This class is used internally by InterSystems. You should not make direct use of it within your applications. There is no guarantee made about either the behavior or future operation of this class.
System Debugging in InterSystems IRIS
The system debugger allows external debugging of processes via a set of debugging
commands provided by the class %Debugger.System.
The debugger may be used to attach to processes running ObjectScript routines, or to start routines for debugging. In
either case, the user must:
Start a target process, specifying what routine it is to
Attach to the target process
Issue commands to the target process to control its execution
executing routines may be attached to by a user
with suitable privileges.
Debugging methods are provided
which allow the user to:
Attach to the process and put it in break mode
Control execution (break, step, step into, step out, continue)
Set and clear breakpoints and watchpoints
View current location and stack information
View and set variables, evaluate expressions, and execute COS
Commands may only be issued when the target is in break mode. Since the state of the target
is uncertain following any debugger command, the method IsStopped() must be used to test if the process is in fact in break mode. After a process
has been attached, this method must be called, and return successfully,
following every debugger command, before another command may be issued. The
exceptions are Unattach()(detach from a process and stop debugging), and Break()
(break into a process which is executing under debugger control).
Location information is
automatically returned whenever the process breaks. The property
Location contains the raw location information. The methods
GetOffset() and GetSource()
may be used to obtain analysed location and source
Two terminal output windows may be started. One of the windows is started when
processes are started by the debugger,and is the principle device for the process.
Another window may be started after any process is attached, which is the debug device
for the process. All debugger output is displayed in this window.
Both of these windows are also available when debugging remote processes. In this case, the windows are
started on the local platform.
Starting a routine
The Debugger provides a stub which is jobbed to create a debug process. This stub awaits debugger commands
to open a terminal window, and execute the desired routine.
The method StartTarget(), which takes a routine name as an argument, uses this stub to begin debugging a
routine. It jobs the stub to begin execution, starts the Cterm
windows, attaches to the process, and signals what routine is to be run. Upon
completion, the process is ready for debugging. Breakpoints may be set and the
Attaching a process
Any process may be attached for debugging. The method Attach() takes a numeric process id as an argument.
Upon successful completion, the target is ready to be debugged.
Remote and local debugging are identical, except for the sequence of commands required
to open the Cterm windows. Since the Cterm windows are on the local platform, a separate %Debugger.System
instance must be used on the local and remote platforms.
To start a process, the user follows this sequence:
Remember that upon successful completion of any command, the target may not be in
break mode. The method IsStopped() must be explicitly invoked, and return a success code,
before any new commands may be issued.