Package org.neo4j.gds.core.loading
Class DeltaVarLongCompressor
- java.lang.Object
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- org.neo4j.gds.core.loading.DeltaVarLongCompressor
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- All Implemented Interfaces:
java.lang.AutoCloseable
,AdjacencyCompressor
public final class DeltaVarLongCompressor extends java.lang.Object implements AdjacencyCompressor
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
DeltaVarLongCompressor.Factory
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
close()
Closing this compressor will release some internal data structures, making them eligible for garbage collection.int
compress(long nodeId, CompressedLongArray values, LongArrayBuffer buffer)
Compress a list of target ids into an adjacency list.
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Method Detail
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compress
public int compress(long nodeId, CompressedLongArray values, LongArrayBuffer buffer)
Description copied from interface:AdjacencyCompressor
Compress a list of target ids into an adjacency list. The inputvalues
are an unsorted and separately compressed list of target ids. Those ids can be unpacked into along[]
usingCompressedLongArray.uncompress(long[])
. The providedlong[]
must be able to hold at leastCompressedLongArray.length()
elements. The inputvalues
might also store properties (called 'weights'). This can be checked withCompressedLongArray.hasWeights()
and read withCompressedLongArray.weights()
. The returnedlong[][]
has the number of properties in the first dimension, followed by an uncompressedlong[]
for each property. Those values belong to the target id that is stored at the same array index in the uncompressed target list. Implementors need to make sure to maintain that order when re-ordering the target ids. Implementors of this method can use the providedLongArrayBuffer
to reuse existing allocations of along[]
or share newly created buffers with next invocations of this method. The buffer exists solely so that implementors can reduce allocations oflong[]
. It is not expected that the buffer contains any useful data after this method invocation. The providedvalues
array will not be used after this method call and should be released at the end usingCompressedLongArray.release()
. Implementors will need to write the resulting target list somewhere. Where exactly is up to the implementation. The results should end up in the data that is returned by theAdjacencyCompressorBlueprint.build()
method. The method only needs to return the degree of the compressed adjacency list. This value can be different fromCompressedLongArray.length()
due to possible deduplication, though it should never be larger. The return value is only used for tracking progress and reporting, it is not stored in the graph. How the degree is stored so that it can be used by the Graph is up the implementor of this method.- Specified by:
compress
in interfaceAdjacencyCompressor
- Parameters:
nodeId
- The node id that is the source node for this adjacency list. The id is from the GDS internal scope, it is *not* the Neo4j ID.values
- A list of target ids, unsorted and compressed.buffer
- A long array that may or may not be used during the compression.- Returns:
- the degree of the compressed adjacency list
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close
public void close()
Description copied from interface:AdjacencyCompressor
Closing this compressor will release some internal data structures, making them eligible for garbage collection. The compressor cannot be used after it has been closed.- Specified by:
close
in interfaceAdjacencyCompressor
- Specified by:
close
in interfacejava.lang.AutoCloseable
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