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## net.metanotion.io.block.index
Class IBSkipSpan

    java.lang.Object
      net.metanotion.util.skiplist.SkipSpan
          net.metanotion.io.block.index.BSkipSpan
              net.metanotion.io.block.index.IBSkipSpan

    public class IBSkipSpan

extends BSkipSpan

I2P version of BSkipSpan BSkipSpan stores all keys and values in-memory, backed by the file. IBSkipSpan stores only the first key, and no values, in-memory. For a get(), here we do a linear search through the span in the file and load only the found value (super() does a binary search in-memory). For a put() or remove(), we load all keys and values for the span from the file, make the modification, flush() out the keys and values, and null out the keys and values in-memory. Recommended span size is 16.

Author:
  zzz

Field Summary

Fields inherited from class net.metanotion.io.block.index.BSkipSpan
`bf, CONT_HEADER_LEN, HEADER_LEN, isKilled, keySer, MAGIC, nextPage, overflowPage, page, prevPage, spanSize, valSer`

Fields inherited from class net.metanotion.util.skiplist.SkipSpan
`keys, MAX_SIZE, next, nKeys, prev, vals`

Constructor Summary
`IBSkipSpan(BlockFile bf, BSkipList bsl, int spanPage, Serializer key, Serializer val)`

Method Summary
`Comparable` | `firstKey()` Does not call super, we always store first key here
`void` | `flush()` Flush to disk and null out in-memory keys and values, saving only the first key
`Object` | `get(Comparable key)` Linear search if in file, Binary search if in memory
`SkipSpan` | `getSpan(Comparable key, int[] search)` Load whole span from file, do the operation, flush out, then null out in-memory data again.
`protected void` | `loadData()` I2P - second half of load() Load the whole span's keys and values into memory
`SkipSpan` | `newInstance(SkipList sl)`
`SkipSpan` | `put(Comparable key, Object val, SkipList sl)` Load whole span from file, do the operation, flush out, then null out in-memory data again.
`Object[]` | `remove(Comparable key, SkipList sl)` Load whole span from file, do the operation, flush out, then null out in-memory data again.
`(package private) void` | `seekAndLoadData()` Seek to the start of the span and load the data Package private so BSkipIterator can call it

Methods inherited from class net.metanotion.io.block.index.BSkipSpan
`init, killInstance, loadData, loadInit, lostEntries, toString`

Methods inherited from class net.metanotion.util.skiplist.SkipSpan
`getEnd, print`

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

Constructor Detail

### IBSkipSpan

    public IBSkipSpan(BlockFile bf,
                      BSkipList bsl,
                      int spanPage,
                      Serializer key,
                      Serializer val)
               throws IOException

Throws:
  `IOException`

Method Detail

### newInstance

    public SkipSpan newInstance(SkipList sl)

  Overrides:
    `newInstance` in class `BSkipSpan`

### flush

    public void flush()

  Flush to disk and null out in-memory keys and values, saving only the first key

  Overrides:
    `flush` in class `BSkipSpan`

### loadData

    protected void loadData()
                     throws IOException

  I2P - second half of load() Load the whole span's keys and values into memory

  Overrides:
    `loadData` in class `BSkipSpan`
  Throws:
    `IOException`

### seekAndLoadData

    void seekAndLoadData()
                   throws IOException

  Seek to the start of the span and load the data Package private so BSkipIterator can call it

  Throws:
    `IOException`

### firstKey

    public Comparable firstKey()

  Does not call super, we always store first key here

  Overrides:
    `firstKey` in class `SkipSpan`

### getSpan

    public SkipSpan getSpan(Comparable key,
                            int[] search)

  Load whole span from file, do the operation, flush out, then null out in-memory data again. This is called only via SkipList.find()

  Overrides:
    `getSpan` in class `SkipSpan`

### get

    public Object get(Comparable key)

  Linear search if in file, Binary search if in memory

  Overrides:
    `get` in class `SkipSpan`

### put

    public SkipSpan put(Comparable key,
                        Object val,
                        SkipList sl)

  Load whole span from file, do the operation, flush out, then null out in-memory data again.

  Overrides:
    `put` in class `SkipSpan`
  Returns:
    the new span if it caused a split, else null if it went in an existing span

### remove

    public Object[] remove(Comparable key,
                           SkipList sl)

  Load whole span from file, do the operation, flush out, then null out in-memory data again.

  Overrides:
    `remove` in class `SkipSpan`
  Returns:
    An array of two objects or null. rv[0] is the removed object. rv[1] is the deleted SkipSpan if the removed object was the last in the SkipSpan. rv is null if no object was removed.

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