huahaofeng
/
aspnetcore
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Optimize manipulation of RouteData.Routers 

This change avoid calling List.Clear() and new List(IEnumerable<T>) which
both end up calling into native methods via the Array static class. These
methods are designed to be performant for large collections, and for our
needs this collection has at most 1-4 items. This is worth 2-3% in
techempower plaintext.
This commit is contained in:
Ryan Nowak 2016-05-11 08:33:21 -07:00
parent 74a246d34c
commit 86a41bc618
1 changed files with 45 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

51
src/Microsoft.AspNetCore.Routing.Abstractions/RouteData.cs
View File

@ -12,7 +12,7 @@ namespace Microsoft.AspNetCore.Routing
public class RouteData
{
private RouteValueDictionary _dataTokens;
private IList<IRouter> _routers;
private List<IRouter> _routers;
private RouteValueDictionary _values;
/// <summary>
@ -126,10 +126,23 @@ namespace Microsoft.AspNetCore.Routing
/// <returns>A <see cref="RouteDataSnapshot"/> that captures the current state.</returns>
public RouteDataSnapshot PushState(IRouter router, RouteValueDictionary values, RouteValueDictionary dataTokens)
{
// Perf: this is optimized for small list sizes, in particular to avoid overhead of a native call in
// Array.CopyTo inside the List(IEnumerable<T>) constructor.
List<IRouter> routers = null;
var count = _routers?.Count;
if (count > 0)
{
routers = new List<IRouter>(count.Value);
for (var i = 0; i < count.Value; i++)
{
routers.Add(_routers[i]);
}
}
var snapshot = new RouteDataSnapshot(
this,
_dataTokens?.Count > 0 ? new RouteValueDictionary(_dataTokens) : null,
_routers?.Count > 0 ? new List<IRouter>(_routers) : null,
routers,
_values?.Count > 0 ? new RouteValueDictionary(_values) : null);
if (router != null)
@ -222,15 +235,41 @@ namespace Microsoft.AspNetCore.Routing
}
else if (_routers == null)
{
_routeData._routers.Clear();
// Perf: this is optimized for small list sizes, in particular to avoid overhead of a native call in
// Array.Clear inside the List.Clear() method.
var routers = _routeData._routers;
for (var i = routers.Count - 1; i >= 0 ; i--)
{
routers.RemoveAt(i);
}
}
else
{
_routeData._routers.Clear();
// Perf: this is optimized for small list sizes, in particular to avoid overhead of a native call in
// Array.Clear inside the List.Clear() method.
//
// We want to basically copy the contents of _routers in _routeData._routers - this change does
// that with the minimal number of reads/writes and without calling Clear().
var routers = _routeData._routers;
var snapshotRouters = _routers;
for (var i = 0; i < _routers.Count; i++)
// This is made more complicated by the fact that List[int] throws if i == Count, so we have
// to do two loops and call Add for those cases.
var i = 0;
for (; i < snapshotRouters.Count && i < routers.Count; i++)
{
_routeData._routers.Add(_routers[i]);
routers[i] = snapshotRouters[i];
}
for (; i < snapshotRouters.Count; i++)
{
routers.Add(snapshotRouters[i]);
}
// Trim excess - again avoiding RemoveRange because it uses native methods.
for (i = routers.Count - 1; i >= snapshotRouters.Count; i--)
{
routers.RemoveAt(i);
}
}