SimpleMappedMemoryHandler

java.lang.Object
- org.jlab.coda.eventViewer.SimpleMappedMemoryHandler

```
public class SimpleMappedMemoryHandler
extends java.lang.Object
```
This is a class designed to handle access files with size greater than 2.1 GBytes. Currently the largest size memory map that Java can handle is Integer.MAX_VALUE which limits the use of memory mapping to looking at files that size or smaller. This class circumvents this limit by viewing large files as a collection of multiple memory maps.
Just a note about synchronization. This object is NOT thread-safe.

Constructor Summary

Constructors
Constructor and Description
`SimpleMappedMemoryHandler(java.nio.ByteBuffer buf)` Constructor.
`SimpleMappedMemoryHandler(java.io.File file, java.nio.ByteOrder order)` Constructor.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`close()` Close unneeded file channel object.
`byte`	`getByteAtBytePos(long bytePosition)` Get the byte value in the file at the given byte index.
`int`	`getExtraByteCount()` Get the number of extra bytes at the very end of this file beyond an integral number of ints.
`java.nio.channels.FileChannel`	`getFileChannel()` Get the file channel object.
`org.jlab.coda.hipo.FileHeader`	`getFileHeader()` Get the file header of a version 6 evio file.
`java.nio.ByteBuffer`	`getFileHeaderData()` Get the file header data of a version 6 evio file including index and user header.
`long`	`getFileSize()` Get the file size in bytes.
`int`	`getFirstDataIndex()` Get the number of 32 bit words comprising the file and first record headers for evio version 6 files, or comprising the first block header for evio versions < 6.
`java.nio.ByteBuffer`	`getFirstMap()` Get the first memory map - used to map the beginning of the file.
`int`	`getInt(long wordPosition)` Get the int value in the file at the given word (4 byte) position.
`int`	`getIntAtBytePos(long bytePosition)` Get the int value in the file at the given byte index.
`java.nio.ByteBuffer`	`getMap(int mapIndex)` Get the indicated memory map.
`int`	`getMapCount()` Get the number of memory maps used to fully map file.
`int`	`getMapIndex(long wordIndex)` Get the index of the map for a given word index.
`int`	`getMapSize(int mapIndex)` Get the size of the given map.
`long`	`getMaxMapSize()` Get the maximum byte size of each memory map (last one will be smaller).
`java.nio.ByteOrder`	`getOrder()` Get the byte order of the data.
`short`	`getShortAtBytePos(long bytePosition)` Get the short value in the file at the given byte index.
`int`	`getTotalFileHeaderBytes()` Get the total number of bytes in file header + index + user header for evio version 6 file.
`boolean`	`haveExtraBytes()` Does this file have 1, 2, or 3 bytes more than an integral number of integers?
`boolean`	`isCompressed()` Does the first record of the first map contain compressed data?
`void`	`setByteOrder(java.nio.ByteOrder order)` Set the byte order of the data.

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

- Constructor Detail
  - SimpleMappedMemoryHandler
```
public SimpleMappedMemoryHandler(java.io.File file,
                                 java.nio.ByteOrder order)
                          throws java.io.IOException
```
    Constructor.
    
    Parameters:
    
    file - file's file channel object
    
    order - byte order of the data
    
    Throws:
    
    java.io.IOException - if could not map file
  - SimpleMappedMemoryHandler
```
public SimpleMappedMemoryHandler(java.nio.ByteBuffer buf)
```
    Constructor.
    
    Parameters:
    
    buf - buffer to analyze
- Method Detail
  - isCompressed
```
public boolean isCompressed()
```
    Does the first record of the first map contain compressed data?
    
    Returns:
    
    true if data in first record of the first memory map is compressed, else false.
  - getFirstDataIndex
```
public int getFirstDataIndex()
```
    Get the number of 32 bit words comprising the file and first record headers for evio version 6 files, or comprising the first block header for evio versions < 6.
    
    Returns:
    
    the position, in 32 bit words, of the first data word from the file start.
  - getTotalFileHeaderBytes
```
public int getTotalFileHeaderBytes()
```
    Get the total number of bytes in file header + index + user header for evio version 6 file.
    
    Returns:
    
    total number of bytes in file header + index + user header for evio version 6 file.
  - getFileHeaderData
```
public java.nio.ByteBuffer getFileHeaderData()
```
    Get the file header data of a version 6 evio file including index and user header.
    
