Upload the contribution of vstf as bottleneck network framework.

[bottlenecks.git] / vstf / vstf / common / daemon.py

diff --git a/vstf/vstf/common/daemon.py b/vstf/vstf/common/daemon.py
new file mode 100755 (executable)
index 0000000..8a29861
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+++ b/vstf/vstf/common/daemon.py
@@ -0,0 +1,145 @@
+#!/usr/bin/env python
+import sys, os, time, atexit
+import logging
+from signal import SIGTERM
+
+LOG = logging.getLogger(__name__)
+
+
+class Daemon(object):
+    """
+    A generic daemon class.
+    
+    Usage: subclass the Daemon class and override the run() method
+    """
+    def __init__(self, pidfile, stdin='/dev/null', stdout='/dev/null', stderr='/dev/null'):
+        super(Daemon, self).__init__()
+        self.stdin = stdin
+        self.stdout = stdout
+        self.stderr = stderr
+        self.pidfile = pidfile
+    
+    def daemonize(self):
+        """
+        do the UNIX double-fork magic, see Stevens' "Advanced 
+        Programming in the UNIX Environment" for details (ISBN 0201563177)
+        http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC16
+        """
+        try: 
+            pid = os.fork() 
+            if pid > 0:
+                sys.exit(0) 
+        except OSError, e: 
+            LOG.error("fork #1 failed: %(errno)s, %(strerror)s",
+                      {'errno':e.errno, 'strerror': e.strerror})
+            sys.exit(1)
+    
+        # decouple from parent environment
+        os.chdir("/") 
+        os.setsid() 
+        os.umask(0) 
+    
+        # do second fork
+        try: 
+            pid = os.fork() 
+            if pid > 0:
+                # exit from second parent
+                sys.exit(0) 
+        except OSError, e: 
+            LOG.error("fork #1 failed: %(errno)s, %(strerror)s",
+                      {'errno':e.errno, 'strerror': e.strerror})
+            sys.exit(1) 
+    
+        # redirect standard file descriptors
+        sys.stdout.flush()
+        sys.stderr.flush()
+        si = file(self.stdin, 'r')
+        so = file(self.stdout, 'a+')
+        se = file(self.stderr, 'a+', 0)
+        os.dup2(si.fileno(), sys.stdin.fileno())
+        os.dup2(so.fileno(), sys.stdout.fileno())
+        os.dup2(se.fileno(), sys.stderr.fileno())
+    
+        # write pidfile
+        atexit.register(self.delpid)
+        pid = str(os.getpid())
+        file(self.pidfile,'w+').write("%s\n" % pid)
+    
+    def delpid(self):
+        os.remove(self.pidfile)
+
+    def start(self):
+        """
+        Start the daemon
+        """
+        
+        # Check for a pidfile to see if the daemon already runs
+        try:
+            pf = file(self.pidfile,'r')
+            pid = int(pf.read().strip())
+            pf.close()
+        except IOError:
+            pid = None
+    
+        if pid:
+            message = "pidfile %s already exist. Daemon already running?\n"
+            sys.stderr.write(message % self.pidfile)
+            sys.exit(1)
+        LOG.info("daemon start to run daemonize")
+        # Start the daemon
+        self.daemonize()
+        self.run()
+
+    def stop(self):
+        """
+        Stop the daemon
+        """
+        # Get the pid from the pidfile
+        try:
+            pf = file(self.pidfile,'r')
+            pid = int(pf.read().strip())
+            pf.close()
+        except IOError:
+            pid = None
+    
+        if not pid:
+            message = "pidfile %s does not exist. Daemon not running?\n"
+            sys.stderr.write(message % self.pidfile)
+            return # not an error in a restart
+
+        # Try killing the daemon process    
+        try:
+            while 1:
+                os.kill(pid, SIGTERM)
+                time.sleep(0.1)
+        except OSError, err:
+            err = str(err)
+            if err.find("No such process") > 0:
+                if os.path.exists(self.pidfile):
+                    os.remove(self.pidfile)
+            else:
+                print str(err)
+                sys.exit(1)
+
+    def restart(self):
+        """
+        Restart the daemon
+        """
+        self.stop()
+        self.start()
+
+    def run(self):
+        """
+        You should override this method when you subclass Daemon. 
+        It will be called after the process has been
+        daemonized by start() or restart().
+        
+        """
+        pass
+        
+    def daemon_die(self):
+        """You should this method when you shutdown daemon
+        this func will be call by stop() before kill the process
+        
+        """
+        pass
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