ouczbs/FastGithub
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缓存枷锁

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陈国伟 2021-09-26 17:28:34 +08:00
parent 9516a22c26
commit a0cb04cec3
1 changed files with 17 additions and 9 deletions
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26
FastGithub.DomainResolve/DnsClient.cs
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@ -6,6 +6,7 @@ using Microsoft.Extensions.Caching.Memory;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using System;
using System.Collections.Concurrent;
using System.Linq;
using System.Net;
using System.Threading;
@ -20,9 +21,10 @@ namespace FastGithub.DomainResolve
{
private readonly ILogger<DnsClient> logger;
private readonly int resolveTimeout = (int)TimeSpan.FromSeconds(2d).TotalMilliseconds;
private readonly ConcurrentDictionary<string, SemaphoreSlim> semaphoreSlims = new();
private readonly IMemoryCache dnsCache = new MemoryCache(Options.Create(new MemoryCacheOptions()));
private readonly TimeSpan dnsExpiration = TimeSpan.FromMinutes(2d);
private readonly int resolveTimeout = (int)TimeSpan.FromSeconds(2d).TotalMilliseconds;
/// <summary>
/// DNS客户端
@ -43,18 +45,20 @@ namespace FastGithub.DomainResolve
public async Task<IPAddress[]> LookupAsync(IPEndPoint dns, string domain, CancellationToken cancellationToken = default)
{
var key = $"{dns}:{domain}";
if (this.dnsCache.TryGetValue<IPAddress[]>(key, out var value))
{
return value;
}
var semaphore = this.semaphoreSlims.GetOrAdd(key, _ => new SemaphoreSlim(1, 1));
try
{
value = await this.LookupCoreAsync(dns, domain, cancellationToken);
this.dnsCache.Set(key, value, this.dnsExpiration);
await semaphore.WaitAsync(CancellationToken.None);
var items = string.Join(", ", value.Select(item => item.ToString()));
this.logger.LogInformation($"{dns}：{domain}->[{items}]");
if (this.dnsCache.TryGetValue<IPAddress[]>(key, out var value) == false)
{
value = await this.LookupCoreAsync(dns, domain, cancellationToken);
this.dnsCache.Set(key, value, this.dnsExpiration);
var items = string.Join(", ", value.Select(item => item.ToString()));
this.logger.LogInformation($"{dns}：{domain}->[{items}]");
}
return value;
}
catch (Exception ex)
@ -62,6 +66,10 @@ namespace FastGithub.DomainResolve
this.logger.LogWarning($"{dns}无法解析{domain}：{ex.Message}");
return Array.Empty<IPAddress>();
}
finally
{
semaphore.Release();
}
}
/// <summary>