build: use a contextmanager for locks

Also don't bother passing logfile to exec_func_python, at least until we start
adding the logfile as a file handler to the bitbake logger.

(Bitbake rev: f99ee4680c9f67b7ed13fc06044ba2382f9a782c)

Signed-off-by: Chris Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

bitbake/lib/bb/utils.py

@@ -26,6 +26,7 @@ import logging
 import bb
 import bb.msg
 from commands import getstatusoutput
+from contextlib import contextmanager
 
 logger = logging.getLogger("BitBake.Util")
 
@@ -398,6 +399,18 @@ def simple_exec(code, context):
 def better_eval(source, locals):
     return eval(source, _context, locals)
 
+@contextmanager
+def fileslocked(files):
+    locks = []
+    if files:
+        for lockfile in files:
+            locks.append(bb.utils.lockfile(lock))
+
+    yield
+
+    for lock in locks:
+        bb.utils.unlockfile(lock)
+
 def lockfile(name):
     """
     Use the file fn as a lock file, return when the lock has been acquired.