Switch db_mutex to a std::mutex. Use modern locking with it. Use zmDbDo or dbQueue.push where appropriate. code cleanup.

src/zm_db.cpp

@@ -23,7 +23,7 @@
 #include <cstdlib>
 
 MYSQL dbconn;
-RecursiveMutex db_mutex;
+std::mutex db_mutex;
 zmDbQueue   dbQueue;
 
 bool zmDbConnected = false;
@@ -108,46 +108,36 @@ bool zmDbConnect() {
 
 void zmDbClose() {
   if (zmDbConnected) {
-    db_mutex.lock();
+    std::lock_guard<std::mutex> lck(db_mutex);
     mysql_close(&dbconn);
     // mysql_init() call implicitly mysql_library_init() but
     // mysql_close() does not call mysql_library_end()
     mysql_library_end();
     zmDbConnected = false;
-    db_mutex.unlock();
   }
 }
 
 MYSQL_RES * zmDbFetch(const char * query) {
-  if ( !zmDbConnected ) {
+  std::lock_guard<std::mutex> lck(db_mutex);
-    Error("Not connected.");
+  if (!zmDbConnected) {
-    return nullptr;
-  }
-  db_mutex.lock();
-  // Might have been disconnected while we waited for the lock
-  if ( !zmDbConnected ) {
-    db_mutex.unlock();
     Error("Not connected.");
     return nullptr;
   }
 
-  if ( mysql_query(&dbconn, query) ) {
+  if (mysql_query(&dbconn, query)) {
-    db_mutex.unlock();
     Error("Can't run query: %s", mysql_error(&dbconn));
     return nullptr;
   }
-  Debug(4, "Success running query: %s", query);
   MYSQL_RES *result = mysql_store_result(&dbconn);
-  if ( !result ) {
+  if (!result) {
     Error("Can't use query result: %s for query %s", mysql_error(&dbconn), query);
   }
-  db_mutex.unlock();
   return result;
 } // end MYSQL_RES * zmDbFetch(const char * query);
 
 zmDbRow *zmDbFetchOne(const char *query) {
   zmDbRow *row = new zmDbRow();
-  if ( row->fetch(query) ) {
+  if (row->fetch(query)) {
     return row;
   } 
   delete row;
@@ -156,10 +146,10 @@ zmDbRow *zmDbFetchOne(const char *query) {
 
 MYSQL_RES *zmDbRow::fetch(const char *query) {
   result_set = zmDbFetch(query);
-  if ( ! result_set ) return result_set;
+  if (!result_set) return result_set;
 
   int n_rows = mysql_num_rows(result_set);
-  if ( n_rows != 1 ) {
+  if (n_rows != 1) {
     Error("Bogus number of lines return from query, %d returned for query %s.", n_rows, query);
     mysql_free_result(result_set);
     result_set = nullptr;
@@ -167,7 +157,7 @@ MYSQL_RES *zmDbRow::fetch(const char *query) {
   }
 
   row = mysql_fetch_row(result_set);
-  if ( !row ) {
+  if (!row) {
     mysql_free_result(result_set);
     result_set = nullptr;
     Error("Error getting row from query %s. Error is %s", query, mysql_error(&dbconn));
@@ -178,38 +168,34 @@ MYSQL_RES *zmDbRow::fetch(const char *query) {
 }
 
 int zmDbDo(const char *query) {
-  db_mutex.lock();
+  std::lock_guard<std::mutex> lck(db_mutex);
+  if (!zmDbConnected)
+    return 0;
   int rc;
-  while ( (rc = mysql_query(&dbconn, query)) and !zm_terminate) {
+  while ((rc = mysql_query(&dbconn, query)) and !zm_terminate) {
-    db_mutex.unlock();
     Error("Can't run query %s: %s", query, mysql_error(&dbconn));
-    if ( (mysql_errno(&dbconn) != ER_LOCK_WAIT_TIMEOUT) )
+    if ( (mysql_errno(&dbconn) != ER_LOCK_WAIT_TIMEOUT) ) {
       return rc;
-
+    }
-    db_mutex.lock();
   }
-  db_mutex.unlock();
   return 1;
 }
 
