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Cache S101FeatureXmlSource XName instances (perf-report P4) #162

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Cache S101FeatureXmlSource XName instances (perf-report P4) #162

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57 changes: 41 additions & 16 deletions src/EncDotNet.S100.Datasets.S101/S101FeatureXmlSource.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,31 @@ public sealed class S101FeatureXmlSource : IFeatureXmlSource

private static readonly XNamespace S100Ns = "http://www.iho.int/s100/5.0";

// Cached XName instances. These are constructed once at class init
// and reused across every feature in every dataset for the lifetime
// of the AppDomain. Per the perf report (§3 P4 / s101-real-cold +
// s101-real-warm), un-cached XName / attribute-name lookups in
// MakePointElement and the per-feature element builders showed up
// as String.Concat(string, string, string) consuming 50 % / 43 %
// of all managed allocations during S-101 portrayal — driven by
// the volume of Point geometry built per cell. Caching avoids the
// XNamespace.GetName hash lookup *and* keeps these names rooted
// by a Gen2 static field so they never participate in GC promotion.
private static readonly XName DatasetName = S100Ns + "Dataset";
private static readonly XName FeatureName = S100Ns + "Feature";
private static readonly XName GeometryName = S100Ns + "Geometry";
private static readonly XName PointName = S100Ns + "Point";
private static readonly XName CurveName = S100Ns + "Curve";
private static readonly XName SurfaceName = S100Ns + "Surface";
private static readonly XName RingName = S100Ns + "Ring";
private static readonly XName AttributeName = S100Ns + "Attribute";

private static readonly XName IdAttrName = "id";
private static readonly XName TypeAttrName = "type";
private static readonly XName CodeAttrName = "code";
private static readonly XName LatAttrName = "lat";
private static readonly XName LonAttrName = "lon";

private readonly S101Dataset _dataset;
private IReadOnlyList<string>? _featureTypes;

Expand Down Expand Up @@ -61,16 +86,16 @@ public XmlReader GetFeatureXml(CancellationToken cancellationToken = default)
private XDocument BuildFeatureXml()
{
var doc = _dataset.Document;
var root = new XElement(S100Ns + "Dataset");
var root = new XElement(DatasetName);

foreach (var feat in doc.Features)
{
var featureType = doc.FeatureTypeCatalogue.TryGetValue(feat.FeatureTypeCode, out var name)
? name : feat.FeatureTypeCode.ToString();

var el = new XElement(S100Ns + "Feature",
new XAttribute("id", feat.RecordId),
new XAttribute("type", featureType));
var el = new XElement(FeatureName,
new XAttribute(IdAttrName, feat.RecordId),
new XAttribute(TypeAttrName, featureType));

// Geometry
if (feat.SpatialAssociations.Length > 0)
Expand All @@ -92,8 +117,8 @@ private XDocument BuildFeatureXml()
{
var attrName = doc.AttributeTypeCatalogue.TryGetValue(attr.NumericCode, out var aName)
? aName : attr.NumericCode.ToString();
el.Add(new XElement(S100Ns + "Attribute",
new XAttribute("code", attrName),
el.Add(new XElement(AttributeName,
new XAttribute(CodeAttrName, attrName),
attr.Value));
}

Expand All @@ -110,7 +135,7 @@ private XDocument BuildFeatureXml()
if (cmfx == 0) cmfx = 10_000_000;
if (cmfy == 0) cmfy = 10_000_000;

var geom = new XElement(S100Ns + "Geometry");
var geom = new XElement(GeometryName);
bool hasPoints = false;

foreach (var spa in feat.SpatialAssociations)
Expand All @@ -127,8 +152,8 @@ private XDocument BuildFeatureXml()

private static XElement? BuildCurveGeometry(S101FeatureRecord feat, S101Document doc)
{
var geom = new XElement(S100Ns + "Geometry");
var curve = new XElement(S100Ns + "Curve");
var geom = new XElement(GeometryName);
var curve = new XElement(CurveName);

foreach (var spa in feat.SpatialAssociations)
{
Expand All @@ -142,17 +167,17 @@ private XDocument BuildFeatureXml()

private static XElement? BuildSurfaceGeometry(S101FeatureRecord feat, S101Document doc)
{
var geom = new XElement(S100Ns + "Geometry");
var geom = new XElement(GeometryName);
bool hasGeometry = false;

foreach (var spa in feat.SpatialAssociations)
{
if (spa.RecordName != RcnmSurface) continue;
if (!doc.Surfaces.TryGetValue(spa.RecordId, out var surface)) continue;

var surfaceEl = new XElement(S100Ns + "Surface");
var exteriorRing = new XElement(S100Ns + "Ring", new XAttribute("type", "exterior"));
var interiorRing = new XElement(S100Ns + "Ring", new XAttribute("type", "interior"));
var surfaceEl = new XElement(SurfaceName);
var exteriorRing = new XElement(RingName, new XAttribute(TypeAttrName, "exterior"));
var interiorRing = new XElement(RingName, new XAttribute(TypeAttrName, "interior"));

foreach (var ring in surface.RingAssociations)
{
Expand Down Expand Up @@ -216,8 +241,8 @@ private static void AddCurvePoints(byte rcnm, uint rcid, byte orientation, S101D

private static XElement MakePointElement(double lat, double lon)
{
return new XElement(S100Ns + "Point",
new XAttribute("lat", lat.ToString(CultureInfo.InvariantCulture)),
new XAttribute("lon", lon.ToString(CultureInfo.InvariantCulture)));
return new XElement(PointName,
new XAttribute(LatAttrName, lat.ToString(CultureInfo.InvariantCulture)),
new XAttribute(LonAttrName, lon.ToString(CultureInfo.InvariantCulture)));
}
}
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