Lock column updates

dataset/table.py

@@ -56,6 +56,7 @@ class Table(object):
         """Get a dictionary of all columns and their case mapping."""
         if not self.exists:
             return {}
+        with self.db.lock:
             if self._columns is None:
                 # Initialise the table if it doesn't exist
                 table = self.table
@@ -68,6 +69,10 @@ class Table(object):
                     self._columns[key] = name
             return self._columns
 
+    def _flush_metadata(self):
+        with self.db.lock:
+            self._columns = None
+
     @property
     def columns(self):
         """Get a listing of all columns that exist in the table."""
@@ -305,7 +310,7 @@ class Table(object):
     def _reflect_table(self):
         """Load the tables definition from the database."""
         with self.db.lock:
-            self._columns = None
+            self._flush_metadata()
             try:
                 self._table = SQLATable(self.name,
                                         self.db.metadata,
@@ -323,7 +328,7 @@ class Table(object):
 
     def _sync_table(self, columns):
         """Lazy load, create or adapt the table structure in the database."""
-        self._columns = None
+        self._flush_metadata()
         if self._table is None:
             # Load an existing table from the database.
             self._reflect_table()
@@ -520,7 +525,7 @@ class Table(object):
                 self._threading_warn()
                 self.table.drop(self.db.executable, checkfirst=True)
                 self._table = None
-                self._columns = None
+                self._flush_metadata()
 
     def has_index(self, columns):
         """Check if an index exists to cover the given ``columns``."""