I have a text file which acts as a source for program A and sink for
program B. Program B responsible for updating the file does so in regular
intervals of time and always overwrite the file. Program A that is reading
the file is constantly reading it and takes in the updated values whenever
that happens. It works fine for sometime. But eventually, Program A
crashes. The error shown is:
File "/home/../baba_rect.py", line 61, in on_draw
if (int(a[core_id]) <= 100):
ValueError: invalid literal for int() with base 10: ''
Here is the code for Program A:
import sys, time, math, os, random
from pyglet.gl import *
red = [255,0,0]
green = [0,255,0]
blue = [0,0,255]
black = [0,0,0]
dim_x = 2;
dim_y = 2;
window = pyglet.window.Window()
label = pyglet.text.Label('Simulation',
font_name='Times New Roman',
font_size=16,
color=(204,204,0,255), #red font (255,0,0)
opacity=255
x=window.width, y=window.height,
anchor_x='right', anchor_y='top')
class FilledSquare:
def __init__(self, width, height, xpos, ypos):
self.xpos = xpos
self.ypos = ypos
self.angle = 0
self.size = 1
x = width/2.0
y = height/2.0
self.vlist = pyglet.graphics.vertex_list(4, ('v2f', [-x,-y, x,-y,
-x,y, x,y]), ('t2f', [0,0, 1,0, 0,1, 1,1]))
def draw(self,w,h,x,y):
self.width=w
self.height=h
self.xpos=x
self.ypos=y
glPushMatrix()
glTranslatef(self.xpos, self.ypos, 0)
self.vlist.draw(GL_TRIANGLE_STRIP)
glPopMatrix()
@window.event
def on_draw():
window.clear()
glClearColor(0, 0.3, 0.5, 0)
glClear(GL_COLOR_BUFFER_BIT)
label.draw()
for i in range(0,dim_x):
for j in range(0,dim_y):
print i,",",j
#read file
f = open('r.txt', 'r')
a = f.readline()
a = a.rstrip('\n')
a = a.split(" ")
f.close()
#core_id
core_id = j*dim_x + i;
if (int(a[core_id]) <= 100):
color = red
elif (int(a[core_id]) <= 200):
color = green
elif (int(a[core_id]) <= 300):
color = blue
else:
color = black
glColor3f(color[0], color[1],color[2])
squares[i+j].draw(60,60,i*50+200,j*50+200)
squares = [FilledSquare(30, 30, 0, 0), FilledSquare(30, 30, 0, 0),
FilledSquare(30, 30, 0, 0), FilledSquare(30, 30, 0, 0)] # 2x2
pyglet.app.run()
This is how the text file *r.txt* may look like at any instant in time:
10 20 120 235
I believe the reason for the crash is because at that point, it so happens
that both Pgm A and Pgm B are accessing the file simultaneously and Pgm A
reads a *" "* instead of the number which can't be converted to int(). If
my conclusion is indeed true, then how can I overcome this?
Or: Is it possible to make pyglet.app.run() sensitive to any change to
*r.txt*? i.e. Pgm A runs only when there is a change in the text file, thus
avoiding the conflict.
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