[API] Logger::EmitLogRecord() is unsafe to use #2666
Description
Consider the following code:
nostd::unique_ptr<opentelemetry::logs::LogRecord> record =
logger->CreateLogRecord();
record->SetSeverity(otel_severity);
opentelemetry::common::AttributeValue otel_body(message);
record->SetBody(otel_body);
logger->EmitLogRecord(record);
This code builds, executes, and produces empty log records downstream.
The issue is that this method is invoked:
template <class... ArgumentType>
void EmitLogRecord(ArgumentType &&... args)
{
nostd::unique_ptr<LogRecord> log_record = CreateLogRecord();
if (!log_record)
{
return;
}
EmitLogRecord(std::move(log_record), std::forward<ArgumentType>(args)...);
}
The log record given in arguments is ignored, and a dummy record, not populated, is used instead.
To fix this, the user code needs to change to:
logger->EmitLogRecord(std::move(record));
which will invoke:
virtual void EmitLogRecord(nostd::unique_ptr<LogRecord> &&log_record) noexcept = 0;
This is a major issue, because a lot of user code will be instrumented for logs, and these mistakes will happen again and again, creating the perception that opentelemetry-cpp does not work for logs.
Code such as:
logger->EmitLogRecord(record);
MUST fail to build instead of ignoring the record argument.