From a1ecebf5bf62ef58fc5e9b5a5f00ae5d294b18e8 Mon Sep 17 00:00:00 2001
From: Daniel Pavel <daniel.pavel@gmail.com>
Date: Fri, 7 Jun 2013 14:24:05 +0200
Subject: [PATCH] documentation and logging for

---
 lib/solaar/appinstance.py | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/lib/solaar/appinstance.py b/lib/solaar/appinstance.py
index 5e149914..fe46bf3f 100644
--- a/lib/solaar/appinstance.py
+++ b/lib/solaar/appinstance.py
@@ -12,18 +12,26 @@ import fcntl as _fcntl
 import os.path as _path
 import os as _os
 
+from solaar import NAME
+_program = NAME.lower()
+del NAME
+
 from logging import getLogger, DEBUG as _DEBUG
-_log = getLogger('solaar.appinstance')
+_log = getLogger(__name__)
 del getLogger
 
 
 def check():
+	"""Select a file lock location and try to acquire it.
+	Suitable locations are $XDG_RUNTIME_DIR, /run/lock, /var/lock, and $TMPDIR.
+	The first one found and writable is used.
+	"""
 	# ensure no more than a single instance runs at a time
 	lock_fd = None
 	for p in _os.environ.get('XDG_RUNTIME_DIR'), '/run/lock', '/var/lock', _os.environ.get('TMPDIR', '/tmp'):
 		# pick the first temporary writable folder
 		if p and _path.isdir(p) and _os.access(p, _os.W_OK):
-			lock_path = _path.join(p, 'solaar.single-instance.%d' % _os.getuid())
+			lock_path = _path.join(p, _program + '.single-instance.' + str(_os.getuid()))
 			try:
 				lock_fd = open(lock_path, 'wb')
 				if _log.isEnabledFor(_DEBUG):
@@ -36,23 +44,24 @@ def check():
 		try:
 			_fcntl.flock(lock_fd, _fcntl.LOCK_EX | _fcntl.LOCK_NB)
 			if _log.isEnabledFor(_DEBUG):
-				_log.debug("acquired single-instance lock (%s)", lock_fd)
+				_log.debug("acquired single-instance lock %s", lock_fd)
 			return lock_fd
 		except IOError as e:
 			if e.errno == 11:
-				_log.warn("lock file is busy, solaar already running: %s", e)
+				_log.warn("lock file is busy, %s already running: %s", _program, e)
 				import sys
-				sys.exit("solaar: error: Solaar is already running.")
+				sys.exit(_program + ": error: already running")
 			else:
 				raise
 	else:
 		import sys
-		print ("solaar: warning: failed to create single instance lock file, ignoring.", file=sys.stderr)
+		print (_program + ": warning: no suitable location for the lockfile found; ignoring", file=sys.stderr)
 
 
 def close(lock_fd):
-	if _log.isEnabledFor(_DEBUG):
-		_log.debug("releasing single-instance lock (%s)", lock_fd)
+	"""Release a file lock."""
 	if lock_fd:
 		_fcntl.flock(lock_fd, _fcntl.LOCK_UN)
 		lock_fd.close()
+		if _log.isEnabledFor(_DEBUG):
+			_log.debug("released single-instance lock %s", lock_fd)