def get_fullpath(mod_dir, mod_name, oid, opts={}):
suffix = build_suffix(mod_name, opts)
if suffix:
store_name = COMPONENT_DELIM.join([oid, suffix])
else:
store_name = oid
filename_fp = os.path.join(mod_dir, store_name)
return filename_fp
def acquire_file_lock(modname, oid, opts, write=False, delay=1, timeout=10):
lockid, lockfile = get_lockfilename(modname, oid, opts)
logger.debug("Locking %s", lockfile)
suffix = build_suffix(modname, opts)
start_time = time.time()
while True:
# Since during processing the lockfile name might change and yet fail
# to open, get the lockfile fresh every iteration of the loop.
lockid, lockfile = get_lockfilename(modname, oid, opts)
try:
# If we have the lock already. Just return.
if lockid in locked_files:
break
# If someone else is writing, we need to wait.
if not os.path.isfile(lockfile+".write"):
other_read_locks = glob(lockfile+"*")
# If someone else is reading...
if other_read_locks:
# If we want to write, we need to wait
if write:
break
# For reading, get the next read lock
lockfile = lockfile + "." + \
str(max([int(s.rsplit('.',1)[-1]) for s in other_read_locks])+1)
# No one else is reading or writing
else:
if write:
lockfile = lockfile + ".write"
else:
lockfile = lockfile + ".0"
fp = os.open(lockfile, os.O_CREAT|os.O_EXCL|os.O_RDWR)
# if we get here, we've got the lock
locked_files[lockid] = dict(fp=fp, mod=modname, oid=oid, suffix=suffix, name=lockfile)
break
except OSError, e:
if e.errno != errno.EEXIST:
logger.error("Unexpected os error trying to get lockfile %s.", lockfile)
print "failed:", e
raise
elif (time.time() - start_time) >= timeout:
logger.error("File locking timeout on lockfile %s.", lockfile)
print "failed:", e
raise
time.sleep(delay)
def get_lockfilename(modname, oid, opts):
lockid = oid + '_' + build_suffix(modname, opts) + "_" + modname
return lockid, os.path.join(datastore_dir, lockid+".lock")