 int zmDbDoInsert(const char *query) {
-  db_mutex.lock();
+  std::lock_guard<std::mutex> lck(db_mutex);
+  if (!zmDbConnected) return 0;
   int rc;
   while ( (rc = mysql_query(&dbconn, query)) and !zm_terminate) {
-    db_mutex.unlock();
     Error("Can't run query %s: %s", query, mysql_error(&dbconn));
     if ( (mysql_errno(&dbconn) != ER_LOCK_WAIT_TIMEOUT) )
       return 0;
-
-    db_mutex.lock();
   }
   int id = mysql_insert_id(&dbconn);
-  db_mutex.unlock();
   return id;
 }
 
 zmDbRow::~zmDbRow() {
-  if ( result_set ) {
+  if (result_set) {
     mysql_free_result(result_set);
     result_set = nullptr;
   }

src/zm_db.h

@@ -62,7 +62,7 @@ class zmDbRow {
 };
 
 extern MYSQL dbconn;
-extern RecursiveMutex db_mutex;
+extern std::mutex db_mutex;
 extern zmDbQueue  dbQueue;
 
 extern bool zmDbConnected;

src/zm_event.cpp

@@ -251,28 +251,25 @@ Event::~Event() {
       frames, alarm_frames,
       tot_score, (int)(alarm_frames?(tot_score/alarm_frames):0), max_score,
       id);
-  db_mutex.lock();
+  {  // scope for lock
-  while ( mysql_query(&dbconn, sql) && !zm_terminate ) {
+    std::lock_guard<std::mutex> lck(db_mutex);
-    db_mutex.unlock();
-    Error("Can't update event: %s reason: %s", sql, mysql_error(&dbconn));
-    db_mutex.lock();
-  }
-  if ( !mysql_affected_rows(&dbconn) ) {
-    // Name might have been changed during recording, so just do the update without changing the name.
-    snprintf(sql, sizeof(sql),
-        "UPDATE Events SET EndDateTime = from_unixtime(%ld), Length = %s%ld.%02ld, Frames = %d, AlarmFrames = %d, TotScore = %d, AvgScore = %d, MaxScore = %d WHERE Id = %" PRIu64,
-        end_time.tv_sec,
-        delta_time.positive?"":"-", delta_time.sec, delta_time.fsec,
-        frames, alarm_frames,
-        tot_score, (int)(alarm_frames?(tot_score/alarm_frames):0), max_score,
-        id);
     while ( mysql_query(&dbconn, sql) && !zm_terminate ) {
-      db_mutex.unlock();
       Error("Can't update event: %s reason: %s", sql, mysql_error(&dbconn));
-      db_mutex.lock();
     }
-  }  // end if no changed rows due to Name change during recording
+    if ( !mysql_affected_rows(&dbconn) ) {
-  db_mutex.unlock();
+      // Name might have been changed during recording, so just do the update without changing the name.
+      snprintf(sql, sizeof(sql),
+          "UPDATE Events SET EndDateTime = from_unixtime(%ld), Length = %s%ld.%02ld, Frames = %d, AlarmFrames = %d, TotScore = %d, AvgScore = %d, MaxScore = %d WHERE Id = %" PRIu64,
+          end_time.tv_sec,
+          delta_time.positive?"":"-", delta_time.sec, delta_time.fsec,
+          frames, alarm_frames,
+          tot_score, (int)(alarm_frames?(tot_score/alarm_frames):0), max_score,
+          id);
+      while ( mysql_query(&dbconn, sql) && !zm_terminate ) {
+        Error("Can't update event: %s reason: %s", sql, mysql_error(&dbconn));
+      }
+    }  // end if no changed rows due to Name change during recording
+  }
 }  // Event::~Event()
 
 void Event::createNotes(std::string &notes) {
@@ -489,14 +486,7 @@ void Event::AddFramesInternal(int n_frames, int start_frame, Image **images, str
 
