Replace lockfile with zc.lockfile. Ref #1193.

4 files changed, 15 insertions, 156 deletions

diff --git a/cherrypy/lib/lockfile.py b/cherrypy/lib/lockfile.py
deleted file mode 100644
index e1fe0b8c..00000000
--- a/cherrypy/lib/lockfile.py
+++ /dev/null
@@ -1,143 +0,0 @@
-"""
-Platform-independent file locking. Inspired by and modeled after zc.lockfile.
-"""
-
-import os
-
-try:
-    import msvcrt
-except ImportError:
-    pass
-
-try:
-    import fcntl
-except ImportError:
-    pass
-
-
-class LockError(Exception):
-
-    'Could not obtain a lock'
-
-    msg = 'Unable to lock %r'
-
-    def __init__(self, path):
-        super(LockError, self).__init__(self.msg % path)
-
-
-class UnlockError(LockError):
-
-    'Could not release a lock'
-
-    msg = 'Unable to unlock %r'
-
-
-# first, a default, naive locking implementation
-class NaiveLockFile(object):
-
-    """
-    A default, naive locking implementation. Always fails if the file
-    already exists.
-    """
-
-    def __init__(self, path):
-        self.path = path
-        try:
-            fd = os.open(path, os.O_CREAT | os.O_WRONLY | os.O_EXCL)
-        except OSError:
-            raise LockError(self.path)
-        os.close(fd)
-
-    def release(self):
-        os.remove(self.path)
-
-    def remove(self):
-        pass
-
-
-class SystemLockFile(object):
-
-    """
-    An abstract base class for platform-specific locking.
-    """
-
-    def __init__(self, path):
-        self.path = path
-
-        try:
-            # Open lockfile for writing without truncation:
-            self.fp = open(path, 'r+')
-        except IOError:
-            # If the file doesn't exist, IOError is raised; Use a+ instead.
-            # Note that there may be a race here. Multiple processes
-            # could fail on the r+ open and open the file a+, but only
-            # one will get the the lock and write a pid.
-            self.fp = open(path, 'a+')
-
-        try:
-            self._lock_file()
-        except Exception:
-            self.fp.seek(1)
-            self.fp.close()
-            del self.fp
-            raise
-
-        self.fp.write(' %s\n' % os.getpid())
-        self.fp.truncate()
-        self.fp.flush()
-
-    def release(self):
-        if not hasattr(self, 'fp'):
-            return
-        self._unlock_file()
-        self.fp.close()
-        del self.fp
-
-    def remove(self):
-        """
-        Attempt to remove the file
-        """
-        try:
-            os.remove(self.path)
-        except Exception:
-            pass
-
-    def _unlock_file(self):
-        """Attempt to obtain the lock on self.fp. Raise UnlockError if not
-        released."""
-
-
-class WindowsLockFile(SystemLockFile):
-
-    def _lock_file(self):
-        # Lock just the first byte
-        try:
-            msvcrt.locking(self.fp.fileno(), msvcrt.LK_NBLCK, 1)
-        except IOError:
-            raise LockError(self.fp.name)
-
-    def _unlock_file(self):
-        try:
-            self.fp.seek(0)
-            msvcrt.locking(self.fp.fileno(), msvcrt.LK_UNLCK, 1)
-        except IOError:
-            raise UnlockError(self.fp.name)
-
-
-class UnixLockFile(SystemLockFile):
-
-    def _lock_file(self):
-        flags = fcntl.LOCK_EX | fcntl.LOCK_NB
-        try:
-            fcntl.flock(self.fp.fileno(), flags)
-        except IOError:
-            raise LockError(self.fp.name)
-
-    # no need to implement _unlock_file, it will be unlocked on close()
-
-
-LockFile = (
-    UnixLockFile if 'fcntl' in globals() else
-    WindowsLockFile if 'msvcrt' in globals() else
-    NaiveLockFile
-)
diff --git a/cherrypy/lib/sessions.py b/cherrypy/lib/sessions.py
index 758e9591..5b49ee13 100644
--- a/cherrypy/lib/sessions.py
+++ b/cherrypy/lib/sessions.py
@@ -109,13 +109,20 @@ import binascii
 
 import six
 from six.moves import cPickle as pickle
+import contextlib2
+
+import zc.lockfile
 
 import cherrypy
 from cherrypy.lib import httputil
-from cherrypy.lib import lockfile
 from cherrypy.lib import locking
 from cherrypy.lib import is_iterator
 
+
+if six.PY2:
+    FileNotFoundError = OSError
+
+
 missing = object()
 
 
@@ -553,8 +560,8 @@ class FileSession(Session):
         checker = locking.LockChecker(self.id, self.lock_timeout)
         while not checker.expired():
             try:
-                self.lock = lockfile.LockFile(path)
-            except lockfile.LockError:
+                self.lock = zc.lockfile.LockFile(path)
+            except zc.lockfile.LockError:
                 time.sleep(0.1)
             else:
                 break
@@ -564,8 +571,9 @@ class FileSession(Session):
 
     def release_lock(self, path=None):
         """Release the lock on the currently-loaded session data."""
-        self.lock.release()
-        self.lock.remove()
+        self.lock.close()
+        with contextlib2.suppress(FileNotFoundError):
+            os.remove(self.lock._path)
         self.locked = False
 
     def clean_up(self):
diff --git a/docs/pkg/cherrypy.lib.rst b/docs/pkg/cherrypy.lib.rst
index 49f10d42..8df1261c 100644
--- a/docs/pkg/cherrypy.lib.rst
+++ b/docs/pkg/cherrypy.lib.rst
@@ -84,14 +84,6 @@ cherrypy.lib.jsontools module
     :undoc-members:
     :show-inheritance:
 
-cherrypy.lib.lockfile module
-----------------------------
-
-.. automodule:: cherrypy.lib.lockfile
-    :members:
-    :undoc-members:
-    :show-inheritance:
-
 cherrypy.lib.locking module
 ---------------------------
 
diff --git a/setup.py b/setup.py
index 79886904..2e6e9d1a 100755
--- a/setup.py
+++ b/setup.py
@@ -64,6 +64,8 @@ params = dict(
         'cheroot>=6.2.4',
         'portend>=2.1.1',
         'more_itertools',
+        'zc.lockfile',
+        'contextlib2',
     ],
     extras_require={
         'docs': [