diff options
Diffstat (limited to 'lib/spack/llnl/util/lock.py')
| -rw-r--r-- | lib/spack/llnl/util/lock.py | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/lib/spack/llnl/util/lock.py b/lib/spack/llnl/util/lock.py index 0d072418cc..794b201668 100644 --- a/lib/spack/llnl/util/lock.py +++ b/lib/spack/llnl/util/lock.py @@ -51,7 +51,7 @@ class Lock(object): is enabled) and recent NFS versions. """ - def __init__(self, path, start=0, length=0): + def __init__(self, path, start=0, length=0, debug=False): """Construct a new lock on the file at ``path``. By default, the lock applies to the whole file. Optionally, @@ -72,7 +72,10 @@ class Lock(object): self._start = start self._length = length - # PID and host of lock holder + # enable debug mode + self.debug = debug + + # PID and host of lock holder (only used in debug mode) self.pid = self.old_pid = None self.host = self.old_host = None @@ -118,12 +121,14 @@ class Lock(object): fcntl.lockf(self._file, op | fcntl.LOCK_NB, self._length, self._start, os.SEEK_SET) - # All locks read the owner PID and host - self._read_lock_data() + # help for debugging distributed locking + if self.debug: + # All locks read the owner PID and host + self._read_debug_data() - # Exclusive locks write their PID/host - if op == fcntl.LOCK_EX: - self._write_lock_data() + # Exclusive locks write their PID/host + if op == fcntl.LOCK_EX: + self._write_debug_data() return @@ -148,15 +153,19 @@ class Lock(object): e.errno == errno.EISDIR): raise - def _read_lock_data(self): + def _read_debug_data(self): """Read PID and host data out of the file if it is there.""" + self.old_pid = self.pid + self.old_host = self.host + line = self._file.read() if line: pid, host = line.strip().split(',') _, _, self.pid = pid.rpartition('=') _, _, self.host = host.rpartition('=') + self.pid = int(self.pid) - def _write_lock_data(self): + def _write_debug_data(self): """Write PID and host data to the file, recording old values.""" self.old_pid = self.pid self.old_host = self.host |