feat(lmxproxy): phase 1 — v2 protocol types and domain model

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lmxproxy/src-reference/ZB.MOM.WW.LmxProxy.Host/Services/RetryPolicies.cs

@@ -0,0 +1,193 @@
+using System;
+using System.Threading.Tasks;
+using Polly;
+using Polly.Timeout;
+using Serilog;
+
+namespace ZB.MOM.WW.LmxProxy.Host.Services
+{
+    /// <summary>
+    ///     Provides retry policies for resilient operations
+    /// </summary>
+    public static class RetryPolicies
+    {
+        private static readonly ILogger Logger = Log.ForContext(typeof(RetryPolicies));
+
+        /// <summary>
+        ///     Creates a retry policy with exponential backoff for read operations
+        /// </summary>
+        public static IAsyncPolicy<T> CreateReadPolicy<T>()
+        {
+            return Policy<T>
+                .Handle<Exception>(ex => !(ex is ArgumentException || ex is InvalidOperationException))
+                .WaitAndRetryAsync(
+                    3,
+                    retryAttempt => TimeSpan.FromSeconds(Math.Pow(2, retryAttempt - 1)),
+                    (outcome, timespan, retryCount, context) =>
+                    {
+                        Exception? exception = outcome.Exception;
+                        Logger.Warning(exception,
+                            "Read operation retry {RetryCount} after {DelayMs}ms. Operation: {Operation}",
+                            retryCount,
+                            timespan.TotalMilliseconds,
+                            context.ContainsKey("Operation") ? context["Operation"] : "Unknown");
+                    });
+        }
+
+        /// <summary>
+        ///     Creates a retry policy with exponential backoff for write operations
+        /// </summary>
+        public static IAsyncPolicy CreateWritePolicy()
+        {
+            return Policy
+                .Handle<Exception>(ex => !(ex is ArgumentException || ex is InvalidOperationException))
+                .WaitAndRetryAsync(
+                    3,
+                    retryAttempt => TimeSpan.FromSeconds(Math.Pow(2, retryAttempt)),
+                    (exception, timespan, retryCount, context) =>
+                    {
+                        Logger.Warning(exception,
+                            "Write operation retry {RetryCount} after {DelayMs}ms. Operation: {Operation}",
+                            retryCount,
+                            timespan.TotalMilliseconds,
+                            context.ContainsKey("Operation") ? context["Operation"] : "Unknown");
+                    });
+        }
+
+        /// <summary>
+        ///     Creates a retry policy for connection operations with longer delays
+        /// </summary>
+        public static IAsyncPolicy CreateConnectionPolicy()
+        {
+            return Policy
+                .Handle<Exception>()
+                .WaitAndRetryAsync(
+                    5,
+                    retryAttempt =>
+                    {
+                        // 2s, 4s, 8s, 16s, 32s
+                        var delay = TimeSpan.FromSeconds(Math.Min(32, Math.Pow(2, retryAttempt)));
+                        return delay;
+                    },
+                    (exception, timespan, retryCount, context) =>
+                    {
+                        Logger.Warning(exception,
+                            "Connection retry {RetryCount} after {DelayMs}ms",
+                            retryCount,
+                            timespan.TotalMilliseconds);
+                    });
+        }
+
+        /// <summary>
+        ///     Creates a circuit breaker policy for protecting against repeated failures
+        /// </summary>
+        public static IAsyncPolicy<T> CreateCircuitBreakerPolicy<T>()
+        {
+            return Policy<T>
+                .Handle<Exception>()
+                .CircuitBreakerAsync(
+                    5,
+                    TimeSpan.FromSeconds(30),
+                    (result, timespan) =>
+                    {
+                        Logger.Error(result.Exception,
+                            "Circuit breaker opened for {BreakDurationSeconds}s due to repeated failures",
+                            timespan.TotalSeconds);
+                    },
+                    () => { Logger.Information("Circuit breaker reset - resuming normal operations"); },
+                    () => { Logger.Information("Circuit breaker half-open - testing operation"); });
+        }
+
+        /// <summary>
+        ///     Creates a combined policy with retry and circuit breaker
+        /// </summary>
+        public static IAsyncPolicy<T> CreateCombinedPolicy<T>()
+        {
+            IAsyncPolicy<T> retry = CreateReadPolicy<T>();
+            IAsyncPolicy<T> circuitBreaker = CreateCircuitBreakerPolicy<T>();
+
+            // Wrap retry around circuit breaker
+            // This means retry happens first, and if all retries fail, it counts toward the circuit breaker
+            return Policy.WrapAsync(retry, circuitBreaker);
+        }
+
+        /// <summary>
+        ///     Creates a timeout policy for operations
+        /// </summary>
+        public static IAsyncPolicy CreateTimeoutPolicy(TimeSpan timeout)
+        {
+            return Policy
+                .TimeoutAsync(
+                    timeout,
+                    TimeoutStrategy.Pessimistic,
+                    async (context, timespan, task) =>
+                    {
+                        Logger.Warning(
+                            "Operation timed out after {TimeoutMs}ms. Operation: {Operation}",
+                            timespan.TotalMilliseconds,
+                            context.ContainsKey("Operation") ? context["Operation"] : "Unknown");
+
+                        if (task != null)
+                        {
+                            try
+                            {
+                                await task;
+                            }
+                            catch
+                            {
+                                // Ignore exceptions from the timed-out task
+                            }
+                        }
+                    });
+        }
+
+        /// <summary>
+        ///     Creates a bulkhead policy to limit concurrent operations
+        /// </summary>
+        public static IAsyncPolicy CreateBulkheadPolicy(int maxParallelization, int maxQueuingActions = 100)
+        {
+            return Policy
+                .BulkheadAsync(
+                    maxParallelization,
+                    maxQueuingActions,
+                    context =>
+                    {
+                        Logger.Warning(
+                            "Bulkhead rejected operation. Max parallelization: {MaxParallel}, Queue: {MaxQueue}",
+                            maxParallelization,
+                            maxQueuingActions);
+                        return Task.CompletedTask;
+                    });
+        }
+    }
+
+    /// <summary>
+    ///     Extension methods for applying retry policies
+    /// </summary>
+    public static class RetryPolicyExtensions
+    {
+        /// <summary>
+        ///     Executes an operation with retry policy
+        /// </summary>
+        public static async Task<T> ExecuteWithRetryAsync<T>(
+            this IAsyncPolicy<T> policy,
+            Func<Task<T>> operation,
+            string operationName)
+        {
+            var context = new Context { ["Operation"] = operationName };
+            return await policy.ExecuteAsync(async ctx => await operation(), context);
+        }
+
+        /// <summary>
+        ///     Executes an operation with retry policy (non-generic)
+        /// </summary>
+        public static async Task ExecuteWithRetryAsync(
+            this IAsyncPolicy policy,
+            Func<Task> operation,
+            string operationName)
+        {
+            var context = new Context { ["Operation"] = operationName };
+            await policy.ExecuteAsync(async ctx => await operation(), context);
+        }
+    }
+}