重新整理 .net core 实践篇——— endpoint[四十七]
前言
简单整理一些endpoint的一些东西，主要是介绍一个这个endpoint是什么。
正文
endpoint 从表面意思是端点的意思，也就是说比如客户端的某一个action 是一个点，那么服务端的action也是一个点，这个端点的意义更加具体，而不是服务端和客户端这么泛指。
比如说客户端的action请求用户信心，那么服务端的action就是GetUserInfo，那么endpoint 在这里是什么意思呢？是GetUserInfo的抽象，或者是GetUserInfo的描述符。
那么netcore 对endpoint的描述是什么呢?
派生 Microsoft.AspNetCore.Routing.RouteEndpoint
RouteEndpoint 是:
那么来看一下:
app.UseRouting();
代码为:
public static IApplicationBuilder UseRouting(this IApplicationBuilder builder)
{
if (builder == null)
throw new ArgumentNullException(nameof (builder));
EndpointRoutingApplicationBuilderExtensions.VerifyRoutingServicesAreRegistered(builder);
DefaultEndpointRouteBuilder endpointRouteBuilder = new DefaultEndpointRouteBuilder(builder);
builder.Properties["__EndpointRouteBuilder"] = (object) endpointRouteBuilder;
return builder.UseMiddleware<EndpointRoutingMiddleware>((object) endpointRouteBuilder);
}
VerifyRoutingServicesAreRegistered 主要验证路由标记服务是否注入了:
private static void VerifyRoutingServicesAreRegistered(IApplicationBuilder app)
{
if (app.ApplicationServices.GetService(typeof (RoutingMarkerService)) == null)
throw new InvalidOperationException(Resources.FormatUnableToFindServices((object) "IServiceCollection", (object) "AddRouting", (object) "ConfigureServices(...)"));
}
然后可以查看一下DefaultEndpointRouteBuilder：
internal class DefaultEndpointRouteBuilder : IEndpointRouteBuilder
{
public DefaultEndpointRouteBuilder(IApplicationBuilder applicationBuilder)
{
IApplicationBuilder applicationBuilder1 = applicationBuilder;
if (applicationBuilder1 == null)
throw new ArgumentNullException(nameof (applicationBuilder));
this.ApplicationBuilder = applicationBuilder1;
this.DataSources = (ICollection<EndpointDataSource>) new List<EndpointDataSource>();
}
public IApplicationBuilder ApplicationBuilder { get; }
public IApplicationBuilder CreateApplicationBuilder()
{
return this.ApplicationBuilder.New();
}
public ICollection<EndpointDataSource> DataSources { get; }
public IServiceProvider ServiceProvider
{
get
{
return this.ApplicationBuilder.ApplicationServices;
}
}
}
我们知道builder 是用来构造某个东西的，从名字上来看是用来构造DefaultEndpointRoute。
建设者，一般分为两种，一种是内部就有构建方法，另一种是构建方法在材料之中或者操作机器之中。
这个怎么说呢？比如说一个构建者相当于一个工人，那么这个工人可能只带材料去完成一个小屋。也可能构建者本身没有带材料，那么可能材料之中包含了制作方法（比如方便面）或者机器中包含了制作方法比如榨汁机。
然后来看一下中间件EndpointRoutingMiddleware:
public EndpointRoutingMiddleware(
MatcherFactory matcherFactory,
ILogger<EndpointRoutingMiddleware> logger,
IEndpointRouteBuilder endpointRouteBuilder,
DiagnosticListener diagnosticListener,
RequestDelegate next)
{
if (endpointRouteBuilder == null)
throw new ArgumentNullException(nameof (endpointRouteBuilder));
MatcherFactory matcherFactory1 = matcherFactory;
if (matcherFactory1 == null)
throw new ArgumentNullException(nameof (matcherFactory));
this._matcherFactory = matcherFactory1;
ILogger<EndpointRoutingMiddleware> logger1 = logger;
if (logger1 == null)
throw new ArgumentNullException(nameof (logger));
this._logger = (ILogger) logger1;
DiagnosticListener diagnosticListener1 = diagnosticListener;
if (diagnosticListener1 == null)
throw new ArgumentNullException(nameof (diagnosticListener));
this._diagnosticListener = diagnosticListener1;
RequestDelegate requestDelegate = next;
if (requestDelegate == null)
throw new ArgumentNullException(nameof (next));
this._next = requestDelegate;
this._endpointDataSource = (EndpointDataSource) new CompositeEndpointDataSource((IEnumerable<EndpointDataSource>) endpointRouteBuilder.DataSources);
}
里面就做一些判断，是否服务注入了。然后值得关注的是几个新鲜事物了，比如MatcherFactory、DiagnosticListener、CompositeEndpointDataSource。
把这些都看一下吧。
internal abstract class MatcherFactory
{
public abstract Matcher CreateMatcher(EndpointDataSource dataSource);
}
CreateMatcher 通过某个端点资源，来创建一个Matcher。
这里猜测，是这样子的，一般来说客户端把某个路由都比作某个资源，也就是uri，这里抽象成EndpointDataSource，那么这个匹配器的作用是：
Attempts to asynchronously select an <see cref="Endpoint"/> for the current request.
