/// <summary>
/// Named Stream Reader
/// i.e. [StreamName]
/// </summary>
/// <param name="streamName">An exact stream name.</param>
/// <param name="checkpoint">The starting point to read from.</param>
/// <param name="count">The count of items to read</param>
/// <param name="readBackwards">Read the stream backwards</param>
/// <returns>Returns true if any events were read from the stream</returns>
public virtual bool Read(
string streamName,
long?checkpoint = null,
long?count = null,
bool readBackwards = false)
{
var eventsRead = false;
if (checkpoint != null)
{
Ensure.Nonnegative((long)checkpoint, nameof(checkpoint));
}
if (count != null)
{
Ensure.Positive((long)count, nameof(count));
}
if (!ValidateStreamName(streamName))
{
throw new ArgumentException("Stream not found.", streamName);
}
_cancelled = false;
firstEventRead = false;
StreamName = streamName;
long sliceStart = checkpoint ?? (readBackwards ? -1 : 0);
long remaining = count ?? long.MaxValue;
StreamEventsSlice currentSlice;
do
{
var page = remaining < ReadPageSize ? remaining: ReadPageSize;
currentSlice = !readBackwards
? _streamStoreConnection.ReadStreamForward(streamName, sliceStart, page)
: _streamStoreConnection.ReadStreamBackward(streamName, sliceStart, page);
if (!(currentSlice is StreamEventsSlice))
{
return(false);
}
remaining -= currentSlice.Events.Length;
sliceStart = currentSlice.NextEventNumber;
Array.ForEach(currentSlice.Events, EventRead);
} while (!currentSlice.IsEndOfStream && !_cancelled && remaining != 0);
return(eventsRead);
}
/// <summary>
/// Named Stream Reader
/// i.e. [StreamName]
/// </summary>
/// <param name="streamName">An exact stream name.</param>
/// <param name="completionCheck">Read will block until true to ensure processing has completed, use '()=> true' to continue without blocking. If cancellation or timeout is required it should be implemented in the completion method</param>
/// <param name="checkpoint">The event number of the last received event. Reading will start with the next event.</param>
/// <param name="count">The count of items to read</param>
/// <param name="readBackwards">Read the stream backwards</param>
/// <returns>Returns true if any events were read from the stream</returns>
public virtual bool Read(
string streamName,
Func <bool> completionCheck,
long?checkpoint = null,
long?count = null,
bool readBackwards = false)
{
if (checkpoint != null)
{
Ensure.Nonnegative((long)checkpoint, nameof(checkpoint));
}
if (count != null)
{
Ensure.Positive((long)count, nameof(count));
}
if (!ValidateStreamName(streamName))
{
throw new ArgumentException("Stream not found.", streamName);
}
_cancelled = false;
FirstEventRead = false;
StreamName = streamName;
long sliceStart;
if (checkpoint is null)
{
sliceStart = readBackwards ? -1 : 0;
}
else
{
sliceStart = checkpoint.Value + (readBackwards ? -1 : 1);
}
long remaining = count ?? long.MaxValue;
StreamEventsSlice currentSlice;
do
{
var page = remaining < ReadPageSize ? remaining : ReadPageSize;
currentSlice = !readBackwards
? _streamStoreConnection.ReadStreamForward(streamName, sliceStart, page)
: _streamStoreConnection.ReadStreamBackward(streamName, sliceStart, page);
if (!(currentSlice is StreamEventsSlice))
{
break;
}
if (currentSlice.Events.Length > 0)
{
FirstEventRead = true;
}
remaining -= currentSlice.Events.Length;
sliceStart = currentSlice.NextEventNumber;
Array.ForEach(currentSlice.Events, EventRead);
} while (!currentSlice.IsEndOfStream && !_cancelled && remaining != 0);
if (FirstEventRead && completionCheck != null)
{
SpinWait.SpinUntil(() => { try { return(completionCheck()); } catch { return(true); } });
}
return(FirstEventRead);
}
