public static RetentionPolicy Parse(string text)
{
var retentionPolicy = new RetentionPolicy();
var parts = text.Split(new[] { ',' }, StringSplitOptions.RemoveEmptyEntries).Select(p => p.Trim());
foreach (var part in parts)
{
var subparts = part.Split(new[] { ':' }, StringSplitOptions.RemoveEmptyEntries);
if (subparts.Length != 2)
{
continue;
}
var precision = TimeSpanParser.ParseTimeSpan(subparts[0]);
var history = TimeSpanParser.ParseTimeSpan(subparts[1]);
if (!precision.HasValue || !history.HasValue)
{
continue;
}
retentionPolicy.Add(precision.Value, history.Value);
} // foreach
return(retentionPolicy);
}
public static void EnsureRetentionPolicyValid(RetentionPolicy retentionPolicy)
{
if (retentionPolicy.Count == 0)
{
throw new RetentionPolicyValidationException("A Statsify database requires at least one Retention");
}
var retentions = retentionPolicy.OrderBy(r => r.Precision).ToList();
for (var i = 1; i < retentions.Count; ++i)
{
var previousRetention = retentions[i - 1];
var retention = retentions[i];
if (previousRetention.Precision == retention.Precision)
{
throw new RetentionPolicyValidationException(
string.Format("A Statsify database may not be created having two Retentions (#{0}, #{1}) with the same precision", i - 1, i));
}
if (retention.Precision % previousRetention.Precision != 0)
{
throw new RetentionPolicyValidationException(
string.Format("Higher precision Retention (#{0}, {1}) must evenly divide lower precision Retention (#{2}, {3})",
i - 1, previousRetention.Precision, i, retention.Precision));
}
if ((TimeSpan)retention.History < previousRetention.History)
{
throw new RetentionPolicyValidationException(
string.Format("Lower precision Retention (#{0}, {1}) must cover larger time intervals than higher precision Retention (#{2}, {3})",
i, retention.History, i - 1, previousRetention.History));
}
var pointsPerDownsample = (long)retention.Precision / previousRetention.Precision;
if (previousRetention.History < pointsPerDownsample)
{
throw new RetentionPolicyValidationException(
string.Format("Retention (#{0}) must have at least enough points to consolidate to the next Retention", i - 1));
}
} // for
}
public static DatapointDatabase Create(string path, float downsamplingFactor, DownsamplingMethod downsamplingMethod, RetentionPolicy retentionPolicy, Func <DateTime> currentTimeProvider = null)
{
EnsureValidRetentionPolicy(retentionPolicy);
using (var fileStream = new FileStream(path, FileMode.Create, FileAccess.ReadWrite, FileShare.Read, 8192, FileOptions.WriteThrough))
return(Create(path, fileStream, downsamplingFactor, downsamplingMethod, retentionPolicy, currentTimeProvider));
}
private static void EnsureValidRetentionPolicy(RetentionPolicy retentionPolicy)
{
RetentionPolicyValidator.EnsureRetentionPolicyValid(retentionPolicy);
}
private static DatapointDatabase Create(string path, FileStream stream, float downsamplingFactor, DownsamplingMethod downsamplingMethod, RetentionPolicy retentionPolicy, Func <DateTime> currentTimeProvider = null)
{
var maxRetention = retentionPolicy.Select(h => h.Precision * h.History).Max();
var headerSize =
sizeof(byte) * Signature.Length +
sizeof(byte) * Version.Length +
sizeof(int) +
sizeof(float) +
sizeof(int) +
sizeof(int) +
ArchiveHeaderSize * retentionPolicy.Count;
var archives = new List <Archive>();
using (var binaryWriter = new BinaryWriter(stream))
{
binaryWriter.Write(Signature);
binaryWriter.Write(Version);
// ReSharper disable RedundantCast
binaryWriter.Write((int)downsamplingMethod);
binaryWriter.Write((float)downsamplingFactor);
binaryWriter.Write((int)maxRetention);
binaryWriter.Write((int)retentionPolicy.Count);
// ReSharper restore RedundantCast
var offset = headerSize;
foreach (var retention in retentionPolicy)
{
// ReSharper disable RedundantCast
binaryWriter.Write((int)offset);
binaryWriter.Write((int)retention.Precision);
binaryWriter.Write((int)retention.History);
// ReSharper restore RedundantCast
archives.Add(new Archive(offset, retention.History * DatapointSize, retention));
offset += retention.History * DatapointSize;
} // foreach
stream.SetLength(offset);
} // using
return(new DatapointDatabase(path, downsamplingFactor, downsamplingMethod, maxRetention, archives, currentTimeProvider));
}
