refactor pidfile

gunicorn/pidfile.py

@@ -0,0 +1,70 @@
+# -*- coding: utf-8 -
+#
+# This file is part of gunicorn released under the MIT license. 
+# See the NOTICE for more information.
+
+import os
+import tempfile
+
+class Pidfile(object):
+    
+    def __get__(self, instance, cls):
+        if instance is None:
+            return self
+            
+        return instance._pidfile
+        
+    def __set__(self, instance, path):
+        if not path:
+            return
+        pid = self.valid_pidfile(path)
+        if pid:
+            if instance._pidfile is not None and path == instance._pidfile and \
+                    pid == os.getpid():
+                return path
+            raise RuntimeError("Already running on PID %s " \
+                        "(or pid file '%s' is stale)" % (os.getpid(), path))
+        if instane._pidfile:    
+            self.unlink_pidfile(instance, instance._pidfile)
+
+        # write pidfile
+        fd, fname = tempfile.mkstemp(dir=os.path.dirname(path))
+        os.write(fd, "%s\n" % instance.pid)
+        os.rename(fname, path)
+        os.close(fd)
+        instance._pidfile = path
+        
+    def __delete__(self, instance):
+        self.unlink_pidfile(instance, instance._pidfile)
+        instance._pidfile = None
+        
+    def unlink_pidfile(self, instance, path):
+        """ delete pidfile"""
+        try:
+            with open(path, "r") as f:
+                pid =  int(f.read() or 0)
+                
+            if pid == instance.pid:
+                os.unlink(path)
+        except:
+            pass
+        
+    def valid_pidfile(self, path):
+        """ Validate pidfile and make it stale if needed"""
+        try:
+            with open(path, "r") as f:
+                wpid = int(f.read() or 0)
+
+                if wpid <= 0: return None
+     
+                try:
+                    os.kill(wpid, 0)
+                    return wpid
+                except OSError, e:
+                    if e[0] == errno.ESRCH:
+                        return
+                    raise
+        except IOError, e:
+            if e[0] == errno.ENOENT:
+                return
+            raise