org.jlab.coda.jevio

Class EvioReader

java.lang.Object

org.jlab.coda.jevio.EvioReader

All Implemented Interfaces:

IEvioReader

public class EvioReader
extends java.lang.Object
implements IEvioReader

This is a class of interest to the user. It is used to read any evio version format file or buffer. Create an EvioReader object corresponding to an event file or file-formatted buffer, and from this class you can test it for consistency and, more importantly, you can call parseNextEvent() or parseEvent(int) to get new events and to stream the embedded structures to an IEvioListener.

A word to the wise, constructors for reading a file in random access mode (by setting "sequential" arg to false), will memory map the file. This is not a good idea if the file is not on a local disk. Due to java restrictions, files over 2.1GB will require multiple memory maps.

The streaming effect of parsing an event is that the parser will read the event and hand off structures, such as banks, to any IEvioListeners. For those familiar with XML, the event is processed SAX-like. It is up to the listener to decide what to do with the structures.

As an alternative to stream processing, after an event is parsed, the user can use the events treeModel for access to the structures. For those familiar with XML, the event is processed DOM-like.

Author:

heddle, timmer

Constructor Summary

Constructors

Constructor and Description
EvioReader(java.nio.ByteBuffer byteBuffer) Constructor for reading a buffer.
EvioReader(java.nio.ByteBuffer byteBuffer, boolean checkBlkNumSeq) Constructor for reading a buffer.
EvioReader(java.nio.ByteBuffer byteBuffer, boolean checkRecNumSeq, boolean synced) Constructor for reading a buffer with option of removing synchronization for much greater speed.
EvioReader(java.io.File file) Constructor for reading an event file.
EvioReader(java.io.File file, boolean checkBlkNumSeq) Constructor for reading an event file.
EvioReader(java.io.File file, boolean checkRecNumSeq, boolean sequential) Constructor for reading an event file.
EvioReader(java.io.File file, boolean checkRecNumSeq, boolean sequential, boolean synced) Constructor for reading an event file.
EvioReader(java.lang.String path) Constructor for reading an event file.
EvioReader(java.lang.String path, boolean checkBlkNumSeq) Constructor for reading an event file.
EvioReader(java.lang.String path, boolean checkBlkNumSeq, boolean sequential) Constructor for reading an event file.

Method Summary

Modifier and Type	Method and Description
boolean	checkBlockNumberSequence() Is this reader checking the block number sequence and throwing an exception if it's not sequential and starting with 1?
void	close() This is closes the file, but for buffers it only sets the position to 0.
long	fileSize() Get the size of the file being read, in bytes.
int	getBlockCount() This is the number of records in the file/buffer including the empty record or trailer at the end.
java.nio.ByteBuffer	getByteBuffer() Get the byte buffer being read directly or corresponding to the event file.
java.nio.ByteOrder	getByteOrder() Get the byte order of the file/buffer being read.
IBlockHeader	getCurrentBlockHeader() This returns the current (active) block (physical record) header.
java.lang.String	getDictionaryXML() Get the XML format dictionary if there is one.
(package private) static EvioEvent	getEvent(byte[] array, int offset, java.nio.ByteOrder order) Transform an event in the form of a byte array into an EvioEvent object.
EvioEvent	getEvent(int index) Get the event in the file/buffer at a given index (starting at 1).
byte[]	getEventArray(int eventNumber) Get an evio bank or event in byte array form.
java.nio.ByteBuffer	getEventBuffer(int eventNumber) Get an evio bank or event in ByteBuffer form.
int	getEventCount() This is the number of events in the file/buffer.
int	getEvioVersion() Get the evio version number.
IBlockHeader	getFirstBlockHeader() This returns the FIRST block (physical record) header.
EvioEvent	getFirstEvent() Get the "first" event if there is one.
int	getNumEventsRemaining() Get the number of events remaining in the file.
EventParser	getParser() Get the file/buffer parser.
java.lang.String	getPath() Get the path to the file.
EvioEvent	gotoEventNumber(int evNumber) Go to a specific event in the file.
boolean	hasDictionaryXML() Does this evio file have an associated XML dictionary?
boolean	hasFirstEvent() Does this evio file have an associated first event? It's also called the Beginning-Of-Run event.
boolean	isClosed() Has IEvioReader.close() been called (without reopening by calling IEvioReader.setBuffer(ByteBuffer))?
EvioEvent	nextEvent() Get the next event in the file/buffer.
static EvioEvent	parseEvent(byte[] array, int offset, java.nio.ByteOrder order) Completely parse the given byte array into an EvioEvent.
void	parseEvent(EvioEvent evioEvent) This will parse an event, SAX-like.
EvioEvent	parseEvent(int index) This is a workhorse method.
EvioEvent	parseNextEvent() This is a workhorse method.
long	position() This is equivalent to obtaining the current position in the file.
void	rewind() The equivalent of rewinding the file.
void	setBuffer(java.nio.ByteBuffer buf) This method can be used to avoid creating additional EvioReader objects by reusing this one with another buffer.
void	setParser(EventParser parser) Set the file/buffer parser.
WriteStatus	toXMLFile(java.lang.String path) Rewrite the file to XML (not including dictionary and "first" event).
WriteStatus	toXMLFile(java.lang.String path, boolean hex) Rewrite the file to XML (not including dictionary and "first" event).
WriteStatus	toXMLFile(java.lang.String path, IEvioProgressListener progressListener) Rewrite the file to XML (not including dictionary and "first" event).
WriteStatus	toXMLFile(java.lang.String path, IEvioProgressListener progressListener, boolean hex) Rewrite the file to XML (not including dictionary and "first" event).

