Add logvisor::LockLog() for ensuring output stream sync

include/logvisor/logvisor.hpp

@@ -8,6 +8,7 @@
 #include <vector>
 #include <atomic>
 #include <memory>
+#include <mutex>
 
 extern "C" void logvisorBp();
 
@@ -79,6 +80,19 @@ extern std::atomic_size_t ErrorCount;
  */
 extern std::atomic_uint_fast64_t FrameIndex;
 
+/**
+ * @brief Centralized logging lock
+ *
+ * Ensures logging streams aren't written concurrently
+ */
+extern std::mutex LogMutex;
+
+/**
+ * @brief Take a centralized lock for the logging output stream(s)
+ * @return RAII mutex lock
+ */
+static inline std::unique_lock<std::mutex> LockLog() {return std::unique_lock<std::mutex>{LogMutex};}
+
 /**
  * @brief Restore centralized logger vector to default state (silent operation)
  */
@@ -145,6 +159,7 @@ public:
     template <typename CharType>
     inline void report(Level severity, const CharType* format, va_list ap)
     {
+        auto lk = LockLog();
         for (auto& logger : MainLoggers)
         {
             va_list apc;
@@ -179,6 +194,7 @@ public:
     template <typename CharType>
     inline void reportSource(Level severity, const char* file, unsigned linenum, const CharType* format, va_list ap)
     {
+        auto lk = LockLog();
         for (auto& logger : MainLoggers)
         {
             va_list apc;

lib/logvisor.cpp

@@ -73,6 +73,7 @@ static std::chrono::steady_clock::time_point GlobalStart = MonoClock.now();
 static inline std::chrono::steady_clock::duration CurrentUptime()
 {return MonoClock.now() - GlobalStart;}
 std::atomic_uint_fast64_t FrameIndex(0);
+std::mutex LogMutex;
 
 static inline int ConsoleWidth()
 {