With the helper type we can move the timestamp logic into the Log::WriteMessage call instead of having it in the macro.

Author: ashgti

lldb/tools/lldb-dap/DAPLog.cpp

@@ -8,18 +8,23 @@
 
 #include "DAPLog.h"
 #include "llvm/ADT/StringRef.h"
+#include "llvm/Support/raw_ostream.h"
+#include <chrono>
 #include <fstream>
 #include <mutex>
+#include <system_error>
 
 using namespace llvm;
 
 namespace lldb_dap {
 
-Log::Log(StringRef filename) : m_stream(std::ofstream(filename.str())) {}
+Log::Log(StringRef filename, std::error_code &EC) : m_stream(filename, EC) {}
 
 void Log::WriteMessage(StringRef message) {
   std::scoped_lock<std::mutex> lock(m_mutex);
-  m_stream << message.str();
+  std::chrono::duration<double> now{
+      std::chrono::system_clock::now().time_since_epoch()};
+  m_stream << formatv("{0:f9} ", now.count()).str() << message << "\n";
   m_stream.flush();
 }
 

lldb/tools/lldb-dap/DAPLog.h

@@ -13,23 +13,17 @@
 #include "llvm/Support/Error.h"
 #include "llvm/Support/FormatAdapters.h"
 #include "llvm/Support/FormatVariadic.h"
-#include <chrono>
-#include <fstream>
+#include "llvm/Support/raw_ostream.h"
 #include <mutex>
 #include <string>
+#include <system_error>
 
 // Write a message to log, if logging is enabled.
 #define DAP_LOG(log, ...)                                                      \
   do {                                                                         \
     ::lldb_dap::Log *log_private = (log);                                      \
     if (log_private) {                                                         \
-      ::std::chrono::duration<double> now{                                     \
-          ::std::chrono::system_clock::now().time_since_epoch()};              \
-      ::std::string out;                                                       \
-      ::llvm::raw_string_ostream os(out);                                      \
-      os << ::llvm::formatv("{0:f9} ", now.count()).str()                      \
-         << ::llvm::formatv(__VA_ARGS__).str() << "\n";                        \
-      log_private->WriteMessage(out);                                          \
+      log_private->WriteMessage(::llvm::formatv(__VA_ARGS__).str());           \
     }                                                                          \
   } while (0)
 
@@ -40,14 +34,8 @@
     ::lldb_dap::Log *log_private = (log);                                      \
     ::llvm::Error error_private = (error);                                     \
     if (log_private && error_private) {                                        \
-      ::std::chrono::duration<double> now{                                     \
-          std::chrono::system_clock::now().time_since_epoch()};                \
-      ::std::string out;                                                       \
-      ::llvm::raw_string_ostream os(out);                                      \
-      os << ::llvm::formatv("{0:f9} ", now.count()).str()                      \
-         << ::lldb_dap::FormatError(::std::move(error_private), __VA_ARGS__)   \
-         << "\n";                                                              \
-      log_private->WriteMessage(out);                                          \
+      log_private->WriteMessage(                                               \
+          ::lldb_dap::FormatError(::std::move(error_private), __VA_ARGS__));   \
     } else                                                                     \
       ::llvm::consumeError(::std::move(error_private));                        \
   } while (0)
@@ -59,19 +47,13 @@ namespace lldb_dap {
 class Log final {
 public:
   /// Creates a log file with the given filename.
-  Log(llvm::StringRef filename);
-
-  /// Log is not copyable.
-  /// @{
-  Log(const Log &) = delete;
-  void operator=(const Log &) = delete;
-  /// @}
+  Log(llvm::StringRef filename, std::error_code &EC);
 
   void WriteMessage(llvm::StringRef message);
 
 private:
   std::mutex m_mutex;
-  std::ofstream m_stream;
+  llvm::raw_fd_ostream m_stream;
 };
 
 template <typename... Args>

lldb/tools/lldb-dap/lldb-dap.cpp

@@ -48,6 +48,7 @@
 #include <memory>
 #include <mutex>
 #include <string>
+#include <system_error>
 #include <thread>
 #include <utility>
 #include <vector>
@@ -486,8 +487,15 @@ int main(int argc, char *argv[]) {
 
   std::unique_ptr<Log> log = nullptr;
   const char *log_file_path = getenv("LLDBDAP_LOG");
-  if (log_file_path)
-    log = std::make_unique<Log>(log_file_path);
+  if (log_file_path) {
+    std::error_code EC;
+    log = std::make_unique<Log>(log_file_path, EC);
+    if (EC) {
+      llvm::logAllUnhandledErrors(llvm::errorCodeToError(EC), llvm::errs(),
+                                  "Failed to create log file: ");
+      return EXIT_FAILURE;
+    }
+  }
 
   // Initialize LLDB first before we do anything.
   lldb::SBError error = lldb::SBDebugger::InitializeWithErrorHandling();