也就是匹配出Endpoint。
那么再看一下DiagnosticListener,DiagnosticListener 源码就不看了，因为其实一个系统类，也就是system下面的类，比较复杂，直接看其描述就会。
DiagnosticListener 是一个 NotificationSource，这意味着返回的结果可用于记录通知，但它也有 Subscribe 方法，因此可以任意转发通知。 因此，其工作是将生成的作业从制造者转发到所有侦听器 (多转换) 。 通常情况下，不应 DiagnosticListener 使用，而是使用默认设置，以便通知尽可能公共。
是一个监听作用的，模式是订阅模式哈。https://docs.microsoft.com/zh-cn/dotnet/api/system.diagnostics.diagnosticlistener?view=net-6.0 有兴趣可以去看一下。
最后这个看一下CompositeEndpointDataSource，表面意思是综合性EndpointDataSource，继承自EndpointDataSource。
public CompositeEndpointDataSource(IEnumerable<EndpointDataSource> endpointDataSources) : this()
{
_dataSources = new List<EndpointDataSource>();
foreach (var dataSource in endpointDataSources)
{
_dataSources.Add(dataSource);
}
}
是用来管理endpointDataSources的，暂且不看其作用。
public Task Invoke(HttpContext httpContext)
{
Endpoint endpoint = httpContext.GetEndpoint();
if (endpoint != null)
{
EndpointRoutingMiddleware.Log.MatchSkipped(this._logger, endpoint);
return this._next(httpContext);
}
Task<Matcher> matcherTask = this.InitializeAsync();
if (!matcherTask.IsCompletedSuccessfully)
return AwaitMatcher(this, httpContext, matcherTask);
Task matchTask = matcherTask.Result.MatchAsync(httpContext);
return !matchTask.IsCompletedSuccessfully ? AwaitMatch(this, httpContext, matchTask) : this.SetRoutingAndContinue(httpContext);
async Task AwaitMatcher(
EndpointRoutingMiddleware middleware,
HttpContext httpContext,
Task<Matcher> matcherTask)
{
await (await matcherTask).MatchAsync(httpContext);
await middleware.SetRoutingAndContinue(httpContext);
}
async Task AwaitMatch(
EndpointRoutingMiddleware middleware,
HttpContext httpContext,
Task matchTask)
{
await matchTask;
await middleware.SetRoutingAndContinue(httpContext);
}
}
一段一段看:
Endpoint endpoint = httpContext.GetEndpoint();
if (endpoint != null)
{
EndpointRoutingMiddleware.Log.MatchSkipped(this._logger, endpoint);
return this._next(httpContext);
}
如果有endpoint，就直接运行下一个中间件。
Task<Matcher> matcherTask = this.InitializeAsync();
看InitializeAsync。
private Task<Matcher> InitializeAsync()
{
var initializationTask = _initializationTask;
if (initializationTask != null)
{
return initializationTask;
}
return InitializeCoreAsync();
}
接着看:InitializeCoreAsync
private Task<Matcher> InitializeCoreAsync()
{
var initialization = new TaskCompletionSource<Matcher>(TaskCreationOptions.RunContinuationsAsynchronously);
var initializationTask = Interlocked.CompareExchange(ref _initializationTask, initialization.Task, null);
if (initializationTask != null)
{
// This thread lost the race, join the existing task.
return initializationTask;
}
// This thread won the race, do the initialization.
try
{
var matcher = _matcherFactory.CreateMatcher(_endpointDataSource);
// Now replace the initialization task with one created with the default execution context.
