How to implement a thread in a wxPython GUI application

Question

I'm having trouble implementing a thread correctly to keep my application from locking up and experiencing weird behavior. The app is designed to log into a ubuntu based server or ubuntu embedded server and search for log files that may be in the clear. The embedded server works, but the app keeps locking up while the search is occurring. The siteserver will not process. I have yet to code the local file search. I would like to add a progress bar once I figure out how to implement threads. I thought this would be straight forward since I've been learning and working with Python for several months now, but working with a GUI has its challenges. I'm still a neophyte and open to all the criticisms; it only helps me to become a better programmer. Any help is greatly appreciated. Here is the code below:

#!c:\python27

import wx
import os
import re
import paramiko
import string
import fileinput
import os.path
import dircache
import sys
import time
import datetime, time
import wx

from wxGui import *



class MyApp(wx.App):
    def OnInit(self):
        frame = MyFrame("SecureTool v2.0.0", (50, 60), (458, 332))
        frame.Show()
        self.SetTopWindow(frame)
        return True



class MyFrame(wx.Frame):
    def __init__(self, title, pos, size):
        wx.Frame.__init__(self, None, -1, title, pos, size)

        toolbar = self.CreateToolBar()
        toolbar.Realize()
        menuFile = wx.Menu()
        menuFile.Append(1, "&About...")
        menuFile.AppendSeparator()
        menuFile.Append(2, "E&xit")
        menuBar = wx.MenuBar()
        menuBar.Append(menuFile, "&File")
        menu2 = wx.Menu()
        menu2.Append(wx.NewId(), "&Copy", "Copy in status bar")
        menu2.AppendSeparator()
        menu2.Append(wx.NewId(), "C&ut", "")
        menu2.AppendSeparator()
        menu2.Append(wx.NewId(), "Paste", "")
        menu2.AppendSeparator()
        menu2.Append(wx.NewId(), "&Options...", "Display Options")
        menuBar.Append(menu2, "&Edit")

        self.SetMenuBar(menuBar)
        self.CreateStatusBar()
        self.SetStatusText("Welcome to SecureTool!")
        self.Bind(wx.EVT_MENU, self.OnAbout, id=1)
        self.Bind(wx.EVT_MENU, self.OnQuit, id=2)
        panel = wx.Panel(self)
        panel.SetBackgroundColour('LIGHT GREY')
        #Close button
        button = wx.Button(panel, label="EXIT", pos=(229, 160), size=(229, 80))
        self.Bind(wx.EVT_BUTTON, self.OnQuit, button)
        self.Bind(wx.EVT_CLOSE, self.OnCloseWindow)
        #Embed Server button
        button2 = wx.Button(panel, label="Embed Server", pos=(0, 160), size=(229, 80))
        self.Bind(wx.EVT_BUTTON, self.OnIP, button2)
        #Site Server
        button3 = wx.Button(panel, label="SITESERVER", pos=(0, 80), size=(229, 80))
        self.Bind(wx.EVT_BUTTON, self.OnUsrPswd, button3)
        #Local Search
        button4 = wx.Button(panel, label="LOCAL SEARCH", pos=(229, 80), size=(229, 80))
        self.Bind(wx.EVT_BUTTON, self.OnOpen, button4)

        EVT_RESULT(self, self.OnResult)
        self.worker = None        

    def OnIP(self, event):
        ip_address = 0
        result = ''
        dlg = wx.TextEntryDialog(None, "Enter the IP Address.",
        'Embed Server Connect', 'xxx.xxx.xxx.xxx')
        if dlg.ShowModal() == wx.ID_OK:
            ip_address = dlg.GetValue()
        if ip_address:    
            cmsg = wx.MessageDialog(None, 'Do you want to connect to: ' + ip_address,
                                    'Connect', wx.YES_NO | wx.ICON_QUESTION)
            result = cmsg.ShowModal()

        if result == wx.ID_YES:
            self.DispConnect(ip_address)

