Package uk.ac.bristol.star.cdf.record

Class 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 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