void IAsyncLogProviderCommandHandler.ContinueAsynchronously(CommandContext ctx)
{
result = new DateBoundPositionResponseData();
result.Position = PositionedMessagesUtils.LocateDateBound(ctx.Reader, date, bound, ctx.Cancellation);
ctx.Tracer.Info("Position to return: {0}", result.Position);
if (result.Position == ctx.Reader.EndPosition)
{
result.IsEndPosition = true;
ctx.Tracer.Info("It is END position");
}
else if (result.Position == ctx.Reader.BeginPosition - 1)
{
result.IsBeforeBeginPosition = true;
ctx.Tracer.Info("It is BEGIN-1 position");
}
else
{
ctx.Cancellation.ThrowIfCancellationRequested();
if (userNeedsDate)
{
result.Date = PositionedMessagesUtils.ReadNearestMessageTimestamp(ctx.Reader, result.Position);
ctx.Tracer.Info("Date to return: {0}", result.Date);
}
}
dateBoundsCache.Set(date, result);
}
async Task IAsyncLogProviderCommandHandler.ContinueAsynchronously(CommandContext ctx)
{
result = new DateBoundPositionResponseData();
result.Position = await PositionedMessagesUtils.LocateDateBound(ctx.Reader, date, bound, ctx.Cancellation);
ctx.Tracer.Info("Position to return: {0}", result.Position);
if (result.Position == ctx.Reader.EndPosition)
{
result.IsEndPosition = true;
ctx.Tracer.Info("It is END position");
}
else if (result.Position == ctx.Reader.BeginPosition - 1)
{
result.IsBeforeBeginPosition = true;
ctx.Tracer.Info("It is BEGIN-1 position");
}
else
{
ctx.Cancellation.ThrowIfCancellationRequested();
if (messageRequested)
{
result.Message = await PositionedMessagesUtils.ReadNearestMessage(ctx.Reader, result.Position, MessagesParserFlag.HintMessageContentIsNotNeeed);
ctx.Tracer.Info("Details to return: {0} at {1}", result.Message?.Time, result.Message?.Position);
}
}
dateBoundsCache.Set(date, result);
}
Task <DateBoundPositionResponseData> ITimeGapsSource.GetDateBoundPosition(DateTime d, ListUtils.ValueBound bound, CancellationToken cancellation)
{
var ret = new DateBoundPositionResponseData()
{
IsEndPosition = true,
IsBeforeBeginPosition = true
};
bool findSmallestDate = bound == ListUtils.ValueBound.Lower || bound == ListUtils.ValueBound.Upper;
foreach (var r in EnumVisibleResults().Select(r => r.GetLastSnapshot()).Where(s => s != null))
{
var bnd = r.GetDateBoundPosition(d, bound);
if (bnd.Date != null)
{
if (ret.Date == null)
{
ret.Date = bnd.Date;
}
else if (findSmallestDate)
{
if (bnd.Date.Value < ret.Date.Value)
{
ret.Date = bnd.Date;
}
}
else
{
if (bnd.Date.Value > ret.Date.Value)
{
ret.Date = bnd.Date;
}
}
}
if (!bnd.IsBeforeBeginPosition)
{
ret.IsBeforeBeginPosition = false;
}
if (!bnd.IsEndPosition)
{
ret.IsEndPosition = false;
}
ret.Position += bnd.Index; // use sum of indexes as virtual position
}
return(Task.FromResult(ret));
}
void IDateBoundsCache.Set(DateTime d, DateBoundPositionResponseData rsp)
{
lock (sync)
{
data[d] = new DateBoundsCache.Entry()
{
lastUsed = ++time,
value = rsp
};
int sizeThreshold = 512;
if (data.Count > sizeThreshold)
{
// drop half of oldest entries when the threshold is reached
data = data
.OrderByDescending(x => x.Value.lastUsed)
.Take(sizeThreshold / 2)
.ToDictionary(x => x.Key, x => x.Value);
}
}
}
bool IAsyncLogProviderCommandHandler.RunSynchronously(CommandContext ctx)
{
if (!userNeedsDate && (result = dateBoundsCache.Get(date)) != null)
{
return(true);
}
if (ctx.Cache == null || ctx.Cache.Messages.Count == 0)
{
return(false);
}
var cache = ctx.Cache;
if ((date < ctx.Stats.AvailableTime.Begin && (bound == ListUtils.ValueBound.LowerReversed || bound == ListUtils.ValueBound.UpperReversed)) ||
date == ctx.Stats.AvailableTime.Begin && (bound == ListUtils.ValueBound.UpperReversed))
{
result = new DateBoundPositionResponseData()
{
IsBeforeBeginPosition = true,
Position = ctx.Stats.PositionsRange.Begin - 1
};
return(true);
}
if ((date >= ctx.Stats.AvailableTime.End && (bound == ListUtils.ValueBound.Lower || bound == ListUtils.ValueBound.Upper)))
{
result = new DateBoundPositionResponseData()
{
IsEndPosition = true,
Position = ctx.Stats.PositionsRange.End
};
return(true);
}
result = cache.Messages.GetDateBoundPosition(date, bound);
if (result.Index == 0)
{
if (cache.MessagesRange.Begin != ctx.Stats.PositionsRange.Begin &&
(bound == ListUtils.ValueBound.Lower || bound == ListUtils.ValueBound.Upper))
{
return(false);
}
}
else if (result.Index == -1)
{
if (cache.MessagesRange.Begin != ctx.Stats.PositionsRange.Begin)
{
return(false);
}
}
if (result.Index == cache.Messages.Count - 1)
{
if (cache.MessagesRange.End != ctx.Stats.PositionsRange.End &&
(bound == ListUtils.ValueBound.LowerReversed || bound == ListUtils.ValueBound.UpperReversed))
{
return(false);
}
}
else if (result.Index == cache.Messages.Count)
{
if (cache.MessagesRange.End != ctx.Stats.PositionsRange.End)
{
return(false);
}
}
return(true);
}
bool HandleResponse(DateBoundPositionResponseData res, bool reversedMode)
{
using (trace.NewFrame)
{
Predicate <MessageTimestamp> shouldAdvanceDate = d =>
reversedMode ? d > currentDate : d < currentDate;
bool readerAdvanced = false;
trace.Info("reader returned ({0}, {1})", res.Position, res.Message?.Time);
trace.Info("reader's current position: {0}", currentPosition);
bool advancePosition = true;
if (reversedMode)
{
if (res.IsBeforeBeginPosition)
{
trace.Info("it's invalid position (before begin)");
advancePosition = false;
}
}
else
{
if (res.IsEndPosition)
{
trace.Info("it's invalid position (end)");
advancePosition = false;
}
}
if (advancePosition && res.Position > currentPosition)
{
trace.Info("reader has advanced its position: {0}", res.Position);
readerAdvanced = true;
currentPosition = res.Position;
}
bool advanceDate;
if (res.Message == null)
{
advanceDate = false;
}
else
{
advanceDate = shouldAdvanceDate(res.Message.Time);
}
if (advanceDate)
{
trace.Info("reader might need to advance the current date from {0} to {1}. Getting writer lock to make final decision...", currentDate, res.Message.Time);
if (shouldAdvanceDate(res.Message.Time))
{
trace.Info("reader is really advancing the current date from {0} to {1}", currentDate, res.Message.Time);
currentDate = res.Message.Time;
}
else
{
trace.Info("false alarm: reader is not advancing the current date because it has been already advanced to {0} by some other reader", currentDate);
}
}
return(readerAdvanced);
}
}