org.neo4j.collection.primitive.hopscotch

Class IntArrayBasedKeyTable<VALUE>

java.lang.Object

org.neo4j.collection.primitive.hopscotch.PowerOfTwoQuantizedTable<VALUE>

org.neo4j.collection.primitive.hopscotch.IntArrayBasedKeyTable<VALUE>

Type Parameters:

VALUE - essentially ignored, since no values are stored in this table. Although subclasses can.

All Implemented Interfaces:

AutoCloseable, Table<VALUE>

Direct Known Subclasses:

IntKeyLongValueTable, IntKeyTable, LongKeyIntValueTable, LongKeyTable

public abstract class IntArrayBasedKeyTable<VALUE>
extends PowerOfTwoQuantizedTable<VALUE>

Table implementation for handling primitive int/long keys and hop bits. The quantized unit is int so a multiple of ints will be used for every entry.

Method Summary

Modifier and Type	Method and Description
void	clear() Removes all entries from this table.
long	hopBits(int index) A short summary of the hop bits format: It's a bit map represented as an int, where each set bit represents an offset where there's a neighbor for this index.
long	move(int fromIndex, int toIndex) Moves the key/value from one index to another, any hop bits stay.
void	moveHopBit(int index, int hd, int delta) Moves one hop bit delta steps.
void	put(int index, long key, VALUE value) Puts (key/value) at the given index.
void	putHopBit(int index, int hd) Adds one hop bit to the set of hop bits at the given index.
VALUE	putValue(int index, VALUE value) Puts, actually overwrites, the value at the given index.
VALUE	remove(int index) Removes the currently assigned key/value from the given index.
void	removeHopBit(int index, int hd) Removes one hop bit from the set of hop bits at the given index.
VALUE	value(int index) OPTIONAL operation.

Methods inherited from class org.neo4j.collection.primitive.hopscotch.PowerOfTwoQuantizedTable

baseCapacity, capacity, close, grow, h, isEmpty, mask, nullKey, size, toString, version, version

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.neo4j.collection.primitive.hopscotch.Table

key

Method Detail

put

public void put(int index,
                long key,
                VALUE value)

Description copied from interface: Table

Puts (key/value) at the given index. This index must contractually be free at the point where the algorithm calls this method.

Parameters:

index - the index to put this key/value in.

key - the key to put.

value - the value to put.

remove

public VALUE remove(int index)

Description copied from interface: Table

Removes the currently assigned key/value from the given index.

Parameters:

index - the index to remove key/value from.

Returns:

the existing value at this index.

move

public long move(int fromIndex,
                 int toIndex)

Description copied from interface: Table

Moves the key/value from one index to another, any hop bits stay. This is equivalent to a remove at fromIndex followed by a put at toIndex. After this method has been called there will no longer be any key/value assigned at fromIndex.

Parameters:

fromIndex - the index to move the key/value from.

toIndex - the index to move the key/value to.

Returns:

the affected key.

value

public VALUE value(int index)

Description copied from interface: Table

OPTIONAL operation. Returns null if unsupported.

Returns:

the value at the given index. If there's no assigned key here then null will be returned.

putValue

public VALUE putValue(int index,
                      VALUE value)

Description copied from interface: Table

Puts, actually overwrites, the value at the given index. This index will contractually be occupied at the point where the algorithm calls this method. This new value replaces the existing value at this index.

Parameters:

index - the index to put this value in.

value - the value to put at this index.

Returns:

the existing value at this index, before this new value was put there.

hopBits

public long hopBits(int index)

Description copied from interface: Table

A short summary of the hop bits format: It's a bit map represented as an int, where each set bit represents an offset where there's a neighbor for this index. Here is the two least significant bytes in an example bit map carrying hop bits:

 ....[0000,0001][0000,0100]
 

In the above example, if we assume the index carrying these hop bits is 5, then index 5 has two neighbors: index 8 and index 14. (the least significant bit represents an offset of 1). Maximum number of hop bits is controlled by Table.h(). Interesting to note is that hop bits for an index and key/value are not really associated, where a key/value can be moved to a new location, but the hop bits stay behind. The location of Hop bits is tied to table index, whereas the location of key/value is tied to table index AND hop bits.

Parameters:

index - the index to get the hop bits for.

Returns:

the hop bits for the given index.

putHopBit

public void putHopBit(int index,
                      int hd)

Description copied from interface: Table

Adds one hop bit to the set of hop bits at the given index.

Parameters:

index - the index to add the hop bit at.

hd - h-delta, i.e. which hop bit to set, zero-based.

See Also:

Table.hopBits(int)

moveHopBit

public void moveHopBit(int index,
                       int hd,
                       int delta)

Description copied from interface: Table

Moves one hop bit delta steps. If delta is positive it will be moved towards msb, if negative towards lsb.

Parameters:

index - the index to move the hop bit for.

hd - the hop bit to move.

delta - how far (and based on sign) which direction to move it in.

removeHopBit

public void removeHopBit(int index,
                         int hd)

Description copied from interface: Table

Removes one hop bit from the set of hop bits at the given index.

Parameters:

index - the index to remove the hop bit from.

hd - h-delta, i.e. which hop bit to remove, zero-based.

See Also:

Table.hopBits(int)

clear

public void clear()

Description copied from interface: Table

Removes all entries from this table.

Specified by:

clear in interface Table<VALUE>

Overrides:

clear in class PowerOfTwoQuantizedTable<VALUE>