreException
```
    Description copied from interface: LinkedDataStore
    
    Replace data in the store at the given position
    
    Parameters:
    
    handle - message handle
    
    obj - the message to store
    
    Throws:
    
    DataStoreException
  - store
```
public final int store(Object obj,
                       int previousHandle)
                throws DataStoreException
```
    Description copied from interface: LinkedDataStore
    
    Put some data under in the store after the previous handle data
    
    previousHandle - previous entry handle, use 0 if the store is empty
    
    Throws:
    
    DataStoreException
  - close
```
public void close()
```
    Description copied from interface: DataStore
    
    Close the store releasing associated system resources
  - toString
```
public String toString()
```
    Overrides:
    
    toString in class Object
  - integrityCheck
```
protected void integrityCheck()
                       throws DataStoreException
```
    Run an integrity check on the store files and fix them as necessary
    
    Throws:
    
    DataStoreException - if the files could not be fixed
  - getBlockSize
```
public final int getBlockSize()
```
  - writeFirstBlock
```
protected abstract void writeFirstBlock()
                                 throws DataStoreException
```
    Write the first block index to disk
    
    Throws:
    
    DataStoreException
  - writeAllocationBlock
```
protected abstract void writeAllocationBlock(int blockIndex)
                                      throws DataStoreException
```
    Write an allocation block to disk
    
    Throws:
    
    DataStoreException
  - writeDataBlock
```
protected abstract void writeDataBlock(byte[] data,
                                       int offset,
                                       int len,
                                       int blockHandle)
                                throws DataStoreException
```
    Write a data block to disk
    
    Throws:
    
    DataStoreException
  - readDataBlock
```
protected abstract void readDataBlock(byte[] data,
                                      int offset,
                                      int len,
                                      int blockHandle)
                               throws DataStoreException
```
    Read a data block to disk
    
    Throws:
    
    DataStoreException
  - extendStoreFiles
```
protected abstract void extendStoreFiles(int oldBlockCount,
                                         int newBlockCount)
                                  throws DataStoreException
```
    Extend the store files to newBlockCount
    
    Throws:
    
    DataStoreException
  - flush
```
protected abstract void flush()
                       throws DataStoreException
```
    Flush internal buffers
    
    Throws:
    
    DataStoreException
  - serializeAllocationBlock
```
protected final byte[] serializeAllocationBlock(int blockIndex)
```
    Serialize allocation block at index blockIndex
    
    Parameters:
    
    blockIndex - the block index
    
    Returns:
    
    the serialized allocation block
  - getStoreUsage
```
public final int getStoreUsage()
```
    Description copied from interface: DataStore
    
    Get the store usage amount (%) (Ratio of used space over currently allocated space)
  - getAbsoluteStoreUsage
```
public int getAbsoluteStoreUsage()
```
    Description copied from interface: DataStore
    
    Get the absolute store usage amount (%) (Ratio of used space over maximum allocatable space)

Class AbstractBlockBasedDataStore

Field Summary

Fields inherited from class net.timewalker.ffmq4.storage.data.impl.AbstractDataStore

Constructor Summary

Method Summary

Methods inherited from class net.timewalker.ffmq4.storage.data.impl.AbstractDataStore

Methods inherited from class java.lang.Object

Methods inherited from interface net.timewalker.ffmq4.storage.data.DataStore

Field Detail

DATA_FILE_SUFFIX

ALLOCATION_TABLE_SUFFIX

AT_HEADER_SIZE

AT_BLOCK_SIZE

AT_HEADER_BLOCKCOUNT_OFFSET

AT_HEADER_FIRSTBLOCK_OFFSET

AB_FLAGS_OFFSET

AB_ALLOCSIZE_OFFSET

AB_PREVBLOCK_OFFSET

AB_NEXTBLOCK_OFFSET

descriptor

blockSize

blockCount

flags

allocatedSize

nextBlock

previousBlock

firstBlock

allocationTableFile

dataFile

allocationTableRandomAccessFile

dataRandomAccessFile

Constructor Detail

AbstractBlockBasedDataStore

Method Detail

init

initFilesystem

checkHandle

first

next

previous

retrieveHeader

retrieve

size

delete

replace

store

close

toString

integrityCheck

getBlockSize

writeFirstBlock

writeAllocationBlock

writeDataBlock

readDataBlock

extendStoreFiles

flush

serializeAllocationBlock

getStoreUsage

getAbsoluteStoreUsage