public static Task TranscodeAsync <T>(
string input,
string output,
ITimeSeriesDecoder <T> decoder,
ITimeSeriesEncoder <T> encoder,
Func <T, T> transform = null)
{
return(TranscodeAsync <T, T>(input, output, decoder, encoder, transform ?? (x => x)));
}
public TimeSeriesChunk(InputChunk chunk, ITimeSeriesDecoder <T> decoder)
{
BeginPosition = chunk.BeginPosition;
EndPosition = chunk.EndPosition;
_data = Decode();
IEnumerable <T> Decode()
{
decoder.DecodePrimary(chunk, new DateTime(chunk.UserData.Long0, DateTimeKind.Utc), out T val);
yield return(val);
while (decoder.DecodeSecondary(chunk, out val))
{
yield return(val);
}
}
}
// Reads all chunks from the ChunkIO file named `input`, decodes their content with `decoder`,
// transforms records with `transform`, encodes them with `encoder` and appends to the ChunkIO
// file named `output`.
//
// The output ChunkIO file is written with default WriterOptions. Some input chunks may get
// merged but no chunks get split.
public static async Task TranscodeAsync <T, U>(
string input,
string output,
ITimeSeriesDecoder <T> decoder,
ITimeSeriesEncoder <U> encoder,
Func <T, U> transform)
{
using (var reader = new TimeSeriesReader <T>(input, decoder)) {
var writer = new TimeSeriesWriter <U>(output, encoder);
try {
long len = await reader.FlushRemoteWriterAsync(flushToDisk : false);
await reader.ReadAfter(DateTime.MinValue, 0, len).ForEachAsync(async(IDecodedChunk <T> c) => {
await writer.WriteBatchAsync(c.Select(transform));
});
} finally {
await writer.DisposeAsync();
}
}
}
// The file must exist and be readable. There is no explicit file format check. If the file
// wasn't created by ChunkWriter, all its content will be simply skipped without any errors.
//
// You can read the file even while there is an active TimeSeriesWriter writing to it. You
// might want to use FlushRemoteWriterAsync() in this case.
//
// Takes ownership of the decoder. TimeSeriesReader.Dispose() will dispose it.
public TimeSeriesReader(string fname, ITimeSeriesDecoder <T> decoder)
{
Decoder = decoder ?? throw new ArgumentNullException(nameof(decoder));
_reader = new BufferedReader(fname);
}
