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feat: HTTP 缓存 #2682

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b9482a6
feat(cahce): 缓存系统
LinQingYuu Apr 6, 2026
7af8c97
fix: 缓存更新可能不生效
LinQingYuu Apr 6, 2026
eb57eb6
fix: 未关联对象、每次查询创建新连接、修复结构
LinQingYuu Apr 6, 2026
3fcdb41
fix: 未添加 Hash,修正链表结构
LinQingYuu Apr 6, 2026
1ea1345
fix: 读取可能死锁、将 SqliteConnection 的生命周期绑定到 SqliteCommand
LinQingYuu Apr 6, 2026
63a6fa0
fix: Memory Leak
LinQingYuu Apr 6, 2026
4f3c32c
chore: remove sync support
LinQingYuu Apr 12, 2026
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57 changes: 57 additions & 0 deletions PCL.Core/IO/Net/Http/Cache/HttpCacheHandler.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,57 @@
using System;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading;
using System.Threading.Tasks;
using PCL.Core.IO.Net.Http.Cache.Models;

namespace PCL.Core.IO.Net.Http.Cache;

/// <summary>
/// HTTP 缓存处理器
/// </summary>
public class HttpCacheHandler:DelegatingHandler
{
private HttpCacheRepository _repository;
public HttpCacheHandler(HttpMessageHandler invoker, HttpCacheRepository repo)
{
InnerHandler = invoker;
_repository = repo;
}

protected override HttpResponseMessage Send(HttpRequestMessage request, CancellationToken cancellationToken)
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{
return SendAsync(request, cancellationToken).GetAwaiter().GetResult();
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}

protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
if(!_repository.TryGetCacheData(request.RequestUri!.ToString(),out var details))
return await base.SendAsync(request, cancellationToken);
if (details.ExpiredAt is not null &&
details.LastUpdate.AddSeconds((double)details.ExpiredAt) < DateTimeOffset.Now
&& _repository.TryGetCacheResponse(request,out var cacheResponse) && !details.EnsureValidate
)
return cacheResponse;

if(details.Tag is not null) request.Headers.IfNoneMatch.Add(new EntityTagHeaderValue(details.Tag));
if(details.LastModify is not null) request.Headers.IfModifiedSince = DateTimeOffset.Parse(details.LastModify);
var response = await base.SendAsync(request, cancellationToken);
if (response.Headers.CacheControl?.NoStore ?? false) return response;
if(response.StatusCode == HttpStatusCode.NotModified && _repository.TryGetCacheResponse(request,out cacheResponse))
return cacheResponse;
var handle = await _repository.TryBeginUpdateAsync(request.RequestUri.ToString());
var newDetails = handle?.Details;
newDetails?.RequestUri = request.RequestUri.ToString();
newDetails?.LastUpdate = DateTimeOffset.Now;
newDetails?.EnsureValidate = response.Headers.CacheControl?.NoCache ?? false;
Comment on lines +35 to +44
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@sourcery-ai sourcery-ai Bot Apr 6, 2026

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suggestion (bug_risk): Last-Modified 处理使用的是 Date 头而不是 Last-Modified，并且可能解析/存储无效的值。

LastModify 通过 If-Modified-Since 头发送，但在更新时你使用的是 response.Headers.Date 并直接调用 ToString()。这会忽略 Last-Modified 头部、可能为 null，并产生后续可能无法稳定解析的字符串。建议优先使用 response.Content.Headers.LastModified（或根据需求使用 response.Headers.LastModified），并将其存为 DateTimeOffset 或标准化字符串（例如 ToString("o")），在下次构建请求时使用不变区域性进行解析。

建议实现如下：

        if(details.Tag is not null) request.Headers.IfNoneMatch.Add(new EntityTagHeaderValue(details.Tag));
        if (details.LastModify is not null &&
            DateTimeOffset.TryParse(
                details.LastModify,
                CultureInfo.InvariantCulture,
                DateTimeStyles.RoundtripKind,
                out var lastModified))
        {
            request.Headers.IfModifiedSince = lastModified;
        }

        var response = await base.SendAsync(request, cancellationToken);
        var handle = await _repository.TryBeginUpdateAsync(request.RequestUri.ToString());
        var newDetails = handle?.Details;
        newDetails?.RequestUri = request.RequestUri.ToString();
        newDetails?.LastUpdate = DateTimeOffset.Now;
        newDetails?.EnsureValidate = response.Headers.CacheControl?.NoCache ?? false;

