internal Core(Func <TItem, TItem, TDistance> distance, SmallWorld <TItem, TDistance> .Parameters parameters)
{
Distance = distance;
Parameters = parameters;
var initialSize = Math.Max(1024, parameters.InitialItemsSize);
Nodes = new List <Node>(initialSize);
Items = new List <TItem>(initialSize);
switch (Parameters.NeighbourHeuristic)
{
case NeighbourSelectionHeuristic.SelectSimple:
{
Algorithm = new Algorithms.Algorithm3 <TItem, TDistance>(this);
break;
}
case NeighbourSelectionHeuristic.SelectHeuristic:
{
Algorithm = new Algorithms.Algorithm4 <TItem, TDistance>(this);
break;
}
}
if (Parameters.EnableDistanceCacheForConstruction)
{
DistanceCache = new DistanceCache <TDistance>();
DistanceCache.Resize(parameters.InitialDistanceCacheSize, false);
}
DistanceCalculationsCount = 0;
}
/// <summary>
/// Initializes a new instance of the <see cref="Core"/> class.
/// </summary>
/// <param name="distance">The distance function in the items space.</param>
/// <param name="parameters">The parameters of the world.</param>
/// <param name="items">The original items.</param>
internal Core(Func <TItem, TItem, TDistance> distance, SmallWorld <TItem, TDistance> .Parameters parameters, IReadOnlyList <TItem> items)
{
this.distance = distance;
this.Parameters = parameters;
this.Items = items;
switch (this.Parameters.NeighbourHeuristic)
{
case SmallWorld <TItem, TDistance> .NeighbourSelectionHeuristic.SelectSimple:
this.Algorithm = new Node.Algorithm3 <TItem, TDistance>(this);
break;
case SmallWorld <TItem, TDistance> .NeighbourSelectionHeuristic.SelectHeuristic:
this.Algorithm = new Node.Algorithm4 <TItem, TDistance>(this);
break;
}
if (this.Parameters.EnableDistanceCacheForConstruction)
{
this.distanceCache = new DistanceCache <TDistance>(this.Items.Count);
}
this.distanceCacheHitCount = 0;
this.distanceCalculationsCount = 0;
}
/// <summary>
/// Deserializes the graph from byte array.
/// </summary>
/// <param name="items">The items to assign to the graph's verticies.</param>
/// <param name="bytes">The serialized parameters and edges.</param>
public static SmallWorld <TItem, TDistance> DeserializeGraph(IReadOnlyList <TItem> items, Func <TItem, TItem, TDistance> distance, IProvideRandomValues generator, Stream stream)
{
var p0 = stream.Position;
string hnswHeader;
try
{
hnswHeader = MessagePackBinary.ReadString(stream);
}
catch (Exception E)
{
if (stream.CanSeek)
{
stream.Position = p0;
} //Resets the stream to original position
throw new InvalidDataException($"Invalid header found in stream, data is corrupted or invalid", E);
}
if (hnswHeader != SERIALIZATION_HEADER)
{
if (stream.CanSeek)
{
stream.Position = p0;
} //Resets the stream to original position
throw new InvalidDataException($"Invalid header found in stream, data is corrupted or invalid");
}
// readStrict: true -> removed, as not available anymore on MessagePack 2.0 - also probably not necessary anymore
// see https://github.com/neuecc/MessagePack-CSharp/pull/663
var parameters = MessagePackSerializer.Deserialize <Parameters>(stream);
//Overwrite previous InitialDistanceCacheSize parameter, so we don't waste time/memory allocating a distance cache for an already existing graph
parameters.InitialDistanceCacheSize = 0;
var world = new SmallWorld <TItem, TDistance>(distance, generator, parameters);
world.Graph.Deserialize(items, stream);
return(world);
}
/// <summary>
/// Initializes a new instance of the <see cref="Graph{TItem, TDistance}"/> class.
/// </summary>
/// <param name="distance">The distance function.</param>
/// <param name="parameters">The parameters of the world.</param>
internal Graph(Func <TItem, TItem, TDistance> distance, SmallWorld <TItem, TDistance> .Parameters parameters)
{
this.distance = distance;
this.Parameters = parameters;
}
