Harden ACC installer update and endpoint performance

src/BizTalkCheckmkPulse/EndpointConnectivityProbe.cs

@@ -120,7 +120,15 @@ namespace BizTalkCheckmkPulse
 
             try
             {
-                foreach (var probeResult in ProbeAllAsync(activeEntries).GetAwaiter().GetResult())
+                var probeStopwatch = Stopwatch.StartNew();
+                var probeResults = ProbeAllAsync(activeEntries).GetAwaiter().GetResult();
+                probeStopwatch.Stop();
+                state.ProbeDurationMilliseconds = probeStopwatch.ElapsedMilliseconds;
+                state.UniqueTargets = activeEntries
+                    .Select(TargetKey)
+                    .Distinct(StringComparer.OrdinalIgnoreCase)
+                    .Count();
+                foreach (var probeResult in probeResults)
                 {
                     state.Results.Add(probeResult);
                     if (!probeResult.Available)
@@ -192,10 +200,9 @@ namespace BizTalkCheckmkPulse
         {
             var catalog = SynchronizeCatalog(existing, candidates, synchronizedUtc);
             catalog.EnvironmentName = _options.EnvironmentName ?? string.Empty;
-            if (catalog.Entries.Count > _options.EndpointMaxCount
-                || catalog.ActiveCandidates > _options.EndpointMaxCount)
+            if (catalog.Entries.Count > _options.EndpointMaxCount)
             {
-                throw new InvalidDataException("Discovered endpoint candidates exceed EndpointMaxCount.");
+                throw new InvalidDataException("Probeable endpoints exceed EndpointMaxCount.");
             }
 
             return catalog;
@@ -221,7 +228,7 @@ namespace BizTalkCheckmkPulse
         private async Task<IReadOnlyCollection<EndpointProbeResult>> ProbeAllAsync(EndpointCatalogEntry[] endpoints)
         {
             var unique = endpoints
-                .GroupBy(x => x.Protocol.ToUpperInvariant() + "|" + x.Host.ToUpperInvariant() + "|" + x.Port)
+                .GroupBy(TargetKey, StringComparer.OrdinalIgnoreCase)
                 .ToArray();
             var outcomes = new Dictionary<string, NetworkOutcome>(StringComparer.OrdinalIgnoreCase);
             using (var gate = new SemaphoreSlim(_options.EndpointProbeMaxConcurrency))
@@ -248,7 +255,7 @@ namespace BizTalkCheckmkPulse
 
             return endpoints.Select(endpoint =>
             {
-                var key = endpoint.Protocol.ToUpperInvariant() + "|" + endpoint.Host.ToUpperInvariant() + "|" + endpoint.Port;
+                var key = TargetKey(endpoint);
                 var outcome = outcomes[key];
                 return new EndpointProbeResult
                 {
@@ -260,6 +267,28 @@ namespace BizTalkCheckmkPulse
             }).ToArray();
         }
 
+        internal static long CalculateWorstCaseProbeMilliseconds(int targetCount, int concurrency, int timeoutMilliseconds)
+        {
+            if (targetCount <= 0)
+            {
+                return 0;
+            }
+
+            if (concurrency <= 0 || timeoutMilliseconds <= 0)
+            {
+                throw new ArgumentOutOfRangeException("concurrency");
+            }
+
+            return ((targetCount + concurrency - 1L) / concurrency) * timeoutMilliseconds;
+        }
+
+        private static string TargetKey(EndpointCatalogEntry endpoint)
+        {
+            return endpoint.Protocol.ToUpperInvariant()
+                + "|" + endpoint.Host.ToUpperInvariant()
+                + "|" + endpoint.Port;
+        }
+
         private async Task<NetworkOutcome> ProbeOneAsync(EndpointCatalogEntry endpoint)
         {
             return string.Equals(endpoint.Protocol, "UDP", StringComparison.OrdinalIgnoreCase)