/// <summary>
/// 使用Cursor读取大数据
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="signal"></param>
/// <param name="fragment"></param>
/// <returns></returns>
public async Task<ICursor> GetCursorAsync<T>(Signal signal, string fragment)
{
//var waveSig = signal as FixedIntervalWaveSignal<T>;
var waveSig = signal as FixedIntervalWaveSignal;
if (waveSig == null)
{
throw new Exception(ErrorMessages.NotValidSignalError);
}
WaveFragment frag = null;
try
{
frag = WaveFragment.Parse(fragment);
}
catch (Exception)
{
throw new Exception(ErrorMessages.NotValidSignalFragmentError);
}
//end smaller then start then read all
if (frag.Start >= frag.End)
{
frag.Start = waveSig.StartTime;
frag.End = waveSig.EndTime;
}
//calc the decimationfactor is count valid
if (frag.Count > 0)
{
//todo can be optimized a little
frag.DecimationFactor = (long)Math.Floor(((frag.End - frag.Start) / waveSig.SampleInterval + 1) / frag.Count);
}
if (frag.DecimationFactor < 1)
{
frag.DecimationFactor = 1;
}
var startIndex = (long)Math.Ceiling((frag.Start - waveSig.StartTime) / waveSig.SampleInterval);
var count = (long)Math.Floor((frag.End - frag.Start) / waveSig.SampleInterval / frag.DecimationFactor) + 1;
return await myStorageEngine.GetCursorAsync<T>(waveSig.Id, new List<long> { startIndex }, new List<long> { count }, new List<long> { frag.DecimationFactor });
}
/// <summary>
/// format is "array"(default) or "complex"
/// review 这个下面很多代码和get curser重复了，可以修改
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="signal"></param>
/// <param name="fragment">fragment: "start=t1&end=t2&decimation=2&count=1000" decimation is optional, if end is no bigger then start then return all</param>
/// <param name="format">format is "array"(default) or "complex" </param>
/// <returns></returns>
public async Task<object> GetDataAsync<T>(Signal signal, string fragment, string format)
{
//var waveSig = signal as FixedIntervalWaveSignal<T>;
var waveSig = signal as FixedIntervalWaveSignal;
if (waveSig == null)
{
throw new Exception(ErrorMessages.NotValidSignalError);
}
WaveFragment frag = null;
try
{
frag = WaveFragment.Parse(fragment);
}
catch (Exception)
{
throw new Exception("Fragment parse error!");
}
//end smaller then start then read all
if (frag.Start >= frag.End)
{
frag.Start = waveSig.StartTime;
frag.End = waveSig.EndTime;
}
if (frag.Start < waveSig.StartTime)
{
frag.Start = waveSig.StartTime;
}
if (frag.End > waveSig.EndTime)
{
frag.End = waveSig.EndTime;
}
//calc the decimationfactor is count valid
if (frag.Count > 0)
{
//todo can be optimized a little
frag.DecimationFactor = (long)Math.Floor(((frag.End - frag.Start) / waveSig.SampleInterval + 1) / frag.Count);
}
if (frag.DecimationFactor < 1)
{
frag.DecimationFactor = 1;
}
var startIndex = (long)Math.Ceiling((frag.Start - waveSig.StartTime) / waveSig.SampleInterval);
var count = (long)Math.Floor((frag.End - frag.Start) / waveSig.SampleInterval / frag.DecimationFactor) + 1;
ICursor<T> cursor = await myStorageEngine.GetCursorAsync<T>(waveSig.Id, new List<long> { startIndex }, new List<long> { count }, new List<long> { frag.DecimationFactor });
List<T> resultArray = new List<T>();
//防止读时越界 review cursor 目前一次只能读1000个点？
while (cursor.LeftPoint > 1000)
{
resultArray.AddRange(await cursor.Read(1000));
}
if (cursor.LeftPoint > 0)
{
resultArray.AddRange(await cursor.Read(cursor.LeftPoint));
}
if (format == "complex")
{
return new FixedIntervalWaveComplex<T>
{
Title = waveSig.Path,
Start = startIndex * waveSig.SampleInterval + waveSig.StartTime,
End = waveSig.StartTime + ((count - 1) * frag.DecimationFactor + startIndex) * waveSig.SampleInterval,
Count = count,
Data = resultArray,
DecimatedSampleInterval = waveSig.SampleInterval * frag.DecimationFactor,
OrignalSampleInterval = waveSig.SampleInterval,
DecimationFactor = frag.DecimationFactor,
StartIndex = startIndex,
Unit = waveSig.Unit
};
}
else if (format == "point")
{
var points = new List<SignalPoint<T>>();
// 计算首尾所需取的采样间隔（一致）、点数
//bug review 这里是不是也有点重复？，我也没看懂，我大概的理解是，不管用户请求什么数据，都把全部的数据返回给用户，不过用户请求区域以外的数据，点数更加稀疏一些（100个点？）？这个逻辑和其他的读取不一样呀，有问题！！！
long headtailDecimationFactor = 0;
long headtailMaxCount = 100;
if ((frag.Start - waveSig.StartTime) > (waveSig.EndTime - frag.End))
{
headtailDecimationFactor = (long)Math.Floor(((frag.Start - waveSig.StartTime) / waveSig.SampleInterval + 1) / headtailMaxCount);
}
else
{
headtailDecimationFactor = (long)Math.Floor(((waveSig.EndTime - frag.End) / waveSig.SampleInterval + 1) / headtailMaxCount);
}
if (headtailDecimationFactor < 1)
{
headtailDecimationFactor = 1;
}
var headCount = (long)Math.Floor((frag.Start - waveSig.StartTime) / waveSig.SampleInterval / headtailDecimationFactor) + 1;
var tailCount = (long)Math.Floor((waveSig.EndTime - frag.End) / waveSig.SampleInterval / headtailDecimationFactor) + 1;
//添加前段概略点
double x = waveSig.StartTime;
if (headCount > 1)
{
ICursor<T> headCursor = await myStorageEngine.GetCursorAsync<T>(waveSig.Id, new List<long> { 0 }, new List<long> { headCount }, new List<long> { headtailDecimationFactor });
//review 这里不应该用foreach，顺序不定，而且即使用循环也不太好，效率有点低，不过好像也没什么别的办法，最好还是不要生成x序列，太浪费服务器资源了，以后，以后我们前端最好还是不要用这个point
foreach (var data in await headCursor.Read(headCursor.LeftPoint))
{
points.Add(new SignalPoint<T>(x, data));
x += waveSig.SampleInterval * headtailDecimationFactor;
}
}
//添加中间详细点
x = frag.Start;
foreach (var data in resultArray)
{
points.Add(new SignalPoint<T>(x, data));
x += waveSig.SampleInterval * frag.DecimationFactor;
}
//添加后段概略点
if (tailCount > 1)
{
ICursor<T> tailCursor = await myStorageEngine.GetCursorAsync<T>(waveSig.Id, new List<long> { 0 }, new List<long> { tailCount }, new List<long> { headtailDecimationFactor });
x = frag.End;
foreach (var data in await tailCursor.Read(tailCursor.LeftPoint))
{
points.Add(new SignalPoint<T>(x, data));
x += waveSig.SampleInterval * headtailDecimationFactor;
}
}
return points;
}
else
{
return resultArray;
}
}