   if ( frameCount ) {
     *(frame_insert_values-1) = '\0';
-    db_mutex.lock();
+    zmDbDo(frame_insert_sql);
-    int rc = mysql_query(&dbconn, frame_insert_sql);
-    db_mutex.unlock();
-    if ( rc ) {
-      Error("Can't insert frames: %s, sql was (%s)", mysql_error(&dbconn), frame_insert_sql);
-    } else {
-      Debug(1, "INSERT %d/%d frames sql %s", frameCount, n_frames, frame_insert_sql);
-    }
     last_db_frame = frames;
   } else {
     Debug(1, "No valid pre-capture frames to add");
@@ -548,16 +538,7 @@ void Event::WriteDbFrames() {
     delete frame;
   }
   *(frame_insert_values_ptr-1) = '\0'; // The -1 is for the extra , added for values above
-  db_mutex.lock();
+  zmDbDo(frame_insert_sql);
-  int rc = mysql_query(&dbconn, frame_insert_sql);
-  db_mutex.unlock();
-
-  if ( rc ) {
-    Error("Can't insert frames: %s, sql was %s", mysql_error(&dbconn), frame_insert_sql);
-    return;
-  } else {
-    Debug(1, "INSERT FRAMES: sql was %s", frame_insert_sql);
-  }
 } // end void Event::WriteDbFrames()
 
 void Event::AddFrame(Image *image, struct timeval timestamp, int score, Image *alarm_image) {

src/zm_libvnc_camera.cpp

@@ -132,7 +132,7 @@ VncCamera::VncCamera(
 }
 
 VncCamera::~VncCamera() {
-  if (capture) {
+  if (capture and mRfb) {
     if (mRfb->frameBuffer)
       free(mRfb->frameBuffer);
     (*rfbClientCleanup_f)(mRfb);
@@ -164,6 +164,7 @@ int VncCamera::PrimeCapture() {
     mRfb->GetCredential = GetCredentialsCallback;
 
     mRfb->programName = "Zoneminder VNC Monitor";
+    if ( mRfb->serverHost ) free(mRfb->serverHost);
     mRfb->serverHost = strdup(mHost.c_str());
     mRfb->serverPort = atoi(mPort.c_str());
   }

src/zm_logger.cpp

@@ -21,10 +21,7 @@
 
 #include "zm_db.h"
 #include "zm_utils.h"
-#include <cerrno>
+
-#include <csignal>
-#include <cstdarg>
-#include <cstring>
 #include <libgen.h>
 #include <syslog.h>
 #include <sys/time.h>
@@ -32,6 +29,11 @@
 #ifdef __FreeBSD__
 #include <sys/thr.h>
 #endif
+#include <cerrno>
+#include <csignal>
+#include <cstdarg>
+#include <cstring>
+
 
 bool Logger::smInitialised = false;
 Logger *Logger::smInstance = nullptr;
@@ -57,16 +59,15 @@ Logger::Logger() :
   mEffectiveLevel(NOLOG),
   mDbConnected(false),
   mLogPath(staticConfig.PATH_LOGS.c_str()),
-  //mLogFile( mLogPath+"/"+mId+".log" ),
+  //  mLogFile( mLogPath+"/"+mId+".log" ),
   mLogFileFP(nullptr),
   mHasTerminal(false),
   mFlush(false) {
-
+  if (smInstance) {
-  if ( smInstance ) {
     Panic("Attempt to create second instance of Logger class");
   }
 
-  if ( !smInitialised ) {
+  if (!smInitialised) {
     smCodes[INFO] = "INF";
     smCodes[WARNING] = "WAR";
     smCodes[ERROR] = "ERR";
@@ -81,16 +82,16 @@ Logger::Logger() :
     smSyslogPriorities[PANIC] = LOG_ERR;
 
     char code[4] = "";
-    for ( int i = DEBUG1; i <= DEBUG9; i++ ) {
+    for (int i = DEBUG1; i <= DEBUG9; i++) {
       snprintf(code, sizeof(code), "DB%d", i);
       smCodes[i] = code;
       smSyslogPriorities[i] = LOG_DEBUG;
     }
 
