From b3d9b3709dd00e2fd55d42b227425425bf8a9fac Mon Sep 17 00:00:00 2001
From: Benjamin Dauvergne <bdauvergne@entrouvert.com>
Date: Thu, 15 Sep 2022 12:25:15 +0200
Subject: [PATCH] sql: load Evolution.parts lazily from database (#69109)

---
 wcs/sql.py | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 62 insertions(+), 1 deletion(-)

diff --git a/wcs/sql.py b/wcs/sql.py
index 03fe92ec3..c56b9b4ee 100644
--- a/wcs/sql.py
+++ b/wcs/sql.py
@@ -102,6 +102,67 @@ def like_escape(value):
     return value
 
 
+class LazyPickleList(list):
+    def __init__(self, dump):
+        self.dump = dump
+
+    def _load(self):
+        try:
+            dump = super().__getattribute__('dump')
+        except AttributeError:
+            pass
+        else:
+            super().__setitem__(slice(0), pickle.loads(dump))
+            del self.dump
+
+    def __getattribute__(self, name):
+        super().__getattribute__('_load')()
+        return super().__getattribute__(name)
+
+    def __bool__(self):
+        self._load()
+        return bool(len(self))
+
+    def __iter__(self):
+        self._load()
+        return super().__iter__()
+
+    def __len__(self):
+        self._load()
+        return super().__len__()
+
+    def __reversed__(self):
+        self._load()
+        return super().__reversed__()
+
+    def __str__(self):
+        self._load()
+        return super().__str__()
+
+    def __getitem__(self, index):
+        self._load()
+        return super().__getitem__(index)
+
+    def __setitem__(self, index, value):
+        self._load()
+        return super().__setitem__(index, value)
+
+    def __delitem__(self, index):
+        self._load()
+        return super().__delitem__(index)
+
+    def __iadd__(self, values):
+        self._load()
+        return super().__add__(values)
+
+    def __contains__(self, value):
+        self._load()
+        return super().__contains__(value)
+
+    def __reduce__(self):
+        return (list, (), None, iter(self))
+
+
 def pickle_loads(value):
     if hasattr(value, 'tobytes'):
         value = value.tobytes()
@@ -2574,7 +2635,7 @@ class SqlDataMixin(SqlMixin):
         if o.time:
             o.time = o.time.timetuple()
         if row[6]:
-            o.parts = pickle_loads(row[6])
+            o.parts = LazyPickleList(row[6])
         return o
 
     def set_evolution(self, value):
-- 
2.37.2