爱站程序员基地【今日推荐】：为什么一到面试就懵逼！>>>
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前言
上一篇文章介绍IOptions的注册,本章我们继续往下看
IOptions
IOptions是一个接口里面只有一个Values属性，该接口通过OptionsManager实现
public interface IOptions<out TOptions> where TOptions : class, new(){/// <summary>/// The default configured <typeparamref name=\"TOptions\"/> instance/// </summary>TOptions Value { get; }}
OptionsManager
OptionsManager实现了IOptions<>和IOptionsSnapshot<>，他使用内部属性OptionsCache 进行缓存操作；实现IOptionsSnapshot接口Get(string name)其实就是获取我们第一章所指定的Name，通过IOptionsFactory<>创建TOptions实例
public class OptionsManager<TOptions> : IOptions<TOptions>, IOptionsSnapshot<TOptions> where TOptions : class, new(){private readonly IOptionsFactory<TOptions> _factory;private readonly OptionsCache<TOptions> _cache = new OptionsCache<TOptions>(); // Note: this is a private cache/// <summary>/// Initializes a new instance with the specified options configurations./// </summary>/// <param name=\"factory\">The factory to use to create options.</param>public OptionsManager(IOptionsFactory<TOptions> factory){_factory = factory;}/// <summary>/// The default configured <typeparamref name=\"TOptions\"/> instance, equivalent to Get(Options.DefaultName)./// </summary>public TOptions Value{get{return Get(Options.DefaultName);}}/// <summary>/// Returns a configured <typeparamref name=\"TOptions\"/> instance with the given <paramref name=\"name\"/>./// </summary>public virtual TOptions Get(string name){name = name ?? Options.DefaultName;// Store the options in our instance cachereturn _cache.GetOrAdd(name, () => _factory.Create(name));}}public interface IOptionsSnapshot<out TOptions> : IOptions<TOptions> where TOptions : class, new(){/// <summary>/// Returns a configured <typeparamref name=\"TOptions\"/> instance with the given name./// </summary>TOptions Get(string name);}
OptionsCache
OptionsCache采用了线程安全字典ConcurrentDictionary进行了封装用于内存缓存
public class OptionsCache<TOptions> : IOptionsMonitorCache<TOptions> where TOptions : class{private readonly ConcurrentDictionary<string, Lazy<TOptions>> _cache = new ConcurrentDictionary<string, Lazy<TOptions>>(StringComparer.Ordinal);/// <summary>/// Clears all options instances from the cache./// </summary>public void Clear() => _cache.Clear();/// <summary>/// Gets a named options instance, or adds a new instance created with <paramref name=\"createOptions\"/>./// </summary>/// <param name=\"name\">The name of the options instance.</param>/// <param name=\"createOptions\">The func used to create the new instance.</param>/// <returns>The options instance.</returns>public virtual TOptions GetOrAdd(string name, Func<TOptions> createOptions){if (createOptions == null){throw new ArgumentNullException(nameof(createOptions));}name = name ?? Options.DefaultName;return _cache.GetOrAdd(name, new Lazy<TOptions>(createOptions)).Value;}/// <summary>/// Tries to adds a new option to the cache, will return false if the name already exists./// </summary>/// <param name=\"name\">The name of the options instance.</param>/// <param name=\"options\">The options instance.</param>/// <returns>Whether anything was added.</returns>public virtual bool TryAdd(string name, TOptions options){if (options == null){throw new ArgumentNullException(nameof(options));}name = name ?? Options.DefaultName;return _cache.TryAdd(name, new Lazy<TOptions>(() => options));}/// <summary>/// Try to remove an options instance./// </summary>/// <param name=\"name\">The name of the options instance.</param>/// <returns>Whether anything was removed.</returns>public virtual bool TryRemove(string name){name = name ?? Options.DefaultName;return _cache.TryRemove(name, out var ignored);}}
OptionsFactory
OptionsFactory实现了 IOptionsFactory.Create(string name);,
而OptionsFactory构造函数中注入了IConfigureOptions<>和IPostConfigureOptions<>，
这里使用了IEnumerable类型标识当注册多个时候按照次数依次的执行，从如下代码中我们也看到了我们在上一章中所说的Configures和postConfigures注册先后顺序问题。
public class OptionsFactory<TOptions> : IOptionsFactory<TOptions> where TOptions : class, new(){private readonly IEnumerable<IConfigureOptions<TOptions>> _setups;private readonly IEnumerable<IPostConfigureOptions<TOptions>> _postConfigures;private readonly IEnumerable<IValidateOptions<TOptions>> _validations;public OptionsFactory(IEnumerable<IConfigureOptions<TOptions>> setups, IEnumerable<IPostConfigureOptions<TOptions>> postConfigures) : this(setups, postConfigures, validations: null){ }public OptionsFactory(IEnumerable<IConfigureOptions<TOptions>> setups, IEnumerable<IPostConfigureOptions<TOptions>> postConfigures, IEnumerable<IValidateOptions<TOptions>> validations){_setups = setups;_postConfigures = postConfigures;_validations = validations;}public TOptions Create(string name){var options = new TOptions();foreach (var setup in _setups){if (setup is IConfigureNamedOptions<TOptions> namedSetup){namedSetup.Configure(name, options);}else if (name == Options.DefaultName){setup.Configure(options);}}foreach (var post in _postConfigures){post.PostConfigure(name, options);}if (_validations != null){var failures = new List<string>();foreach (var validate in _validations){var result = validate.Validate(name, options);if (result.Failed){failures.AddRange(result.Failures);}}if (failures.Count > 0){throw new OptionsValidationException(name, typeof(TOptions), failures);}}return options;}}
