server/process: Improve lockfile handling at exit

If memory resident bitbake is active and the build directory is renamed upon
build completion, several bad things can happen:

* the old build directory could be re-created to contain a lockfile
  leaving an empty directory behind
* a lockfile for a new build could be found and attempt to be locked

This patch avoids creating an empty directory (not perfectly, but should
work in the majority of cases - an empty directory is cosmetic).

It also now compares the lock file contents to it's own pid and
just exits if it doesn't match, it is clearly then belonging to some
new process.

This will be combined with bitbake shutdown calls on the autobuilder to
ensure "saved" build directories, or build directories being deleted by
clobberdir don't do strange things.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 5 insertions, 4 deletions

diff --git a/lib/bb/server/process.py b/lib/bb/server/process.py
index 529196b78..8d12f00bd 100644
--- a/lib/bb/server/process.py
+++ b/lib/bb/server/process.py
@@ -361,20 +361,21 @@ class ProcessServer():
             except FileNotFoundError:
                 return None
 
-        lockcontents = get_lock_contents(lockfile)
-        serverlog("Original lockfile contents: " + str(lockcontents))
-
         lock.close()
         lock = None
 
         while not lock:
             i = 0
             lock = None
+            if not os.path.exists(os.path.basename(lockfile)):
+                serverlog("Lockfile directory gone, exiting.")
+                return
+
             while not lock and i < 30:
                 lock = bb.utils.lockfile(lockfile, shared=False, retry=False, block=False)
                 if not lock:
                     newlockcontents = get_lock_contents(lockfile)
-                    if newlockcontents != lockcontents:
+                    if not newlockcontents.startswith([os.getpid() + "\n", os.getpid() + " "]):
                         # A new server was started, the lockfile contents changed, we can exit
                         serverlog("Lockfile now contains different contents, exiting: " + str(newlockcontents))
                         return