This commit was generated by cvs2svn to compensate for changes in r2,

[monitor.git] / util / process.py

diff --git a/util/process.py b/util/process.py
new file mode 100644 (file)
index 0000000..f74d856
--- /dev/null
+++ b/util/process.py
@@ -0,0 +1,68 @@
+#!/usr/bin/python
+#
+# Utility functions
+#
+# Mark Huang <mlhuang@cs.princeton.edu>
+# Copyright (C) 2006 The Trustees of Princeton University
+#
+# $Id: pl_mom.py,v 1.4 2006/06/02 04:00:00 mlhuang Exp $
+#
+
+import os
+import sys
+
+def writepid(prog):
+    """
+    Check PID file. Exit if already running. Update PID file.
+    """
+
+    try:
+        pidfile = file("/var/run/%s.pid" % prog, "r")
+        pid = pidfile.readline().strip()
+        pidfile.close()
+        if os.path.isdir("/proc/" + pid):
+            print "Error: Another copy of %s is still running (%s)" % (prog, pid)
+            sys.exit(1)
+    except IOError:
+        pass
+
+    pidfile = file("/var/run/%s.pid" % prog, "w")
+    pidfile.write(str(os.getpid()))
+    pidfile.close()
+
+
+def removepid(prog):
+    os.unlink("/var/run/%s.pid" % prog)
+
+
+def daemonize():
+    """
+    Daemonize self. Detach from terminal, close all open files, and fork twice.
+    """
+
+    pid = os.fork()
+    if pid == 0:
+        # Detach from terminal
+        os.setsid()
+        # Orphan myself
+        pid = os.fork()
+        if pid == 0:
+            os.chdir("/")
+        else:
+            os._exit(0)
+    else:
+        os._exit(0)
+
+    # Close all open file descriptors
+    import resource
+    maxfd = resource.getrlimit(resource.RLIMIT_NOFILE)[1]
+    if (maxfd == resource.RLIM_INFINITY):
+        maxfd = 1024
+    for fd in range(0, maxfd):
+        try:
+            os.close(fd)
+        except OSError:
+            pass
+
+    # Redirect stdin to /dev/null
+    os.open("/dev/null", os.O_RDWR)