private async Task <ReadAllPage> ReloadAfterDelay(long fromPositionInclusive, int maxCount, bool prefetch,
ReadNextAllPage readNext, CancellationToken cancellationToken)
{
Logger.InfoFormat($"ReadAllForwards: gap detected in position, reloading after {DefaultReloadInterval}ms");
await Task.Delay(DefaultReloadInterval, cancellationToken);
var reloadedPage = await ReadAllForwardsInternal(fromPositionInclusive, maxCount, prefetch, readNext, cancellationToken)
.NotOnCapturedContext();
return(await FilterExpired(reloadedPage, readNext, cancellationToken).NotOnCapturedContext());
}
public async Task <ReadAllPage> ReadAllForwards(
long fromPositionInclusive,
int maxCount,
bool prefetchJsonData,
CancellationToken cancellationToken = default(CancellationToken))
{
Ensure.That(fromPositionInclusive, nameof(fromPositionInclusive)).IsGte(0);
Ensure.That(maxCount, nameof(maxCount)).IsGte(1);
GuardAgainstDisposed();
cancellationToken.ThrowIfCancellationRequested();
if (Logger.IsDebugEnabled())
{
Logger.DebugFormat("ReadAllForwards from position {fromPositionInclusive} with max count " +
"{maxCount}.", fromPositionInclusive, maxCount);
}
ReadNextAllPage readNext = (nextPosition, ct) => ReadAllForwards(nextPosition, maxCount, prefetchJsonData, ct);
var page = await ReadAllForwardsInternal(fromPositionInclusive, maxCount, prefetchJsonData, readNext, cancellationToken)
.NotOnCapturedContext();
// https://github.com/damianh/SqlStreamStore/issues/31
// Under heavy parallel load, gaps may appear in the position sequence due to sequence
// number reservation of in-flight transactions.
// Here we check if there are any gaps, and in the unlikely event there is, we delay a little bit
// and re-issue the read. This is expected
if (!page.IsEnd || page.Messages.Length <= 1)
{
return(await FilterExpired(page, readNext, cancellationToken).NotOnCapturedContext());
}
// Check for gap between last page and this.
if (page.Messages[0].Position != fromPositionInclusive)
{
page = await ReloadAfterDelay(fromPositionInclusive, maxCount, prefetchJsonData, readNext, cancellationToken);
}
// check for gap in messages collection
for (int i = 0; i < page.Messages.Length - 1; i++)
{
if (page.Messages[i].Position + 1 != page.Messages[i + 1].Position)
{
page = await ReloadAfterDelay(fromPositionInclusive, maxCount, prefetchJsonData, readNext, cancellationToken);
break;
}
}
return(await FilterExpired(page, readNext, cancellationToken).NotOnCapturedContext());
}
/// <summary>
/// Initializes a new instance of <see cref="ReadAllPage"/>
/// </summary>
/// <param name="fromPosition">A long representing the position where this page was read from.</param>
/// <param name="nextPosition">A long representing the position where the next page should be read from.</param>
/// <param name="isEnd">True if page reach end of the all stream at time of reading. Otherwise false.</param>
/// <param name="direction">The direction of the the read request.</param>
/// <param name="readNext">An operation to read the next page of messages.</param>
/// <param name="messages">The collection messages read.</param>
public ReadAllPage(
long fromPosition,
long nextPosition,
bool isEnd,
ReadDirection direction,
ReadNextAllPage readNext,
StreamMessage[] messages = null)
{
FromPosition = fromPosition;
NextPosition = nextPosition;
IsEnd = isEnd;
Direction = direction;
_readNext = readNext;
Messages = messages ?? new StreamMessage[0];
}
public ReadAllPage(
long fromPosition,
long nextPosition,
bool isEnd,
ReadDirection direction,
StreamMessage[] messages,
