implement database migrations and add delivery_attempts and next_delivery_attempt_at columns to lxmf messages table

database.py

@@ -1,8 +1,24 @@
 from datetime import datetime, timezone
 
 from peewee import *
+from playhouse.migrate import migrate as migrate_database, SqliteMigrator
 
+latest_version = 2  # increment each time new database migrations are added
 database = DatabaseProxy()  # use a proxy object, as we will init real db client inside web.py
+migrator = SqliteMigrator(database)
+
+
+# migrates the database
+def migrate(current_version):
+
+    # migrate to version 2
+    if current_version < 2:
+        migrate_database(
+            migrator.add_column("lxmf_messages", 'delivery_attempts', LxmfMessage.delivery_attempts),
+            migrator.add_column("lxmf_messages", 'next_delivery_attempt_at', LxmfMessage.next_delivery_attempt_at),
+        )
+
+    return latest_version
 
 
 class BaseModel(Model):
@@ -49,6 +65,8 @@ class LxmfMessage(BaseModel):
     state = CharField()  # state is converted from internal int to a human friendly string
     progress = FloatField()  # progress is converted from internal float 0.00-1.00 to float between 0.00/100 (2 decimal places)
     is_incoming = BooleanField()  # if true, we should ignore state, it's set to draft by default on incoming messages
+    delivery_attempts = IntegerField(default=0)  # how many times delivery has been attempted for this message
+    next_delivery_attempt_at = FloatField(null=True)  # timestamp of when the message will attempt delivery again
     title = TextField()
     content = TextField()
     fields = TextField()  # json string

web.py

@@ -57,6 +57,9 @@ class ReticulumMeshChat:
         self.database_path = os.path.join(self.storage_path, "database.db")
         lxmf_router_path = os.path.join(self.storage_path, "lxmf_router")
 
+        # check if database already exists, before initialization
+        database_already_exists = os.path.exists(self.database_path)
+
         # init database
         sqlite_database = SqliteDatabase(self.database_path)
         database.database.initialize(sqlite_database)
@@ -69,6 +72,22 @@ class ReticulumMeshChat:
             database.LxmfConversationReadState,
         ])
 
+        # init config
+        self.config = Config()
+
+        # if database already existed before init, and we don't have a previous version set, we are on version 1
+        if database_already_exists and self.config.database_version.get() is None:
+            self.config.database_version.set(1)
+
+        # if database didn't already exist, it was just fully migrated when it was created, so set the current version
+        if not database_already_exists:
+            self.config.database_version.set(database.latest_version)
+
+        # migrate database
+        current_database_version = self.config.database_version.get()
+        migrated_database_version = database.migrate(current_version=current_database_version)
+        self.config.database_version.set(migrated_database_version)
+
         # vacuum database on start to shrink its file size
         sqlite_database.execute_sql("VACUUM")
 
@@ -77,9 +96,6 @@ class ReticulumMeshChat:
          .where(database.LxmfMessage.state == "outbound")
          .orwhere(database.LxmfMessage.state == "sending").execute())
 
-        # init config
-        self.config = Config()
-
         # init reticulum
         self.reticulum = RNS.Reticulum(reticulum_config_dir)
         self.identity = identity
@@ -1298,6 +1314,8 @@ class ReticulumMeshChat:
             "is_incoming": lxmf_message.incoming,
             "state": self.convert_lxmf_state_to_string(lxmf_message),
             "progress": progress_percentage,
+            "delivery_attempts": lxmf_message.delivery_attempts,
+            "next_delivery_attempt_at": getattr(lxmf_message, "next_delivery_attempt", None),  # attribute may not exist yet
             "title": lxmf_message.title.decode('utf-8'),
             "content": lxmf_message.content.decode('utf-8'),
             "fields": fields,
@@ -1386,6 +1404,8 @@ class ReticulumMeshChat:
             "is_incoming": lxmf_message_dict["is_incoming"],
             "state": lxmf_message_dict["state"],
             "progress": lxmf_message_dict["progress"],
+            "delivery_attempts": lxmf_message_dict["delivery_attempts"],
+            "next_delivery_attempt_at": lxmf_message_dict["next_delivery_attempt_at"],
             "title": lxmf_message_dict["title"],
             "content": lxmf_message_dict["content"],
             "fields": json.dumps(lxmf_message_dict["fields"]),
@@ -1719,6 +1739,7 @@ class Config:
             Config.set(self.key, str(value))
 
     # all possible config items
+    database_version = IntConfig("database_version", None)
     display_name = StringConfig("display_name", "Anonymous Peer")
     auto_announce_enabled = BoolConfig("auto_announce_enabled", False)
     auto_announce_interval_seconds = IntConfig("auto_announce_interval_seconds", 0)