Message Classes

Currently, there are following classes of messages:

Memory Messages
Debug Messages
Job Messages
Queued Job Messages
Error Messages

Memory Messages

Memory messages are messages that are edited into a memory buffer. Generally they are used in low level routines. These routines do not generally have access to the Job Control Record and so they return messages reformatted in a memory buffer.

Mmsg(resultmessage, "3603 JobId=%u device %s is busy reading.\n", jobid);

Debug Messages

Debug messages are designed to be turned on at a specified debug level and are always sent to STDOUT. There are designed to only be used in the development debug process. They are coded as:

DmsgN(level, message, arg1, ...)

where

N is a number indicating how many arguments are to be substituted into the message (i.e. it is a count of the number arguments you have in your message – generally the number of percent signs (%)).
level is the debug level at which you wish the message to be printed.
message is the message to be printed, and
arg1, ... are the arguments to be substituted.

Since not all compilers support #defines with varargs, you must explicitly specify how many arguments you have.

When the debug message is printed, it will automatically be prefixed by the name of the daemon which is running, the filename where the Dmsg is, and the line number within the file.

Some actual examples are:

Dmsg2(20, “MD5len=%d MD5=%s\n”, strlen(buf), buf);
Dmsg1(9, “Created client %s record\n”, client->hdr.name);

Job Messages

Job messages are messages that pertain to a particular job such as a file that could not be saved, or the number of files and bytes that were saved. They are coded as:

Jmsg(JCR, ERROR_CODE, 0, message, arg1, ...);

where

JCR is the Job Control Record. If JCR == NULL and the JCR can not be determined, the message is treated as Daemon message, with fallback to output to STDOUT.
ERROR_CODE indicates the severity or class of error
0 might be a timestamp, but is generally 0 (timestamp will be set to current time)
message is the message to be printed, and
arg1, ... are the arguments to be substituted.

ERROR_CODE is one of the following:

ERROR OR CODE	Description
M_ABORT	Causes the daemon to immediately abort. This should be used only in extrem e cases. It attempts to produce a traceback.
M_ERROR_TERM	Causes the daemon to immediately terminate. This should be used only in extreme cases. It does not produce a traceback.
M_FATAL	Causes the daemon to terminate the current job, but the daemon keeps running.
M_ERROR	Reports the error. The daemon and the job continue running.
M_WARNING	Reports an warning message. The daemon and the job continue running.
M_INFO	Reports an informational message.

The Jmsg() takes varargs so can have any number of arguments for substituted in a printf like format. Output from the Jmsg() will go to the Job report.

If the Jmsg is followed with a number such as Jmsg1(…), the number indicates the number of arguments to be substituted (varargs is not standard for #defines), and what is more important is that the file and line number will be prefixed to the message. This permits a sort of debug from user’s output.

Jmsg1(jcr, M_WARNING, 0, "Plugin=%s not found.\n", cmd);
Jmsg1(jcr, M_ERROR, 0, "%s exists but is not a directory.\n", path);
Jmsg0(NULL, M_ERROR_TERM, 0, "Failed to find config filename.\n");

The Message Resource configuration defines how and to what destinations will be sent.

Special Cases

JCR == NULL: in this case, it is tried to identify the JCR automatically. If no JCR is found, the message is treated as Daemon message, with fallback to output to STDOUT.
JCR.JobId == 0 and JCR.dir_socket != NULL: a socket connection to the Director exists (normally on the File or Storage Daemon). The message is send directly to the Director via this socket connection.

Queued Job Messages

Queued Job messages are similar to Jmsg()s except that the message is Queued rather than immediately dispatched. This is necessary within the network subroutines and in the message editing routines. This is to prevent recursive loops, and to ensure that messages can be delivered even in the event of a network error.

Qmsg(jcr, M_INFO, 0, "File skipped. Not newer: %s\n", attr->ofname);

Error Messages

Error messages are messages that are related to the daemon as a whole rather than a particular job. For example, an out of memory condition my generate an error message. They should be very rarely needed. In general, you should be using Job and Job Queued messages (Jmsg and Qmsg). They are coded as:

EmsgN(ERROR_CODE, 0, message, arg1, ...)

As with debug messages, you must explicitly code the of arguments to be substituted in the message.

Some actual examples are:

Emsg1(M_ABORT, 0, “Cannot create message thread: %s\n”, strerror(status));
Emsg3(M_WARNING, 0, “Connect to File daemon %s at %s:%d failed. Retrying ...\n”, client->hdr.name, client->address, client->port);
Emsg3(M_FATAL, 0, “Bad response from File daemon to %s command: %d %s\n”, cmd, n, strerror(errno));

In essence, a EmsgN(ERROR_CODE, 0, message, arg1, ...) call resolves to:

DmsgN(10, message, arg1, ...)
JmsgN(NULL, ERROR_CODE, 0, message, arg1, ...)