ReadNextAllPage readNext)
{
FromPosition = fromPosition;
NextPosition = nextPosition;
IsEnd = isEnd;
Direction = direction;
Messages = messages;
_readNext = readNext;
}
protected override async Task <ReadAllPage> ReadAllForwardsInternal(
long fromPositionExclusive,
int maxCount,
bool prefetch,
ReadNextAllPage readNext,
CancellationToken cancellationToken)
{
maxCount = maxCount == int.MaxValue ? maxCount - 1 : maxCount;
try
{
var commandText = prefetch
? _schema.ReadAllForwardsWithData
: _schema.ReadAllForwards;
using (var connection = await OpenConnection(cancellationToken))
using (var transaction = await connection.BeginTransactionAsync(cancellationToken).ConfigureAwait(false))
using (var command = BuildStoredProcedureCall(
commandText,
transaction,
Parameters.Count(maxCount + 1),
Parameters.Position(fromPositionExclusive)))
using (var reader = await command
.ExecuteReaderAsync(CommandBehavior.SequentialAccess, cancellationToken)
.ConfigureAwait(false))
{
if (!reader.HasRows)
{
return(new ReadAllPage(
fromPositionExclusive,
fromPositionExclusive,
true,
ReadDirection.Forward,
readNext,
Array.Empty <StreamMessage>()));
}
var messages = new List <(StreamMessage message, int?maxAge)>();
while (await reader.ReadAsync(cancellationToken).ConfigureAwait(false))
{
if (messages.Count == maxCount)
{
messages.Add(default);
private async Task <ReadAllPage> FilterExpired(
ReadAllPage readAllPage,
ReadNextAllPage readNext,
CancellationToken cancellationToken)
{
if (_disableMetadataCache)
{
return(readAllPage);
}
var valid = new List <StreamMessage>();
var currentUtc = GetUtcNow();
foreach (var streamMessage in readAllPage.Messages)
{
if (streamMessage.StreamId.StartsWith("$"))
{
valid.Add(streamMessage);
continue;
}
int?maxAge = _metadataMaxAgeCache == null
? null
: 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 ReadAllPage(
readAllPage.FromPosition,
readAllPage.NextPosition,
readAllPage.IsEnd,
readAllPage.Direction,
readNext,
valid.ToArray()));
}
protected override async Task <ReadAllPage> ReadAllForwardsInternal(
long fromPosition,
int maxCount,
bool prefetch,
ReadNextAllPage readNext,
CancellationToken cancellationToken)
{
maxCount = maxCount == int.MaxValue ? maxCount - 1 : maxCount;
long position = fromPosition;
using (var connection = _createConnection())
{
await connection.OpenAsync(cancellationToken).ConfigureAwait(false);
var commandText = prefetch ? _scripts.ReadAllForwardWithData : _scripts.ReadAllForward;
using (var command = new SqlCommand(commandText, connection))
{
command.CommandTimeout = _commandTimeout;
command.Parameters.AddWithValue("position", position);
command.Parameters.AddWithValue("count", maxCount + 1); //Read extra row to see if at end or not
var reader = await command
.ExecuteReaderAsync(CommandBehavior.SequentialAccess, cancellationToken)
.ConfigureAwait(false);
List <StreamMessage> messages = new List <StreamMessage>();
if (!reader.HasRows)
{
return(new ReadAllPage(
fromPosition,
fromPosition,
true,
ReadDirection.Forward,
readNext,
messages.ToArray()));
}
while (await reader.ReadAsync(cancellationToken).ConfigureAwait(false))
{
if (messages.Count == maxCount)
{
messages.Add(default);
protected override async Task <ReadAllPage> ReadAllForwardsInternal(
long fromPositionExclusive,
int maxCount,
bool prefetch,
ReadNextAllPage readNext,
CancellationToken cancellationToken)
{
maxCount = maxCount == int.MaxValue ? maxCount - 1 : maxCount;
using (var connection = await OpenConnection(cancellationToken))
using (var transaction = _createTransaction(connection))
