IndexReadEventResult IIndexReader.ReadEvent(string streamId, int eventNumber)
{
Ensure.NotNullOrEmpty(streamId, "streamId");
if (eventNumber < -1)
{
throw new ArgumentOutOfRangeException("eventNumber");
}
using (var reader = _cache.BorrowReader())
{
return(ReadEventInternal(reader, streamId, eventNumber));
}
}
public IndexReadAllResult ReadAllEventsForward(TFPos pos, int maxCount)
{
var records = new List <CommitEventRecord>();
var nextPos = pos;
// in case we are at position after which there is no commit at all, in that case we have to force
// PreparePosition to long.MaxValue, so if you decide to read backwards from PrevPos,
// you will receive all prepares.
var prevPos = new TFPos(pos.CommitPosition, long.MaxValue);
long count = 0;
bool firstCommit = true;
using (var reader = _cache.BorrowReader())
{
long nextCommitPos = pos.CommitPosition;
while (count < maxCount)
{
reader.Reposition(nextCommitPos);
SeqReadResult result;
while ((result = reader.TryReadNext()).Success && !IsCommitAlike(result.LogRecord))
{
// skip until commit
}
if (!result.Success) // no more records in TF
{
break;
}
nextCommitPos = result.RecordPostPosition;
switch (result.LogRecord.RecordType)
{
case LogRecordType.Prepare:
{
var prepare = (PrepareLogRecord)result.LogRecord;
if (firstCommit)
{
firstCommit = false;
prevPos = new TFPos(result.RecordPrePosition, result.RecordPrePosition);
}
if (prepare.Flags.HasAnyOf(PrepareFlags.Data | PrepareFlags.StreamDelete) &&
new TFPos(prepare.LogPosition, prepare.LogPosition) >= pos)
{
var eventRecord = new EventRecord(prepare.ExpectedVersion + 1 /* EventNumber */, prepare);
records.Add(new CommitEventRecord(eventRecord, prepare.LogPosition));
count++;
nextPos = new TFPos(result.RecordPostPosition, result.RecordPostPosition);
}
break;
}
case LogRecordType.Commit:
{
var commit = (CommitLogRecord)result.LogRecord;
if (firstCommit)
{
firstCommit = false;
// for backward pass we want to allow read the same commit and skip read prepares,
// so we put post-position of commit and post-position of prepare as TFPos for backward pass
prevPos = new TFPos(result.RecordPostPosition, pos.PreparePosition);
}
reader.Reposition(commit.TransactionPosition);
while (count < maxCount)
{
result = reader.TryReadNext();
if (!result.Success) // no more records in TF
{
break;
}
// prepare with TransactionEnd could be scavenged already
// so we could reach the same commit record. In that case have to stop
if (result.LogRecord.LogPosition >= commit.LogPosition)
{
break;
}
if (result.LogRecord.RecordType != LogRecordType.Prepare)
{
continue;
}
var prepare = (PrepareLogRecord)result.LogRecord;
if (prepare.TransactionPosition != commit.TransactionPosition) // wrong prepare
{
continue;
}
// prepare with useful data or delete tombstone
if (prepare.Flags.HasAnyOf(PrepareFlags.Data | PrepareFlags.StreamDelete) &&
new TFPos(commit.LogPosition, prepare.LogPosition) >= pos)
{
var eventRecord = new EventRecord(commit.FirstEventNumber + prepare.TransactionOffset, prepare);
records.Add(new CommitEventRecord(eventRecord, commit.LogPosition));
count++;
// for forward pass position is inclusive,
// so we put pre-position of commit and post-position of prepare
nextPos = new TFPos(commit.LogPosition, result.RecordPostPosition);
}
if (prepare.Flags.HasAnyOf(PrepareFlags.TransactionEnd))
{
break;
}
}
break;
}
default:
throw new Exception(string.Format("Unexpected log record type: {0}.", result.LogRecord.RecordType));
}
}
return(new IndexReadAllResult(records, pos, nextPos, prevPos));
}
}