    Returns:
    
    file header data of a version 6 evio file including index and user header, or null if evio version < 6.
  - getFileHeader
```
public org.jlab.coda.hipo.FileHeader getFileHeader()
```
    Get the file header of a version 6 evio file.
    
    Returns:
    
    file header of a version 6 evio file, or null if evio version < 6.
  - close
```
public void close()
```
    Close unneeded file channel object.
  - haveExtraBytes
```
public boolean haveExtraBytes()
```
    Does this file have 1, 2, or 3 bytes more than an integral number of integers?
    
    Returns:
    
    false if file is integral number of ints, else true.
  - getExtraByteCount
```
public int getExtraByteCount()
```
    Get the number of extra bytes at the very end of this file beyond an integral number of ints.
    
    Returns:
    
    number of extra bytes at the very end of this file beyond an integral number of ints.
  - getMaxMapSize
```
public long getMaxMapSize()
```
    Get the maximum byte size of each memory map (last one will be smaller).
    
    Returns:
    
    max byte size of each memory map.
  - getFileChannel
```
public java.nio.channels.FileChannel getFileChannel()
```
    Get the file channel object.
    
    Returns:
    
    file channel object.
  - getFileSize
```
public long getFileSize()
```
    Get the file size in bytes.
    
    Returns:
    
    file size in bytes.
  - getMapSize
```
public int getMapSize(int mapIndex)
```
    Get the size of the given map.
    
    Parameters:
    
    mapIndex - index of map.
    
    Returns:
    
    size of map in bytes
  - getMapCount
```
public int getMapCount()
```
    Get the number of memory maps used to fully map file.
    
    Returns:
    
    number of memory maps used to fully map file.
  - getFirstMap
```
public java.nio.ByteBuffer getFirstMap()
```
    Get the first memory map - used to map the beginning of the file.
    
    Returns:
    
    first memory map - used to map the beginning of the file.
  - setByteOrder
```
public void setByteOrder(java.nio.ByteOrder order)
```
    Set the byte order of the data.
    
    Parameters:
    
    order - byte order of the data.
  - getOrder
```
public java.nio.ByteOrder getOrder()
```
    Get the byte order of the data.
    
    Returns:
    
    byte order of the data.
  - getMap
```
public java.nio.ByteBuffer getMap(int mapIndex)
```
    Get the indicated memory map.
    
    Parameters:
    
    mapIndex - index into map holding memory mapped ByteBuffers
    
    Returns:
    
    indicated memory map.
  - getInt
```
public int getInt(long wordPosition)
```
    Get the int value in the file at the given word (4 byte) position.
    
    Parameters:
    
    wordPosition - word position in file
    
    Returns:
    
    int value in file at word position
  - getIntAtBytePos
```
public int getIntAtBytePos(long bytePosition)
```
    Get the int value in the file at the given byte index.
    
    Parameters:
    
    bytePosition - byte index into file
    
    Returns:
    
    int value in file at byte index
  - getShortAtBytePos
```
public short getShortAtBytePos(long bytePosition)
```
    Get the short value in the file at the given byte index.
    
    Parameters:
    
    bytePosition - byte index into file
    
    Returns:
    
    short value in file at byte index
  - getByteAtBytePos
```
public byte getByteAtBytePos(long bytePosition)
```
    Get the byte value in the file at the given byte index.
    
    Parameters:
    
    bytePosition - byte index into file
    
    Returns:
    
    byte value in file at byte index
  - getMapIndex
```
public int getMapIndex(long wordIndex)
```
    Get the index of the map for a given word index.
    
    Parameters:
    
    wordIndex - index of word
    
    Returns:
    
    index of map containing word

Class SimpleMappedMemoryHandler

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

SimpleMappedMemoryHandler

SimpleMappedMemoryHandler

Method Detail

isCompressed

getFirstDataIndex

getTotalFileHeaderBytes

getFileHeaderData

getFileHeader

close

haveExtraBytes

getExtraByteCount

getMaxMapSize

getFileChannel

getFileSize

getMapSize

getMapCount

getFirstMap

setByteOrder

getOrder

getMap

getInt

getIntAtBytePos

getShortAtBytePos

getByteAtBytePos

getMapIndex