logging: Add threadsafety comments

MarcoFalke · MarcoFalke · commit faa2a47cd7bc · 2019-05-28T14:27:08.000-04:00
diff --git a/src/logging.cpp b/src/logging.cpp
@@ -41,7 +41,7 @@ static int FileWriteStr(const std::string &str, FILE *fp)
 
 bool BCLog::Logger::StartLogging()
 {
-    std::lock_guard<std::mutex> scoped_lock(m_file_mutex);
+    std::lock_guard<std::mutex> scoped_lock(m_cs);
 
     assert(m_buffering);
     assert(m_fileout == nullptr);
@@ -216,9 +216,9 @@ std::string BCLog::Logger::LogTimestampStr(const std::string& str)
     return strStamped;
 }
 
-void BCLog::Logger::LogPrintStr(const std::string &str)
+void BCLog::Logger::LogPrintStr(const std::string& str)
 {
-    std::lock_guard<std::mutex> scoped_lock(m_file_mutex);
+    std::lock_guard<std::mutex> scoped_lock(m_cs);
     std::string str_prefixed = str;
 
     if (m_log_threadnames && m_started_new_line) {
diff --git a/src/logging.h b/src/logging.h
@@ -60,10 +60,10 @@ namespace BCLog {
     class Logger
     {
     private:
-        FILE* m_fileout = nullptr;
-        std::mutex m_file_mutex;
-        std::list<std::string> m_msgs_before_open;
-        bool m_buffering = true; //!< Buffer messages before logging can be started
+        mutable std::mutex m_cs;                   // Can not use Mutex from sync.h because in debug mode it would cause a deadlock when a potential deadlock was detected
+        FILE* m_fileout = nullptr;                 // GUARDED_BY(m_cs)
+        std::list<std::string> m_msgs_before_open; // GUARDED_BY(m_cs)
+        bool m_buffering{true};                    //!< Buffer messages before logging can be started. GUARDED_BY(m_cs)
 
         /**
          * m_started_new_line is a state variable that will suppress printing of
@@ -89,10 +89,14 @@ namespace BCLog {
         std::atomic<bool> m_reopen_file{false};
 
         /** Send a string to the log output */
-        void LogPrintStr(const std::string &str);
+        void LogPrintStr(const std::string& str);
 
         /** Returns whether logs will be written to any output */
-        bool Enabled() const { return m_buffering || m_print_to_console || m_print_to_file; }
+        bool Enabled() const
+        {
+            std::lock_guard<std::mutex> scoped_lock(m_cs);
+            return m_buffering || m_print_to_console || m_print_to_file;
+        }
 
         /** Start logging (and flush all buffered messages) */
         bool StartLogging();

Original file line number	Diff line number	Diff line change
`@@ -41,7 +41,7 @@ static int FileWriteStr(const std::string &str, FILE *fp)`
`41`	`41`
`42`	`42`	`bool BCLog::Logger::StartLogging()`
`43`	`43`	`{`
`44`		`- std::lock_guard<std::mutex> scoped_lock(m_file_mutex);`
	`44`	`+ std::lock_guard<std::mutex> scoped_lock(m_cs);`
`45`	`45`
`46`	`46`	`assert(m_buffering);`
`47`	`47`	`assert(m_fileout == nullptr);`
`@@ -216,9 +216,9 @@ std::string BCLog::Logger::LogTimestampStr(const std::string& str)`
`216`	`216`	`return strStamped;`
`217`	`217`	`}`
`218`	`218`
`219`		`-void BCLog::Logger::LogPrintStr(const std::string &str)`
	`219`	`+void BCLog::Logger::LogPrintStr(const std::string& str)`
`220`	`220`	`{`
`221`		`- std::lock_guard<std::mutex> scoped_lock(m_file_mutex);`
	`221`	`+ std::lock_guard<std::mutex> scoped_lock(m_cs);`
`222`	`222`	`std::string str_prefixed = str;`
`223`	`223`
`224`	`224`	`if (m_log_threadnames && m_started_new_line) {`