Methods inherited from class java.lang.Object

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

Constructor Detail

EvioReader

public EvioReader(java.lang.String path)
           throws EvioException,
                  java.io.IOException

Constructor for reading an event file.

Parameters:

path - the full path to the file that contains events. For writing event files, use an EventWriter object.

Throws:

java.io.IOException - if read failure

EvioException - if file arg is null

See Also:

EventWriter

EvioReader

public EvioReader(java.lang.String path,
                  boolean checkBlkNumSeq)
           throws EvioException,
                  java.io.IOException

Constructor for reading an event file.

Parameters:

path - the full path to the file that contains events. For writing event files, use an EventWriter object.

checkBlkNumSeq - if true check the block number sequence and throw an exception if it is not sequential starting with 1

Throws:

java.io.IOException - if read failure

EvioException - if file arg is null; if first block number != 1 when checkBlkNumSeq arg is true

See Also:

EventWriter

EvioReader

public EvioReader(java.io.File file)
           throws EvioException,
                  java.io.IOException

Constructor for reading an event file. Sequential reading and not memory-mapped buffer.

Parameters:

file - the file that contains events.

Throws:

java.io.IOException - if read failure

EvioException - if file arg is null

See Also:

EventWriter

EvioReader

public EvioReader(java.io.File file,
                  boolean checkBlkNumSeq)
           throws EvioException,
                  java.io.IOException

Constructor for reading an event file. Sequential reading and not memory-mapped buffer.

Parameters:

file - the file that contains events.

checkBlkNumSeq - if true check the block number sequence and throw an exception if it is not sequential starting with 1

Throws:

java.io.IOException - if read failure

EvioException - if file arg is null; if first block number != 1 when checkBlkNumSeq arg is true

See Also:

EventWriter

EvioReader

public EvioReader(java.lang.String path,
                  boolean checkBlkNumSeq,
                  boolean sequential)
           throws EvioException,
                  java.io.IOException

Constructor for reading an event file. Do not set sequential to false for remote files.

Parameters:

path - the full path to the file that contains events. For writing event files, use an EventWriter object.

checkBlkNumSeq - if true check the block number sequence and throw an exception if it is not sequential starting with 1

sequential - if true read the file sequentially, else use memory mapped buffers. If file > 2.1 GB, reads are always sequential for the older evio format.

Throws:

java.io.IOException - if read failure

EvioException - if file arg is null; if first block number != 1 when checkBlkNumSeq arg is true

See Also:

EventWriter

EvioReader

public EvioReader(java.io.File file,
                  boolean checkRecNumSeq,
                  boolean sequential)
           throws EvioException,
                  java.io.IOException

Constructor for reading an event file. Do not set sequential to false for remote files.

