From 28588269215aebf36c89cbb4c1b8014929340ac4 Mon Sep 17 00:00:00 2001
From: Daniel Thompson <daniel@redfelineninja.org.uk>
Date: Wed, 28 Jul 2021 22:01:04 +0100
Subject: [PATCH] apps: Replace del self.x with self.x = None in all apps

Testing has demonstrated that del self.x does not make the memory used to
store x available for garbage collection.

There is clearly an additional reference from another place. In fact
*after* del self.x then the memory can be made available for GC by
assignment (e.g. self.x = None). However I haven't found how to release
this reference and there is nothing in self.__dict__ that can help.

For now we'll use a twp-step process where we set the variable to None
before deleting it.

This has a big impact on memory usage. For Software it is almost 1k
(a.k.a. about 10% impact on free RAM).

Signed-off-by: Daniel Thompson <daniel@redfelineninja.org.uk>
---
 wasp/apps/alarm.py    | 7 ++++++-
 wasp/apps/faces.py    | 3 +++
 wasp/apps/software.py | 3 +++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/wasp/apps/alarm.py b/wasp/apps/alarm.py
index 4d87b0c..1792bc6 100644
--- a/wasp/apps/alarm.py
+++ b/wasp/apps/alarm.py
@@ -124,10 +124,15 @@ class AlarmApp:
 
         self.page = _HOME_PAGE
 
+        self.del_alarm_btn = None
         del self.del_alarm_btn
+        self.hours_wid = None
         del self.hours_wid
+        self.min_wid = None
         del self.min_wid
+        self.alarm_checks = None
         del self.alarm_checks
+        self.day_btns = None
         del self.day_btns
 
         self._set_pending_alarms()
@@ -373,4 +378,4 @@ class AlarmApp:
         elif days == 0:
             return "once"
         else:
-            return "cust"
\ No newline at end of file
+            return "cust"
diff --git a/wasp/apps/faces.py b/wasp/apps/faces.py
index 7e3ed3e..9ce8083 100644
--- a/wasp/apps/faces.py
+++ b/wasp/apps/faces.py
@@ -37,8 +37,11 @@ class FacesApp():
         wasp.system.request_event(wasp.EventMask.SWIPE_UPDOWN)
 
     def background(self):
+        self.choices = None
         del self.choices
+        self.choice = None
         del self.choice
+        self.si = None
         del self.si
 
         # When the watch face redraws then the change to the scrolling indicator
diff --git a/wasp/apps/software.py b/wasp/apps/software.py
index 9e764bc..91bde38 100644
--- a/wasp/apps/software.py
+++ b/wasp/apps/software.py
@@ -67,8 +67,11 @@ class SoftwareApp():
                                   wasp.EventMask.SWIPE_UPDOWN)
 
     def background(self):
+        self.si = None
         del self.si
+        self.page = None
         del self.page
+        self.db = None
         del self.db
 
     def get_page(self):