fix default log timestamps, setting to current time. Fixes #193

Author: duncanpo

api/logs/src/LoggerProxy.cpp

@@ -9,6 +9,7 @@
 #include "opentelemetry/logs/log_record.h"
 #include "opentelemetry/trace/context.h"
 #include "opentelemetry/context/context.h"
+#include "opentelemetry/common/timestamp.h"
 
 #include "MatlabDataArray.hpp"
 
@@ -40,6 +41,12 @@ void LoggerProxy::emitLogRecord(libmexclass::proxy::method::Context& context) {
 
     nostd::unique_ptr<logs_api::LogRecord> rec = CppLogger->CreateLogRecord();
 
+    // Do not use the default timestamp, which is set to the start of UNIX epoch. Set both the 
+    // default timestamp and default observed timestamp to the current time
+    auto now = common::SystemTimestamp(std::chrono::system_clock::now());
+    rec->SetTimestamp(now);
+    rec->SetObservedTimestamp(now);
+
     // Add size attribute if body is nonscalar
     if (array_body) {
        rec->SetAttribute(bodyattrs.Attributes.back().first, bodyattrs.Attributes.back().second);

test/tlogs.m

@@ -75,7 +75,10 @@ function testBasic(testCase)
                 tol = seconds(4);
                 verifyLessThanOrEqual(testCase, abs(datetime(double(string(...
                     results.resourceLogs.scopeLogs.logRecords.observedTimeUnixNano))/1e9, ...
-                    "convertFrom", "posixtime", "TimeZone", "UTC") - expectedtimestamp), tol);
+                    "convertFrom", "posixtime", "TimeZone", "UTC") - expectedtimestamp), tol); 
+                % by default, Timestamp and ObservedTimestamp should be identical
+                verifyEqual(testCase, results.resourceLogs.scopeLogs.logRecords.observedTimeUnixNano, ...
+                    results.resourceLogs.scopeLogs.logRecords.timeUnixNano);
 
                 % check resource
                 resourcekeys = string({results.resourceLogs.resource.attributes.key});