using (var command = BuildFunctionCommand(
_schema.ReadAll,
transaction,
Parameters.Count(maxCount + 1),
Parameters.Position(fromPositionExclusive),
Parameters.ReadDirection(ReadDirection.Forward),
Parameters.Prefetch(prefetch)))
using (var reader = await command
.ExecuteReaderAsync(CommandBehavior.SequentialAccess, cancellationToken)
.NotOnCapturedContext())
{
if (!reader.HasRows)
{
return(new ReadAllPage(
fromPositionExclusive,
fromPositionExclusive,
true,
ReadDirection.Forward,
readNext,
Array.Empty <StreamMessage>()));
}
var messages = new List <(StreamMessage message, int?maxAge)>();
while (await reader.ReadAsync(cancellationToken).NotOnCapturedContext())
{
if (messages.Count == maxCount)
{
messages.Add(default);
public async Task <ReadAllPage> ReadAllBackwards(
long fromPositionInclusive,
int maxCount,
bool prefetchJsonData,
CancellationToken cancellationToken = default)
{
Ensure.That(fromPositionInclusive, nameof(fromPositionInclusive)).IsGte(-1);
Ensure.That(maxCount, nameof(maxCount)).IsGte(1);
GuardAgainstDisposed();
cancellationToken.ThrowIfCancellationRequested();
Logger.Debug(
"ReadAllBackwards from position {fromPositionInclusive} with max count {maxCount}.",
fromPositionInclusive,
maxCount);
ReadNextAllPage readNext = (nextPosition, ct) => ReadAllBackwards(nextPosition, maxCount, prefetchJsonData, ct);
var page = await ReadAllBackwardsInternal(fromPositionInclusive, maxCount, prefetchJsonData, readNext, cancellationToken);
return(await FilterExpired(page, readNext, cancellationToken));
}
protected override Task <ReadAllPage> ReadAllBackwardsInternal(long fromPositionExclusive, int maxCount, bool prefetch, ReadNextAllPage readNext, CancellationToken cancellationToken)
{
throw new NotImplementedException();
}
protected override async Task <ReadAllPage> ReadAllForwardsInternal(
long fromPositionExlusive,
int maxCount,
bool prefetch,
ReadNextAllPage readNext,
CancellationToken cancellationToken)
{
maxCount = maxCount == int.MaxValue ? maxCount - 1 : maxCount;
long ordinal = fromPositionExlusive;
using (var connection = _createConnection())
{
await connection.OpenAsync(cancellationToken).NotOnCapturedContext();
var commandText = prefetch ? _scripts.ReadAllForwardWithData : _scripts.ReadAllForward;
using (var command = new SqlCommand(commandText, connection))
{
command.Parameters.AddWithValue("ordinal", ordinal);
command.Parameters.AddWithValue("count", maxCount + 1); //Read extra row to see if at end or not
var reader = await command
.ExecuteReaderAsync(cancellationToken)
.NotOnCapturedContext();
List <StreamMessage> messages = new List <StreamMessage>();
if (!reader.HasRows)
{
return(new ReadAllPage(
fromPositionExlusive,
fromPositionExlusive,
true,
ReadDirection.Forward,
readNext,
messages.ToArray()));
}
while (await reader.ReadAsync(cancellationToken).NotOnCapturedContext())
{
if (messages.Count == maxCount)
{
messages.Add(default(StreamMessage));
}
else
{
var streamId = reader.GetString(0);
var streamVersion = reader.GetInt32(1);
ordinal = reader.GetInt64(2);
var eventId = reader.GetGuid(3);
var created = reader.GetDateTime(4);
var type = reader.GetString(5);
var jsonMetadata = reader.GetString(6);
Func <CancellationToken, Task <string> > getJsonData;
if (prefetch)
{
var jsonData = reader.GetString(7);
getJsonData = _ => Task.FromResult(jsonData);
}
else
{
var streamIdInfo = new StreamIdInfo(streamId);
getJsonData = ct => GetJsonData(streamIdInfo.SqlStreamId.Id, streamVersion, ct);
}
var message = new StreamMessage(streamId,