     smInitialised = true;
-  }
+  }  // end if ! smInitialised
 
-  if ( fileno(stderr) && isatty(fileno(stderr)) ) {
+  if (fileno(stderr) && isatty(fileno(stderr))) {
     mHasTerminal = true;
     mTerminalLevel = WARNING;
   }
@@ -101,14 +102,6 @@ Logger::~Logger() {
   smCodes.clear();
   smSyslogPriorities.clear();
   smInitialised = false;
-#if 0
-  for ( StringMap::iterator itr = smCodes.begin(); itr != smCodes.end(); itr ++ ) {
-      smCodes.erase( itr );
-  }
-  for ( IntMap::iterator itr = smSyslogPriorities.begin(); itr != smSyslogPriorities.end(); itr ++ ) {
-      smSyslogPriorities.erase(itr);
-  }
-#endif
 }
 
 void Logger::initialise(const std::string &id, const Options &options) {
@@ -185,7 +178,7 @@ void Logger::initialise(const std::string &id, const Options &options) {
           }
         }
       }
-    } // end foreach target
+    }  // end foreach target
   } else {
     // if we don't have debug turned on, then the max effective log level is INFO
     if ( tempSyslogLevel > INFO ) tempSyslogLevel = INFO;
@@ -193,7 +186,7 @@ void Logger::initialise(const std::string &id, const Options &options) {
     if ( tempTerminalLevel > INFO ) tempTerminalLevel = INFO;
     if ( tempDatabaseLevel > INFO ) tempDatabaseLevel = INFO;
     if ( tempLevel > INFO ) tempLevel = INFO;
-  } // end if config.log_debug
+  }  // end if config.log_debug
 
   logFile(tempLogFile);
 
@@ -355,11 +348,11 @@ Logger::Level Logger::databaseLevel(Logger::Level databaseLevel) {
 }
 
 Logger::Level Logger::fileLevel(Logger::Level fileLevel) {
-  if ( fileLevel > NOOPT ) {
+  if (fileLevel > NOOPT) {
     fileLevel = limit(fileLevel);
     // Always close, because we may have changed file names
-    if ( mFileLevel > NOLOG )
+    if (mFileLevel > NOLOG)
-	    closeFile();
+      closeFile();
     mFileLevel = fileLevel;
     // Don't try to open it here because it will create the log file even if we never write to it.
   }
@@ -367,13 +360,13 @@ Logger::Level Logger::fileLevel(Logger::Level fileLevel) {
 }
 
 Logger::Level Logger::syslogLevel(Logger::Level syslogLevel) {
-  if ( syslogLevel > NOOPT ) {
+  if (syslogLevel > NOOPT) {
     syslogLevel = limit(syslogLevel);
-    if ( mSyslogLevel != syslogLevel ) {
+    if (mSyslogLevel != syslogLevel) {
-      if ( mSyslogLevel > NOLOG )
+      if (mSyslogLevel > NOLOG)
         closeSyslog();
       mSyslogLevel = syslogLevel;
-      if ( mSyslogLevel > NOLOG )
+      if (mSyslogLevel > NOLOG)
         openSyslog();
     }
   }
@@ -383,31 +376,31 @@ Logger::Level Logger::syslogLevel(Logger::Level syslogLevel) {
 void Logger::logFile(const std::string &logFile) {
   bool addLogPid = false;
   std::string tempLogFile = logFile;
-  if ( tempLogFile[tempLogFile.length()-1] == '+' ) {
+  if (tempLogFile[tempLogFile.length()-1] == '+') {
     tempLogFile.resize(tempLogFile.length()-1);
     addLogPid = true;
   }
-  if ( addLogPid )
+  if (addLogPid)
     mLogFile = stringtf("%s.%05d", tempLogFile.c_str(), getpid());
   else
     mLogFile = tempLogFile;
 }
 
 void Logger::openFile() {
-  if ( mLogFile.size() ) {
+  if (mLogFile.size()) {
-   if ( (mLogFileFP = fopen(mLogFile.c_str(), "a")) == nullptr ) {
+    if ( (mLogFileFP = fopen(mLogFile.c_str(), "a")) == nullptr ) {
-    mFileLevel = NOLOG;
+      mFileLevel = NOLOG;
-    Error("fopen() for %s, error = %s", mLogFile.c_str(), strerror(errno));
+      Error("fopen() for %s, error = %s", mLogFile.c_str(), strerror(errno));
-   }
+    }
   } else {
     puts("Called Logger::openFile() without a filename");
   }
 }
 
