ucar.nc2.iosp

Class AbstractIOServiceProvider

java.lang.Object

ucar.nc2.iosp.AbstractIOServiceProvider

All Implemented Interfaces:

IOServiceProvider

public abstract class AbstractIOServiceProvider
extends Object
implements IOServiceProvider

Abstract base class for IOSP implementations that provides default implementations of readToByteChannel(...) and readSection(...).

Implementations should make sure to handle the RandomAccessFile properly by doing one of the following:

1. Write your own open(...) and close() methods that keep track of the RandomAccessFile, be sure to close the RandomAccessFile in your close() method.
2. Write your own open(...) and close() methods that call the open(...) and close() methods defined here, use the "raf" variable also defined here.
3. Don't write an open(...) or close() method, so that those defined here are used.

Constructor Summary

Constructors

Constructor and Description
AbstractIOServiceProvider()

Method Summary

Modifier and Type	Method and Description
void	build(RandomAccessFile raf, Group.Builder rootGroup, CancelTask cancelTask) Open existing file, and populate it.
void	buildFinish(NetcdfFile ncfile) Sometimes the builder needs access to the finished objects.
void	close() Close the file.
String	getDetailInfo() Show debug / underlying implementation details
String	getFileTypeVersion() Get the version of this file type.
long	getLastModified() Returns the time that the underlying file(s) were last modified.
StructureDataIterator	getStructureIterator(Structure s, int bufferSize) Get the structure iterator.
boolean	isBuilder() If this iosp implements build().
void	open(RandomAccessFile raf, NetcdfFile ncfile, CancelTask cancelTask) Open existing file, and populate ncfile with it.
void	reacquire() Reacquire any resources like file handles Used when reactivating in cache.
Array	readSection(ParsedSectionSpec cer) Allows reading sections of nested variables
long	readToByteChannel(Variable v2, Section section, WritableByteChannel channel) Read data from a top level Variable and send data to a WritableByteChannel.
long	readToOutputStream(Variable v2, Section section, OutputStream out) Read data from a top level Variable and send data to a OutputStream.
void	release() Release any system resources like file handles.
Object	sendIospMessage(Object message) A way to communicate arbitrary information to an iosp.
void	setNetcdfFile(NetcdfFile ncfile)
long	streamToByteChannel(Variable v2, Section section, WritableByteChannel channel)
boolean	syncExtend() Extend the NetcdfFile if the underlying dataset has changed in a way that is compatible with the current metadata.
String	toStringDebug(Object o) Debug info for this object.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface ucar.nc2.iosp.IOServiceProvider

getFileTypeDescription, getFileTypeId, isValidFile, readData

Constructor Detail

AbstractIOServiceProvider

public AbstractIOServiceProvider()

Method Detail

open

public void open(RandomAccessFile raf,
                 NetcdfFile ncfile,
                 CancelTask cancelTask)
          throws IOException

Description copied from interface: IOServiceProvider

Open existing file, and populate ncfile with it. This method is only called by the NetcdfFile constructor on itself. The provided NetcdfFile object will be empty except for the location String and the IOServiceProvider associated with this NetcdfFile object.

Specified by:

open in interface IOServiceProvider

Parameters:

raf - the file to work on, it has already passed the isValidFile() test.

ncfile - add objects to this empty NetcdfFile

cancelTask - used to monitor user cancellation; may be null.

Throws:

IOException - if read error

setNetcdfFile

public void setNetcdfFile(NetcdfFile ncfile)

isBuilder

public boolean isBuilder()

Description copied from interface: IOServiceProvider

If this iosp implements build().

Specified by:

isBuilder in interface IOServiceProvider

build

public void build(RandomAccessFile raf,
                  Group.Builder rootGroup,
                  CancelTask cancelTask)
           throws IOException

Description copied from interface: IOServiceProvider

Open existing file, and populate it. Note that you cannot reference the NetcdfFile within this routine. This is the bridge to immutable objects that will be used exclusively in version 6.

Specified by:

build in interface IOServiceProvider

Parameters:

raf - the file to work on, it has already passed the isValidFile() test.

rootGroup - add objects to the root group.

cancelTask - used to monitor user cancellation; may be null.

Throws:

IOException - if read error

buildFinish

public void buildFinish(NetcdfFile ncfile)

Description copied from interface: IOServiceProvider

Sometimes the builder needs access to the finished objects. This is called after ncfile.build()

Specified by:

buildFinish in interface IOServiceProvider

close

public void close()
           throws IOException

Description copied from interface: IOServiceProvider

Close the file. It is the IOServiceProvider's job to close the file (even though it didnt open it), and to free any other resources it has used.

Specified by:

close in interface IOServiceProvider

Throws:

IOException - if read error

release

public void release()
             throws IOException

Description copied from interface: IOServiceProvider

Release any system resources like file handles. Optional, implement only if you are able to reacquire. Used when object is made inactive in cache.