Parameters:

file - the file that contains events.

checkRecNumSeq - if true check the block number sequence and throw an exception if it is not sequential starting with 1

sequential - if true read the file sequentially, else use memory mapped buffers. If file > 2.1 GB, reads are always sequential for the older evio format.

Throws:

java.io.IOException - if read failure

EvioException - if file arg is null; if file is too small to have valid evio format data if first block number != 1 when checkBlkNumSeq arg is true

See Also:

EventWriter

EvioReader

public EvioReader(java.io.File file,
                  boolean checkRecNumSeq,
                  boolean sequential,
                  boolean synced)
           throws EvioException,
                  java.io.IOException

Constructor for reading an event file. Do not set sequential to false for remote files.

Parameters:

file - the file that contains events.

checkRecNumSeq - if true check the block number sequence and throw an exception if it is not sequential starting with 1

sequential - if true read the file sequentially, else use memory mapped buffers. If file > 2.1 GB, reads are always sequential for the older evio format.

synced - if true, methods are synchronized for thread safety, else false.

Throws:

java.io.IOException - if read failure

EvioException - if file arg is null; bad evio version #; if file is too small to have valid evio format data; if first block number != 1 when checkBlkNumSeq arg is true

See Also:

EventWriter

EvioReader

public EvioReader(java.nio.ByteBuffer byteBuffer)
           throws EvioException

Constructor for reading a buffer.

Parameters:

byteBuffer - the buffer that contains events.

Throws:

EvioException - if buffer arg is null

See Also:

EventWriter

EvioReader

public EvioReader(java.nio.ByteBuffer byteBuffer,
                  boolean checkBlkNumSeq)
           throws EvioException

Constructor for reading a buffer.

Parameters:

byteBuffer - the buffer that contains events.

checkBlkNumSeq - if true check the block number sequence and throw an exception if it is not sequential starting with 1

Throws:

EvioException - if buffer arg is null; if first block number != 1 when checkBlkNumSeq arg is true

See Also:

EventWriter

EvioReader

public EvioReader(java.nio.ByteBuffer byteBuffer,
                  boolean checkRecNumSeq,
                  boolean synced)
           throws EvioException

Constructor for reading a buffer with option of removing synchronization for much greater speed.

Parameters:

byteBuffer - the buffer that contains events.

checkRecNumSeq - if true check the record number sequence and throw an exception if it is not sequential starting with 1

synced - if true, methods are synchronized for thread safety, else false.

Throws:

EvioException - if buffer arg is null; bad version #; failure to read first block header

See Also:

EventWriter

Method Detail

setBuffer

public void setBuffer(java.nio.ByteBuffer buf)
               throws EvioException,
                      java.io.IOException

This method can be used to avoid creating additional EvioReader objects by reusing this one with another buffer. The method IEvioReader.close() is called before anything else.

Specified by:

setBuffer in interface IEvioReader

Parameters:

buf - ByteBuffer to be read

Throws:

EvioException - if buf is null; if first block number != 1 when checkBlkNumSeq arg is true

java.io.IOException - if read failure

isClosed

public boolean isClosed()

Has IEvioReader.close() been called (without reopening by calling IEvioReader.setBuffer(ByteBuffer))?

Specified by:

isClosed in interface IEvioReader

Returns:

true if this object closed, else false.

checkBlockNumberSequence

public boolean checkBlockNumberSequence()

Is this reader checking the block number sequence and throwing an exception if it's not sequential and starting with 1?

Specified by:

checkBlockNumberSequence in interface IEvioReader

Returns:

true if checking block number sequence, else false

getByteOrder

public java.nio.ByteOrder getByteOrder()

Get the byte order of the file/buffer being read.

Specified by:

getByteOrder in interface IEvioReader

Returns:

byte order of the file/buffer being read.

getEvioVersion

public int getEvioVersion()

Get the evio version number.

Specified by:

getEvioVersion in interface IEvioReader

Returns:

evio version number.

getPath

public java.lang.String getPath()

Get the path to the file.

Specified by:

getPath in interface IEvioReader

Returns:

path to the file

getParser

public EventParser getParser()

Get the file/buffer parser.

