summary: Log Forwarding Updates

feat: Allow forwarding of logs where context data is present but the message and exception are missing. Previously, logs with no message or exception were not forwarded, even if they held context data.

feat: Add a supportability metric (Supportability/Logging/Forwarding/Empty) when an "empty" log event is not forwarded. Resolves #1472

Author: tippmar-nr

src/Agent/NewRelic/Agent/Core/Agent.cs

@@ -439,14 +439,15 @@ public void RecordLogMessage(string frameworkName, object logEvent, Func<object,
 
                 var logMessage = getLogMessage(logEvent);
                 var logException = getLogException(logEvent);
+                var logContextData = _configurationService.Configuration.ContextDataEnabled ? getContextData(logEvent) : null;
 
-                // exit quickly if the message and exception are missing
-                if (string.IsNullOrWhiteSpace(logMessage) && logException is null)
+                // exit quickly if the message, exception and context data are missing
+                if (string.IsNullOrWhiteSpace(logMessage) && logException is null && (logContextData is null || logContextData.Count == 0))
                 {
+                    _agentHealthReporter.ReportLoggingEventsEmpty();
                     return;
                 }
 
-                var logContextData = _configurationService.Configuration.ContextDataEnabled ? getContextData(logEvent) : null;
                 var timestamp = getTimestamp(logEvent).ToUnixTimeMilliseconds();
 
                 LogEventWireModel logEventWireModel;

src/Agent/NewRelic/Agent/Core/AgentHealth/AgentHealthReporter.cs

@@ -571,6 +571,11 @@ public void ReportLogForwardingEnabledWithFramework(string logFramework)
             _loggingForwardingEnabledWithFrameworksReported.TryAdd(logFramework, false);
         }
 
+        public void ReportLoggingEventsEmpty(int count = 1)
+        {
+            ReportSupportabilityCountMetric(MetricNames.SupportabilityLoggingEventEmpty);
+        }
+
         public void CollectLoggingMetrics()
         {
             var totalCount = 0;

src/Agent/NewRelic/Agent/Core/AgentHealth/IAgentHealthReporter.cs

@@ -148,5 +148,6 @@ public interface IAgentHealthReporter : IOutOfBandMetricSource
         void ReportLoggingEventsDropped(int droppedCount);
         void ReportLogForwardingFramework(string logFramework);
         void ReportLogForwardingEnabledWithFramework(string logFramework);
+        void ReportLoggingEventsEmpty(int count = 1);
     }
 }

src/Agent/NewRelic/Agent/Core/Metrics/MetricNames.cs

@@ -199,6 +199,7 @@ static MetricNames()
                 });
         }
 
+        
         public static MetricName GetCustom(string suffix)
         {
             return MetricName.Create(Custom, suffix);
@@ -1045,6 +1046,7 @@ public static string GetPerDestinationAreaDataUsageMetricName(string destination
         public const string SupportabilityLoggingEventsSent = SupportabilityLoggingEventsPs + Forwarding + PathSeparator + "Sent";
         public const string SupportabilityLoggingEventsCollected = SupportabilityLoggingEventsPs + Forwarding + PathSeparator + "Seen";
         public const string SupportabilityLoggingEventsDropped = SupportabilityLoggingEventsPs + Forwarding + PathSeparator + "Dropped";
+        public const string SupportabilityLoggingEventEmpty = SupportabilityLoggingEventsPs + Forwarding + PathSeparator + "Empty";
 
         public static string GetLoggingMetricsLinesBySeverityName(string logLevel)
         {

tests/Agent/UnitTests/Core.UnitTest/AgentHealth/AgentHealthReporterTests.cs

@@ -312,6 +312,7 @@ public void ReportLoggingSupportabilityMetrics()
             _agentHealthReporter.ReportLoggingEventCollected();
             _agentHealthReporter.ReportLoggingEventsSent(2);
             _agentHealthReporter.ReportLoggingEventsDropped(3);
+            _agentHealthReporter.ReportLoggingEventsEmpty();
             _agentHealthReporter.ReportLogForwardingFramework("log4net");
 
             _agentHealthReporter.ReportLogForwardingEnabledWithFramework("Framework1");
@@ -325,6 +326,7 @@ public void ReportLoggingSupportabilityMetrics()
                 { "Supportability/Logging/Forwarding/Seen", 1 },
                 { "Supportability/Logging/Forwarding/Sent", 2 },
                 { "Supportability/Logging/Forwarding/Dropped", 3 },
+                { "Supportability/Logging/Forwarding/Empty", 1 },
                 { "Supportability/Logging/Metrics/DotNET/enabled", 1 },
                 { "Supportability/Logging/Forwarding/DotNET/enabled", 1 },
                 { "Supportability/Logging/LocalDecorating/DotNET/enabled", 1 },

tests/Agent/UnitTests/Core.UnitTest/Wrapper/AgentWrapperApi/AgentWrapperApiTests.cs

@@ -1351,7 +1351,50 @@ public void RecordLogMessage_NoTransaction_NoMessage_WithException_Success()
         }
 
