为什么要用？
有些时候经常会遇到重复提交的问题，为了避免这个问题，可以使用缓存锁的方式，主要是利用存取缓存比较快的原理。
当提交某个操作的时候，第一次提交会创建一个缓存，当有相同提交的时候，就可以判定为重复提交。当第一次提交完成或者抛错的时候，清除缓存。
使用什么方式？
使用AOP，也可以使用Filter，这里使用AOP：
public class CacheLockAttribute : BaseAOPAttribute
{
readonly string _cacheKeyFormat;
readonly string[] _keyDataFieldNames;
readonly string _errorMessage;
readonly int _objectIndex;
readonly int _expiredMinutes;
public CacheLockAttribute(string cacheKeyFormat, string[] keyDataFieldNames, string errorMessage,
int objectIndex=0, int expiredMinutes=15)
{
_cacheKeyFormat = cacheKeyFormat;
_keyDataFieldNames = keyDataFieldNames;
_errorMessage = errorMessage;
_objectIndex = objectIndex;
_expiredMinutes = expiredMinutes;
}
string cacheKey = string.Empty;
public override async Task Befor(IAOPContext context)
{
cacheKey = await CreateCacheKey(context);
var cacheService = GetCacheService(context);
if (await cacheService.HasCache(cacheKey))
{
throw new BusException(_errorMessage);
}
await cacheService.SetData(cacheKey, cacheKey, _expiredMinutes);
}
public override Task After(IAOPContext context) => ClearLockCache(context);
public override Task HandlerException(IAOPContext context) => ClearLockCache(context);
private async Task ClearLockCache(IAOPContext context)
{
if (cacheKey.IsNotNullOrEmpty())
{
var cacheService = GetCacheService(context);
await cacheService.Remove(cacheKey);
}
}
async Task<string> CreateCacheKey(IAOPContext context)
{
var obj = context.Arguments[_objectIndex];
var cacheKeyDatas = _keyDataFieldNames.Select(s => obj.GetPropertyValue(s)).ToArray();
return string.Format(_cacheKeyFormat, cacheKeyDatas);
}
ICacheService GetCacheService(IAOPContext context) =>
context.ServiceProvider.GetService<icacheservice>();
}
</icacheservice></string>
单元测试：
public class CacheLockAopTests : BaseTests
{
[Fact(DisplayName = "cache lock tests")]
public async Task CacheLockTests()
{
var mockAop = new Mock<iaopcontext>();
var mockCacheService = new Mock<icacheservice>();
var cacheDict = new Dictionary<string, string>();
var obj = new { Id = "123", Name = "james" };
mockCacheService.Setup(m => m.HasCache(It.IsAny<string>()))
.Returns((string s) => Task.FromResult(cacheDict.ContainsKey(s)));
mockCacheService.Setup(m => m.SetData(It.IsAny<string>(), It.IsAny<string>(), It.IsAny<int>()))
.Returns((string key, string value, int m) =>
{
cacheDict.Add(key, value);
return Task.CompletedTask;
});
mockCacheService.Setup(m => m.Remove(It.IsAny<string>())).Returns((string key) =>
{
cacheDict.Remove(key);
return Task.CompletedTask;
});
mockAop.Setup(a => a.ServiceProvider.GetService(typeof(ICacheService)))
.Returns(() => mockCacheService.Object);
mockAop.Setup(a => a.Arguments).Returns(() => new []{obj});
CacheLockAttribute cacheLockAttribute_1 =
new CacheLockAttribute("test_key_{0}_{1}", new[] { "Id", "Name" }, "test error");
CacheLockAttribute cacheLockAttribute_2 =
new CacheLockAttribute("test_key_{0}_{1}", new[] { "Id", "Name" }, "test error");
await cacheLockAttribute_1.Befor(mockAop.Object);
Assert.Single(cacheDict);
await Assert.ThrowsAsync<busexception>(async () =>
{
await cacheLockAttribute_2.Befor(mockAop.Object);
});
Assert.Single(cacheDict);
await cacheLockAttribute_1.After(mockAop.Object);
Assert.Empty(cacheDict);
}
}
</busexception></string></int></string></string></string></string,></icacheservice></iaopcontext>
如何使用？
在某个提交的方法上，加上 [CacheLock(keyFormat, datafileds, errormessage, index, expiredMinutes]
- keyFormat：缓存键的Format
- datafileds：对象数据的字段名数组
- errormessage：抛错的错误信息
- index：参数中的第几个参数
- expiredMinutes：过期时间（分钟）默认15分钟
举例：
[CacheLock("payment_record_{0}", new []{"Id"}, "请不要重复提交")]
public async Task AddDataAsync(PaymentRecord data)
{
await Task.Delay(5000);
}
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Original: https://www.cnblogs.com/inday/p/asp-net-core-aop-cache-lock-resubmit.html
Author: James.Ying
Title: Asp.NetCore利用缓存使用AOP方式防止重复提交
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