From 43a3f405271560d705d5c3cc1f7ffb647ce477b9 Mon Sep 17 00:00:00 2001
From: Lonami Exo <totufals@hotmail.com>
Date: Fri, 26 Jan 2018 09:59:49 +0100
Subject: [PATCH] Properly close the sqlite3 connection (#560)

---
 telethon/session.py              | 42 ++++++++++++++++++++++----------
 telethon/telegram_bare_client.py |  1 +
 2 files changed, 30 insertions(+), 13 deletions(-)

diff --git a/telethon/session.py b/telethon/session.py
index 5657f339..266d732e 100644
--- a/telethon/session.py
+++ b/telethon/session.py
@@ -7,7 +7,7 @@ import time
 from base64 import b64decode
 from enum import Enum
 from os.path import isfile as file_exists
-from threading import Lock
+from threading import Lock, RLock
 
 from . import utils
 from .crypto import AuthKey
@@ -89,7 +89,7 @@ class Session:
         # Cross-thread safety
         self._seq_no_lock = Lock()
         self._msg_id_lock = Lock()
-        self._db_lock = Lock()
+        self._db_lock = RLock()
 
         # These values will be saved
         self._dc_id = 0
@@ -100,8 +100,8 @@ class Session:
         # Migrating from .json -> SQL
         entities = self._check_migrate_json()
 
-        self._conn = sqlite3.connect(self.filename, check_same_thread=False)
-        c = self._conn.cursor()
+        self._conn = None
+        c = self._cursor()
         c.execute("select name from sqlite_master "
                   "where type='table' and name='version'")
         if c.fetchone():
@@ -186,7 +186,7 @@ class Session:
                 return []  # No entities
 
     def _upgrade_database(self, old):
-        c = self._conn.cursor()
+        c = self._cursor()
         # old == 1 doesn't have the old sent_files so no need to drop
         if old == 2:
             # Old cache from old sent_files lasts then a day anyway, drop
@@ -223,7 +223,7 @@ class Session:
         self._update_session_table()
 
         # Fetch the auth_key corresponding to this data center
-        c = self._conn.cursor()
+        c = self._cursor()
         c.execute('select auth_key from sessions')
         tuple_ = c.fetchone()
         if tuple_:
@@ -251,7 +251,7 @@ class Session:
 
     def _update_session_table(self):
         with self._db_lock:
-            c = self._conn.cursor()
+            c = self._cursor()
             # While we can save multiple rows into the sessions table
             # currently we only want to keep ONE as the tables don't
             # tell us which auth_key's are usable and will work. Needs
@@ -271,6 +271,22 @@ class Session:
         with self._db_lock:
             self._conn.commit()
 
+    def _cursor(self):
+        """Asserts that the connection is open and returns a cursor"""
+        with self._db_lock:
+            if self._conn is None:
+                self._conn = sqlite3.connect(self.filename,
+                                             check_same_thread=False)
+            return self._conn.cursor()
+
+    def close(self):
+        """Closes the connection unless we're working in-memory"""
+        if self.filename != ':memory:':
+            with self._db_lock:
+                if self._conn is not None:
+                    self._conn.close()
+                    self._conn = None
+
     def delete(self):
         """Deletes the current session file"""
         if self.filename == ':memory:':
@@ -385,10 +401,10 @@ class Session:
             return
 
         with self._db_lock:
-            self._conn.executemany(
+            self._cursor().executemany(
                 'insert or replace into entities values (?,?,?,?,?)', rows
             )
-        self.save()
+            self.save()
 
     def get_input_entity(self, key):
         """Parses the given string, integer or TLObject key into a
@@ -413,7 +429,7 @@ class Session:
             if isinstance(key, TLObject):
                 key = utils.get_peer_id(key)
 
-        c = self._conn.cursor()
+        c = self._cursor()
         if isinstance(key, str):
             phone = utils.parse_phone(key)
             if phone:
@@ -444,7 +460,7 @@ class Session:
     # File processing
 
     def get_file(self, md5_digest, file_size, cls):
-        tuple_ = self._conn.execute(
+        tuple_ = self._cursor().execute(
             'select id, hash from sent_files '
             'where md5_digest = ? and file_size = ? and type = ?',
             (md5_digest, file_size, _SentFileType.from_type(cls).value)
@@ -458,10 +474,10 @@ class Session:
             raise TypeError('Cannot cache %s instance' % type(instance))
 
         with self._db_lock:
-            self._conn.execute(
+            self._cursor().execute(
                 'insert or replace into sent_files values (?,?,?,?,?)', (
                     md5_digest, file_size,
                     _SentFileType.from_type(type(instance)).value,
                     instance.id, instance.access_hash
             ))
-        self.save()
+            self.save()
diff --git a/telethon/telegram_bare_client.py b/telethon/telegram_bare_client.py
index c2955469..fe63ab8a 100644
--- a/telethon/telegram_bare_client.py
+++ b/telethon/telegram_bare_client.py
@@ -253,6 +253,7 @@ class TelegramBareClient:
 
         # TODO Shall we clear the _exported_sessions, or may be reused?
         self._first_request = True  # On reconnect it will be first again
+        self.session.close()
 
     def __del__(self):
         self.disconnect()