Changeset 255 for Evidence

Timestamp:

07/21/10 15:07:37 (14 years ago)

Author:

ogrimm

Message:

Added special handling of code 0 in exitHandler(), fixed recursion bug in Lock()/Unlock() by not calling Message()

Location:

Evidence

Files:

• Alarm.cc (modified) (4 diffs)
• Doc/Evidence.tex (modified) (4 diffs, 1 prop)
• Evidence.cc (modified) (8 diffs)
• readme.txt (modified) (2 diffs)

Evidence/Alarm.cc

@@ -124 +124 @@
   // Identify status service
   for (int i=0; i<List.size(); i++) if (getInfo() == List[i].Subscription) {
-        // Update level: unavailable or current severity of status  
+        // Update level: unavailable or current severity of status (safely extracted)  
         if (!ServiceOK(getInfo())) List[i].Level = 4;
-        else if (getInfo()->getInt() > List[i].Level) List[i].Level = getInfo()->getInt();
+        else {
+          int Severity = atoi(ToString(getInfo()->getFormat(), getInfo()->getData(), getInfo()->getSize()).c_str());
+          if (Severity > List[i].Level) List[i].Level = Severity;
+        }
   }
 
@@ -140 +143 @@
   if (getCommand() != Command || Server.empty()) return;
  
-  // Reset alarm level and publish/log action
+  // Reset alarm level, publish/log action and reset server message severity
   for (int i=0; i<List.size(); i++) if (List[i].Server == Server) {
     Message(INFO, "Alarm level of server %s reset by %s (ID %d)", Server.c_str(), getClientName(), getClientId());
         List[i].Level = 0;
         List[i].WarnedLevel = 0;
+        if (Server != "DIS_DNS") sendCommandNB((Server+"/EXIT").c_str(), (int) 0);
   }
   
@@ -155 +159 @@
 
   ostringstream Buf;
-  int Alarm, Ret;  
+  int Alarm = 0, Ret;  
 
   Lock();
@@ -223 +227 @@
       }
           if (!Exist) Alarm.List[i].Level = 4;
-          else if (Alarm.List[i].Level = -1) Alarm.List[i].Level = 0;
+          else if (Alarm.List[i].Level == -1) Alarm.List[i].Level = 0;
     }
     

Evidence/Doc/Evidence.tex

@@ -39 +39 @@
 \maketitle
 
-This report describes the design and basic functionality of the \E control system. This essentially is a C++ class and a set of programs running on Linux for controlling small scale experiments. It is based on CERN's DIM library for interprocess communication over TCP/IP connections.
+This report describes the design and basic functionality of the \E control system. This essentially is a C++ class and a set of programs running on Linux for controlling small scale experiments. It is based on CERN's DIM library for interprocess communication over TCP/IP connections. \lstinline{$Rev$}
 
 \tableofcontents
@@ -130 +130 @@
 \item Provides a method for configuration requests. If the configuration data is not available, the application terminates with a  message of FATAL severity unless default data is given.
 \item Provides a method for safely translating DIM service data into text.
-\item Implements the virtual DIM methods \lstinline{exitHandler()} and \lstinline{errorHandler()}. The exit handler can be called through a standard DIM command and will, upon first invocation, just set the flag \lstinline{ExitRequest} which then should be handled by the application. Upon second invocation, it will call \lstinline{exit()}. The error handler will issue a message with ERROR severity.The user application can override these handlers.
+\item Implements the virtual DIM methods \lstinline{exitHandler()}. It can be called through a standard DIM command \lstinline{SvrName/EXIT}, taking a single integer as argument. Upon first invocation, the handler just sets the flag \lstinline{ExitRequest} which should be handled by the application. Upon second invocation, it will call \lstinline{exit()}. A special functionality is given to the argument value 0: it instructs the server to reset its message severity to INFO, without exiting. This is used by the \lstinline{Alarm} server if it receives a command to reset an alarm level, but is also available to the user. The user application can override this handler.
+\item Implements the virtual DIM methods \lstinline{errorHandler()}. The error handler will issue a message with ERROR severity that contains the DIM error code. The user application can override this handler.
 \item Installs signal handler for SIGQUIT (ctrl-backspace), SIGTERM, SIGINT (ctrl-c), and SIGHUP (terminal closed). The signal handler sets first \lstinline{ExitRequest}, and on second invocation calls \lstinline{exit()}. After instantiating the class, the programmer may override the handlers.
 \item Catches un-handled C++ exceptions and extracts as much information from the exception as possible.\footnote{This termination handler is taken directly from the code of the \lstinline{g++} compiler and is thus compiler specific.} That information is also published as a message.
@@ -140 +141 @@
 \label{EvidenceServer-Methods}
 
