public void Apply(IEnumerable <IShard> shards, IShardOperation operation)
{
foreach (var shard in GetNextOrderingOfShards(shards))
{
var shardOperation = operation.Prepare(shard);
shardOperation();
}
}
public T Apply <T>(IEnumerable <IShard> shards, IShardOperation <T> operation, IExitStrategy <T> exitStrategy)
{
foreach (var shard in GetNextOrderingOfShards(shards))
{
var shardOperation = operation.Prepare(shard);
var result = shardOperation();
if (result != null && exitStrategy.AddResult(result, shard))
{
Log.Debug("Short-circuiting operation {0} after execution against shard {1}", operation.OperationName, shard);
break;
}
}
return(exitStrategy.CompileResults());
}
private void ExecuteForShard(object state)
{
var s = (IShard)state;
try
{
Func <T> shardOperation;
// Perform thread-safe preparation of the operation for a single shard.
lock (this)
{
// Prevent execution if parallel operation has already been cancelled.
if (_isCancelled)
{
if (--_activeCount <= 0)
{
Monitor.Pulse(this);
}
return;
}
shardOperation = _operation.Prepare(s);
}
// Perform operation execution on multiple shards in parallel.
var result = shardOperation();
// Perform thread-safe aggregation of operation results.
lock (this)
{
// Only add result if operation still has not been cancelled and result is not null.
if (!_isCancelled && !Equals(result, null))
{
_isCancelled = _exitStrategy.AddResult(result, s);
}
if (--_activeCount <= 0)
{
Monitor.Pulse(this);
}
}
}
catch (Exception e)
{
lock (this)
{
if (!_isCancelled)
{
_exception = e;
_isCancelled = true;
}
if (--_activeCount <= 0)
{
Monitor.Pulse(this);
}
}
Log.DebugFormat("Failed parallel operation '{0}' on shard '{1:X}'.",
_operation.OperationName, s.ShardIds.First());
}
}