/// <summary>
/// Serializes all the tags in the given index. This serialization preserves the id's of each tag collection.
/// </summary>
/// <param name="stream">The target stream.</param>
/// <param name="tagsIndex">The tags index to serialize.</param>
public static void Serialize(Stream stream, ITagsCollectionIndex tagsIndex)
{
int begin = (int)stream.Position;
// build a string index.
ObjectTable <string> stringTable = new ObjectTable <string>(false);
// convert tag collections to simpler objects.
List <KeyValuePair <uint, List <KeyValuePair <uint, uint> > > > tagsIndexList = new List <KeyValuePair <uint, List <KeyValuePair <uint, uint> > > >();
for (uint tagId = 0; tagId < tagsIndex.Max; tagId++)
{
TagsCollectionBase tagsCollection = tagsIndex.Get(tagId);
if (tagsCollection != null)
{ // convert the tags collection to a list and add to the tag index.
List <KeyValuePair <uint, uint> > tagsList = new List <KeyValuePair <uint, uint> >();
foreach (Tag tag in tagsCollection)
{
uint keyId = stringTable.Add(tag.Key);
uint valueId = stringTable.Add(tag.Value);
tagsList.Add(new KeyValuePair <uint, uint>(
keyId, valueId));
}
tagsIndexList.Add(new KeyValuePair <uint, List <KeyValuePair <uint, uint> > >(tagId, tagsList));
}
}
// do the serialization.
TagIndexSerializer.Serialize(begin, stream, tagsIndexList, stringTable);
// clear everything.
tagsIndexList.Clear();
}
/// <summary>
/// Serializes the tags into different indexed blocks of given size.
/// </summary>
/// <param name="stream"></param>
/// <param name="tagsIndex"></param>
/// <param name="blockSize"></param>
public static void SerializeBlocks(Stream stream, ITagsCollectionIndexReadonly tagsIndex, uint blockSize)
{
int begin = (int)stream.Position;
// calculate the amount of blocks.
uint blocks = (uint)System.Math.Ceiling((float)tagsIndex.Max / (float)blockSize);
// store block count.
stream.Write(BitConverter.GetBytes((int)blocks), 0, 4);
// store block size.
stream.Write(BitConverter.GetBytes((int)blockSize), 0, 4);
// move the stream to make room for the index.
stream.Seek((blocks + 2) * 4 + begin, SeekOrigin.Begin);
int beginBlocks = (int)stream.Position;
// keep looping over these blocks.
int[] blockPositions = new int[blocks];
for (uint blockIdx = 0; blockIdx < blocks; blockIdx++)
{
uint from = blockIdx * blockSize;
uint to = from + blockSize;
MemoryStream memoryStream = new MemoryStream();
TagIndexSerializer.Serialize(memoryStream, tagsIndex, from, to);
byte[] compressed = Ionic.Zlib.GZipStream.CompressBuffer(memoryStream.ToArray());
memoryStream.Dispose();
stream.Write(compressed, 0, compressed.Length);
blockPositions[blockIdx] = (int)stream.Position - beginBlocks;
}
// write the block positions.
stream.Seek(begin + 8, SeekOrigin.Begin);
for (int blockIdx = 0; blockIdx < blocks; blockIdx++)
{
stream.Write(BitConverter.GetBytes(blockPositions[blockIdx]), 0, 4);
}
}