-The \lstinline{public} part of the header file \lstinline{Evidence.h} is as follows. The namespace designation \lstinline{std} has been left out for clarity in this listing. 
+The \lstinline{public} part of the header file \lstinline{Evidence.h} is as follows. The namespace designation \lstinline{std} has been left out for clarity in this listing.
 
 \begin{lstlisting}[numbers=left,numberstyle=\tiny,stepnumber=2,numbersep=5pt]
@@ -180 +181 @@
 \underline{\lstinline{ActivateSignal()}} is used to define a signal that should be emitted to the main thread in case the configuration file changes. See Sect.\,\ref{ConfigHandling} for details. No signal will be emitted if not set by this routine.
 
-The methods \underline{\lstinline{Lock()}} and \underline{\lstinline{Unlock()}} work on an internal mutex.\footnote{Its type is \lstinline{PTHREAD_MUTEX_ERRORCHECK}. In case an already locked mutex is re-locked, the corresponding system call will therefore return a error and thus avoid dead-locking.} They are used by \lstinline{GetConfig()} but are also available for the user application to serialize access from multiple threads. If a signal is set by \lstinline{ActivateSignal()}, it is masked before locking and unmasked after unlocking. 
+The methods \underline{\lstinline{Lock()}} and \underline{\lstinline{Unlock()}} work on an internal mutex.\footnote{Its type is \lstinline{PTHREAD_MUTEX_ERRORCHECK}. In case an already locked mutex is re-locked, the corresponding system call will therefore return a error and thus avoid dead-locking. Error messages from \lstinline{Lock()} and \lstinline{Unlock()} are written to the console and to the log file. They are not published using \lstinline{Message()} since this method itself uses locking and calling it would result in an infinite recursion.} They are used by \lstinline{GetConfig()} but are also available for the user application to serialize access from multiple threads. If a signal is set by \lstinline{ActivateSignal()}, it is masked before locking and unmasked after unlocking. Calling functions in the locked state should be avoided as it might result in re-locking.
 
 The static method \underline{\lstinline{ToString()}} translates the contents of a DIM service safely into a string that is returned. As no consistency between a service format and the contained data is guaranteed by DIM, precautions are necessary to avoid buffer overruns. The method currently handles the standardized message format \lstinline{"I:1;C"}, arrays of numbers and strings. All other formats are translated into a hex representation. The arguments are the DIM service format, a pointer to the service data and the data size in bytes. It is thread safe as it uses only the arguments and dynamically allocated storage.

Evidence/Evidence.cc

@@ -122 +122 @@
           // Return current value
           Result = List[Item].Value;
-          This->Unlock();
         }
+        This->Unlock();
   }
 
@@ -200 +200 @@
 void EvidenceServer::exitHandler(int Code) {
 
-  Message(INFO, "Exit handler called (DIM exit code %d)", Code);
-  exit(EXIT_SUCCESS);
+  if (Code == 0) Message(INFO, "Message cleared by %s (ID %d)", getClientName(), getClientId());
+  else {
+        Message(INFO, "Exit handler called (DIM exit code %d)", Code);
+        exit(EXIT_SUCCESS);
+  }
 }
 
