private int SortBlocksParallel(RecordsReader recordsReader, int field, int workersCount,
out RecordsBuffer firstBlock)
{
firstBlock = null;
IEnumerator <RecordsBuffer> blocks = recordsReader.ReadBlocks().GetEnumerator();
if (!blocks.MoveNext())
{
return(0);
}
if (recordsReader.IsLastBlock)
{
firstBlock = blocks.Current;
firstBlock.Sort(field);
return(1);
}
int blockIndex = 0;
using (var blockCollection = new BlockingCollection <Tuple <RecordsBuffer, int> >(workersCount))
using (var sortCompletionCollection = new BlockingCollection <bool>(workersCount))
{
Task blocksReadingTask = Task.Factory.StartNew(() =>
{
do
{
blockCollection.Add(new Tuple <RecordsBuffer, int>(blocks.Current, blockIndex++));
sortCompletionCollection.Add(true);
} while (blocks.MoveNext());
blockCollection.CompleteAdding();
});
Task blocksSortingTask = Task.Factory.StartNew(() =>
{
List <Task> sortTasks = new List <Task>();
try
{
while (true)
{
Tuple <RecordsBuffer, int> blockAndIndex = blockCollection.Take();
Task t = StartBlockSortingTask(blockAndIndex.Item1, blockAndIndex.Item2,
field, sortCompletionCollection);
sortTasks.Add(t);
}
}
catch (InvalidOperationException)
{
// An InvalidOperationException means that Take() was called on a completed collection
}
Task.WaitAll(sortTasks.ToArray());
});
Task.WaitAll(blocksReadingTask, blocksSortingTask);
}
return(blockIndex);
}
private Task StartBlockSortingTask(RecordsBuffer block, int blockIndex, int field,
BlockingCollection <bool> sortCompletionCollection)
{
return(Task.Factory.StartNew(() =>
{
block.Sort(field);
WriteBlock(block, blockIndex);
sortCompletionCollection.Take();
Console.WriteLine($"Block {blockIndex} sorted");
}));
}