 void Logger::closeFile() {
-  if ( mLogFileFP ) {
+  if (mLogFileFP) {
     fflush(mLogFileFP);
-    if ( fclose(mLogFileFP) < 0 ) {
+    if (fclose(mLogFileFP) < 0) {
       mLogFileFP = nullptr;
       Error("fclose(), error = %s", strerror(errno));
     }
@@ -416,7 +409,6 @@ void Logger::closeFile() {
 }
 
 void Logger::closeDatabase() {
-
 }
 
 void Logger::openSyslog() {
@@ -428,12 +420,12 @@ 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;
-  if ( level > mEffectiveLevel ) {
+  if (level < PANIC || level > DEBUG9)
-    return;
+    Panic("Invalid logger level %d", level);
-  }
     
   log_mutex.lock();
+  // Can we save some cycles by having these as members and not allocate them on the fly? I think so.
   char            timeString[64];
   char            logString[8192];
   va_list         argPtr;
@@ -443,9 +435,6 @@ void Logger::logPrint(bool hex, const char * const filepath, const int line, con
   const char *file = base ? base+1 : filepath;
   const char *classString = smCodes[level].c_str();
 
-  if ( level < PANIC || level > DEBUG9 )
-    Panic("Invalid logger level %d", level);
-
   gettimeofday(&timeVal, nullptr);
 
 #if 0
@@ -474,12 +463,12 @@ void Logger::logPrint(bool hex, const char * const filepath, const int line, con
 #else
   #ifdef HAVE_SYSCALL
     #ifdef __FreeBSD_kernel__
-    if ( (syscall(SYS_thr_self, &tid)) < 0 ) // Thread/Process id
+    if ((syscall(SYS_thr_self, &tid)) < 0)  // Thread/Process id
 
     # else
       // SOLARIS doesn't have SYS_gettid; don't assume
       #ifdef SYS_gettid
-    if ( (tid = syscall(SYS_gettid)) < 0 ) // Thread/Process id
+    if ((tid = syscall(SYS_gettid)) < 0)  // Thread/Process id
       #endif // SYS_gettid
     #endif
   #endif // HAVE_SYSCALL
@@ -513,61 +502,63 @@ void Logger::logPrint(bool hex, const char * const filepath, const int line, con
   char *syslogEnd = logPtr;
   strncpy(logPtr, "]\n", sizeof(logString)-(logPtr-logString));
 
-  if ( level <= mTerminalLevel ) {
+  if (level <= mTerminalLevel) {
     puts(logString);
     fflush(stdout);
   }
 
-  if ( level <= mFileLevel ) {
+  if (level <= mFileLevel) {
-    if ( !mLogFileFP ) {
+    if (!mLogFileFP) {
-      // We do this here so that we only create the file if we ever write to it.
+      // FIXME unlocking here is a problem. Another thread could sneak in.
       log_mutex.unlock();
+      // We do this here so that we only create the file if we ever write to it.
       openFile();
       log_mutex.lock();
     }
-    if ( mLogFileFP ) {
+    if (mLogFileFP) {
       fputs(logString, mLogFileFP);
-      if ( mFlush )
+      if (mFlush) fflush(mLogFileFP);
-        fflush(mLogFileFP);
     } else {
       puts("Logging to file, but failed to open it\n");
     }
   }  // end if level <= mFileLevel
 
-  if ( level <= mDatabaseLevel ) {
+  if (level <= mDatabaseLevel) {
-    int syslogSize = syslogEnd-syslogStart;
+    if (zmDbConnected) {
-    char escapedString[(syslogSize*2)+1];
+      int syslogSize = syslogEnd-syslogStart;
-    mysql_real_escape_string(&dbconn, escapedString, syslogStart, syslogSize);
+      char escapedString[(syslogSize*2)+1];
+      mysql_real_escape_string(&dbconn, escapedString, syslogStart, syslogSize);
 
