From a04f0c15e8c0ef8d5b7df29955c932b95bc1d777 Mon Sep 17 00:00:00 2001
From: mailchuck <dev@mailchuck.com>
Date: Tue, 26 Jan 2016 13:01:28 +0100
Subject: [PATCH] Cleanup lockfile on exit

singleton.py design was broken.
Fixed Bitmessage#775
---
 src/bitmessagemain.py        |  4 +---
 src/bitmessageqt/__init__.py |  1 +
 src/shared.py                |  4 +++-
 src/singleton.py             | 24 ++++++++++++++----------
 4 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/src/bitmessagemain.py b/src/bitmessagemain.py
index 609c5580..64eec766 100755
--- a/src/bitmessagemain.py
+++ b/src/bitmessagemain.py
@@ -152,13 +152,11 @@ if shared.useVeryEasyProofOfWorkForTesting:
 
 class Main:
     def start(self, daemon=False):
-        global thisapp
-        
         _fixWinsock()
 
         shared.daemon = daemon
         # is the application already running?  If yes then exit.
-        thisapp = singleton.singleinstance("", daemon)
+        shared.thisapp = singleton.singleinstance("", daemon)
 
         # get curses flag
         curses = False
diff --git a/src/bitmessageqt/__init__.py b/src/bitmessageqt/__init__.py
index 62c58831..b3e98ec9 100644
--- a/src/bitmessageqt/__init__.py
+++ b/src/bitmessageqt/__init__.py
@@ -2843,6 +2843,7 @@ class MyForm(settingsmixin.SMainWindow):
 
         self.statusBar().showMessage(_translate(
             "MainWindow", "All done. Closing user interface..."))
+        shared.thisapp.cleanup()
         os._exit(0)
 
     # window close event
diff --git a/src/shared.py b/src/shared.py
index 2a62a178..8a8f7339 100644
--- a/src/shared.py
+++ b/src/shared.py
@@ -55,6 +55,7 @@ appdata = '' #holds the location of the application data storage directory
 statusIconColor = 'red'
 connectedHostsList = {} #List of hosts to which we are connected. Used to guarantee that the outgoingSynSender threads won't connect to the same remote node twice.
 shutdown = 0 #Set to 1 by the doCleanShutdown function. Used to tell the proof of work worker threads to exit.
+thisapp = None # singleton lock instance
 alreadyAttemptedConnectionsList = {
 }  # This is a list of nodes to which we have already attempted a connection
 alreadyAttemptedConnectionsListLock = threading.Lock()
@@ -392,7 +393,7 @@ def isProofOfWorkSufficient(data,
     return POW <= 2 ** 64 / (nonceTrialsPerByte*(len(data) + payloadLengthExtraBytes + ((TTL*(len(data)+payloadLengthExtraBytes))/(2 ** 16))))
 
 def doCleanShutdown():
-    global shutdown
+    global shutdown, thisapp
     shutdown = 1 #Used to tell proof of work worker threads and the objectProcessorThread to exit.
     broadcastToSendDataQueues((0, 'shutdown', 'no data'))   
     objectProcessorQueue.put(('checkShutdownVariable', 'no data'))
@@ -440,6 +441,7 @@ def doCleanShutdown():
 
     if safeConfigGetBoolean('bitmessagesettings','daemon'):
         logger.info('Clean shutdown complete.')
+        thisapp.cleanup()
         os._exit(0)
 
 # If you want to command all of the sendDataThreads to do something, like shutdown or send some data, this
diff --git a/src/singleton.py b/src/singleton.py
index f3124424..a4b6c678 100644
--- a/src/singleton.py
+++ b/src/singleton.py
@@ -1,10 +1,16 @@
 #! /usr/bin/env python
 
-import sys
-import os
+import atexit
 import errno
-import shared
 from multiprocessing import Process
+import os
+import sys
+import shared
+
+try:
+    import fcntl  # @UnresolvedImport
+except:
+    pass
 
 class singleinstance:
     """
@@ -14,9 +20,8 @@ class singleinstance:
     which is under the Python Software Foundation License version 2    
     """
     def __init__(self, flavor_id="", daemon=False):
-        import sys
         self.initialized = False
-        self.daemon = daemon;
+        self.daemon = daemon
         self.lockfile = os.path.normpath(os.path.join(shared.appdata, 'singleton%s.lock' % flavor_id))
 
         if not self.daemon:
@@ -38,7 +43,6 @@ class singleinstance:
                 print(e.errno)
                 raise
         else:  # non Windows
-            import fcntl  # @UnresolvedImport
             self.fp = open(self.lockfile, 'w')
             try:
                 fcntl.lockf(self.fp, fcntl.LOCK_EX | fcntl.LOCK_NB)
@@ -46,20 +50,20 @@ class singleinstance:
                 print 'Another instance of this application is already running'
                 sys.exit(-1)
         self.initialized = True
+        atexit.register(self.cleanup)
 
-    def __del__(self):
-        import sys
+    def cleanup(self):
         if not self.initialized:
             return
+        print "Cleaning up lockfile"
         try:
             if sys.platform == 'win32':
                 if hasattr(self, 'fd'):
                     os.close(self.fd)
                     os.unlink(self.lockfile)
             else:
-                import fcntl  # @UnresolvedImport
                 fcntl.lockf(self.fp, fcntl.LOCK_UN)
                 if os.path.isfile(self.lockfile):
                     os.unlink(self.lockfile)
         except Exception, e:
-            sys.exit(-1)
+            pass