// This is important because capturing the execution context will leak memory in ASP.NET Core.
using (ExecutionContext.SuppressFlow())
{
_initializationTask = Task.FromResult(matcher);
}
// Complete the task, this will unblock any requests that came in while initializing.
initialization.SetResult(matcher);
return initialization.Task;
}
catch (Exception ex)
{
// Allow initialization to occur again. Since DataSources can change, it's possible
// for the developer to correct the data causing the failure.
_initializationTask = null;
// Complete the task, this will throw for any requests that came in while initializing.
initialization.SetException(ex);
return initialization.Task;
}
}
这里面作用就是创建matcher,值得注意的是这一句代码：var matcher = _matcherFactory.CreateMatcher(_endpointDataSource);
创建匹配器的资源对象是_endpointDataSource。
this._endpointDataSource = (EndpointDataSource) new CompositeEndpointDataSource((IEnumerable<EndpointDataSource>) endpointRouteBuilder.DataSources);
这个_endpointDataSource 并不是值某一个endpointDataSource，而是全部的endpointDataSource，这一点前面就有介绍CompositeEndpointDataSource。
然后看最后一段：
if (!matcherTask.IsCompletedSuccessfully)
return AwaitMatcher(this, httpContext, matcherTask);
Task matchTask = matcherTask.Result.MatchAsync(httpContext);
return !matchTask.IsCompletedSuccessfully ? AwaitMatch(this, httpContext, matchTask) : this.SetRoutingAndContinue(httpContext);
async Task AwaitMatcher(
EndpointRoutingMiddleware middleware,
HttpContext httpContext,
Task<Matcher> matcherTask)
{
await (await matcherTask).MatchAsync(httpContext);
await middleware.SetRoutingAndContinue(httpContext);
}
async Task AwaitMatch(
EndpointRoutingMiddleware middleware,
HttpContext httpContext,
Task matchTask)
{
await matchTask;
await middleware.SetRoutingAndContinue(httpContext);
}
这里面其实就表达一个意思哈，如果task完成了，然后就直接运行下一步，如果没有完成就await,总之是要执行MatchAsync然后再执行SetRoutingAndContinue。
internal abstract class Matcher
{
/// <summary>
/// Attempts to asynchronously select an <see cref="Endpoint"/> for the current request.
/// </summary>
/// <param name="httpContext">The <see cref="HttpContext"/> associated with the current request.</param>
/// <returns>A <see cref="Task"/> which represents the asynchronous completion of the operation.</returns>
public abstract Task MatchAsync(HttpContext httpContext);
}
MatchAsync 前面也提到过就是匹配出Endpoint的。
然后SetRoutingAndContinue:
[MethodImpl(MethodImplOptions.AggressiveInlining)]
private Task SetRoutingAndContinue(HttpContext httpContext)
{
// If there was no mutation of the endpoint then log failure
var endpoint = httpContext.GetEndpoint();
if (endpoint == null)
{
Log.MatchFailure(_logger);
}
else
{
// Raise an event if the route matched
if (_diagnosticListener.IsEnabled() && _diagnosticListener.IsEnabled(DiagnosticsEndpointMatchedKey))
{
// We're just going to send the HttpContext since it has all of the relevant information
_diagnosticListener.Write(DiagnosticsEndpointMatchedKey, httpContext);
}
Log.MatchSuccess(_logger, endpoint);
}
return _next(httpContext);
}
这里没有匹配到也没有终结哈，为什么这么做呢？因为匹配不到，下一个中间件可以做到如果没有endpoint，那么就指明做什么事情，不要一下子写死。
如何如果匹配成功了，那么发送一个事件，这个事件是DiagnosticsEndpointMatchedKey,然后打印匹配成功的一些log了。
private const string DiagnosticsEndpointMatchedKey = "Microsoft.AspNetCore.Routing.EndpointMatched";
那么这里我们可以监听做一些事情,看项目需求了。
其实看到这里有两点疑问了Matcher的具体实现和EndpointDataSource 是怎么来的。
先看一下Matcher吧，这个肯定要在路由服务中去查看了。
public static IServiceCollection AddRouting(
this IServiceCollection services,
Action<RouteOptions> configureOptions)
{
if (services == null)
{
throw new ArgumentNullException(nameof(services));
}
if (configureOptions == null)
{
throw new ArgumentNullException(nameof(configureOptions));
}
services.Configure(configureOptions);
services.AddRouting();
return services;
}
然后在AddRouting 中查看,这里面非常多，这里我直接放出这个的依赖注入:
services.TryAddSingleton<MatcherFactory, DfaMatcherFactory>();
那么这里进入看DfaMatcherFactory。
public override Matcher CreateMatcher(EndpointDataSource dataSource)
{
if (dataSource == null)
{
throw new ArgumentNullException(nameof(dataSource));
}
// Creates a tracking entry in DI to stop listening for change events
// when the services are disposed.
