Error Logging System

• Error message routines that can be called by  ioc code.
• Provision for multiple system wide error loggers..
• A task (errlog) that handles the messages generated by the client routines. It displays messages on the target console and also gives them to any registered system wide error loggers.
• iocLog: A system wide error logger that writes all error message to a file.

Overview

• The error message routines can be called by any non-interrupt level code.
• Task errlog manages the messages. Messages are placed in a message queue, which is read by the errlog task. The message queue uses a fixed block of memory to hold all messages. When the message queue is full additional messages are rejected but a count of missed messages is kept. The next time the message queue empties an extra message about the missed messages is generated.
• The maximum message size  is 256  characters. If a message is longer, the message is truncated and a message explaining that it was truncated is appended. There is a chance that long messages corrupt memory. This  only happens if client code is defective. Long messages most likely result from "%s" formats with a bad string argument.
• The error message routines are partially implemented on the host. The host version just calls fprintf or vfprintf instead of using a separate task and a message queue. Thus host messages are NOT sent to a system wide error logger.

Client Routines

typedef enum {
    errlogInfo,errlogMinor,errlogMajor,errlogFatal
}errlogSevEnum;

int errlogPrintf(const char *pformat, ...);
int errlogVprintf(const char *pformat,va_list pvar);

int errlogSevPrintf(const errlogSevEnum severity,
    const char *pformat, ...);
int errlogSevVprintf(const errlogSevEnum severity,
    const char *pformat,va_list pvar);

int errlogMessage( const char *message);

char * errlogGetSevEnumString(const errlogSevEnum severity);

void errlogSetSevToLog(const errlogSevEnum severity );
errlogSevEnum errlogGetSevToLog(void);

These are the basic client routines.

errlogPrintf and errlogVprintf act just like printf and vprintf.

errlogSevPrintf and errlogSevVprintf are similar except that they also add the severity to the beginning of the message in the form "sevr=<value>" where value is on of "info, minor, major, fatal". Also the message is suppressed if  severity is less than the current severity to suppress.

errlogMessage just logs message.

errlogGetSevEnumString gets the string value of severity.

errlogSetSevToLog sets the severity to log. errlogGetSevToLog gets the current severity to log.

void errMessage(long status, char *message);

void errPrintf(long status, const char *pFileName,
    int lineno, const char *pformat, ...);

errMessage is just a macro that calls errPrintf. errPrintf is meant to be called as follows:

 errPrintf(status,__FILE__, __LINE__,"<format>",...)

 The argument status is described in the Application Developer's guide. The arguments __FILE__ and  __LINE__ are standard C preprocessor variables.
 

int epicsPrintf(const char *pformat, ...);
int epicsVprintf(const char *pformat,va_list pvar);

These are exactly like errlogPrintf and errlogVprintf. They are provided because a lot of existing code calls them,. 

typedef void(*errlogListener) (const char *message);
void errlogAddListener(errlogListener listener);
void errlogRemoveListener(errlogListener listener);

These routines add/remove a callback that receives each error message.
 

void eltc(int yesno); /* error log to console (0 or 1) */
void errlogInit(int bufsize);

errlogInit can be used to initialize the error logging system with a larger buffer. The default is 1280 bytes. An extra MAX_MESSAGE_SIZE (currently 256) bytes are allocated but never used. This is a small extra protection against long error messages.

iocLog

iocLogServer

iocLogClient