PYTHON-979 - Use fsync command

Author: aherlihy

pymongo/mongo_client.py

@@ -43,6 +43,7 @@
 from bson.son import SON
 from pymongo import (common,
  database,
+ helpers,
  message,
  periodic_executor,
  uri_parser)
@@ -1091,9 +1092,18 @@ def fsync(self, **kwargs):
  def unlock(self):
  """Unlock a previously locked server.
  """
- coll = self.admin.get_collection(
- "$cmd.sys.unlock", read_preference=ReadPreference.PRIMARY)
- coll.find_one()
+ with self._socket_for_writes() as sock_info:
+ if sock_info.max_wire_version >= 4:
+ try:
+ sock_info.command("admin", {"fsyncUnlock": 1})
+ except OperationFailure as exc:
+ # Ignore "DB not locked" to replicate old behavior
+ if exc.code != 125:
+ raise
+ else:
+ helpers._first_batch(sock_info, "admin.$cmd.sys.unlock",
+ {}, -1, True, self.codec_options, ReadPreference.PRIMARY)
+
 
  def __enter__(self):
  return self