var lifetime = _services.GetRequiredService<DataSourceDependentMatcher.Lifetime>();
return new DataSourceDependentMatcher(dataSource, lifetime, () =>
{
return _services.GetRequiredService<DfaMatcherBuilder>();
});
}
查看DataSourceDependentMatcher.Lifetime:
public sealed class Lifetime : IDisposable
{
private readonly object _lock = new object();
private DataSourceDependentCache<Matcher>? _cache;
private bool _disposed;
public DataSourceDependentCache<Matcher>? Cache
{
get => _cache;
set
{
lock (_lock)
{
if (_disposed)
{
value?.Dispose();
}
_cache = value;
}
}
}
public void Dispose()
{
lock (_lock)
{
_cache?.Dispose();
_cache = null;
_disposed = true;
}
}
}
Lifetime 是生命周期的意思，里面实现的比较简单，单纯从功能上看似乎只是缓存，但是其之所以取这个名字是因为Dispose，在Lifetime结束的时候带走了DataSourceDependentCache
为了让大家更清晰一写，DataSourceDependentCache,将其标红。
然后CreateMatcher 创建了DataSourceDependentMatcher。
return new DataSourceDependentMatcher(dataSource, lifetime, () =>
{
return _services.GetRequiredService<DfaMatcherBuilder>();
});
看一下DataSourceDependentMatcher：
public DataSourceDependentMatcher(
EndpointDataSource dataSource,
Lifetime lifetime,
Func<MatcherBuilder> matcherBuilderFactory)
{
_matcherBuilderFactory = matcherBuilderFactory;
_cache = new DataSourceDependentCache<Matcher>(dataSource, CreateMatcher);
_cache.EnsureInitialized();
// This will Dispose the cache when the lifetime is disposed, this allows
// the service provider to manage the lifetime of the cache.
lifetime.Cache = _cache;
}
这里创建了一个DataSourceDependentCache。
public DataSourceDependentCache(EndpointDataSource dataSource, Func<IReadOnlyList<Endpoint>, T> initialize)
{
if (dataSource == null)
{
throw new ArgumentNullException(nameof(dataSource));
}
if (initialize == null)
{
throw new ArgumentNullException(nameof(initialize));
}
_dataSource = dataSource;
_initializeCore = initialize;
_initializer = Initialize;
_initializerWithState = (state) => Initialize();
_lock = new object();
}
// Note that we don't lock here, and think about that in the context of a 'push'. So when data gets 'pushed'
// we start computing a new state, but we're still able to perform operations on the old state until we've
// processed the update.
public T Value => _value;
public T EnsureInitialized()
{
return LazyInitializer.EnsureInitialized<T>(ref _value, ref _initialized, ref _lock, _initializer);
}
private T Initialize()
{
lock (_lock)
{
var changeToken = _dataSource.GetChangeToken();
_value = _initializeCore(_dataSource.Endpoints);
// Don't resubscribe if we're already disposed.
if (_disposed)
{
return _value;
}
_disposable = changeToken.RegisterChangeCallback(_initializerWithState, null);
return _value;
}
}
这里Initialize可以看到调用了_initializeCore，这个_initializeCore就是传递进来的DataSourceDependentMatcher的CreateMatcher，如下：
private Matcher CreateMatcher(IReadOnlyList<Endpoint> endpoints)
{
var builder = _matcherBuilderFactory();
for (var i = 0; i < endpoints.Count; i++)
{
// By design we only look at RouteEndpoint here. It's possible to
// register other endpoint types, which are non-routable, and it's
// ok that we won't route to them.
if (endpoints[i] is RouteEndpoint endpoint && endpoint.Metadata.GetMetadata<ISuppressMatchingMetadata>()?.SuppressMatching != true)
{
builder.AddEndpoint(endpoint);
}
}
return builder.Build();
}
这里可以看到这里endpoint 必须没有带ISuppressMatchingMetadata，否则将不会被匹配。
这个_matcherBuilderFactory 是：
也就是:
看一下builder:
public override Matcher Build()
{
#if DEBUG
var includeLabel = true;
#else
var includeLabel = false;
#endif
var root = BuildDfaTree(includeLabel);
// State count is the number of nodes plus an exit state
var stateCount = 1;
var maxSegmentCount = 0;
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 +1 to capture any additional content after the 'last' segment.
