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Avoid allocating in TemplateMatcher on failure 

This change rejiggers the URL matching algorithm into using a two-pass
system to avoid allocating anything when a URL fails to match a route.
This commit is contained in:
Ryan Nowak 2015-10-05 18:13:34 -07:00
parent 371d4e62da
commit e5f4aa03d2
3 changed files with 149 additions and 93 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
src/Microsoft.AspNet.Routing/Template/RouteTemplate.cs
View File

@ -41,6 +41,16 @@ namespace Microsoft.AspNet.Routing.Template
public IList<TemplateSegment> Segments { get; private set; }
public TemplateSegment GetSegment(int index)
{
if (index < 0)
{
throw new IndexOutOfRangeException();
}
return index >= Segments.Count ? null : Segments[index];
}
private string DebuggerToString()
{
return string.Join(SeparatorString, Segments.Select(s => s.DebuggerToString()));

225
src/Microsoft.AspNet.Routing/Template/TemplateMatcher.cs
View File

@ -40,85 +40,151 @@ namespace Microsoft.AspNet.Routing.Template
public IDictionary<string, object> Match(PathString path)
{
var values = new RouteValueDictionary();
var i = 0;
var pathTokenizer = new PathTokenizer(path);
var requestSegments = new PathTokenizer(path);
for (var i = 0; i < requestSegments.Count; i++)
// Perf: We do a traversal of the request-segments + route-segments twice.
//
// For most segment-types, we only really need to any work on one of the two passes.
//
// On the first pass, we're just looking to see if there's anything that would disqualify us from matching.
// The most common case would be a literal segment that doesn't match.
//
// On the second pass, we're almost certainly going to match the URL, so go ahead and allocate the 'values'
// and start capturing strings.
foreach (var requestSegment in pathTokenizer)
{
var routeSegment = Template.Segments.Count > i ? Template.Segments[i] : null;
var requestSegment = requestSegments[i];
if (routeSegment == null)
var routeSegment = Template.GetSegment(i++);
if (routeSegment == null && requestSegment.Length > 0)
{
// If pathSegment is null, then we're out of route segments. All we can match is the empty
// string.
if (requestSegment.Length > 0)
return null;
}
else if (routeSegment.IsSimple && routeSegment.Parts[0].IsLiteral)
{
// This is a literal segment, so we need to match the text, or the route isn't a match.
var part = routeSegment.Parts[0];
if (!requestSegment.Equals(part.Text))
{
return null;
}
}
else if (routeSegment.Parts.Count == 1)
else if (routeSegment.IsSimple && routeSegment.Parts[0].IsCatchAll)
{
// Optimize for the simple case - the segment is made up for a single part
// Nothing to validate for a catch-all - it can match any string, including the empty string.
//
// Also, a catch-all has to be the last part, so we're done.
break;
}
else if (routeSegment.IsSimple && routeSegment.Parts[0].IsParameter)
{
// For a parameter, validate that it's a has some length, or we have a default, or it's optional.
var part = routeSegment.Parts[0];
if (part.IsLiteral)
if (requestSegment.Length == 0 &&
!Defaults.ContainsKey(part.Name) &&
!part.IsOptional)
{
if (!requestSegment.Equals(part.Text))
{
return null;
}
}
else
{
Debug.Assert(part.IsParameter);
if (part.IsCatchAll)
{
var captured = requestSegment.GetRemainingPath();
if (captured.Length > 0)
{
values.Add(part.Name, captured);
}
else
{
// It's ok for a catch-all to produce a null value
object defaultValue;
Defaults.TryGetValue(part.Name, out defaultValue);
values.Add(part.Name, defaultValue);
}
// A catch-all has to be the last part, so we're done.
break;
}
else
{
if (requestSegment.Length > 0)
{
values.Add(part.Name, requestSegment.ToString());
}
else
{
object defaultValue;
if (Defaults.TryGetValue(part.Name, out defaultValue))
{
values.Add(part.Name, defaultValue);
}
else if (part.IsOptional)
{
// This is optional (with no default value)
// - there's nothing to capture here, so just move on.
}
else
{
// There's no default for this parameter
return null;
}
}
}
// There's no value for this parameter, the route can't match.
return null;
}
}
else
{
Debug.Assert(!routeSegment.IsSimple);
// Don't attempt to validate a complex segment at this point other than being non-emtpy,
// do it in the second pass.
}
}
for (; i < Template.Segments.Count; i++)