            cmsg.Destroy()
        dlg.Destroy()
        return True

    def OnUsrPswd(self, event):
        passwrd = 0
        result = ''
        result = wx.TextEntryDialog(None, 'Enter Weekly Password', 'Site Server login','')
        if result.ShowModal() == wx.ID_OK:
            passwrd = result.GetValue()
        if passwrd:
            psmsg = wx.MessageDialog(None, 'Do you want to connect to the Siteserver?', 'Connect',
                                 wx.YES_NO | wx.ICON_QUESTION)
            result = psmsg.ShowModal()
        if result == wx.ID_YES:
            self.SiteserverConnect(passwrd)

            psmsg.Destroy()
        result.Destroy()
        return True

    def ErrMsg(self):
        ermsg = wx.MessageDialog(None, 'Invalid Entry!', 'ConnectionDialog', wx.ICON_ERROR)
        ermsg.ShowModal()
        ermsg.Destroy()

    def GoodConnect(self):
        gdcnt = wx.MessageDialog(None, 'You are connected!', 'ConnectionStatus', wx.ICON_INFORMATION)
        gdcnt.ShowModal()
        #if gdcnt.ShowModal() == wx.ID_OK:
        gdcnt.Destroy()

    def OnFinish(self):
        finish = wx.MessageDialog(None, 'Job is finished!', 'WorkStatus', wx.ICON_INFORMATION)
        finish.ShowModal()
        finish.Destroy()


    def DispConnect(self, address):
        pattern = r"\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b"
        port = 22
        user = 'root'
        password ='******'
        if re.match(pattern, address):
            ssh = paramiko.SSHClient()
            ssh.load_system_host_keys()
            ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
            ssh.connect(address,port,user,password)
            Ssh = ssh
            self.GoodConnect()
            self.OnSearch(Ssh)
        else:
            self.ErrMsg()

    def SiteserverConnect(self, password):
        port = 22
        user = 'root2'
        address = '10.5.48.2'
        if password:
            ssh = paramiko.SSHClient()
            ssh.load_system_host_keys()
            ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
            ssh.connect(address,port,user,password)
            Ssh = ssh
            self.GoodConnect()
            self.OnSiteSearch(Ssh)
        else:
            self.ErrMsg()

    def startWorker(self,a, b, c):
        self.button2.Disable()
        self.thread = Thread(target=self.LongRunningSearch)
        self.thread.start()

    def OnSearch(self, sssh):
        self.startWorker(self.OnFinish, self.LongRunningSearch, wargs=[sssh])
        self.OnFinish()

    def LongRunningSearch(sssh):
        ssh = sssh
        apath = '/'
        apattern = '"*.txt" -o -name "*.log"' 
        rawcommand = 'find {path} -name "*.txt" -o -name "*.log"' 
        command1 = rawcommand.format(path=apath, pattern=apattern)
        stdin, stdout, stderr = ssh.exec_command(command1)
        filelist = stdout.read().splitlines()
        ftp = ssh.open_sftp()
        for afile in filelist:
            (head, filename) = os.path.split(afile)

        paths = '/dispenser_result.log'
        temp = ftp.file(paths, 'w')
        from time import strftime
        temp.write("{0:^75}".format("Company -Security Report" ) + strftime("    %Y-%m-%d %H:%M:%S") + "\n\n")   
        ustring = wx.TextEntryDialog(None, 'Enter a search string below:', 'Search', 'String Name')
        if ustring.ShowModal() == wx.ID_OK:
            userstring = ustring.GetValue()

        if userstring:
        userStrHEX = userstring.encode('hex')
        userStrASCII = ''.join(str(ord(char)) for char in userstring)
        regex = re.compile(r"(%s|%s|%s)" % ( re.escape( userstring ), re.escape( userStrHEX ), re.escape( userStrASCII )))      
    else:
        sys.exit('You Must Enter A String!!!')