maxSegmentCount++;
var states = new DfaState[stateCount];
var exitDestination = stateCount - 1;
AddNode(root, states, exitDestination);
// The root state only has a jump table.
states[exitDestination] = new DfaState(
Array.Empty<Candidate>(),
Array.Empty<IEndpointSelectorPolicy>(),
JumpTableBuilder.Build(exitDestination, exitDestination, null),
null);
return new DfaMatcher(_loggerFactory.CreateLogger<DfaMatcher>(), _selector, states, maxSegmentCount);
}
BuildDfaTree 这个是一个算法哈，这里就不介绍哈，是dfa 算法，这里理解为将endpoint创建为一颗数，有利于匹配就好。
最后返回了一个return new DfaMatcher(_loggerFactory.CreateLogger
DfaMatcher 就是endpoint匹配器。
那么进去看DfaMatcher 匹配方法MatchAsync。
public sealed override Task MatchAsync(HttpContext httpContext)
{
if (httpContext == null)
{
throw new ArgumentNullException(nameof(httpContext));
}
// All of the logging we do here is at level debug, so we can get away with doing a single check.
var log = _logger.IsEnabled(LogLevel.Debug);
// The sequence of actions we take is optimized to avoid doing expensive work
// like creating substrings, creating route value dictionaries, and calling
// into policies like versioning.
var path = httpContext.Request.Path.Value!;
// First tokenize the path into series of segments.
Span<PathSegment> buffer = stackalloc PathSegment[_maxSegmentCount];
var count = FastPathTokenizer.Tokenize(path, buffer);
var segments = buffer.Slice(0, count);
// FindCandidateSet will process the DFA and return a candidate set. This does
// some preliminary matching of the URL (mostly the literal segments).
var (candidates, policies) = FindCandidateSet(httpContext, path, segments);
var candidateCount = candidates.Length;
if (candidateCount == 0)
{
if (log)
{
Logger.CandidatesNotFound(_logger, path);
}
return Task.CompletedTask;
}
if (log)
{
Logger.CandidatesFound(_logger, path, candidates);
}
var policyCount = policies.Length;
// This is a fast path for single candidate, 0 policies and default selector
if (candidateCount == 1 && policyCount == 0 && _isDefaultEndpointSelector)
{
ref readonly var candidate = ref candidates[0];
// Just strict path matching (no route values)
if (candidate.Flags == Candidate.CandidateFlags.None)
{
httpContext.SetEndpoint(candidate.Endpoint);
// We're done
return Task.CompletedTask;
}
}
// At this point we have a candidate set, defined as a list of endpoints in
// priority order.
//
// We don't yet know that any candidate can be considered a match, because
// we haven't processed things like route constraints and complex segments.
//
// Now we'll iterate each endpoint to capture route values, process constraints,
// and process complex segments.
// `candidates` has all of our internal state that we use to process the
// set of endpoints before we call the EndpointSelector.
//
// `candidateSet` is the mutable state that we pass to the EndpointSelector.
var candidateState = new CandidateState[candidateCount];
for (var i = 0; i < candidateCount; i++)
{
// PERF: using ref here to avoid copying around big structs.
//
// Reminder!
// candidate: readonly data about the endpoint and how to match
// state: mutable storarge for our processing
ref readonly var candidate = ref candidates[i];
ref var state = ref candidateState[i];
state = new CandidateState(candidate.Endpoint, candidate.Score);
var flags = candidate.Flags;
// First process all of the parameters and defaults.
if ((flags & Candidate.CandidateFlags.HasSlots) != 0)
{
// The Slots array has the default values of the route values in it.
//
// We want to create a new array for the route values based on Slots
// as a prototype.
var prototype = candidate.Slots;
var slots = new KeyValuePair<string, object?>[prototype.Length];
if ((flags & Candidate.CandidateFlags.HasDefaults) != 0)
{
Array.Copy(prototype, 0, slots, 0, prototype.Length);
}
if ((flags & Candidate.CandidateFlags.HasCaptures) != 0)
{
ProcessCaptures(slots, candidate.Captures, path, segments);
}
if ((flags & Candidate.CandidateFlags.HasCatchAll) != 0)
{
ProcessCatchAll(slots, candidate.CatchAll, path, segments);
}
state.Values = RouteValueDictionary.FromArray(slots);
}
// Now that we have the route values, we need to process complex segments.
