Move logging args

Args captured by logging functions should be captured by rvalue, and use
std::forward to get perfect forwarding.  In addition, separate out the
various std::out lines.

While we're here, also try to optimize a little.  We should ideally be
writing each log line to the output once, and ideally not use iostreams,
which induce a lot of overhead.

Similar to spdlog[1] (which at one point this codebase used), construct
the string, then call fwrite and fflush once, rather than calling
std::cout repeatedly.

Now that we don't have a dependency on iostreams anymore, we can remove
it from the places where it has snuck in.

Tested:
Logging still functions as before.  Logs present.

[1] https://github.com/gabime/spdlog/blob/27cb4c76708608465c413f6d0e6b8d99a4d84302/include/spdlog/sinks/stdout_sinks-inl.h#L70C7-L70C13

Change-Id: I1dd4739e06eb506d68989a066d122109b71b92cd
Signed-off-by: Ed Tanous <ed@tanous.net>

3 files changed, 32 insertions, 11 deletions

diff --git a/http/http_client.hpp b/http/http_client.hpp
index ac231b42e7..0bfb3818df 100644
--- a/http/http_client.hpp
+++ b/http/http_client.hpp
@@ -44,7 +44,6 @@
 
 #include <cstdlib>
 #include <functional>
-#include <iostream>
 #include <memory>
 #include <queue>
 #include <string>
diff --git a/http/logging.hpp b/http/logging.hpp
index cf908771bb..4b9eab967c 100644
--- a/http/logging.hpp
+++ b/http/logging.hpp
@@ -65,7 +65,7 @@ const void* logPtr(T p)
 }
 
 template <LogLevel level, typename... Args>
-inline void vlog(std::format_string<Args...> format, Args... args,
+inline void vlog(std::format_string<Args...>&& format, Args&&... args,
                  const std::source_location& loc) noexcept
 {
     if constexpr (bmcwebCurrentLoggingLevel < level)
@@ -78,9 +78,27 @@ inline void vlog(std::format_string<Args...> format, Args... args,
     constexpr std::string_view levelString = mapLogLevelFromName[stringIndex];
     std::string_view filename = loc.file_name();
     filename = filename.substr(filename.rfind('/') + 1);
-    std::cout << std::format("[{} {}:{}] ", levelString, filename, loc.line())
-              << std::format(format, std::forward<Args>(args)...) << '\n'
-              << std::flush;
+    std::string logLocation;
+    logLocation = std::format("[{} {}:{}] ", levelString, filename, loc.line());
+    try
+    {
+        // TODO, multiple static analysis tools flag that this could potentially
+        // throw Based on the documentation, it shouldn't throw, so long as none
+        // of the formatters throw, so unclear at this point why this try/catch
+        // is required, but add it to silence the static analysis tools.
+        logLocation += std::format(std::move(format),
+                                   std::forward<Args>(args)...);
+    }
+    catch (const std::format_error& /*error*/)
+    {
+        logLocation += "Failed to format";
+        // Nothing more we can do here if logging is broken.
+    }
+    logLocation += '\n';
+    // Intentionally ignore error return.
+    fwrite(logLocation.data(), sizeof(std::string::value_type),
+           logLocation.size(), stdout);
+    fflush(stdout);
 }
 } // namespace crow
 
@@ -92,7 +110,8 @@ struct BMCWEB_LOG_CRITICAL
                         const std::source_location& loc =
                             std::source_location::current()) noexcept
     {
-        crow::vlog<crow::LogLevel::Critical, Args...>(format, args..., loc);
+        crow::vlog<crow::LogLevel::Critical, Args...>(
+            std::move(format), std::forward<Args>(args)..., loc);
     }
 };
 
@@ -104,7 +123,8 @@ struct BMCWEB_LOG_ERROR
                      const std::source_location& loc =
                          std::source_location::current()) noexcept
     {
-        crow::vlog<crow::LogLevel::Error, Args...>(format, args..., loc);
+        crow::vlog<crow::LogLevel::Error, Args...>(
+            std::move(format), std::forward<Args>(args)..., loc);
     }
 };
 
@@ -116,7 +136,8 @@ struct BMCWEB_LOG_WARNING
                        const std::source_location& loc =
                            std::source_location::current()) noexcept
     {
-        crow::vlog<crow::LogLevel::Warning, Args...>(format, args..., loc);
+        crow::vlog<crow::LogLevel::Warning, Args...>(
+            std::move(format), std::forward<Args>(args)..., loc);
     }
 };
 
@@ -128,7 +149,8 @@ struct BMCWEB_LOG_INFO
                     const std::source_location& loc =
                         std::source_location::current()) noexcept
     {
-        crow::vlog<crow::LogLevel::Info, Args...>(format, args..., loc);
+        crow::vlog<crow::LogLevel::Info, Args...>(
+            std::move(format), std::forward<Args>(args)..., loc);
     }
 };
 
@@ -140,7 +162,8 @@ struct BMCWEB_LOG_DEBUG
                      const std::source_location& loc =
                          std::source_location::current()) noexcept
     {
-        crow::vlog<crow::LogLevel::Debug, Args...>(format, args..., loc);
+        crow::vlog<crow::LogLevel::Debug, Args...>(
+            std::move(format), std::forward<Args>(args)..., loc);
     }
 };
 
diff --git a/http/verb.hpp b/http/verb.hpp
index 5859d10b0d..b96008de18 100644
--- a/http/verb.hpp
+++ b/http/verb.hpp
@@ -2,7 +2,6 @@
 
 #include <boost/beast/http/verb.hpp>
 
-#include <iostream>
 #include <optional>
 #include <string_view>