public void ChainedRangeReadWriteTest()
{
var stream = new MemoryStream();
var chain = new ListChain <DocumentId>()
{
new RangePostingsList()
{
0, 1, 2
},
GetDocIds(10, 11),
new RangePostingsList()
{
12, 13, 14, 15, 100, 111
},
};
using var writer = new PostingsListWriter(stream);
writer.Write(chain);
stream.Seek(0, SeekOrigin.Begin);
using var reader = new PostingsListReader(stream, leaveOpen: false);
var count = reader.ReadCount(0);
var deserialized = reader.Read(0);
Assert.Equal(chain.Count, count);
Assert.True(deserialized is RangePostingsList);
Assert.Equal(chain, deserialized);
}
public ExternalIndex <T> Build()
{
var composer = new ExternalIndexComposer <T>(stream);
var indexInfoList = indexManager.GetIndices();
var indices = indexManager.GetIndices().Where(i => i.GetCount() > 0).ToArray();
AddAllDocs(composer, indices);
var minHeapComparer = Comparer <IEnumerator <(T Term, IReadOnlyCollection <DocumentId> PostingsList)> > .Create(
(x, y) => ComparePostingLists(y.Current, x.Current));
var queue = new PriorityQueue <IEnumerator <(T Term, IReadOnlyCollection <DocumentId> PostingsList)> >(
indices.Length,
minHeapComparer);
foreach (var index in indices)
{
var enumerator = ReadIndex(index);
if (enumerator.MoveNext())
{
queue.Push(enumerator);
}
}
var docs = new ListChain <DocumentId>(indices.Length);
T currentTerm = default !;
private void WriteChainedVarint(ListChain <DocumentId> chain)
{
var varint = new VarintPostingsList(32);
foreach (var id in chain)
{
varint.Add(id);
}
WriteVarint(varint);
}
public void ListChainCreateTest()
{
var chain = new ListChain <int>
{
new[] { 4, 5, 6, 7 },
new[] { 1, 2 },
new[] { 3 }
};
Assert.Equal(7, chain.Count);
Assert.Equal(new[] { 4, 5, 6, 7, 1, 2, 3 }, chain.ToArray());
Assert.Equal(3, chain.Chains.Count);
}
public void ListChainClearTest()
{
var chain = new ListChain <int>
{
new[] { 4, 5, 6, 7 },
new[] { 1, 2 },
new[] { 3 }
};
chain.Clear();
Assert.Empty(chain);
Assert.Equal(Array.Empty <int>(), chain.ToArray());
}
public void ListChainSortTest()
{
var chain = new ListChain <int>
{
new[] { 4, 5, 6, 7 },
new[] { 1, 2 },
new[] { 3 }
};
chain.Sort((a, b) => a.First().CompareTo(b.First()));
Assert.Equal(7, chain.Count);
Assert.Equal(new[] { 1, 2, 3, 4, 5, 6, 7 }, chain.ToArray());
}
private static PostingsListType DetectType(ListChain <DocumentId> chain)
{
if (chain.Chains.Count > 0 && chain.Chains[0] is VarintPostingsList)
{
return(PostingsListType.Varint);
}
if (chain.Chains.Count > 0 && chain.Chains[0] is RangePostingsList)
{
return(PostingsListType.Ranged);
}
if (chain.Chains.Count > 1 && chain.Chains[1] is RangePostingsList)
{
return(PostingsListType.Ranged);
}
return(PostingsListType.Uncompressed);
}
/// <summary>
/// This complicated logis below was implemented for the sake of performance only.
/// We can always process ListChain as uncompressed list of Ids.
/// </summary>
/// <param name="chain">List of chains</param>
private void WriteChained(ListChain <DocumentId> chain)
{
switch (DetectType(chain))
{
case PostingsListType.Ranged:
writer.Write((byte)PostingsListType.Ranged);
WriteChainedRanges(chain);
break;
case PostingsListType.Varint:
writer.Write((byte)PostingsListType.Varint);
WriteChainedVarint(chain);
break;
default:
writer.Write((byte)PostingsListType.Uncompressed);
WriteUncompressed(chain);
break;
}
}
private void WriteChainedRanges(ListChain <DocumentId> chain)
{
var start = stream.Position;
int numBlocks = 0;
writer.Write(numBlocks); // we do not know a number of block at the moment
foreach (var c in chain.Chains)
{
var range = GetRange(c);
foreach (var v in range.Ranges)
{
writer.Write(v);
++numBlocks;
}
}
var finish = stream.Position;
stream.Seek(start, SeekOrigin.Begin);
writer.Write(numBlocks); // write correct number of blocks
stream.Seek(finish, SeekOrigin.Begin); // go back
}