-    std::string sql_string = stringtf(
+      std::string sql_string = stringtf(
-        "INSERT INTO `Logs` "
+          "INSERT INTO `Logs` "
-        "( `TimeKey`, `Component`, `ServerId`, `Pid`, `Level`, `Code`, `Message`, `File`, `Line` )"
+          "( `TimeKey`, `Component`, `ServerId`, `Pid`, `Level`, `Code`, `Message`, `File`, `Line` )"
-        " VALUES "
+          " VALUES "
-        "( %ld.%06ld, '%s', %d, %d, %d, '%s', '%s', '%s', %d )",
+          "( %ld.%06ld, '%s', %d, %d, %d, '%s', '%s', '%s', %d )",
-        timeVal.tv_sec, timeVal.tv_usec, mId.c_str(), staticConfig.SERVER_ID, tid, level, classString, escapedString, file, line
+          timeVal.tv_sec, timeVal.tv_usec, mId.c_str(), staticConfig.SERVER_ID, tid, level, classString, escapedString, file, line
-        );
+          );
-    dbQueue.push(sql_string);
+      dbQueue.push(sql_string);
+    } else {
+      puts("Db is closed");
+    }
   }  // end if level <= mDatabaseLevel
 
-  if ( level <= mSyslogLevel ) {
+  if (level <= mSyslogLevel) {
     *syslogEnd = '\0';
     syslog(smSyslogPriorities[level], "%s [%s] [%s]", classString, mId.c_str(), syslogStart);
   }
 
   log_mutex.unlock();
-  if ( level <= FATAL ) {
+  if (level <= FATAL) {
     logTerm();
     zmDbClose();
-    if ( level <= PANIC )
+    if (level <= PANIC) abort();
-      abort();
     exit(-1);
   }
 }  // end logPrint
 
 void logInit(const char *name, const Logger::Options &options) {
-  if ( Logger::smInstance ) {
+  if (Logger::smInstance) {
     delete Logger::smInstance;
-    Logger::smInstance = nullptr;
   }
 
   Logger::smInstance = new Logger();
@@ -575,7 +566,7 @@ void logInit(const char *name, const Logger::Options &options) {
 }
 
 void logTerm() {
-  if ( Logger::smInstance ) {
+  if (Logger::smInstance) {
     delete Logger::smInstance;
     Logger::smInstance = nullptr;
   }

src/zm_logger.h

@@ -153,18 +153,12 @@ public:
   void terminate();
 
   const std::string &id(const std::string &id);
-  const std::string &id() const {
+  const std::string &id() const { return mId; }
-    return mId;
-  }
 
-  Level level() const {
+  Level level() const { return mLevel; }
-    return mLevel;
-  }
   Level level(Level=NOOPT);
 
-  bool debugOn() const {
+  bool debugOn() const { return mEffectiveLevel >= DEBUG1; }
-    return mEffectiveLevel >= DEBUG1;
-  }
 
   Level terminalLevel(Level=NOOPT);
   Level databaseLevel(Level=NOOPT);

src/zm_monitor.cpp

@@ -1692,7 +1692,6 @@ void Monitor::UpdateCaptureFPS() {
       last_fps_time = now_double;
       last_capture_image_count = image_count;
 