        if (newDetails is not null)
        {
            var lastModifiedHeader =
                response.Content?.Headers.LastModified
                ?? response.Headers.LastModified
                ?? response.Headers.Date;

            newDetails.LastModify = lastModifiedHeader.HasValue
                ? lastModifiedHeader.Value.ToString("o", CultureInfo.InvariantCulture)
                : null;
        }
  1. 确保在 HttpCacheHandler.cs 顶部添加 using System.Globalization;，以便 CultureInfo 和 DateTimeStyles 能够正确解析。
  2. 上述改动假定 LastModify 是一个可空的 string。如果你更倾向将其存为 DateTimeOffset?，请相应更新 Details 模型，并去掉 .ToString("o", ...) 与解析调用，直接使用 DateTimeOffset? 赋值。
Original comment in English

suggestion (bug_risk): Last-modified handling uses the Date header instead of Last-Modified and may parse/store invalid values.

LastModify is sent as If-Modified-Since, but when updating you use response.Headers.Date and ToString(). That ignores the Last-Modified header, may be null, and produces a value that might not parse reliably later. Prefer response.Content.Headers.LastModified (or response.Headers.LastModified if intended), store it as a DateTimeOffset or a standardized string (e.g. ToString("o")), and parse using invariant culture when creating the next request.

Suggested implementation:

        if(details.Tag is not null) request.Headers.IfNoneMatch.Add(new EntityTagHeaderValue(details.Tag));
        if (details.LastModify is not null &&
            DateTimeOffset.TryParse(
                details.LastModify,
                CultureInfo.InvariantCulture,
                DateTimeStyles.RoundtripKind,
                out var lastModified))
        {
            request.Headers.IfModifiedSince = lastModified;
        }

        var response = await base.SendAsync(request, cancellationToken);
        var handle = await _repository.TryBeginUpdateAsync(request.RequestUri.ToString());
        var newDetails = handle?.Details;
        newDetails?.RequestUri = request.RequestUri.ToString();
        newDetails?.LastUpdate = DateTimeOffset.Now;
        newDetails?.EnsureValidate = response.Headers.CacheControl?.NoCache ?? false;

        if (newDetails is not null)
        {
            var lastModifiedHeader =
                response.Content?.Headers.LastModified
                ?? response.Headers.LastModified
                ?? response.Headers.Date;

            newDetails.LastModify = lastModifiedHeader.HasValue
                ? lastModifiedHeader.Value.ToString("o", CultureInfo.InvariantCulture)
                : null;
        }
  1. Ensure using System.Globalization; is present at the top of HttpCacheHandler.cs so CultureInfo and DateTimeStyles resolve correctly.
  2. This change assumes LastModify is a nullable string. If you prefer to store it as DateTimeOffset?, update the Details model accordingly and remove the .ToString("o", ...)/parse calls, assigning the DateTimeOffset? directly instead.

newDetails?.LastModify = response.Content.Headers.LastModified.ToString();
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@sourcery-ai sourcery-ai Bot Apr 6, 2026

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issue (bug_risk): 对 LastModified 调用 ToString() 而不进行空检查，可能抛出异常或生成与区域设置相关的值。

LastModified 是一个 DateTimeOffset?；当它为 null 时，.ToString() 会返回空字符串，这在之后调用 DateTimeOffset.Parse 时会导致异常。

建议：

  • 保留 null 而不是空字符串：newDetails.LastModify = response.Content.Headers.LastModified?.ToString("O");
  • 使用不依赖区域设置的往返格式（例如 "O"），以保证解析与区域设置无关。
Original comment in English

issue (bug_risk): Using ToString() on LastModified without null checks can throw or produce culture-dependent values.

LastModified is a DateTimeOffset?; when it's null, .ToString() returns an empty string, which will later cause DateTimeOffset.Parse to throw.

Recommend:

  • Preserve nulls instead of empty strings: newDetails.LastModify = response.Content.Headers.LastModified?.ToString("O");
  • Use an invariant, round-trip format (e.g. "O") so parsing is culture-independent.

newDetails?.Tag = response.Headers.ETag?.Tag;
if (handle is not null)
response.Content = new StreamContent(new CacheStream(handle,
await response.Content.ReadAsStreamAsync(cancellationToken)));
return response;
}
}
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