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Avoid resizing large struct arrays (#767)

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James Newton-King 2018-09-06 13:10:17 +12:00 committed by GitHub
parent 0f5d471dfd
commit abc378d3dc
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1 changed files with 35 additions and 18 deletions
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53
src/Microsoft.AspNetCore.Routing/Matching/DfaMatcherBuilder.cs
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@ -26,6 +26,8 @@ namespace Microsoft.AspNetCore.Routing.Matching
private readonly List<(RoutePatternPathSegment pathSegment, int segmentIndex)> _complexSegments; private readonly List<(RoutePatternPathSegment pathSegment, int segmentIndex)> _complexSegments;
private readonly List<KeyValuePair<string, IRouteConstraint>> _constraints; private readonly List<KeyValuePair<string, IRouteConstraint>> _constraints;
private int _stateIndex;
public DfaMatcherBuilder( public DfaMatcherBuilder(
ParameterPolicyFactory parameterPolicyFactory, ParameterPolicyFactory parameterPolicyFactory,
EndpointSelector selector, EndpointSelector selector,
@ -273,22 +275,29 @@ namespace Microsoft.AspNetCore.Routing.Matching
{ {
var root = BuildDfaTree(); var root = BuildDfaTree();
// State count is the number of nodes plus an exit state
var stateCount = 1;
var maxSegmentCount = 0; var maxSegmentCount = 0;
root.Visit((node) => maxSegmentCount = Math.Max(maxSegmentCount, node.PathDepth)); root.Visit((node) =>
{
stateCount++;
maxSegmentCount = Math.Max(maxSegmentCount, node.PathDepth);
});
_stateIndex = 0;
// The max segment count is the maximum path-node-depth +1. We need // The max segment count is the maximum path-node-depth +1. We need
// the +1 to capture any additional content after the 'last' segment. // the +1 to capture any additional content after the 'last' segment.
maxSegmentCount++; maxSegmentCount++;
var states = new List<DfaState>(); var states = new DfaState[stateCount];
var tableBuilders = new List<(JumpTableBuilder pathBuilder, PolicyJumpTableBuilder policyBuilder)>(); var tableBuilders = new (JumpTableBuilder pathBuilder, PolicyJumpTableBuilder policyBuilder)[stateCount];
AddNode(root, states, tableBuilders); AddNode(root, states, tableBuilders);
var exit = states.Count; var exit = stateCount - 1;
states.Add(new DfaState(Array.Empty<Candidate>(), null, null)); states[exit] = new DfaState(Array.Empty<Candidate>(), null, null);
tableBuilders.Add((new JumpTableBuilder() { DefaultDestination = exit, ExitDestination = exit, }, null)); tableBuilders[exit] = (new JumpTableBuilder() { DefaultDestination = exit, ExitDestination = exit, }, null);
for (var i = 0; i < tableBuilders.Count; i++) for (var i = 0; i < tableBuilders.Length; i++)
{ {
if (tableBuilders[i].pathBuilder?.DefaultDestination == JumpTableBuilder.InvalidDestination) if (tableBuilders[i].pathBuilder?.DefaultDestination == JumpTableBuilder.InvalidDestination)
{ {
@ -306,31 +315,31 @@ namespace Microsoft.AspNetCore.Routing.Matching
} }
} }
for (var i = 0; i < states.Count; i++) for (var i = 0; i < states.Length; i++)
{ {
states[i] = new DfaState( states[i] = new DfaState(
states[i].Candidates, states[i].Candidates,
tableBuilders[i].pathBuilder?.Build(), tableBuilders[i].pathBuilder?.Build(),
tableBuilders[i].policyBuilder?.Build()); tableBuilders[i].policyBuilder?.Build());
} }
return new DfaMatcher(_selector, states.ToArray(), maxSegmentCount); return new DfaMatcher(_selector, states, maxSegmentCount);
} }
private int AddNode( private int AddNode(
DfaNode node, DfaNode node,
List<DfaState> states, DfaState[] states,
List<(JumpTableBuilder pathBuilder, PolicyJumpTableBuilder policyBuilder)> tableBuilders) (JumpTableBuilder pathBuilder, PolicyJumpTableBuilder policyBuilder)[] tableBuilders)
{ {
node.Matches?.Sort(_comparer); node.Matches?.Sort(_comparer);
var stateIndex = states.Count; var currentStateIndex = _stateIndex;
var candidates = CreateCandidates(node.Matches); var candidates = CreateCandidates(node.Matches);
states.Add(new DfaState(candidates, null, null)); states[currentStateIndex] = new DfaState(candidates, null, null);
var pathBuilder = new JumpTableBuilder(); var pathBuilder = new JumpTableBuilder();
tableBuilders.Add((pathBuilder, null)); tableBuilders[currentStateIndex] = (pathBuilder, null);
if (node.Literals != null) if (node.Literals != null)
{ {
@ -377,7 +386,7 @@ namespace Microsoft.AspNetCore.Routing.Matching
if (node.PolicyEdges != null && node.PolicyEdges.Count > 0) if (node.PolicyEdges != null && node.PolicyEdges.Count > 0)
{ {
var policyBuilder = new PolicyJumpTableBuilder(node.NodeBuilder); var policyBuilder = new PolicyJumpTableBuilder(node.NodeBuilder);
tableBuilders[stateIndex] = (pathBuilder, policyBuilder); tableBuilders[currentStateIndex] = (pathBuilder, policyBuilder);
foreach (var kvp in node.PolicyEdges) foreach (var kvp in node.PolicyEdges)
{ {
@ -385,12 +394,20 @@ namespace Microsoft.AspNetCore.Routing.Matching
} }
} }
return stateIndex; return currentStateIndex;
int Transition(DfaNode next) int Transition(DfaNode next)
{ {
// Break cycles // Break cycles
return ReferenceEquals(node, next) ? stateIndex : AddNode(next, states, tableBuilders); if (ReferenceEquals(node, next))
{
return _stateIndex;
}
else
{
_stateIndex++;
return AddNode(next, states, tableBuilders);
}
} }
} }