private async Task <AllMessagesPage> FilterExpired(
AllMessagesPage allMessagesPage,
CancellationToken cancellationToken)
{
var valid = new List <StreamMessage>();
var currentUtc = GetUtcNow();
foreach (var streamMessage in allMessagesPage.Messages)
{
if (streamMessage.StreamId.StartsWith("$"))
{
valid.Add(streamMessage);
continue;
}
var maxAge = await _metadataMaxAgeCache.GetMaxAge(streamMessage.StreamId, cancellationToken);
if (!maxAge.HasValue)
{
valid.Add(streamMessage);
continue;
}
if (streamMessage.CreatedUtc.AddSeconds(maxAge.Value) > currentUtc)
{
valid.Add(streamMessage);
}
else
{
PurgeExpiredMessage(streamMessage);
}
}
return(new AllMessagesPage(
allMessagesPage.FromPosition,
allMessagesPage.NextPosition,
allMessagesPage.IsEnd,
allMessagesPage.Direction,
valid.ToArray()));
}
protected override Task <AllMessagesPage> ReadAllBackwardsInternal(
long fromPositionExclusive,
int maxCount,
CancellationToken cancellationToken)
{
GuardAgainstDisposed();
using (_lock.UseReadLock())
{
if (fromPositionExclusive == Position.End)
{
fromPositionExclusive = _allStream.Last.Value.Position;
}
// Find the node to start from (it may not be equal to the exact position)
var current = _allStream.First;
if (current.Next == null) //Empty store
{
return(Task.FromResult(
new AllMessagesPage(Position.Start, Position.Start, true, ReadDirection.Backward)));
}
var previous = current.Previous;
while (current.Value.Position < fromPositionExclusive)
{
if (current.Next == null) // fromPosition is past end of store
{
return(Task.FromResult(
new AllMessagesPage(fromPositionExclusive,
fromPositionExclusive,
true,
ReadDirection.Backward)));
}
previous = current;
current = current.Next;
}
var messages = new List <StreamMessage>();
while (maxCount > 0 && current != _allStream.First)
{
var message = new StreamMessage(
current.Value.StreamId,
current.Value.MessageId,
current.Value.StreamVersion,
current.Value.Position,
current.Value.Created,
current.Value.Type,
current.Value.JsonData,
current.Value.JsonMetadata);
messages.Add(message);
maxCount--;
previous = current;
current = current.Previous;
}
bool isEnd;
if (previous == null || previous.Value.Position == 0)
{
isEnd = true;
}
else
{
isEnd = false;
}
var nextCheckPoint = isEnd
? 0
: current.Value.Position;
fromPositionExclusive = messages.Any() ? messages[0].Position : 0;
var page = new AllMessagesPage(
fromPositionExclusive,
nextCheckPoint,
isEnd,
ReadDirection.Backward,
messages.ToArray());
return(Task.FromResult(page));
}
}