eventId,
streamVersion,
ordinal,
created,
type,
jsonMetadata,
getJsonData);
messages.Add(message);
}
}
bool isEnd = true;
if (messages.Count == maxCount + 1) // An extra row was read, we're not at the end
{
isEnd = false;
messages.RemoveAt(maxCount);
}
var nextPosition = messages[messages.Count - 1].Position + 1;
return(new ReadAllPage(
fromPositionExlusive,
nextPosition,
isEnd,
ReadDirection.Forward,
readNext,
messages.ToArray()));
}
}
}
protected abstract Task <ReadAllPage> ReadAllBackwardsInternal(
long fromPositionExclusive,
int maxCount,
bool prefetch,
ReadNextAllPage readNext,
CancellationToken cancellationToken);
protected override Task <ReadAllPage> ReadAllBackwardsInternal(
long fromPositionExclusive,
int maxCount,
bool prefetch,
ReadNextAllPage readNext,
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
{
var result = new ReadAllPage(Position.Start, Position.Start, true, ReadDirection.Backward,
StreamMessage.EmptyArray, readNext);
return(Task.FromResult(result));
}
var previous = current.Previous;
while (current.Value.Position < fromPositionExclusive)
{
if (current.Next == null) // fromPosition is past end of store
{
var result = new ReadAllPage(fromPositionExclusive, fromPositionExclusive, true,
ReadDirection.Backward, StreamMessage.EmptyArray, readNext);
return(Task.FromResult(result));
}
previous = current;
current = current.Next;
}
var messages = new List <StreamMessage>();
while (maxCount > 0 && current != _allStream.First)
{
StreamMessage message;
if (prefetch)
{
message = new StreamMessage(
current.Value.StreamId,
current.Value.MessageId,
current.Value.StreamVersion,
current.Value.Position,
current.Value.Created,
current.Value.Type,
current.Value.JsonMetadata,
current.Value.JsonData);
}
else
{
var currentCopy = current;
message = new StreamMessage(
current.Value.StreamId,
current.Value.MessageId,
current.Value.StreamVersion,
current.Value.Position,
current.Value.Created,
current.Value.Type,
current.Value.JsonMetadata,
ct =>
{
return(Task.Run(
() => ReadMessageData(currentCopy.Value.StreamId, currentCopy.Value.MessageId), ct));
});
}
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 ReadAllPage(
fromPositionExclusive,
nextCheckPoint,
isEnd,
ReadDirection.Backward,
messages.ToArray(),
readNext);
return(Task.FromResult(page));
}
}
protected override async Task <ReadAllPage> ReadAllForwardsInternal(
long fromPosition,
int maxCount,
bool prefetch,
ReadNextAllPage readNext,
CancellationToken cancellationToken)
{
maxCount = maxCount == int.MaxValue ? maxCount - 1 : maxCount;
long position = fromPosition;
using (var connection = _createConnection())
{
await connection.OpenAsync(cancellationToken).NotOnCapturedContext();
var commandText = prefetch ? _scripts.ReadAllForwardWithData : _scripts.ReadAllForward;
using (var command = new SqlCommand(commandText, connection))
{
command.CommandTimeout = _commandTimeout;
command.Parameters.AddWithValue("position", position);
command.Parameters.AddWithValue("count", maxCount + 1); //Read extra row to see if at end or not
var reader = await command
.ExecuteReaderAsync(CommandBehavior.SequentialAccess, cancellationToken)
.NotOnCapturedContext();
if (!reader.HasRows)
{
return(new ReadAllPage(
fromPosition,
fromPosition,
true,
ReadDirection.Forward,
readNext,
Array.Empty <StreamMessage>()));
}
var messages = new List <(StreamMessage, int?)>();
while (await reader.ReadAsync(cancellationToken).NotOnCapturedContext())
{
var ordinal = 0;
var streamId = reader.GetString(ordinal++);
var maxAge = reader.GetNullableInt32(ordinal++);
