add a mutex in logging functions so that multiple threads can log at the same time

src/zm_logger.cpp

@@ -444,6 +444,7 @@ void Logger::closeSyslog() {
 void Logger::logPrint( bool hex, const char * const filepath, const int line, const int level, const char *fstring, ... ) {
   if ( level > mEffectiveLevel ) 
     return;
+  log_mutex.lock();
   char            timeString[64];
   char            logString[8192];
   va_list         argPtr;
@@ -579,6 +580,7 @@ void Logger::logPrint( bool hex, const char * const filepath, const int line, co
       abort();
     exit(-1);
   }
+  log_mutex.unlock();
 }
 
 

src/zm_logger.h

@@ -30,6 +30,8 @@
 #endif // HAVE_SYS_SYSCALL_H
 #include <mysql/mysql.h>
 
+#include "zm_thread.h"
+
 class Logger {
 public:
   enum { 
@@ -82,6 +84,8 @@ private:
   static bool smInitialised;
   static Logger *smInstance;
 
+  RecursiveMutex log_mutex;
+
   static StringMap smCodes;
   static IntMap smSyslogPriorities;