public static Cursor Clone(Cursor cursor)
{
return new Cursor
{
Id = cursor.Id,
Key = cursor.Key
};
}
public static Cursor[] GetCursors(string cursor)
{
var cursors = new List<Cursor>();
var current = new Cursor();
bool escape = false;
var sb = new StringBuilder();
foreach (var ch in cursor)
{
if (escape)
{
sb.Append(ch);
escape = false;
}
else
{
if (ch == '\\')
{
escape = true;
}
else if (ch == ',')
{
current.Key = sb.ToString();
sb.Clear();
}
else if (ch == '|')
{
current.Id = UInt64.Parse(sb.ToString(), NumberStyles.HexNumber);
cursors.Add(current);
current = new Cursor();
sb.Clear();
}
else
{
sb.Append(ch);
}
}
}
if (sb.Length > 0)
{
current.Id = UInt64.Parse(sb.ToString(), NumberStyles.HexNumber);
cursors.Add(current);
}
return cursors.ToArray();
}
protected override void PerformWork(ref List<ArraySegment<Message>> items, out string nextCursor, ref int totalCount, out object state)
{
// The list of cursors represent (streamid, payloadid)
var cursors = new List<Cursor>();
foreach (var stream in _streams)
{
// Get the mapping for this stream
Linktionary<ulong, ScaleoutMapping> mapping = stream.Value;
// See if we have a cursor for this key
Cursor cursor = null;
// REVIEW: We should optimize this
int index = _cursors.FindIndex(c => c.Key == stream.Key);
bool consumed = true;
if (index != -1)
{
cursor = Cursor.Clone(_cursors[index]);
// If there's no node for this cursor id it's likely because we've
// had an app domain restart and the cursor position is now invalid.
if (mapping[cursor.Id] == null)
{
// Set it to the first id in this mapping
cursor.Id = stream.Value.MinKey;
// Mark this cursor as unconsumed
consumed = false;
}
}
else
{
// Create a cursor and add it to the list.
// Point the Id to the first value
cursor = new Cursor
{
Id = stream.Value.MinKey,
Key = stream.Key
};
consumed = false;
}
cursors.Add(cursor);
// Try to find a local mapping for this payload
LinkedListNode<KeyValuePair<ulong, ScaleoutMapping>> node = mapping[cursor.Id];
// Skip this node only if this isn't a new cursor
if (node != null && consumed)
{
// Skip this node since we've already consumed it
node = node.Next;
}
while (node != null)
{
KeyValuePair<ulong, ScaleoutMapping> pair = node.Value;
// Stop if we got more than max messages
if (totalCount >= MaxMessages)
{
break;
}
// It should be ok to lock here since groups aren't modified that often
lock (EventKeys)
{
// For each of the event keys we care about, extract all of the messages
// from the payload
foreach (var eventKey in EventKeys)
{
LocalEventKeyInfo info;
if (pair.Value.EventKeyMappings.TryGetValue(eventKey, out info))
{
int maxMessages = Math.Min(info.Count, MaxMessages);
MessageStoreResult<Message> storeResult = info.Store.GetMessages(info.MinLocal, maxMessages);
if (storeResult.Messages.Count > 0)
{
items.Add(storeResult.Messages);
totalCount += storeResult.Messages.Count;
}
}
}
}
// Update the cursor id
cursor.Id = pair.Key;
node = node.Next;
}
}
nextCursor = Cursor.MakeCursor(cursors);
state = cursors;
}