dvc: use zc.lockfile instead of fasteners

fasteners' InterProcessLock doesn't work within
one process, thus it is not suitable for our dvc
library.

Signed-off-by: Ruslan Kuprieiev <[email protected]>

dvc/lock.py

@@ -1,5 +1,7 @@
 import os
-import fasteners
+import time
+import zc.lockfile
+
 from dvc.exceptions import DvcException
 
 
@@ -13,18 +15,30 @@ class Lock(object):
 
     def __init__(self, dvc_dir):
         self.lock_file = os.path.join(dvc_dir, self.LOCK_FILE)
-        self._lock = fasteners.InterProcessLock(self.lock_file)
+        self._lock = None
 
     @staticmethod
     def init(dvc_dir):
         return Lock(dvc_dir)
 
-    def lock(self):
-        if not self._lock.acquire(timeout=self.TIMEOUT):
+    def _do_lock(self):
+        try:
+            self._lock = zc.lockfile.LockFile(self.lock_file)
+        except zc.lockfile.LockError:
             raise LockError('Cannot perform the cmd since DVC is busy and locked. Please retry the cmd later.')
 
+    def lock(self):
+        try:
+            self._do_lock()
+            return
+        except LockError:
+            time.sleep(self.TIMEOUT)
+
+        self._do_lock()
+
     def unlock(self):
-        self._lock.release()
+        self._lock.close()
+        self._lock = None
 
     def __enter__(self):
         self.lock()

requirements.txt

@@ -1,7 +1,7 @@
 boto>=2.46.1
 google-compute-engine>=2.4.1 #required by boto
 configparser>=3.5.0
-fasteners>=0.14.1
+zc.lockfile>=1.2.1
 future>=0.16.0
 google-cloud>=0.24.0
 PyInstaller>=3.2.1

setup.py

@@ -7,7 +7,7 @@ install_requires = [
     "boto>=2.46.1",
     "google-compute-engine>=2.4.1", #required by boto
     "configparser>=3.5.0",
-    "fasteners>=0.14.1",
+    "zc.lockfile>=1.2.1",
     "future>=0.16.0",
     "google-cloud>=0.24.0",
     "colorama>=0.3.9",

tests/test_lock.py

@@ -1,19 +1,21 @@
+from dvc.lock import LockError
+from dvc.main import main
 from dvc.lock import Lock
 
 from tests.basic_env import TestDvc
 
 
 class TestLock(TestDvc):
-    def test_lock(self):
-        lock = Lock(self.dvc.dvc_dir)
-        lock.lock()
-        self.assertTrue(lock._lock.exists())
-        self.assertTrue(lock._lock.acquired)
-        lock.unlock()
-        self.assertFalse(lock._lock.acquired)
-
     def test_with(self):
         lock = Lock(self.dvc.dvc_dir)
         with lock:
-            self.assertTrue(lock._lock.acquired)
-        self.assertFalse(lock._lock.acquired)
+            with self.assertRaises(LockError):
+                lock2 = Lock(self.dvc.dvc_dir)
+                with lock2:
+                    self.assertTrue(False)
+
+    def test_cli(self):
+        lock = Lock(self.dvc.dvc_dir)
+        with lock:
+            ret = main(['add', self.FOO])
+            self.assertEqual(ret, 1)