Specified by:

release in interface IOServiceProvider

Throws:

IOException

reacquire

public void reacquire()
               throws IOException

Description copied from interface: IOServiceProvider

Reacquire any resources like file handles Used when reactivating in cache.

Specified by:

reacquire in interface IOServiceProvider

Throws:

IOException

readToByteChannel

public long readToByteChannel(Variable v2,
                              Section section,
                              WritableByteChannel channel)
                       throws IOException,
                              InvalidRangeException

Description copied from interface: IOServiceProvider

Read data from a top level Variable and send data to a WritableByteChannel. Must be in big-endian order.

Specified by:

readToByteChannel in interface IOServiceProvider

Parameters:

v2 - a top-level Variable

section - the section of data to read. There must be a Range for each Dimension in the variable, in order. Note: no nulls allowed. IOSP may not modify.

channel - write data to this WritableByteChannel

Returns:

the number of bytes written to the channel

Throws:

IOException - if read error

InvalidRangeException - if invalid section

readToOutputStream

public long readToOutputStream(Variable v2,
                               Section section,
                               OutputStream out)
                        throws IOException,
                               InvalidRangeException

Description copied from interface: IOServiceProvider

Read data from a top level Variable and send data to a OutputStream. Must be in big-endian order, following ncstream conventions. Default implementation just reads to memory and writes to stream. Allow override for possible performance improvements.

Specified by:

readToOutputStream in interface IOServiceProvider

Parameters:

v2 - a top-level Variable

section - the section of data to read. There must be a Range for each Dimension in the variable, in order. Note: no nulls allowed. IOSP may not modify.

out - write data to this OutputStream

Returns:

the number of bytes written to the channel

Throws:

IOException - if read error

InvalidRangeException - if invalid section

streamToByteChannel

public long streamToByteChannel(Variable v2,
                                Section section,
                                WritableByteChannel channel)
                         throws IOException,
                                InvalidRangeException

Specified by:

streamToByteChannel in interface IOServiceProvider

Throws:

IOException

InvalidRangeException

readSection

public Array readSection(ParsedSectionSpec cer)
                  throws IOException,
                         InvalidRangeException

Description copied from interface: IOServiceProvider

Allows reading sections of nested variables

Specified by:

readSection in interface IOServiceProvider

Parameters:

cer - section specification : what data is wanted

Returns:

requested data array

Throws:

IOException - on read error

InvalidRangeException - if section spec is invalid

getStructureIterator

public StructureDataIterator getStructureIterator(Structure s,
                                                  int bufferSize)
                                           throws IOException

Description copied from interface: IOServiceProvider

Get the structure iterator. iosps with top level sequences must override. Not threadsafe; do not use multiple StructureDataIterator for the same iosp.

Specified by:

getStructureIterator in interface IOServiceProvider

Parameters:

s - the Structure

bufferSize - the buffersize

Returns:

the data iterator

Throws:

IOException - if problem reading data

sendIospMessage

public Object sendIospMessage(Object message)

Description copied from interface: IOServiceProvider

A way to communicate arbitrary information to an iosp.

Specified by:

sendIospMessage in interface IOServiceProvider

Parameters:

message - opaque message sent to the IOSP object when its opened (not when isValidFile() is called)

Returns:

opaque return, may be null.

syncExtend

public boolean syncExtend()
                   throws IOException

Description copied from interface: IOServiceProvider

Extend the NetcdfFile if the underlying dataset has changed in a way that is compatible with the current metadata. For example, if the unlimited dimension has grown.

Specified by:

syncExtend in interface IOServiceProvider

Returns:

true if the NetcdfFile was extended.

Throws:

IOException - if a read error occured when accessing the underlying dataset.

getLastModified

public long getLastModified()

Returns the time that the underlying file(s) were last modified. If they've changed since they were stored in the cache, they will be closed and reopened with FileFactory.

Returns:

a long value representing the time the file(s) were last modified or 0L if the last-modified time couldn't be determined for any reason.

toStringDebug

public String toStringDebug(Object o)

Description copied from interface: IOServiceProvider

Debug info for this object.

Specified by:

toStringDebug in interface IOServiceProvider

Parameters:

o - which object

Returns:

debug info for this object

getDetailInfo

public String getDetailInfo()

Description copied from interface: IOServiceProvider

Show debug / underlying implementation details

Specified by:

getDetailInfo in interface IOServiceProvider

Returns:

debug info

getFileTypeVersion

public String getFileTypeVersion()

Description copied from interface: IOServiceProvider

Get the version of this file type.

Specified by:

getFileTypeVersion in interface IOServiceProvider

Returns:

version of the file type

See Also:

"https://www.unidata.ucar.edu/software/netcdf-java/formats/FileTypes.html"