Merge pull request #3142 from Carbenium/log-db-lock

Logger: Try harder to obtain the DB lock

src/zm_logger.cpp

@@ -534,7 +534,7 @@ void Logger::logPrint(bool hex, const char * const filepath, const int line, con
   }  // end if level <= mFileLevel
 
   if ( level <= mDatabaseLevel ) {
-    if ( !db_mutex.trylock() ) {
+    if (db_mutex.try_lock_for(1)) {
       char escapedString[(strlen(syslogStart)*2)+1];
       mysql_real_escape_string(&dbconn, escapedString, syslogStart, strlen(syslogStart));
 
@@ -556,7 +556,7 @@ void Logger::logPrint(bool hex, const char * const filepath, const int line, con
     } else {
       Level tempDatabaseLevel = mDatabaseLevel;
       databaseLevel(NOLOG);
-      Error("Can't insert log entry: sql(%s) error(%s)", syslogStart, mysql_error(&dbconn));
+      Error("Can't insert log entry since the DB lock could not be obtained. Message: %s", syslogStart);
       databaseLevel(tempDatabaseLevel);
     }
   }  // end if level <= mDatabaseLevel

src/zm_thread.cpp

@@ -59,7 +59,7 @@ Mutex::~Mutex() {
     Error("Unable to destroy pthread mutex: %s", strerror(errno));
 }
 
-int Mutex::trylock() {
+int Mutex::try_lock() {
   return pthread_mutex_trylock(&mMutex);
 }
 void Mutex::lock() {
@@ -68,16 +68,14 @@ void Mutex::lock() {
   //Debug(3, "Lock");
 }
 
-void Mutex::lock( int secs ) {
+bool Mutex::try_lock_for(int secs) {
   struct timespec timeout = getTimeout(secs);
-  if ( pthread_mutex_timedlock(&mMutex, &timeout) < 0 )
-    throw ThreadException(stringtf("Unable to timedlock pthread mutex: %s", strerror(errno)));
+  return pthread_mutex_timedlock(&mMutex, &timeout) == 0;
 }
 
-void Mutex::lock( double secs ) {
+bool Mutex::try_lock_for(double secs) {
   struct timespec timeout = getTimeout(secs);
-  if ( pthread_mutex_timedlock(&mMutex, &timeout) < 0 )
-    throw ThreadException(stringtf("Unable to timedlock pthread mutex: %s", strerror(errno)));
+  return pthread_mutex_timedlock(&mMutex, &timeout) == 0;
 }
 
 void Mutex::unlock() {

src/zm_thread.h

@@ -78,10 +78,10 @@ class Mutex {
     }
 
   public:
-    int trylock();
+    int try_lock();
     void lock();
-    void lock( int secs );
-    void lock( double secs );
+    bool try_lock_for(int secs);
+    bool try_lock_for(double secs);
     void unlock();
     bool locked();
 };