@@ -241 +244 @@
   }
 
-  // Terminate if severity if FATAL  
-  if (Severity == FATAL) exit(EXIT_FAILURE);
-
   // Delete old message
-  // Note that Lock()/Unlock() might fail with a FATAL message. To avoid an infinite loop,
-  // check for FATAL severity is done before here.
   Lock();
   delete[] MessageData;
   MessageData = NewMsg;
   Unlock();  
-}
-
-
-// Set to central logging server with non-blocking command (may be used in DIM handler)
+
+  // Terminate if severity if FATAL  
+  if (Severity == FATAL) exit(EXIT_FAILURE);
+}
+
+
+// Send to central logging server with non-blocking command
 void EvidenceServer::SendToLog(const char *Format, ...) {
 
+  static char ErrorString[] = "vasprintf() failed in SendToLog()";
   char *Buffer;
   int Ret;
@@ -271 +273 @@
         free (Buffer);
   }
-  else Message(ERROR, "Could not create logging text in SendToLog(), vasprintf() failed");
+  else DimClient::sendCommandNB("DColl/Log", ErrorString);
 }
 
@@ -300 +302 @@
 
 
-// Locking and unlocking for list access
-// Signal blocked before locking to avoid dead-lock by calling GetConfig() from ConfigChanged().
+// Locking and unlocking functions.
+// Signal blocked before locking (pthread_mutex_lock() not asynch-signal safe).
+// Message() is not used to avoid infinite recursion
 void EvidenceServer::Lock() {
 
@@ -312 +315 @@
         Ret += abs(pthread_sigmask(SIG_BLOCK, &Set, NULL));
 
-        if (Ret != 0) Message(FATAL, "Signal masking failed in Lock()");
+        if (Ret != 0) {
+          printf("Signal masking failed in Lock()");
+          SendToLog("Signal masking failed in Lock()");
+          exit(EXIT_FAILURE);
+        }
   }
 
   if ((Ret = pthread_mutex_lock(&Mutex)) != 0) {
-        Message(FATAL, "pthread_mutex_lock() failed in Lock() (%s)", strerror(Ret));
+        printf("pthread_mutex_lock() failed in Lock() (%s)", strerror(Ret));
+        SendToLog("pthread_mutex_lock() failed in Lock() (%s)", strerror(Ret));
+        exit(EXIT_FAILURE);
   }
 }
@@ -326 +335 @@
 
   if ((Ret = pthread_mutex_unlock(&Mutex)) != 0) {
-        Message(FATAL, "pthread_mutex_unlock() failed in Unlock() (%s)", strerror(Ret));
+        printf("pthread_mutex_unlock() failed in Unlock() (%s)", strerror(Ret));
+        SendToLog("pthread_mutex_unlock() failed in Unlock() (%s)", strerror(Ret));
+        exit(EXIT_FAILURE);
   }
   
@@ -334 +345 @@
         Ret += abs(pthread_sigmask(SIG_UNBLOCK, &Set, NULL));
 
-        if (Ret != 0) Message(FATAL, "Signal unmasking failed in Unlock()");
+        if (Ret != 0) {
+          printf("Signal unmasking failed in Unlock()");
+          SendToLog("Signal unmasking failed in Unlock()");
+          exit(EXIT_FAILURE);
+        }
   }
 }

Evidence/readme.txt

@@ -1 @@
-Short description of Evidence control system
 
 This directory contains the backbone of the control system. See directory Doc for documentation.
@@ -44 +43 @@
                         second-last message will not be freed correctly if severity is FATAL). Added
                         History server configuration parameters to adjust buffer size.
-
+20/7/2010       SendToLog() does not call Message() in case of error, but writes error message to log.
+21/7/2010       Lock()/Unlock() do not report errors via Message(), but print to console and use 
+                        SendToLog(). That avoids a recursion problem since Message() also uses locking.
+                        The general exitHandler() will react in a special way to code 0: it will reset
+                        the message severity. This feature is used by Alarm if it receives a command to
+                        reset an alarm level.