Provide a %Library.SysLog class to allow logging of events while programs are running in a consistent fashion.
The advantage of using this is that we can use standard utilities to manage and display this log. Also all
log entries automatically get the current namespace, date/time, routine name and process Id logged.
To make logging easier there are three macros defined in %occDiagnostics.inc. This file is included automatically
when compiling any class and so you only need to include it manually if you are compiling a MAC file. The macros are:
$$$SysLog(level,category,message,data) - If the logging level is greater or equal to 'level' this calls
Log^%SYS.ISCLOG with the same parameters except 'routine' is set to $ZNAME. If 'data' is an array
then pass it by reference
$$$SysLogError(category,message) - If the logging level is greater than zero it will call LogError^%SYS.ISCLOG
with the same parameters except 'routine' is set to $ZNAME.
$$$SysLogUser - If the logging level is greater than 1 it calls
LogUserInfo^%SYS.ISCLOG with 'routine' set to $ZNAME and the other parameters coming from $ZU(67)
One of the advantages of these macros is that they check the logging level before calling the Log()
method and so if logging is not turned on at this level then the log macro takes almost no time to execute.
Log an event to the system log if the system logging level is greater or equal to the level passed in.
You must specify a level to log this event at, the choice being:
0 - No logging
1 - Exceptional events logged, e.g. error messages
2 - Detailed event log information, e.g. 'method ABC invoked with parameters X,Y,Z and returned 1234'
3 - Raw information logging, e.g. the byte contents of the TCP/IP request sent from the client
The category is a text field that allows you to subdivide the log entries into various types
you normally pick a name for each application such as 'HTTP' for the in build web server in Cache or 'CMT' for
the Cache Message Transport application. The message is any text message that you wish to be recorded,
data is any extra data you wish to log. routine is optional and is the routine name you called from.
Note that data can be passed by reference and if done it will merge all this information into
a subscript of the log global so you can store large quantities of information if needed.
The return value of this function is the node number where this data is logged or 0 if no log entry was written
typically because the system log level was not set to log an event of the level passed in.
So if you wish to log a problem with a Http request because the Type is wrong while reading it into
the local variable 'request' you could call:
Do ##class(%Library.SysLog).Log(1,"HTTP","Invalid Http request type. Type="_type,request)
Besides the information you pass to the Log method it will automatically log the current date and time
along with the process Id the calling routine name and the current namespace.
Call this to log an unexpected Cache Object Script error. Pass in the category to log this
error under, the message you want reported and the routine that you are logging the
error from (this is optional). The level of detail the error is logged at is determined by the system wide setting, see
ErrorDetailGet() and ErrorDetailSet() to set/get this value. The choices are:
0 - Just log the message and the value of $ZE and $ZU(56,5)
1 - Log the message, the value of $ZE and $ZU(56,5) and the call stack
2 - Log the local symbol table $ZE, $ZU(56,5) and the call stack
Log the user information at log level 2 (operational) to category 'UserInfo'. If any of username
or machinename or exename or IPaddress are blank or missing then they
default to the values setup in the partition in $ZU(67,n,$J). You normally call without any parameters
at the start of your application to log the person using this job, but you can override the value from $ZU(67)
is you need to. If category is blank it defaults to "UserInfo". routine is the optional
routine you are logging this from, if not specified it defaults to the value found from $Stack($Stack-1,"PLACE").
Set the maximum number of entries that this log will hold. If this is not set it defaults to 5,000 entries before
it starts removing old entries.
If there are more than MaxLogEntriesGet() in the log then remove any old entries that
we no longer need. This is called automatically by Log() and LogUserInfo() every
10 entries and so you do not normally need to call this manually.