{
// We've matched the request path so far, but still have remaining route segments. These need
// to be all single-part parameter segments with default values or else they won't match.
var routeSegment = Template.GetSegment(i);
Debug.Assert(routeSegment != null);
if (!routeSegment.IsSimple)
{
// If the segment is a complex segment, it MUST contain literals, and we've parsed the full
// path so far, so it can't match.
return null;
}
var part = routeSegment.Parts[0];
if (part.IsLiteral)
{
// If the segment is a simple literal - which need the URL to provide a value, so we don't match.
return null;
}
if (part.IsCatchAll)
{
// Nothing to validate for a catch-all - it can match any string, including the empty string.
//
// Also, a catch-all has to be the last part, so we're done.
break;
}
// If we get here, this is a simple segment with a parameter. We need it to be optional, or for the
// defaults to have a value.
Debug.Assert(routeSegment.IsSimple && part.IsParameter);
if (!Defaults.ContainsKey(part.Name) && !part.IsOptional)
{
// There's no default for this (non-optional) parameter so it can't match.
return null;
}
}
// At this point we've very likely got a match, so start capturing values for real.
var values = new RouteValueDictionary();
i = 0;
foreach (var requestSegment in pathTokenizer)
{
var routeSegment = Template.GetSegment(i++);
if (routeSegment.IsSimple && routeSegment.Parts[0].IsCatchAll)
{
// A catch-all captures til the end of the string.
var part = routeSegment.Parts[0];
var captured = requestSegment.GetRemainingPath();
if (captured.Length > 0)
{
values.Add(part.Name, captured);
}
else
{
// It's ok for a catch-all to produce a null value
object defaultValue;
Defaults.TryGetValue(part.Name, out defaultValue);
values.Add(part.Name, defaultValue);
}
// A catch-all has to be the last part, so we're done.
break;
}
else if (routeSegment.IsSimple && routeSegment.Parts[0].IsParameter)
{
// A simple parameter captures the whole segment, or a default value if nothing was
// provided.
var part = routeSegment.Parts[0];
if (requestSegment.Length > 0)
{
values.Add(part.Name, requestSegment.ToString());
}
else
{
object defaultValue;
if (Defaults.TryGetValue(part.Name, out defaultValue))
{
values.Add(part.Name, defaultValue);
}
}
}
else if (!routeSegment.IsSimple)
{
if (!MatchComplexSegment(routeSegment, requestSegment.ToString(), Defaults, values))
{
@ -127,40 +193,23 @@ namespace Microsoft.AspNet.Routing.Template
}
}
for (var i = requestSegments.Count; i < Template.Segments.Count; i++)
for (; i < Template.Segments.Count; i++)
{
// We've matched the request path so far, but still have remaining route segments. These need
// to be all single-part parameter segments with default values or else they won't match.
var routeSegment = Template.Segments[i];
if (routeSegment.Parts.Count > 1)
{
// If it has more than one part it must contain literals, so it can't match.
return null;
}
// We've matched the request path so far, but still have remaining route segments. We already know these
// are simple parameters that either have a default, or don't need to produce a value.
var routeSegment = Template.GetSegment(i);
Debug.Assert(routeSegment != null);
Debug.Assert(routeSegment.IsSimple);
var part = routeSegment.Parts[0];
if (part.IsLiteral)
{
return null;
}
Debug.Assert(part.IsParameter);
// It's ok for a catch-all to produce a null value
object defaultValue;
if (Defaults.TryGetValue(part.Name, out defaultValue) || part.IsCatchAll)
{
values.Add(part.Name, defaultValue);
}
else if (part.IsOptional)
{
// This is optional (with no default value) - there's nothing to capture here, so just move on.
}
else
{
// There's no default for this (non-catch-all) parameter so it can't match.
return null;
}
}
// Copy all remaining default values to the route data

7
src/Microsoft.AspNet.Routing/Template/TemplateSegment.cs
View File

@ -10,12 +10,9 @@ namespace Microsoft.AspNet.Routing.Template
[DebuggerDisplay("{DebuggerToString()}")]
public class TemplateSegment
{
private readonly List<TemplatePart> _parts = new List<TemplatePart>();
public bool IsSimple => Parts.Count == 1;
public List<TemplatePart> Parts
{
get { return _parts; }
}
public List<TemplatePart> Parts { get; } = new List<TemplatePart>();
internal string DebuggerToString()
{