var streamVersion = reader.GetInt32(ordinal++);
position = reader.GetInt64(ordinal++);
var eventId = reader.GetGuid(ordinal++);
var created = reader.GetDateTime(ordinal++);
var type = reader.GetString(ordinal++);
var jsonMetadata = reader.GetString(ordinal++);
Func <CancellationToken, Task <string> > getJsonData;
if (prefetch)
{
var jsonData = await reader.GetTextReader(ordinal).ReadToEndAsync();
getJsonData = _ => Task.FromResult(jsonData);
}
else
{
var streamIdInfo = new StreamIdInfo(streamId);
getJsonData = ct => GetJsonData(streamIdInfo.SqlStreamId.Id, streamVersion, ct);
}
var message = new StreamMessage(streamId,
eventId,
streamVersion,
position,
created,
type,
jsonMetadata,
getJsonData);
messages.Add((message, maxAge));
}
bool isEnd = true;
if (messages.Count == maxCount + 1) // An extra row was read, we're not at the end
{
isEnd = false;
messages.RemoveAt(maxCount);
}
var filteredMessages = FilterExpired(messages);
var nextPosition = filteredMessages[filteredMessages.Count - 1].Position + 1;
return(new ReadAllPage(
fromPosition,
nextPosition,
isEnd,
ReadDirection.Forward,
readNext,
filteredMessages.ToArray()));
}
}
}
protected override async Task <ReadAllPage> ReadAllForwardsInternal(
long fromPositionExclusive,
int maxCount,
bool prefetch,
ReadNextAllPage readNext,
CancellationToken cancellationToken)
{
GuardAgainstDisposed();
cancellationToken.ThrowIfCancellationRequested();
using (var connection = OpenConnection())
{
// find starting node.
var allStreamPosition = await connection.AllStream()
.HeadPosition(cancellationToken);
if (allStreamPosition == Position.None)
{
return(new ReadAllPage(
Position.Start,
Position.Start,
true,
ReadDirection.Forward,
readNext));
}
if (allStreamPosition < fromPositionExclusive)
{
return(new ReadAllPage(
fromPositionExclusive,
fromPositionExclusive,
true,
ReadDirection.Forward,
readNext));
}
var remaining = await connection.AllStream()
.Remaining(ReadDirection.Forward, fromPositionExclusive);
if (remaining == Position.End)
{
return(new ReadAllPage(
fromPositionExclusive,
Position.End,
true,
ReadDirection.Forward,
readNext));
}
var messages = await connection.AllStream()
.Read(ReadDirection.Forward,
fromPositionExclusive,
maxCount,
prefetch,
cancellationToken);
bool isEnd = remaining - messages.Count <= 0;
var nextPosition = messages.Any()
? messages.Last().Position + 1
: Position.End;
return(new ReadAllPage(
fromPositionExclusive,
nextPosition,
isEnd,
ReadDirection.Forward,
readNext,
messages.ToArray()));
}
}
protected override async Task <ReadAllPage> ReadAllBackwardsInternal(
long fromPosition,
int maxCount,
bool prefetch,
ReadNextAllPage readNext,
CancellationToken cancellationToken)
{
GuardAgainstDisposed();
cancellationToken.ThrowIfCancellationRequested();
using (var connection = OpenConnection())
{
long?beginningPosition = fromPosition;
var allStreamPosition = await connection.AllStream()
.HeadPosition(cancellationToken);
if (allStreamPosition == Position.None)
{
return(new ReadAllPage(
Position.Start,
Position.Start,
true,
ReadDirection.Backward,
readNext));
}
if (fromPosition == Position.End)
{
beginningPosition = allStreamPosition > fromPosition ? allStreamPosition : fromPosition;
}
if (fromPosition > allStreamPosition && fromPosition > Position.Start)
{
return(new ReadAllPage(
fromPosition,
fromPosition,
true,
ReadDirection.Backward,
readNext));
}
// For reading $all, in the case where no events have been entered into
// the root stream yet, we need to have a min beginning position of Position.Start (0).
