lock: print msg if dvc is busy

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

dvc/command/common/base.py

@@ -3,6 +3,7 @@ import os
 from dvc.project import Project
 from dvc.logger import Logger
 from dvc.exceptions import DvcException
+from dvc.lock import LockError
 
 
 class CmdBase(object):
@@ -26,8 +27,12 @@ class CmdBase(object):
         raise DvcException(msg.format(root))
 
     def run_cmd(self):
-        with self.project.lock:
+        try:
+            with self.project.lock:
                 return self.run()
+        except LockError as ex:
+            self.project.logger.error(str(ex)) 
+            return 1
 
     # Abstract methods that have to be implemented by any inheritance class
     def run(self):

dvc/lock.py

@@ -1,5 +1,11 @@
 import os
 import fasteners
+from dvc.exceptions import DvcException
+
+
+class LockError(DvcException):
+    pass
+
 
 class Lock(object):
     LOCK_FILE = 'lock'
@@ -14,7 +20,8 @@ class Lock(object):
         return Lock(dvc_dir)
 
     def lock(self):
-        self._lock.acquire(timeout=self.TIMEOUT)
+        if not self._lock.acquire(timeout=self.TIMEOUT):
+            raise LockError('Cannot perform the cmd since DVC is busy and locked. Please retry the cmd later.')
 
     def unlock(self):
         self._lock.release()