49 lines
1.9 KiB
C#
49 lines
1.9 KiB
C#
namespace ScadaLink.Host;
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/// <summary>
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/// Bounded retry-with-backoff for startup preconditions.
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///
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/// Host-010 / REQ-HOST-4a: a Central node applies/validates database migrations
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/// before the host begins serving traffic. In container orchestration the database
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/// and the app frequently start together, so the database may be briefly
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/// unreachable. Rather than crashing the process on the first connection failure,
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/// the migration step is wrapped in this bounded exponential backoff: it tolerates a
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/// short outage and only fails fatally once attempts are exhausted.
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/// </summary>
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public static class StartupRetry
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{
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public static async Task ExecuteWithRetryAsync(
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string operationName,
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Func<Task> operation,
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int maxAttempts,
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TimeSpan initialDelay,
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ILogger logger,
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CancellationToken cancellationToken = default)
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{
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var delay = initialDelay;
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for (var attempt = 1; ; attempt++)
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{
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cancellationToken.ThrowIfCancellationRequested();
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try
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{
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await operation();
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if (attempt > 1)
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logger.LogInformation(
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"Startup operation '{Operation}' succeeded on attempt {Attempt}.",
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operationName, attempt);
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return;
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}
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catch (Exception ex) when (attempt < maxAttempts)
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{
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logger.LogWarning(ex,
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"Startup operation '{Operation}' failed on attempt {Attempt}/{MaxAttempts}; " +
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"retrying in {Delay}.",
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operationName, attempt, maxAttempts, delay);
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await Task.Delay(delay, cancellationToken);
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// Exponential backoff, capped so the total wait stays bounded.
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delay = TimeSpan.FromTicks(Math.Min(delay.Ticks * 2, TimeSpan.FromSeconds(30).Ticks));
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}
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}
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}
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}
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