Merge lp:~ovais-tariq/twindb-agent/bug-1409358 into lp:twindb-agent

[Ovais Tariq]

[Aleksandr Kuzminsky (akuzminsky)]

review: Approve

=== modified file 'twindb.py'
--- twindb.py	2015-04-10 17:38:22 +0000
+++ twindb.py	2015-04-12 22:47:52 +0000
@@ -1964,21 +1964,14 @@
                     return False
                 else:
                     # It's some other process, not a twindb agent
-                    return True
+                    remove_pid()
             except IOError as err:
-                logger.error("Can't read from file /proc/%d/cmdline:%s " % (pid, err))
-                return False
+                remove_pid()
         else:
-            try:
-                os.remove(pid_file)
-                # It's a stale pid file
-                return True
-            except IOError as err:
-                logger.error("Can't remove file %s: %s" % (pid_file, err))
-                return False
-    else:
-        # pid file doesn't exist
-        return True
+            remove_pid()
+
+    # pid file doesn't exist
+    return True
 
 
 def read_pid():
@@ -2051,12 +2044,14 @@
         logger.info("Pid file %s does not exist. Probably twindb agent isn't running" % pid_file)
         sys.exit(0)
     pid = None
+
     try:
-        f = open(pid_file, 'r')
-        pid = int(f.readline())
-        os.kill(pid, signal.SIGTERM)
-        wait_pid(pid, 300)
-        f.close()
+        pid = read_pid()
+
+        if pid_exists(pid):
+            os.kill(pid, signal.SIGTERM)
+            wait_pid(pid, 300)
+
         remove_pid()
     except OSError as err:
         logger.error("Couldn't kill process %d" % pid)
@@ -2064,6 +2059,7 @@
     except IOError as err:
         logger.error("Couldn't read from %s" % pid_file)
         exit_on_error(err)
+
     logger.info("TwinDB agent successfully shut down")
     sys.exit(0)
 
@@ -2076,10 +2072,6 @@
     global job_id
     logger.info("Starting TwinDB agent")
 
-    if check_pid():
-        write_pid()
-    else:
-        exit_on_error("Another instance of TwinDB agent is running. Exiting")
     try:
         while True:
             read_config()
@@ -2263,6 +2255,13 @@
         check_period = 1
 
     if action == "start":
+        # Create the PID if it does not already exist
+        # If the PID already exists then we bail out
+        if check_pid():
+            write_pid()
+        else:
+            exit_on_error("Another instance of TwinDB agent is running. Exiting")
+
         while True:
             # It'll keep checking until the agent is registered
             # Then it starts