persist_data: implement comparison, same as dict

Signed-off-by: Chris Larson <chris_larson@mentor.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/lib/bb/persist_data.py b/lib/bb/persist_data.py
index af96b76f4..03adc7cc5 100644
--- a/lib/bb/persist_data.py
+++ b/lib/bb/persist_data.py
@@ -26,7 +26,8 @@ import logging
 import os.path
 import sys
 import warnings
-import bb.msg, bb.data, bb.utils
+from bb.compat import total_ordering
+from collections import Mapping
 
 try:
     import sqlite3
@@ -43,6 +44,7 @@ if hasattr(sqlite3, 'enable_shared_cache'):
     sqlite3.enable_shared_cache(True)
 
 
+@total_ordering
 class SQLTable(collections.MutableMapping):
     """Object representing a table/domain in the database"""
     def __init__(self, cursor, table):
@@ -102,6 +104,12 @@ class SQLTable(collections.MutableMapping):
         data = self._execute("SELECT key FROM %s;" % self.table)
         return (row[0] for row in data)
 
+    def __lt__(self, other):
+        if not isinstance(other, Mapping):
+            raise NotImplemented
+
+        return len(self) < len(other)
+
     def values(self):
         return list(self.itervalues())
 
@@ -175,6 +183,7 @@ def connect(database):
 
 def persist(domain, d):
     """Convenience factory for SQLTable objects based upon metadata"""
+    import bb.data, bb.utils
     cachedir = (bb.data.getVar("PERSISTENT_DIR", d, True) or
                 bb.data.getVar("CACHE", d, True))
     if not cachedir: