DebugClients/Python3/DebugThread.py

# -*- coding: utf-8 -*-

# Copyright (c) 2009 - 2014 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing the debug thread.
"""

import bdb
import sys

from DebugBase import DebugBase


class DebugThread(DebugBase):
    """
    Class implementing a debug thread.

    It represents a thread in the python interpreter that we are tracing.
    
    Provides simple wrapper methods around bdb for the 'owning' client to
    call to step etc.
    """
    def __init__(self, dbgClient, targ=None, args=None, kwargs=None,
                 mainThread=False):
        """
        Constructor
        
        @param dbgClient the owning client
        @param targ the target method in the run thread
        @param args  arguments to be passed to the thread
        @param kwargs arguments to be passed to the thread
        @param mainThread 0 if this thread is not the mainscripts thread
        """
        DebugBase.__init__(self, dbgClient)
        
        self._target = targ
        self._args = args
        self._kwargs = kwargs
        self._mainThread = mainThread
        # thread running tracks execution state of client code
        # it will always be False for main thread as that is tracked
        # by DebugClientThreads and Bdb...
        self._threadRunning = False
        
        self.__ident = None  # id of this thread.
        self.__name = ""
    
    def set_ident(self, id):
        """
        Public method to set the id for this thread.
        
        @param id id for this thread (int)
        """
        self.__ident = id
    
    def get_ident(self):
        """
        Public method to return the id of this thread.
        
        @return the id of this thread (int)
        """
        return self.__ident
    
    def get_name(self):
        """
        Public method to return the name of this thread.
        
        @return name of this thread (string)
        """
        return self.__name
    
    def traceThread(self):
        """
        Public method to setup tracing for this thread.
        """
        self.set_trace()
        if not self._mainThread:
            self.set_continue(False)
    
    def bootstrap(self):
        """
        Public method to bootstrap the thread.
        
        It wraps the call to the user function to enable tracing
        before hand.
        """
        try:
            self._threadRunning = True
            self.traceThread()
            self._target(*self._args, **self._kwargs)
        except bdb.BdbQuit:
            pass
        finally:
            self._threadRunning = False
            self.quitting = True
            self._dbgClient.threadTerminated(self)
            sys.settrace(None)
            sys.setprofile(None)
    
    def trace_dispatch(self, frame, event, arg):
        """
        Public method wrapping the trace_dispatch of bdb.py.
        
        It wraps the call to dispatch tracing into
        bdb to make sure we have locked the client to prevent multiple
        threads from entering the client event loop.
        
        @param frame The current stack frame.
        @param event The trace event (string)
        @param arg The arguments
        @return local trace function
        """
        try:
            self._dbgClient.lockClient()
            # if this thread came out of a lock, and we are quitting
            # and we are still running, then get rid of tracing for this thread
            if self.quitting and self._threadRunning:
                sys.settrace(None)
                sys.setprofile(None)
            import threading
            self.__name = threading.current_thread().name
            retval = DebugBase.trace_dispatch(self, frame, event, arg)
        finally:
            self._dbgClient.unlockClient()
        
        return retval