         [Test]
-        public void RecordLogMessage_NoTransaction_NoMessage_NoException_DropsEvent()
+        public void RecordLogMessage_NoTransaction_NoMessage_NoException_WithContextData_Success()
+        {
+            Mock.Arrange(() => _configurationService.Configuration.LogEventCollectorEnabled)
+                .Returns(true);
+            Mock.Arrange(() => _configurationService.Configuration.ContextDataEnabled)
+                .Returns(true);
+
+            var timestamp = DateTime.Now;
+            var timestampUnix = timestamp.ToUnixTimeMilliseconds();
+            var level = "DEBUG";
+            string message = null;
+            var contextData = new Dictionary<string, object>() { { "key1", "value1" }, { "key2", 1 } };
+
+            Func<object, string> getLevelFunc = (l) => level;
+            Func<object, DateTime> getTimestampFunc = (l) => timestamp;
+            Func<object, string> getMessageFunc = (l) => message;
+            Func<object, Exception> getLogExceptionFunc = (l) => null;
+            Func<object, Dictionary<string, object>> getContextDataFunc = (l) => contextData;
+
+            var spanId = "spanid";
+            var traceId = "traceid";
+            var loggingFramework = "testFramework";
+
+            var xapi = _agent as IAgentExperimental;
+            xapi.RecordLogMessage(loggingFramework, new object(), getTimestampFunc, getLevelFunc, getMessageFunc, getLogExceptionFunc, getContextDataFunc, spanId, traceId);
+
+            // Access the private collection of events to get the number of add attempts.
+            var privateAccessor = new PrivateAccessor(_logEventAggregator);
+            var logEvents = privateAccessor.GetField("_logEvents") as ConcurrentPriorityQueue<PrioritizedNode<LogEventWireModel>>;
+
+            var logEvent = logEvents?.FirstOrDefault()?.Data;
+            Assert.AreEqual(1, logEvents.Count);
+            Assert.IsNotNull(logEvent);
+            Assert.AreEqual(timestampUnix, logEvent.TimeStamp);
+            Assert.AreEqual(level, logEvent.Level);
+            Assert.AreEqual(message, logEvent.Message);
+            Assert.AreEqual(spanId, logEvent.SpanId);
+            Assert.AreEqual(traceId, logEvent.TraceId);
+            Assert.AreEqual(contextData, logEvent.ContextData);
+            Assert.IsNotNull(logEvent.Priority);
+        }
+
+        [Test]
+        public void RecordLogMessage_NoTransaction_NoMessage_NoException_NoContextData_DropsEvent()
         {
             Mock.Arrange(() => _configurationService.Configuration.LogEventCollectorEnabled)
                 .Returns(true);
@@ -1473,7 +1516,51 @@ public void RecordLogMessage_WithTransaction_NoMessage_WithException_Success()
         }
 
         [Test]
-        public void RecordLogMessage_WithTransaction_NoMessage_NoException_DropsEvent()
+        public void RecordLogMessage_WithTransaction_NoMessage_NoException_WithContextData_Success()
+        {
+            Mock.Arrange(() => _configurationService.Configuration.LogEventCollectorEnabled)
+                .Returns(true);
+            Mock.Arrange(() => _configurationService.Configuration.ContextDataEnabled)
+                .Returns(true);
+
+            var timestamp = DateTime.Now;
+            var timestampUnix = timestamp.ToUnixTimeMilliseconds();
+            var level = "DEBUG";
+            string message = null;
+            var contextData = new Dictionary<string, object>() { { "key1", "value1" }, { "key2", 1 } };
+
+            Func<object, string> getLevelFunc = (l) => level;
+            Func<object, DateTime> getTimestampFunc = (l) => timestamp;
+            Func<object, string> getMessageFunc = (l) => message;
+            Func<object, Exception> getLogExceptionFunc = (l) => null;
+            Func<object, Dictionary<string, object>> getContextDataFunc = (l) => contextData;
+
+            var spanId = "spanid";
+            var traceId = "traceid";
+            var loggingFramework = "testFramework";
+
+            SetupTransaction();
+            var transaction = _transactionService.GetCurrentInternalTransaction();
+            var priority = transaction.Priority;
+
+            var xapi = _agent as IAgentExperimental;
+            xapi.RecordLogMessage(loggingFramework, new object(), getTimestampFunc, getLevelFunc, getMessageFunc, getLogExceptionFunc, getContextDataFunc, spanId, traceId);
+
+            var harvestedLogEvents = transaction.HarvestLogEvents();
+            var logEvent = harvestedLogEvents.FirstOrDefault();
+            Assert.AreEqual(1, harvestedLogEvents.Count);
+            Assert.IsNotNull(logEvent);
+            Assert.AreEqual(timestampUnix, logEvent.TimeStamp);
+            Assert.AreEqual(level, logEvent.Level);
+            Assert.AreEqual(message, logEvent.Message);
+            Assert.AreEqual(spanId, logEvent.SpanId);
+            Assert.AreEqual(traceId, logEvent.TraceId);
+            Assert.AreEqual(contextData, logEvent.ContextData);
+            Assert.AreEqual(priority, logEvent.Priority);
+        }
+
+        [Test]
+        public void RecordLogMessage_WithTransaction_NoMessage_NoException_NoContextData_DropsEvent()
         {
             Mock.Arrange(() => _configurationService.Configuration.LogEventCollectorEnabled)
                 .Returns(true);