    count = 0
    for afile in filelist:
        (head, filename) = os.path.split(afile)
        if afile.endswith(".log") or afile.endswith(".txt"):
            f=ftp.open(afile, 'r')
            for i, line in enumerate(f.readlines()):
                result = regex.search(line)
                if result:
                    count += 1
                    ln = str(i)
                    pathname = os.path.join(afile)
                    template = "\n\nLine: {0}\nFile: {1}\nString Type: {2}\n\n"
                    output = template.format(ln, pathname, result.group())
                    ftp.get(afile, 'c:\\Extracted\\' + filename)
                    temp.write(output)
                    break
            else:
                #print "No Match in: " + os.path.join(afile)
                temp.write("\nNo Match in: " + os.path.join(afile))
            f.close()

    for fnum in filelist:
        #print "\nFiles Searched: ", len(filelist)
        #print "Files Matched: ", count
        num = len(filelist)

        temp.write("\n\nFiles Searched:" + '%s\n' % (num))
        temp.write("Files Matched:"+ '%s\n' % (count))
        temp.write("Search String:"+ '%s\n' % (userstring))
        break
        temp.close()
    defaultFolder = "DispenserLogResults"
    if not defaultFolder.endswith(':') and not os.path.exists('c:\\Extracted\\DispenserLogResults'):
        os.mkdir('c:\\Extracted\\DispenserLogResults')
    else:
         pass
    ftp.get(paths, 'c:\\Extracted\\DispenserLogResults\\dispenser_result.log')

    ftp.remove(paths)

    re.purge()
    ftp.close()
    ssh.close()

    def OnSiteSearch(self, sssh):
        ssh = sssh
        apath = '/var/log/apache2 /var/opt/smartmerch/log/'
        apattern = '"*.log"' 
        rawcommand = 'find {path} -type f -name "*.log"' 
        command1 = rawcommand.format(path=apath, pattern=apattern)
        stdin, stdout, stderr = ssh.exec_command(command1)
        filelist = stdout.read().splitlines()
        ftp = ssh.open_sftp()
        for afile in filelist:
            (head, filename) = os.path.split(afile)

        paths = '/var/tmp/siteserver_result.log'
        temp = ftp.file(paths, 'w')
        from time import strftime
        temp.write("{0:^75}".format("Gilbarco - SQA Security Report" ) + strftime("    %Y-%m-%d %H:%M:%S") + "\n\n")   
        temp.write("\n{0:^75}".format("SiteServer Logs" ))
        ustring = wx.TextEntryDialog(None, 'Enter a search string below:', 'Search', 'String Name')
        if ustring.ShowModal() == wx.ID_OK:
            userstring = ustring.GetValue()

        if userstring:
            userStrHEX = userstring.encode('hex')
            userStrASCII = ''.join(str(ord(char)) for char in userstring)
            regex = re.compile(r"(%s|%s|%s)" % ( re.escape( userstring ), re.escape( userStrHEX ), re.escape( userStrASCII )))      
        else:
            sys.exit('You Must Enter A String!!!')

        count = 0
        for afile in filelist:
            (head, filename) = os.path.split(afile)
            if afile.endswith(".log") or afile.endswith(".txt"):
                f=ftp.open(afile, 'r')
                for i, line in enumerate(f.readlines()):
                    result = regex.search(line)
                    if result:
                        count += 1
                        ln = str(i)
                        pathname = os.path.join(afile)
                        template = "\n\nLine: {0}\nFile: {1}\nString Type: {2}\n\n"
                        output = template.format(ln, pathname, result.group())
                        ftp.get(afile, 'c:\\Extracted\\' + filename)
                        temp.write(output)
                        break
                else:
                    temp.write("\nNo Match in: " + os.path.join(afile))
                f.close()

        for fnum in filelist:
            num = len(filelist)

            temp.write("\n\nFiles Searched:" + '%s\n' % (num))
            temp.write("Files Matched:"+ '%s\n' % (count))
            temp.write("Search String:"+ '%s\n' % (userstring))
            break
            temp.close()
        defaultFolder = "SiteServerLogResults"
        if not defaultFolder.endswith(':') and not os.path.exists('c:\\Extracted\\SiteServerLogResults'):
            os.mkdir('c:\\Extracted\\SiteServerLogResults')
        else:
            pass
        ftp.get(paths, 'c:\\Extracted\\SiteServerLogResults\\siteserver_result.log')

        ftp.remove(paths)

        re.purge()
        ftp.close()
        ssh.close()
        self.OnFinish()

