sendreports now can be run concurrently too

hc/api/management/commands/sendreports.py

@@ -30,6 +30,7 @@ class Command(BaseCommand):
     def handle_one_run(self):
         now = timezone.now()
         month_before = now - timedelta(days=30)
+        month_after = now + timedelta(days=30)
 
         report_due = Q(next_report_date__lt=now)
         report_not_scheduled = Q(next_report_date__isnull=True)
@@ -37,12 +38,25 @@ class Command(BaseCommand):
         q = Profile.objects.filter(report_due | report_not_scheduled)
         q = q.filter(reports_allowed=True)
         q = q.filter(user__date_joined__lt=month_before)
+        profiles = list(q)
+
         sent = 0
-        for profile in q:
-            if num_pinged_checks(profile) > 0:
-                self.stdout.write(self.tmpl % profile.user.email)
-                profile.send_report()
-                sent += 1
+        for profile in profiles:
+            qq = Profile.objects
+            qq = qq.filter(id=profile.id,
+                           next_report_date=profile.next_report_date)
+
+            num_updated = qq.update(next_report_date=month_after)
+            if num_updated != 1:
+                # Was updated elsewhere, skipping
+                continue
+
+            if num_pinged_checks(profile) == 0:
+                continue
+
+            self.stdout.write(self.tmpl % profile.user.email)
+            profile.send_report()
+            sent += 1
 
         return sent