BufferChannel (Apache Jena - DBOE Base 4.2.0)

All Superinterfaces:

org.apache.jena.atlas.lib.Closeable, org.apache.jena.atlas.lib.Sync

All Known Implementing Classes:

BufferChannelFile, BufferChannelMem
```
public interface BufferChannel
extends org.apache.jena.atlas.lib.Sync, org.apache.jena.atlas.lib.Closeable
```
Interface to storage : a simplified version of FileChannel. Read and write bytes, passed via ByteBuffers, addressed by file location. This interface is not suitable for memory mapped I/O - there is no ability to use slices of a memory mapped file. This interface does not insert size of ByteBuffer, the size of ByteBuffer passed to read controls the number of bytes read. Having our own abstraction enables us to implement memory-backed versions.

See Also:

BlockAccess, FileChannel

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`BufferChannel`	`duplicate()`	Return another channel to the same storage but with independent position.
`java.lang.String`	`getFilename()`	Filename for this BufferChannel (maybe null)
`java.lang.String`	`getLabel()`	useful display string
`boolean`	`isEmpty()`	Is it empty?
`long`	`position()`	return the position
`void`	`position(long pos)`	set the position
`int`	`read(java.nio.ByteBuffer buffer)`	Read into a ByteBuffer.
`int`	`read(java.nio.ByteBuffer buffer, long loc)`	Read into a ByteBuffer, starting at position loc.
`long`	`size()`	Length of storage, in bytes.
`void`	`truncate(long size)`	Truncate the file.
`int`	`write(java.nio.ByteBuffer buffer)`	Write from ByteBuffer, starting at the current position.
`int`	`write(java.nio.ByteBuffer buffer, long loc)`	Write from ByteBuffer, starting at position loc.

Methods inherited from interface org.apache.jena.atlas.lib.Closeable
close

Methods inherited from interface org.apache.jena.atlas.lib.Sync
sync

- Method Detail
  - duplicate
```
BufferChannel duplicate()
```
    Return another channel to the same storage but with independent position. Chaos may result due to concurrent use.
  - position
```
long position()
```
    return the position
  - position
```
void position(long pos)
```
    set the position
  - read
```
int read(java.nio.ByteBuffer buffer)
```
    Read into a ByteBuffer. Returns the number of bytes read. -1 for end of file.
  - read
```
int read(java.nio.ByteBuffer buffer,
         long loc)
```
    Read into a ByteBuffer, starting at position loc. Return the number of bytes read. loc must be within the file.
  - write
```
int write(java.nio.ByteBuffer buffer)
```
    Write from ByteBuffer, starting at the current position. Return the number of bytes written
  - write
```
int write(java.nio.ByteBuffer buffer,
          long loc)
```
    Write from ByteBuffer, starting at position loc. Return the number of bytes written. loc must be within 0 to length - writing at length is append
  - truncate
```
void truncate(long size)
```
    Truncate the file.
    
    See Also:
    
    FileChannel.truncate(long)
  - size
```
long size()
```
    Length of storage, in bytes.
  - isEmpty
```
boolean isEmpty()
```
    Is it empty?
  - getLabel
```
java.lang.String getLabel()
```
    useful display string
  - getFilename
```
java.lang.String getFilename()
```
    Filename for this BufferChannel (maybe null)