    def OnOpen(self,e):
        self.dirname = ''
        dlg = wx.FileDialog(self, "Choose a file", self.dirname, "", "*.*", wx.OPEN)
        if dlg.ShowModal() == wx.ID_OK:
            self.filename = dlg.GetFilename()
            self.dirname = dlg.GetDirectory()
            f = open(os.path.join(self.dirname, self.filename), 'r')
            self.control.SetValue(f.read())
            f.close()
        dlg.Destroy()   

    def OnQuit(self, event):
        self.Close(True)

    def OnAbout(self, event):
        wx.MessageBox("This is sQAST v2.0.0",
            "About secureTool", wx.OK | wx.ICON_INFORMATION, self)



    def OnCloseWindow(self, event):
        self.Destroy()

if __name__ == '__main__':
    app = MyApp(False)
    app.MainLoop()

Traceback Error after running:

Traceback (most recent call last):
File "C:\SQA_log\wxGui.py", line 87, in OnIP
self.DispConnect(ip_address)
File "C:\SQA_log\wxGui.py", line 143, in DispConnect
self.OnSearch(Ssh)
File "C:\SQA_log\wxGui.py", line 169, in OnSearch
self.startWorker(self.OnFinish, self.LongRunningSearch, wargs=[sssh])

Answer 1

I don't see any threading in your application at all. Whenever you make a call to something that will take a while, that something needs to run in a separate thread or it will block the main loop of your GUI.

You should read the following wiki entry on threading in wxPython: http://wiki.wxpython.org/LongRunningTasks

I have used the information therein to successfully create threaded wxPython applications. There's also a simple threading tutorial here: http://www.blog.pythonlibrary.org/2010/05/22/wxpython-and-threads/

Hope that helps. If you get stuck, you should post to the official wxPython mailing group: https://groups.google.com/forum/#!forum/wxpython-users Those guys will set you straight.

Answer 2

In your particular case I would do something like:

1) Encapsulate the long task and separate it from the GUI reaction, simplify your method:

def OnSearch(self, sssh):
    self.LongRunningSearch(sssh) # Move all the blocking code here,
                                 # just NOT the GUI reaction !
                                 # Meaning self.OnFinish()...
    self.OnFinish()

2) Verify that it still runs fine. Then modify the method to add the thread:

def OnSearch(self, sssh):
    startWorker(self.OnFinish, self.LongRunningSearch, wargs=[sssh])

self.OnSearch will end immediately and self.OnFinish will be called after the thread running self.LongRunningSearch has finished. It may still need some tuning as I am unable to run your code on my computer.

Answer 3

You can also have a look at convenience module for threading implemented in the wx, wx.lib.delayedresult. It is very easy to use and to add when you find it is needed. I am not sure why it is ignored so often. I have written an example which uses it some time ago here.

It basically needs you to create two functions / methods. First, which will be ran in another thread, and second, which will be ran after another thread finishes. Then you just call startWorker(LongTaskDone, LongTask).

Example 1: Using wx.lib.delayedresult. wx.CallAfter is used to show progress in GUI thread using gauge widget. Official Documentation.

from time import sleep
import wx
from wx.lib.delayedresult import startWorker

class MainWindow(wx.Frame):
    def __init__(self, *args, **kwargs):
        wx.Frame.__init__(self, *args, **kwargs)

        self.panel = wx.Panel(self)
        self.startButton = wx.Button(self.panel, label="Long Task")
        self.abortButton = wx.Button(self.panel, label="Abort")
        self.abortButton.Disable()
        self.gauge = wx.Gauge(self.panel, size=(-1, 20))
        self.shouldAbort = False

        self.startButton.Bind(wx.EVT_BUTTON, self.OnStartButton)
        self.abortButton.Bind(wx.EVT_BUTTON, self.OnAbortButton)

        self.windowSizer = wx.BoxSizer()
        self.windowSizer.Add(self.panel, 1, wx.ALL | wx.EXPAND)

        self.sizer = wx.BoxSizer(wx.VERTICAL)
        self.sizer.Add(self.startButton)
        self.sizer.Add(self.abortButton)
        self.sizer.Add((10, 10))
        self.sizer.Add(self.gauge)