// Complex segments go through an old API that requires a fully-materialized
// route value dictionary.
var isMatch = true;
if ((flags & Candidate.CandidateFlags.HasComplexSegments) != 0)
{
state.Values ??= new RouteValueDictionary();
if (!ProcessComplexSegments(candidate.Endpoint, candidate.ComplexSegments, path, segments, state.Values))
{
CandidateSet.SetValidity(ref state, false);
isMatch = false;
}
}
if ((flags & Candidate.CandidateFlags.HasConstraints) != 0)
{
state.Values ??= new RouteValueDictionary();
if (!ProcessConstraints(candidate.Endpoint, candidate.Constraints, httpContext, state.Values))
{
CandidateSet.SetValidity(ref state, false);
isMatch = false;
}
}
if (log)
{
if (isMatch)
{
Logger.CandidateValid(_logger, path, candidate.Endpoint);
}
else
{
Logger.CandidateNotValid(_logger, path, candidate.Endpoint);
}
}
}
if (policyCount == 0 && _isDefaultEndpointSelector)
{
// Fast path that avoids allocating the candidate set.
//
// We can use this when there are no policies and we're using the default selector.
DefaultEndpointSelector.Select(httpContext, candidateState);
return Task.CompletedTask;
}
else if (policyCount == 0)
{
// Fast path that avoids a state machine.
//
// We can use this when there are no policies and a non-default selector.
return _selector.SelectAsync(httpContext, new CandidateSet(candidateState));
}
return SelectEndpointWithPoliciesAsync(httpContext, policies, new CandidateSet(candidateState));
}
这一段代码我看了一下，就是通过一些列的判断，来设置httpcontext 的 Endpoint,这个有兴趣可以看一下.
这里提一下上面这个_selector：
services.TryAddSingleton<EndpointSelector, DefaultEndpointSelector>();
看一下DefaultEndpointSelector：
internal static void Select(HttpContext httpContext, CandidateState[] candidateState)
{
// Fast path: We can specialize for trivial numbers of candidates since there can
// be no ambiguities
switch (candidateState.Length)
{
case 0:
{
// Do nothing
break;
}
case 1:
{
ref var state = ref candidateState[0];
if (CandidateSet.IsValidCandidate(ref state))
{
httpContext.SetEndpoint(state.Endpoint);
httpContext.Request.RouteValues = state.Values!;
}
break;
}
default:
{
// Slow path: There's more than one candidate (to say nothing of validity) so we
// have to process for ambiguities.
ProcessFinalCandidates(httpContext, candidateState);
break;
}
}
}
private static void ProcessFinalCandidates(
HttpContext httpContext,
CandidateState[] candidateState)
{
Endpoint? endpoint = null;
RouteValueDictionary? values = null;
int? foundScore = null;
for (var i = 0; i < candidateState.Length; i++)
{
ref var state = ref candidateState[i];
if (!CandidateSet.IsValidCandidate(ref state))
{
continue;
}
if (foundScore == null)
{
// This is the first match we've seen - speculatively assign it.
endpoint = state.Endpoint;
values = state.Values;
foundScore = state.Score;
}
else if (foundScore < state.Score)
{
// This candidate is lower priority than the one we've seen
// so far, we can stop.
//
// Don't worry about the 'null < state.Score' case, it returns false.
break;
}
else if (foundScore == state.Score)
{
// This is the second match we've found of the same score, so there
// must be an ambiguity.
//
// Don't worry about the 'null == state.Score' case, it returns false.
ReportAmbiguity(candidateState);
// Unreachable, ReportAmbiguity always throws.
throw new NotSupportedException();
}
}
if (endpoint != null)
{
httpContext.SetEndpoint(endpoint);
httpContext.Request.RouteValues = values!;
}
}
这里可以看一下Select。
如果候选项是0，那么跳过这个就没什么好说的。
如果候选项是1，那么就设置这个的endpoint。
如果匹配到多个,如果两个相同得分相同的，就会抛出异常，否则就是最后一个，也就是说我们不能设置完全相同的路由。
然后对于匹配策略而言呢，是:
感兴趣可以看一下。
HttpMethodMatcherPolicy 这个是匹配405的。
HostMatcherPolicy 这个是用来匹配host的,如果不符合匹配到的endpoint，会设置验证不通过。
结
下一节把app.UseEndpoints 介绍一下。
