uk.ac.bristol.star.cdf.record

Class RecordMap

java.lang.Object

uk.ac.bristol.star.cdf.record.RecordMap

public class RecordMap
extends java.lang.Object

Keeps track of where a variable's record data is stored.

To work out the buffer and offset from which to read a record value, you can do something like this:

     int ient = recMap.getEntryIndex(irec);
     Object value =
            ient >= 0
          ? readBuffer(recMap.getBuf(ient), recMap.getOffset(ient,irec))
          : NO_STORED_VALUE;
 

Since:

21 Jun 2013

Method Summary

Modifier and Type	Method and Description
static RecordMap	createRecordMap(VariableDescriptorRecord vdr, RecordFactory recFact, int recSize) Returns a record map for a given variable.
Buf	getBuf(int ient) Returns the data buffer for a given entry.
int	getEntryCount() Returns the number of entries managed by this map.
int	getEntryIndex(int irec) Returns the index of the entry containing a given record.
long	getFinalOffsetInEntry(int ient) Returns the offset of the last record in a given entry.
long	getOffset(int ient, int irec) Returns the byte offset for a record in a given entry.

Methods inherited from class java.lang.Object

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

Method Detail

getEntryCount

public int getEntryCount()

Returns the number of entries managed by this map.

Returns:

entry count

getEntryIndex

public int getEntryIndex(int irec)

Returns the index of the entry containing a given record. If one of the entries contains the given record, return its index. If no entry contains it (the record is in a sparse region), return (-fr-2), where fr is the index of the previous entry. A value of -1 indicates that the requested record is in a sparse region before the first stored record.

If non-negative, the result can be used with the getBuf and getOffset methods.

Parameters:

irec - record index

Returns:

index of entry covering irec, or a negative value if no entry covers it

getBuf

public Buf getBuf(int ient)

Returns the data buffer for a given entry. The entry index must correspond to an actual entry, that is it must not be negative.

Parameters:

ient - entry index

Returns:

buf

See Also:

getEntryIndex(int)

getOffset

public long getOffset(int ient,
                      int irec)

Returns the byte offset for a record in a given entry. The ient parameter must reference an actual entry (it must be non-negative), and that entry must contain the given record irec,

Parameters:

ient - entry index for entry containing irec

irec - record index

Returns:

offset into the entry's buffer at which irec can be found

See Also:

getEntryIndex(int)

getFinalOffsetInEntry

public long getFinalOffsetInEntry(int ient)

Returns the offset of the last record in a given entry.

Parameters:

ient - non-negative entry index

Returns:

offset into ient's buffer of ient's final record

createRecordMap

public static RecordMap createRecordMap(VariableDescriptorRecord vdr,
                                        RecordFactory recFact,
                                        int recSize)
                                 throws java.io.IOException

Returns a record map for a given variable.

Parameters:

vdr - variable descriptor record

recFact - record factory

recSize - size in bytes of each variable value record

Returns:

record map

Throws:

java.io.IOException