/// <summary>
/// Initializes a new instance of the <see cref="WindowsFileSystemWatcher"/> class.
/// </summary>
/// <param name="watcherExecute"> Instance of IWatcherExecute</param>
/// <param name="retryOption"> Instance of RetryOption, default can be null</param>
public WindowsFileSystemWatcher(IWatcherExecute watcherExecute, RetryOption retryOption = null)
{
// Domain or WindowsService needs to inject IWatcherExecute implementation to this WindowsFileSystemWatcher
// to avoid coupling of WindowsFileSystemWatcher and WatcherExecute in Persistence Layer
this.watcherExecute = watcherExecute;
this.retryOption = retryOption;
}
/// <summary>
/// Exponentially with jitter on each retries
/// </summary>
/// <typeparam name="T">The type of response.</typeparam>
/// <param name="option">The retry option.</param>
/// <param name="context">Request context.</param>
/// <param name="action">Action to execute.</param>
/// <param name="predicate">Handle result predicate.</param>
/// <param name="onRetry">Handle custom on retries.</param>
/// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
/// <remarks>
/// exponential back-off: 2, 4, 8 etc
/// plus some jitter: up to 1 second
/// </remarks>
public static Task <T> SimpleExponentialJitterBackoff <T>(
RetryOption option,
Context context,
Func <Context, Task <T> > action,
Func <T, bool> predicate,
Action <DelegateResult <T>, TimeSpan, Context> onRetry)
{
if (option is null)
{
throw new ArgumentNullException(nameof(option));
}
var jitterer = new Random();
return(Policy
.HandleResult(predicate)
.WaitAndRetryAsync(
5,
retryAttempt =>
{
return TimeSpan.FromSeconds(Math.Pow(2, retryAttempt - 1))
+ TimeSpan.FromMilliseconds(jitterer.Next(option.JitterStart, option.JitterEnd));
},
onRetry)
.ExecuteAsync(async(arg) => await action(arg).ConfigureAwait(false), context));
}
public static void AddNRetry(this IServiceCollection services, Action <RetryOption> actionOptions)
{
RetryOption retryOption = new RetryOption();
actionOptions.Invoke(retryOption);
services.AddSingleton(retryOption);
}
/// <summary>
/// 检查是否满足重试条件
/// </summary>
/// <param name="option"></param>
/// <param name="record"></param>
/// <param name="retryCount"></param>
/// <returns></returns>
private bool CanRetry(RetryOption option, RequestRecord record, int retryCount)
{
if (option == null ||
option.RetryCount <= 0 ||
retryCount >= option.RetryCount)
{
return(false);
}
if (option.CanRetry != null)
{
return(option.CanRetry(record));
}
if ((option.TransientErrorRetry ?? false) && record.Exception != null)
{
if (record.Exception is TimeoutException ||
record.Exception is OperationCanceledException ||
record.Exception is HttpRequestException)
{
return(true);
}
return(false);
}
var statusCode = (int)record.Response.StatusCode;
var method = record.Response.RequestMessage.Method.ToString();
if (option.RetryStatusCodes?.Contains(statusCode) ?? false &&
(option.RetryMethods?.Contains(method, StringComparer.CurrentCultureIgnoreCase) ?? false))
{
return(true);
}
return(false);
}
/// <summary>
/// Initializes a new instance of the <see cref="MirrorFreezeCopyService"/> class.
/// </summary>
public MirrorFreezeCopyService()
{
this.watcherConfig = new WatcherConfig();
this.watcherConfigService = new WatcherConfigService(this.watcherConfig);
this.Precheck();
this.retryOption = this.watcherConfigService.GetRetryOptionFromXMLFile(ConfigFilePath);
this.listWatcher = this.watcherConfigService.PopulateWatchersFromXMLFile(ConfigFilePath);
this.listWatcherExecute = new List <WatcherExecute>();
this.listWindowsFileSystemWatcher = new List <WindowsFileSystemWatcher>();
}
/// <summary>
/// Create a linear retry delay of 1, 2, 3, 4s.