-      db_mutex.lock();
       static char sql[ZM_SQL_SML_BUFSIZ];
       // The reason we update the Status as well is because if mysql restarts, the Monitor_Status table is lost,
       // and nothing else will update the status until zmc restarts. Since we are successfully capturing we can
@@ -1702,9 +1701,7 @@ void Monitor::UpdateCaptureFPS() {
           "VALUES (%d, %.2lf, %u, 'Connected') ON DUPLICATE KEY UPDATE "
           "CaptureFPS = %.2lf, CaptureBandwidth=%u, Status='Connected'",
           id, new_capture_fps, new_capture_bandwidth, new_capture_fps, new_capture_bandwidth);
-      int rc = mysql_query(&dbconn, sql);
+      dbQueue.push(sql);
-      db_mutex.unlock();
-      if ( rc ) Error("Can't run query: %s", mysql_error(&dbconn));
     } // now != last_fps_time
   } // end if report fps
 }  // void Monitor::UpdateCaptureFPS()
@@ -1745,10 +1742,7 @@ void Monitor::UpdateAnalysisFPS() {
             "INSERT INTO Monitor_Status (MonitorId,AnalysisFPS) VALUES (%d, %.2lf)"
             " ON DUPLICATE KEY UPDATE AnalysisFPS = %.2lf",
             id, new_analysis_fps, new_analysis_fps);
-        db_mutex.lock();
+        dbQueue.push(sql);
-        int rc = mysql_query(&dbconn, sql);
-        db_mutex.unlock();
-        if ( rc ) Error("Can't run query: %s", mysql_error(&dbconn));
         last_analysis_fps_time = now_double;
         last_motion_frame_count = motion_frame_count;
       } else {
@@ -2324,7 +2318,7 @@ void Monitor::ReloadLinkedMonitors(const char *p_linked_monitors) {
       for ( int i = 0; i < n_link_ids; i++ ) {
         Debug(1, "Checking linked monitor %d", link_ids[i]);
 
-        db_mutex.lock();
+        std::lock_guard<std::mutex> lck(db_mutex);
         static char sql[ZM_SQL_SML_BUFSIZ];
         snprintf(sql, sizeof(sql),
             "SELECT `Id`, `Name` FROM `Monitors`"
@@ -2333,14 +2327,12 @@ void Monitor::ReloadLinkedMonitors(const char *p_linked_monitors) {
             "   AND `Function` != 'Monitor'"
             "   AND `Enabled`=1",
             link_ids[i]);
-        if ( mysql_query(&dbconn, sql) ) {
+        if (mysql_query(&dbconn, sql)) {
-					db_mutex.unlock();
           Error("Can't run query: %s", mysql_error(&dbconn));
           continue;
         }
 
         MYSQL_RES *result = mysql_store_result(&dbconn);
-        db_mutex.unlock();
         if ( !result ) {
           Error("Can't use query result: %s", mysql_error(&dbconn));
           continue;
@@ -2354,11 +2346,11 @@ void Monitor::ReloadLinkedMonitors(const char *p_linked_monitors) {
           Warning("Can't link to monitor %d, invalid id, function or not enabled", link_ids[i]);
         }
         mysql_free_result(result);
-      } // end foreach link_id
+      }  // end foreach link_id
       n_linked_monitors = count;
-    } // end if has link_ids
+    }  // end if has link_ids
-  } // end if p_linked_monitors
+  }  // end if p_linked_monitors
-} // end void Monitor::ReloadLinkedMonitors(const char *p_linked_monitors)
+}  // end void Monitor::ReloadLinkedMonitors(const char *p_linked_monitors)
 
 std::vector<std::shared_ptr<Monitor>> Monitor::LoadMonitors(std::string sql, Purpose purpose) {
   Debug(1, "Loading Monitors with %s", sql.c_str());

src/zm_zone.cpp

@@ -134,16 +134,11 @@ Zone::~Zone() {
 
 void Zone::RecordStats(const Event *event) {
   static char sql[ZM_SQL_MED_BUFSIZ];
-  db_mutex.lock();
   snprintf(sql, sizeof(sql),
       "INSERT INTO Stats SET MonitorId=%d, ZoneId=%d, EventId=%" PRIu64 ", FrameId=%d, PixelDiff=%d, AlarmPixels=%d, FilterPixels=%d, BlobPixels=%d, Blobs=%d, MinBlobSize=%d, MaxBlobSize=%d, MinX=%d, MinY=%d, MaxX=%d, MaxY=%d, Score=%d",
       monitor->Id(), id, event->Id(), event->Frames(), pixel_diff, alarm_pixels, alarm_filter_pixels, alarm_blob_pixels, alarm_blobs, min_blob_size, max_blob_size, alarm_box.LoX(), alarm_box.LoY(), alarm_box.HiX(), alarm_box.HiY(), score
       );
-  int rc = mysql_query(&dbconn, sql);
+  zmDbDo(sql);
-  db_mutex.unlock();
-  if ( rc ) {
-    Error("Can't insert event stats: %s", mysql_error(&dbconn));
-  }
 }  // end void Zone::RecordStats( const Event *event )
 
