private static void ExtractContracts <TEntity, TContract>(ISessionWrapper session, ZipArchive zip,
Func <QueryOverProjectionBuilder <TEntity>, QueryOverProjectionBuilder <TEntity> > fieldBuilder)
where TEntity : class
where TContract : class
{
var records = session.QueryOver <TEntity>()
.SelectList(fieldBuilder)
.List <object[]>();
var jsonSerializer = new JsonSerializer
{
Formatting = Formatting.Indented,
NullValueHandling = NullValueHandling.Include
};
var zipLock = new object();
// We should be able to get a bit of a perf boost using parallelism. However, since we're locking on
// writing to the zip archive, using any more than 2 threads would be pointless in this case
Parallel.ForEach(records, new ParallelOptions {
MaxDegreeOfParallelism = 2
}, record =>
{
string zipEntryName = record[0].ToString();
int contractLen = (int)record[1];
byte[] contractBinary = (byte[])record[2];
if (contractLen > 0 && contractBinary != null)
{
TContract contract = CompressionHelper.DeserializeObject <TContract>(contractBinary, contractLen);
lock (zipLock)
{
ZipArchiveEntry archiveEntry = zip.CreateEntry(zipEntryName, CompressionLevel.Optimal);
using (StreamWriter writer = new StreamWriter(archiveEntry.Open(), Encoding.UTF8))
{
jsonSerializer.Serialize(writer, contract);
}
}
}
});
}