Hi,
Vladimir Pouzanov wrote:
Is there any way to read stdin line by line without blocking? My application
receives data over stdin (one command per line) and should react immediately.
Your story sounds a lot like the world of confusion and pain I found
myself in when I wanted to read a pipe in an async way. I couldn't find
a way that actually worked in a decent way. Here is my non-decent way of
reading a pipe. Pure distilled madness.
-----------------------------------------------
#!/usr/bin/python
import os
import sys
import time
from PyQt4 import QtCore
# Frequency to poll the file for more data.
POLL_INTERVAL = 250 #ms
# Maximum amount of time to use reading logs without returning to the
main event loop.
MAX_TIME_SLICE= 0.1 # seconds
class LogReader(QtCore.QObject):
def __init__(self, filename):
QtCore.QObject.__init__(self)
self.filename = filename
self.log_file = None
self.connectToFile()
def connectToFile(self):
if self.log_file is not None:
gobject.source_remove(self.log_event_source)
self.log_file.close()
self.log_file = None
self.log_file_fd = os.open(self.filename,os.O_RDONLY|os.O_NONBLOCK)
self.log_file = os.fdopen(self.log_file_fd,"r")
self.timer_id = self.startTimer(0)
def timerEvent(self,event):
if event.timerId()==self.timer_id:
self.killTimer(self.timer_id)
self.timer_id = None
self.fileReady()
else:
QObject.timerEvent(self,event)
def fileReady(self):
try:
enter_time = time.time()
restart_time = POLL_INTERVAL
while True:
data = self.log_file.readline()
if data=="":
break
self.emit(QtCore.SIGNAL("newLine"), data)
new_time = time.time()
if (new_time-enter_time) > MAX_TIME_SLICE:
restart_time = 0
break
self.timer_id = self.startTimer(restart_time)
except IOError,e:
self.connectToFile()
def handleLine(self, line):
print line
def main():
app = QtCore.QCoreApplication(sys.argv)
log_reader = LogReader("/var/log/messages")
app.exec_()
if __name__=="__main__":
main()
-----------------------------------------------
--
Simon Edwards | KDE-NL, Guidance tools, Guarddog Firewall
[EMAIL PROTECTED] | http://www.simonzone.com/software/
Nijmegen, The Netherlands | "ZooTV? You made the right choice."
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