Specified by:

getParser in interface IEvioReader

Returns:

file/buffer parser.

setParser

public void setParser(EventParser parser)

Set the file/buffer parser.

Specified by:

setParser in interface IEvioReader

Parameters:

parser - file/buffer parser.

getDictionaryXML

public java.lang.String getDictionaryXML()

Get the XML format dictionary if there is one.

Specified by:

getDictionaryXML in interface IEvioReader

Returns:

XML format dictionary, else null.

hasDictionaryXML

public boolean hasDictionaryXML()

Does this evio file have an associated XML dictionary?

Specified by:

hasDictionaryXML in interface IEvioReader

Returns:

true if this evio file has an associated XML dictionary, else false

getFirstEvent

public EvioEvent getFirstEvent()

Get the "first" event if there is one. It's also called the Beginning-Of-Run event. This event is defined once but included in each of the related split files written out.

Specified by:

getFirstEvent in interface IEvioReader

Returns:

the first event if it existed, else null.

hasFirstEvent

public boolean hasFirstEvent()

Does this evio file have an associated first event? It's also called the Beginning-Of-Run event. This event is defined once but included in each of the related split files written out.

Specified by:

hasFirstEvent in interface IEvioReader

Returns:

true if this evio file has an associated first event, else false

getNumEventsRemaining

public int getNumEventsRemaining()
                          throws java.io.IOException,
                                 EvioException

Get the number of events remaining in the file. Useful only if doing a sequential read.

Specified by:

getNumEventsRemaining in interface IEvioReader

Returns:

number of events remaining in the file

Throws:

java.io.IOException - if failed file access

EvioException - if failed reading from coda v3 file

getByteBuffer

public java.nio.ByteBuffer getByteBuffer()

Get the byte buffer being read directly or corresponding to the event file. Not a very useful method. For files, it works only for evio format versions 2,3 and returns the internal buffer containing an evio block if using sequential access (for example files > 2.1 GB). It returns the memory mapped buffer otherwise. For reading buffers it returns the buffer being read.

Specified by:

getByteBuffer in interface IEvioReader

Returns:

the byte buffer being read (in certain cases).

fileSize

public long fileSize()

Get the size of the file being read, in bytes. For small files, obtain the file size using the memory mapped buffer's capacity.

Specified by:

fileSize in interface IEvioReader

Returns:

the file size in bytes

getFirstBlockHeader

public IBlockHeader getFirstBlockHeader()

This returns the FIRST block (physical record) header.

Specified by:

getFirstBlockHeader in interface IEvioReader

Returns:

the first block header.

getEvent

public EvioEvent getEvent(int index)
                   throws java.io.IOException,
                          EvioException

Get the event in the file/buffer at a given index (starting at 1). As useful as this sounds, most applications will probably call IEvioReader.parseNextEvent() or IEvioReader.parseEvent(int) instead, since it combines combines getting an event with parsing it.

Specified by:

getEvent in interface IEvioReader

Parameters:

index - number of event desired, starting at 1, from beginning of file/buffer

Returns:

the event in the file/buffer at the given index or null if none

Throws:

java.io.IOException - if failed file access

EvioException - if failed read due to bad file/buffer format; if out of memory; if index out of bounds; if object closed

parseEvent

public EvioEvent parseEvent(int index)
                     throws java.io.IOException,
                            EvioException

This is a workhorse method. It retrieves the desired event from the file/buffer, and then parses it SAX-like. It will drill down and uncover all structures (banks, segments, and tagsegments) and notify any interested listeners.

Specified by:

parseEvent in interface IEvioReader

Parameters:

index - number of event desired, starting at 1, from beginning of file/buffer

Returns:

the parsed event at the given index or null if none

Throws:

java.io.IOException - if failed file access

EvioException - if failed read due to bad file/buffer format; if out of memory; if index out of bounds; if object closed

nextEvent

public EvioEvent nextEvent()
                    throws java.io.IOException,
                           EvioException

Get the next event in the file/buffer. As useful as this sounds, most applications will probably call IEvioReader.parseNextEvent() instead, since it combines getting the next event with parsing the next event.

