Stop serialization if queue is full

Fixes the excessive number of exceptions from being thrown when Bosun is down

Author: bretcope

BosunReporter/Exceptions.cs

@@ -1,17 +1,18 @@
 using System;
 using System.Net;
+using BosunReporter.Infrastructure;
 
 namespace BosunReporter
 {
     public class BosunPostException : Exception
     {
-        public BosunPostException(HttpStatusCode statusCode, string responseBody, Exception innerException) 
+        internal BosunPostException(HttpStatusCode statusCode, string responseBody, Exception innerException) 
             : base("Posting to the Bosun API failed with status code " + statusCode, innerException)
         {
             Data["ResponseBody"] = responseBody;
         }
 
-        public BosunPostException(Exception innerException)
+        internal BosunPostException(Exception innerException)
             : base("Posting to the Bosun API failed. Bosun did not respond.", innerException)
         {
         }
@@ -22,8 +23,8 @@ public class BosunQueueFullException : Exception
         public int MetricsCount { get; }
         public int Bytes { get; }
 
-        public BosunQueueFullException(int metricsCount, int bytes)
-            : base("Bosun metric queue is full. Metric data is likely being lost due to repeated failures in posting to the Bosun API.")
+        internal BosunQueueFullException(QueueType queueType, int metricsCount, int bytes)
+            : base($"Bosun {queueType} metric queue is full. Metric data is likely being lost due to repeated failures in posting to the Bosun API.")
         {
             MetricsCount = metricsCount;
             Bytes = bytes;

BosunReporter/Infrastructure/PayloadQueue.cs

@@ -1,10 +1,14 @@
 using System;
 using System.Collections.Generic;
-using System.IO;
-using System.Threading;
 
 namespace BosunReporter.Infrastructure
 {
+    internal enum QueueType
+    {
+        Local,
+        ExternalCounters,
+    }
+
     internal class PayloadQueue
     {
         private int _cacheLimit = 1;
@@ -17,12 +21,18 @@ internal class PayloadQueue
         internal int MaxPendingPayloads { get; set; }
         internal int LastBatchPayloadCount { get; private set; }
         internal int DroppedPayloads { get; private set; }
+        internal QueueType Type { get; }
 
         internal int PendingPayloadsCount => _pendingPayloads.Count;
         internal bool IsFull => PendingPayloadsCount >= MaxPendingPayloads;
 
         internal event Action<BosunQueueFullException> PayloadDropped;
 
+        internal PayloadQueue(QueueType type)
+        {
+            Type = type;
+        }
+
         internal MetricWriter GetWriter()
         {
             // sure, we could keep a cache of writers, but seriously, it's one object per serialization interval
@@ -64,7 +74,7 @@ internal void AddPendingPayload(Payload payload)
                 }
                 else
                 {
-                    ex = new BosunQueueFullException(payload.MetricsCount, payload.Used);
+                    ex = new BosunQueueFullException(Type, payload.MetricsCount, payload.Used);
                     DroppedPayloads++;
                     ReleasePayload(payload);
                 }

BosunReporter/MetricsCollector.cs

@@ -122,8 +122,8 @@ public int MaxPayloadSize
 
         public MetricsCollector(BosunOptions options)
         {
-            _localMetricsQueue = new PayloadQueue();
-            _externalCounterQueue = new PayloadQueue();
+            _localMetricsQueue = new PayloadQueue(QueueType.Local);
+            _externalCounterQueue = new PayloadQueue(QueueType.ExternalCounters);
 
             _localMetricsQueue.PayloadDropped += OnPayloadDropped;
             _externalCounterQueue.PayloadDropped += OnPayloadDropped;
@@ -729,39 +729,34 @@ private void SerializeMetrics(out int metricsCount, out int bytesWritten)
 
                 metricsCount = 0;
                 bytesWritten = 0;
-                MetricWriter localWriter = null;
-                MetricWriter externalCounterWriter = null;
-                try
-                {
-                    if (_localMetrics.Count > 0)
-                    {
-                        localWriter = _localMetricsQueue.GetWriter();
-                        SerializeMetricListToWriter(localWriter, _localMetrics, timestamp);
-                        metricsCount += localWriter.MetricsCount;
-                        bytesWritten += localWriter.TotalBytesWritten;
-                    }
-
-                    if (_externalCounterMetrics.Count > 0)
-                    {
-                        externalCounterWriter = _externalCounterQueue.GetWriter();
-                        SerializeMetricListToWriter(externalCounterWriter, _externalCounterMetrics, timestamp);
-                        metricsCount += externalCounterWriter.MetricsCount;
-                        bytesWritten += externalCounterWriter.TotalBytesWritten;
-                    }
-                }
-                finally
-                {
-                    localWriter?.EndBatch();
-                    externalCounterWriter?.EndBatch();
-                }
+                SerializeMetricListToWriter(_localMetricsQueue, _localMetrics, timestamp, ref metricsCount, ref bytesWritten);
+                SerializeMetricListToWriter(_externalCounterQueue, _externalCounterMetrics, timestamp, ref metricsCount, ref bytesWritten);
             }
         }
 
-        private static void SerializeMetricListToWriter(MetricWriter writer, List<BosunMetric> metrics, DateTime timestamp)
+        private static void SerializeMetricListToWriter(PayloadQueue queue, List<BosunMetric> metrics, DateTime timestamp, ref int metricsCount, ref int bytesWritten)
         {
-            foreach (var m in metrics)
+            if (metrics.Count == 0)
+                return;
+
+            var writer = queue.GetWriter();
+
+            try
+            {
+                foreach (var m in metrics)
+                {
+                    m.SerializeInternal(writer, timestamp);
+
+                    if (queue.IsFull)
+                        break;
+                }
+
+                metricsCount += writer.MetricsCount;
+                bytesWritten += writer.TotalBytesWritten;
+            }
+            finally
             {
-                m.SerializeInternal(writer, timestamp);
+                writer.EndBatch();
             }
         }