models: Add UserProfile.uuid field and backfill migrations.

zerver/migrations/0379_userprofile_uuid.py

@@ -0,0 +1,18 @@
+# Generated by Django 3.2.12 on 2022-03-05 14:40
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("zerver", "0378_alter_realmuserdefault_realm"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="userprofile",
+            name="uuid",
+            field=models.UUIDField(null=True, unique=True),
+        ),
+    ]

zerver/migrations/0380_userprofile_uuid_backfill.py

@@ -0,0 +1,40 @@
+import uuid
+
+from django.db import migrations, models
+from django.db.backends.postgresql.schema import DatabaseSchemaEditor
+from django.db.migrations.state import StateApps
+
+
+def backfill_user_profile_uuid(apps: StateApps, schema_editor: DatabaseSchemaEditor) -> None:
+    UserProfile = apps.get_model("zerver", "UserProfile")
+
+    max_id = UserProfile.objects.aggregate(models.Max("id"))["id__max"]
+    if max_id is None:
+        # Nothing to do if there are no users yet.
+        return
+
+    BATCH_SIZE = 10000
+    lower_bound = 0
+
+    while lower_bound < max_id:
+        user_profiles_to_update = []
+        for user_profile in UserProfile.objects.filter(
+            id__gt=lower_bound, id__lte=lower_bound + BATCH_SIZE, uuid=None
+        ).only("id", "uuid"):
+            user_profile.uuid = uuid.uuid4()
+            user_profiles_to_update.append(user_profile)
+        lower_bound += BATCH_SIZE
+
+        UserProfile.objects.bulk_update(user_profiles_to_update, ["uuid"])
+
+
+class Migration(migrations.Migration):
+    atomic = False
+
+    dependencies = [
+        ("zerver", "0379_userprofile_uuid"),
+    ]
+
+    operations = [
+        migrations.RunPython(backfill_user_profile_uuid, reverse_code=migrations.RunPython.noop),
+    ]

zerver/models.py

@@ -17,6 +17,7 @@ from typing import (
     TypeVar,
     Union,
 )
+from uuid import UUID, uuid4
 
 import django.contrib.auth
 import orjson
@@ -1688,6 +1689,12 @@ class UserProfile(AbstractBaseUser, PermissionsMixin, UserBaseSettings):
     tos_version: Optional[str] = models.CharField(null=True, max_length=10)
     api_key: str = models.CharField(max_length=API_KEY_LENGTH)
 
+    # A UUID generated on user creation. Introduced primarily to
+    # provide a unique key for a user for the mobile push
+    # notifications bouncer that will not have collisions after doing
+    # a data export and then import.
+    uuid: Optional[UUID] = models.UUIDField(null=True, default=uuid4, unique=True)
+
     # Whether the user has access to server-level administrator pages, like /activity
     is_staff: bool = models.BooleanField(default=False)