Although this method can get events in versions 4+, it now delegates that to another method. No changes were made to this method from versions 1-3 in order to read the version 4 format as it is subset of versions 1-3 with variable block length.

Specified by:

nextEvent in interface IEvioReader

Returns:

the next event in the file. On error it throws an EvioException. On end of file, it returns null.

Throws:

java.io.IOException - if failed file access

EvioException - if failed read due to bad buffer format; if object closed

parseNextEvent

public EvioEvent parseNextEvent()
                         throws java.io.IOException,
                                EvioException

This is a workhorse method. It retrieves the next event from the file/buffer, and then parses it SAX-like. It will drill down and uncover all structures (banks, segments, and tagsegments) and notify any interested listeners.

Specified by:

parseNextEvent in interface IEvioReader

Returns:

the event that was parsed. On error it throws an EvioException. On end of file, it returns null.

Throws:

java.io.IOException - if failed file access

EvioException - if read failure or bad format if object closed

parseEvent

public void parseEvent(EvioEvent evioEvent)
                throws EvioException

This will parse an event, SAX-like. It will drill down and uncover all structures (banks, segments, and tagsegments) and notify any interested listeners.

As useful as this sounds, most applications will probably call IEvioReader.parseNextEvent() instead, since it combines combines getting the next event with parsing the next event.

This method is only called by synchronized methods and therefore is not synchronized.

Specified by:

parseEvent in interface IEvioReader

Parameters:

evioEvent - the event to parse.

Throws:

EvioException - if bad format

getEvent

static EvioEvent getEvent(byte[] array,
                          int offset,
                          java.nio.ByteOrder order)
                   throws EvioException

Transform an event in the form of a byte array into an EvioEvent object. However, only top level header is parsed. Most users will want to call parseEvent(byte[], int, ByteOrder) instead since it returns a fully parsed event. Byte array must not be in file format (have record headers), but must consist of only the bytes comprising the evio event.

Parameters:

array - array to parse into EvioEvent object.

offset - offset into array.

order - byte order to use.

Returns:

an EvioEvent object parsed from the given array.

Throws:

EvioException - if null arg, too little data, length too large, or data not in evio format.

parseEvent

public static EvioEvent parseEvent(byte[] array,
                                   int offset,
                                   java.nio.ByteOrder order)
                            throws EvioException

Completely parse the given byte array into an EvioEvent. Byte array must not be in file format (have record headers), but must consist of only the bytes comprising the evio event.

Parameters:

array - array to parse into EvioEvent object.

offset - offset into array.

order - byte order to use.

Returns:

the EvioEvent object parsed from the given bytes.

Throws:

EvioException - if null arg, too little data, length too large, or data not in evio format.

getEventArray

public byte[] getEventArray(int eventNumber)
                     throws EvioException,
                            java.io.IOException

Get an evio bank or event in byte array form.

Specified by:

getEventArray in interface IEvioReader

Parameters:

eventNumber - number of event of interest (starting at 1).

Returns:

array containing bank's/event's bytes.

Throws:

EvioException - if eventNumber out of bounds (starts at 1); if the event number does not correspond to an existing event; if object closed

java.io.IOException - if failed file access

getEventBuffer

public java.nio.ByteBuffer getEventBuffer(int eventNumber)
                                   throws EvioException,
                                          java.io.IOException

Get an evio bank or event in ByteBuffer form.

Specified by:

getEventBuffer in interface IEvioReader

Parameters:

eventNumber - number of event of interest

Returns:

buffer containing bank's/event's bytes.

Throws:

EvioException - if eventNumber is out of bounds; if the event number does not correspond to an existing event; if object closed

java.io.IOException - if failed file access

rewind

public void rewind()
            throws java.io.IOException,
                   EvioException

The equivalent of rewinding the file. What it actually does is set the position of the file/buffer back to where it was after calling the constructor - after the first header. This method, along with the two position() and the close() method, allows applications to treat files in a normal random access manner.

Specified by:

rewind in interface IEvioReader

Throws:

java.io.IOException - if failed file access or buffer/file read

EvioException - if object closed

position

public long position()
              throws java.io.IOException,
                     EvioException

This is equivalent to obtaining the current position in the file. What it actually does is return the position of the buffer. This method, along with the rewind(), position(int) and the close() method, allows applications to treat files in a normal random access manner. Only meaningful to evio versions 1-3 and for sequential reading.