/// </summary>
/// <typeparam name="T">The type of response.</typeparam>
/// <param name="option">The retry option.</param>
/// <param name="context">Request context.</param>
/// <param name="action">Action to execute.</param>
/// <param name="predicate">Handle result predicate.</param>
/// <param name="onRetry">Handle custom on retries.</param>
/// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
public static Task <T> LinearBackoff <T>(
RetryOption option,
Context context,
Func <Context, Task <T> > action,
Func <T, bool> predicate,
Action <DelegateResult <T>, TimeSpan, Context> onRetry)
{
if (option is null)
{
throw new ArgumentNullException(nameof(option));
}
var delay = Backoff.LinearBackoff(TimeSpan.FromMilliseconds(option.MinDelayIsMs), retryCount: option.MaxRetry);
return(HandleRetry(context, action, predicate, onRetry, delay));
}
/// <summary>
/// First, new Random() is not quite random, when it comes to reducing concurrency.
/// You can get multiple instances with the same seed, if many retries are issued simultaneously.
/// https://github.com/App-vNext/Polly/issues/530.
/// </summary>
/// <typeparam name="T">The type of response.</typeparam>
/// <param name="option">The retry option.</param>
/// <param name="context">Request context.</param>
/// <param name="action">Action to execute.</param>
/// <param name="predicate">Handle result predicate.</param>
/// <param name="onRetry">Handle custom on retries.</param>
/// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
public static Task <T> DecorrelatedJitterBackoffV2 <T>(
RetryOption option,
Context context,
Func <Context, Task <T> > action,
Func <T, bool> predicate,
Action <DelegateResult <T>, TimeSpan, Context> onRetry)
{
if (option is null)
{
throw new ArgumentNullException(nameof(option));
}
var maxDelay = TimeSpan.FromSeconds(option.MaxDelayIsMs);
var delay = Backoff
.DecorrelatedJitterBackoffV2(medianFirstRetryDelay: TimeSpan.FromMilliseconds(option.MinDelayIsMs), retryCount: option.MaxRetry)
.Select(s => TimeSpan.FromTicks(Math.Min(s.Ticks, maxDelay.Ticks)));
return(HandleRetry(context, action, predicate, onRetry, delay));
}
/// <summary>
/// Create an retry after backoff retry delay which returned by server.
/// </summary>
/// <typeparam name="T">The type of response.</typeparam>
/// <param name="option">The retry option.</param>
/// <param name="context">Request context.</param>
/// <param name="action">Action to execute.</param>
/// <param name="predicate">Handle result predicate.</param>
/// <param name="sleepDurationProvider">Sleep duration provider.</param>
/// <param name="onRetryAsync">Handle custom on retries.</param>
/// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
public static Task <T> RetryAfterBackOff <T>(
RetryOption option,
Context context,
Func <Context, Task <T> > action,
Func <T, bool> predicate,
Func <int, DelegateResult <T>, Context, TimeSpan> sleepDurationProvider,
Func <DelegateResult <T>, TimeSpan, int, Context, Task> onRetryAsync)
{
if (option is null)
{
throw new ArgumentNullException(nameof(option));
}
return(Policy
.HandleResult(predicate)
.WaitAndRetryAsync(
retryCount: option.MaxRetry,
sleepDurationProvider,
onRetryAsync)
.ExecuteAsync(async(arg) => await action(arg).ConfigureAwait(false), context));
}
/// <summary>
/// 重试逻辑
/// </summary>
/// <param name="option"></param>
/// <param name="request"></param>
/// <param name="sending"></param>
/// <param name="records"></param>
/// <param name="timeoutToken"></param>
/// <param name="retryCount"></param>
/// <returns></returns>
private async Task <RequestRecord> SendWithRetryAsync(RetryOption option, HttpRequest request,
Func <HttpRequest, Task <HttpResponse> > sending,
List <RequestRecord> records, CancellationToken timeoutToken, int retryCount = 0)
{
if (timeoutToken.IsCancellationRequested)
{
throw new ExecutionHttpException(request, new TimeoutException($"请求超时，在{option.TotalTimeout}ms内未获取到结果"));
}
records = records ?? new List <RequestRecord>();
var record = await HandleException(request, async() =>
{
var response = await sending(request);
var requestRecord = new RequestRecord
{
Request = request,
Response = response,
Duration = response.Duration
};
return(requestRecord);
}, requestRecord =>
{
records.Add(requestRecord);
return(requestRecord);
});
if (!CanRetry(option, record, retryCount))
{
return(record);
}
//重试间隔时间
var waitTime = option.WaitIntervals[retryCount];
//等待重试间隔时间
await Waiting(request, waitTime, option.TotalTimeout, timeoutToken);
request = request.Clone();
//开始重试
return(await SendWithRetryAsync(option, request, sending, records, timeoutToken, ++retryCount));
}