 bool Zone::CheckOverloadCount() {
@@ -824,23 +819,24 @@ bool Zone::ParseZoneString(const char *zone_string, int &zone_id, int &colour, P
 
 int Zone::Load(Monitor *monitor, Zone **&zones) {
   static char sql[ZM_SQL_MED_BUFSIZ];
+  MYSQL_RES *result;
 
-  db_mutex.lock();
+  {  // scope for lock
-  snprintf(sql, sizeof(sql), "SELECT Id,Name,Type+0,Units,Coords,AlarmRGB,CheckMethod+0,"
+    std::lock_guard<std::mutex> lck(db_mutex);
-      "MinPixelThreshold,MaxPixelThreshold,MinAlarmPixels,MaxAlarmPixels,"
+    snprintf(sql, sizeof(sql), "SELECT Id,Name,Type+0,Units,Coords,AlarmRGB,CheckMethod+0,"
-      "FilterX,FilterY,MinFilterPixels,MaxFilterPixels,"
+        "MinPixelThreshold,MaxPixelThreshold,MinAlarmPixels,MaxAlarmPixels,"
-      "MinBlobPixels,MaxBlobPixels,MinBlobs,MaxBlobs,"
+        "FilterX,FilterY,MinFilterPixels,MaxFilterPixels,"
-      "OverloadFrames,ExtendAlarmFrames"
+        "MinBlobPixels,MaxBlobPixels,MinBlobs,MaxBlobs,"
-      " FROM Zones WHERE MonitorId = %d ORDER BY Type, Id", monitor->Id());
+        "OverloadFrames,ExtendAlarmFrames"
-  if ( mysql_query(&dbconn, sql) ) {
+        " FROM Zones WHERE MonitorId = %d ORDER BY Type, Id", monitor->Id());
-    db_mutex.unlock();
+    if ( mysql_query(&dbconn, sql) ) {
-    Error("Can't run query: %s", mysql_error(&dbconn));
+      Error("Can't run query: %s", mysql_error(&dbconn));
-    return 0;
+      return 0;
+    }
+
+    result = mysql_store_result(&dbconn);
   }
-
+  if (!result) {
-  MYSQL_RES *result = mysql_store_result(&dbconn);
-  db_mutex.unlock();
-  if ( !result ) {
     Error("Can't use query result: %s", mysql_error(&dbconn));
     return 0;
   }
@@ -848,7 +844,7 @@ int Zone::Load(Monitor *monitor, Zone **&zones) {
   Debug(1, "Got %d zones for monitor %s", n_zones, monitor->Name());
   delete[] zones;
   zones = new Zone *[n_zones];
-  for( int i = 0; MYSQL_ROW dbrow = mysql_fetch_row(result); i++ ) {
+  for(int i = 0; MYSQL_ROW dbrow = mysql_fetch_row(result); i++) {
     int col = 0;
 
     int Id = atoi(dbrow[col++]);

src/zmc.cpp

@@ -266,6 +266,7 @@ int main(int argc, char *argv[]) {
                monitor->Id());
       zmDbDo(sql);
     }  // end foreach monitor
+    if (zm_terminate) break;
 
 #if HAVE_RTSP_SERVER
     RTSPServerThread ** rtsp_server_threads = nullptr;
@@ -418,9 +419,7 @@ int main(int argc, char *argv[]) {
     snprintf(sql, sizeof(sql),
         "INSERT INTO Monitor_Status (MonitorId,Status) VALUES (%d, 'Connected') ON DUPLICATE KEY UPDATE Status='NotRunning'", 
         monitor->Id());
-    if (mysql_query(&dbconn, sql)) {
+    zmDbDo(sql);
-      Error("Can't run query: %s", mysql_error(&dbconn));
-    }
   }
 
   Image::Deinitialise();