Specified by:

position in interface IEvioReader

Returns:

the position of the buffer; -1 if version 4+

Throws:

java.io.IOException - if error accessing file

EvioException - if object closed

close

public void close()
           throws java.io.IOException

This is closes the file, but for buffers it only sets the position to 0. This method, along with the rewind() and the two position() methods, allows applications to treat files in a normal random access manner.

Specified by:

close in interface IEvioReader

Throws:

java.io.IOException - if error accessing file

getCurrentBlockHeader

public IBlockHeader getCurrentBlockHeader()

This returns the current (active) block (physical record) header. Since most users have no interest in physical records, this method should not be used.

Specified by:

getCurrentBlockHeader in interface IEvioReader

Returns:

the current block header.

gotoEventNumber

public EvioEvent gotoEventNumber(int evNumber)
                          throws java.io.IOException,
                                 EvioException

Go to a specific event in the file. The events are numbered 1..N. This number is transient--it is not part of the event as stored in the evio file. In versions 4 and up this is just a wrapper on IEvioReader.getEvent(int).

Specified by:

gotoEventNumber in interface IEvioReader

Parameters:

evNumber - the event number in a 1..N counting sense, from the start of the file.

Returns:

the specified event in file or null if there's an error or nothing at that event #.

Throws:

java.io.IOException - if failed file access

EvioException - if object closed

toXMLFile

public WriteStatus toXMLFile(java.lang.String path)
                      throws java.io.IOException,
                             EvioException

Rewrite the file to XML (not including dictionary and "first" event).

Specified by:

toXMLFile in interface IEvioReader

Parameters:

path - the path to the XML file.

Returns:

the status of the write.

Throws:

java.io.IOException - if failed file access

EvioException - if object closed

toXMLFile

public WriteStatus toXMLFile(java.lang.String path,
                             boolean hex)
                      throws java.io.IOException,
                             EvioException

Rewrite the file to XML (not including dictionary and "first" event).

Specified by:

toXMLFile in interface IEvioReader

Parameters:

path - the path to the XML file.

hex - if true, ints get displayed in hexadecimal

Returns:

the status of the write.

Throws:

java.io.IOException - if failed file access

EvioException - if object closed

toXMLFile

public WriteStatus toXMLFile(java.lang.String path,
                             IEvioProgressListener progressListener)
                      throws java.io.IOException,
                             EvioException

Rewrite the file to XML (not including dictionary and "first" event).

Specified by:

toXMLFile in interface IEvioReader

Parameters:

path - the path to the XML file.

progressListener - and optional progress listener, can be null.

Returns:

the status of the write.

Throws:

java.io.IOException - if failed file access

EvioException - if object closed

See Also:

IEvioProgressListener

toXMLFile

public WriteStatus toXMLFile(java.lang.String path,
                             IEvioProgressListener progressListener,
                             boolean hex)
                      throws java.io.IOException,
                             EvioException

Rewrite the file to XML (not including dictionary and "first" event).

Specified by:

toXMLFile in interface IEvioReader

Parameters:

path - the path to the XML file.

progressListener - and optional progress listener, can be null.

hex - if true, ints get displayed in hexadecimal

Returns:

the status of the write.

Throws:

java.io.IOException - if failed file access

EvioException - if object closed

See Also:

IEvioProgressListener

getEventCount

public int getEventCount()
                  throws java.io.IOException,
                         EvioException

This is the number of events in the file/buffer. Any dictionary or first event are not included in the count.

Specified by:

getEventCount in interface IEvioReader

Returns:

the number of events in the file/buffer.

Throws:

java.io.IOException - if failed file access

EvioException - if read failure; if object closed

getBlockCount

public int getBlockCount()
                  throws EvioException

This is the number of records in the file/buffer including the empty record or trailer at the end.

Specified by:

getBlockCount in interface IEvioReader

Returns:

the number of records in the file/buffer (estimate for version 3 files).

Throws:

EvioException - if object closed.