        self.border = wx.BoxSizer()
        self.border.Add(self.sizer, 1, wx.ALL | wx.EXPAND, 5)

        self.panel.SetSizerAndFit(self.border)  
        self.SetSizerAndFit(self.windowSizer)   
        self.Show()

    def OnStartButton(self, e):
        self.startButton.Disable()
        self.abortButton.Enable()
        startWorker(self.LongTaskDone, self.LongTask)

    def OnAbortButton(self, e):
        self.shouldAbort = True

    def LongTask(self):
        for a in range(101):
            sleep(0.05)
            wx.CallAfter(self.gauge.SetValue, a)
            if self.shouldAbort:
                break
        return self.shouldAbort

    def LongTaskDone(self, result):
        r = result.get()
        if r:
            print("Aborted!")
        else:
            print("Ended!")
        self.startButton.Enable()
        self.abortButton.Disable()
        self.shouldAbort = False
        self.gauge.SetValue(0)

app = wx.App(False)
win = MainWindow(None)
app.MainLoop()

Example 2: Using standard threading module. In some cases this may be more "ugly". I would recommend using wx.lib.delayedresult. Official Documentation.

from time import sleep
from threading import Thread
import wx

class MainWindow(wx.Frame):
    def __init__(self, *args, **kwargs):
        wx.Frame.__init__(self, *args, **kwargs)

        self.panel = wx.Panel(self)
        self.startButton = wx.Button(self.panel, label="Long Task")
        self.abortButton = wx.Button(self.panel, label="Abort")
        self.abortButton.Disable()
        self.gauge = wx.Gauge(self.panel, size=(-1, 20))
        self.shouldAbort = False
        self.thread = None

        self.startButton.Bind(wx.EVT_BUTTON, self.OnStartButton)
        self.abortButton.Bind(wx.EVT_BUTTON, self.OnAbortButton)

        self.windowSizer = wx.BoxSizer()
        self.windowSizer.Add(self.panel, 1, wx.ALL | wx.EXPAND)

        self.sizer = wx.BoxSizer(wx.VERTICAL)
        self.sizer.Add(self.startButton)
        self.sizer.Add(self.abortButton)
        self.sizer.Add((10, 10))
        self.sizer.Add(self.gauge)

        self.border = wx.BoxSizer()
        self.border.Add(self.sizer, 1, wx.ALL | wx.EXPAND, 5)

        self.panel.SetSizerAndFit(self.border)  
        self.SetSizerAndFit(self.windowSizer)   
        self.Show()

    def OnStartButton(self, e):
        self.startButton.Disable()
        self.abortButton.Enable()
        self.thread = Thread(target=self.LongTask)
        self.thread.start()

    def OnAbortButton(self, e):
        self.shouldAbort = True

    def LongTask(self):
        for a in range(101):
            sleep(0.05)
            wx.CallAfter(self.gauge.SetValue, a)
            if self.shouldAbort:
                break
        wx.CallAfter(self.LongTaskDone, self.shouldAbort)

    def LongTaskDone(self, r):
        if r:
            print("Aborted!")
        else:
            print("Ended!")
        self.startButton.Enable()
        self.abortButton.Disable()
        self.shouldAbort = False
        self.gauge.SetValue(0)

app = wx.App(False)
win = MainWindow(None)
app.MainLoop()

Note: threading.Lock may be needed for thread-safe passing of more complicated variables and data than simple boolean flag.

Edit: Added examples.

Edit: Added ability to abort the thread.

Edit: Simplified the examples. Got rid of timer based on tom10's idea and also deleted threading.Lock as it is not needed here.

Answer 4

In wxPython, all calls to methods of GUI objects and event handlers need to happen in the main thread. Because of this, you need to be careful when using threading with wx, but it's usually easy to make the required modifications.

In your code, for example, you could do the call to wx.TextEntryDialog from the main thread, and then pass this information to the search thread.

If you need to request action of the GUI from the thread, the easiest way is to use wx.CallAfter, though there are other approaches that work as well.