beginningPosition = beginningPosition < Position.Start
? Position.Start
: beginningPosition;
var remaining = await connection.AllStream()
.Remaining(ReadDirection.Backward, beginningPosition);
if (remaining == Position.End)
{
return(new ReadAllPage(
allStreamPosition ?? Position.Start,
Position.End,
true,
ReadDirection.Backward,
readNext));
}
var messages = await connection.AllStream()
.Read(ReadDirection.Backward,
beginningPosition,
maxCount,
prefetch,
cancellationToken);
bool isEnd = remaining - messages.Count <= 0;
var nextPosition = messages.Any() ? Math.Max(messages.Last().Position - 1, Position.Start) : Position.Start;
return(new ReadAllPage(
beginningPosition.Value,
nextPosition,
isEnd,
ReadDirection.Backward,
readNext,
messages.ToArray()));
}
}
protected override async Task <ReadAllPage> ReadAllBackwardsInternal(
long fromPositionExclusive,
int maxCount,
bool prefetch,
ReadNextAllPage readNext,
CancellationToken cancellationToken)
{
maxCount = maxCount == int.MaxValue ? maxCount - 1 : maxCount;
long position = fromPositionExclusive == Position.End ? long.MaxValue : fromPositionExclusive;
using (var connection = _createConnection())
{
await connection.OpenAsync(cancellationToken).NotOnCapturedContext();
var commandText = prefetch ? _scripts.ReadAllBackwardWithData : _scripts.ReadAllBackward;
using (var command = new SqlCommand(commandText, connection))
{
command.Parameters.AddWithValue("position", position);
command.Parameters.AddWithValue("count", maxCount + 1); //Read extra row to see if at end or not
var reader = await command
.ExecuteReaderAsync(cancellationToken)
.NotOnCapturedContext();
var messages = new List <(StreamMessage, int?)>();
if (!reader.HasRows)
{
// When reading backwards and there are no more items, then next position is LongPosition.Start,
// regardles of what the fromPosition is.
return(new ReadAllPage(
Position.Start,
Position.Start,
true,
ReadDirection.Backward,
readNext,
Array.Empty <StreamMessage>()));
}
long lastPosition = 0;
while (await reader.ReadAsync(cancellationToken).NotOnCapturedContext())
{
var ordinal = 0;
var streamId = reader.GetString(ordinal++);
var maxAge = reader.GetNullableInt32(ordinal++);
var streamVersion = reader.GetInt32(ordinal++);
position = reader.GetInt64(ordinal++);
var messageId = reader.GetGuid(ordinal++);
var created = reader.GetDateTime(ordinal++);
var type = reader.GetString(ordinal++);
var jsonMetadata = reader.GetString(ordinal++);
Func <CancellationToken, Task <string> > getJsonData;
if (prefetch)
{
var jsonData = reader.GetString(ordinal);
getJsonData = _ => Task.FromResult(jsonData);
}
else
{
var streamIdInfo = new StreamIdInfo(streamId);
getJsonData = ct => GetJsonData(streamIdInfo.SqlStreamId.Id, streamVersion, ct);
}
var message = new StreamMessage(
streamId,
messageId,
streamVersion,
position,
created,
type,
jsonMetadata,
getJsonData);
messages.Add((message, maxAge));
lastPosition = position;
}
bool isEnd = true;
var nextPosition = lastPosition;
if (messages.Count == maxCount + 1) // An extra row was read, we're not at the end
{
isEnd = false;
messages.RemoveAt(maxCount);
}
var filteredMessages = FilterExpired(messages);
fromPositionExclusive = filteredMessages.Any() ? filteredMessages[0].Position : 0;
return(new ReadAllPage(
fromPositionExclusive,
nextPosition,
isEnd,
ReadDirection.Backward,
readNext,
filteredMessages.ToArray()));
}
}
}
