From c83e4e523008337a6f8f638e65ca217177d8ed5c Mon Sep 17 00:00:00 2001
From: Jordan Cook <jordan.cook.git@proton.me>
Date: Tue, 28 Feb 2023 19:05:55 -0600
Subject: Share SQLite connection objects among threads and use lock for write
 operations instead of using thread-local connections

---
 requests_cache/backends/sqlite.py | 46 ++++++++++++++++++++++-----------------
 1 file changed, 26 insertions(+), 20 deletions(-)

(limited to 'requests_cache')

diff --git a/requests_cache/backends/sqlite.py b/requests_cache/backends/sqlite.py
index 0a892ec..2b03d4a 100644
--- a/requests_cache/backends/sqlite.py
+++ b/requests_cache/backends/sqlite.py
@@ -100,7 +100,7 @@ class SQLiteCache(BaseCache):
 
     def _delete_expired(self):
         """A more efficient implementation deleting expired responses in SQL"""
-        with self.responses._lock, self.responses.connection(commit=True) as con:
+        with self.responses.connection(commit=True) as con:
             con.execute(
                 f'DELETE FROM {self.responses.table_name} WHERE expires <= ?', (round(time()),)
             )
@@ -181,9 +181,10 @@ class SQLiteDict(BaseStorage):
     ):
         super().__init__(serializer=serializer, **kwargs)
         self._can_commit = True
-        self._local_context = threading.local()
+        self._connection: Optional[sqlite3.Connection] = None
         self._lock = threading.RLock()
         self.connection_kwargs = get_valid_kwargs(sqlite_template, kwargs)
+        self.connection_kwargs.setdefault('check_same_thread', False)
         if use_memory:
             self.connection_kwargs['uri'] = True
         self.db_path = _get_sqlite_cache_path(db_path, use_cache_dir, use_temp, use_memory)
@@ -195,7 +196,7 @@ class SQLiteDict(BaseStorage):
     def init_db(self):
         """Initialize the database, if it hasn't already been"""
         self.close()
-        with self._lock, self.connection() as con:
+        with self.connection(commit=True) as con:
             # Add new column to tables created before 1.0
             try:
                 con.execute(f'ALTER TABLE {self.table_name} ADD COLUMN expires INTEGER')
@@ -214,26 +215,31 @@ class SQLiteDict(BaseStorage):
     @contextmanager
     def connection(self, commit=False) -> Iterator[sqlite3.Connection]:
         """Get a thread-local database connection"""
-        if not getattr(self._local_context, 'con', None):
+        if not self._connection:
             logger.debug(f'Opening connection to {self.db_path}:{self.table_name}')
-            self._local_context.con = sqlite3.connect(self.db_path, **self.connection_kwargs)
+            self._connection = sqlite3.connect(self.db_path, **self.connection_kwargs)
             if self.fast_save:
-                self._local_context.con.execute('PRAGMA synchronous = 0;')
+                self._connection.execute('PRAGMA synchronous = 0;')
             if self.wal:
-                self._local_context.con.execute('PRAGMA journal_mode = wal')
-        yield self._local_context.con
+                self._connection.execute('PRAGMA journal_mode = wal')
+
+        # Any write operations need to be run in serial
+        if commit and self._can_commit:
+            self._lock.acquire()
+        yield self._connection
         if commit and self._can_commit:
-            self._local_context.con.commit()
+            self._connection.commit()
+            self._lock.release()
 
     def close(self):
         """Close any active connections"""
-        if getattr(self._local_context, 'con', None):
-            self._local_context.con.close()
-            self._local_context.con = None
+        if self._connection:
+            self._connection.close()
+            self._connection = None
 
     @contextmanager
     def bulk_commit(self):
-        """Context manager used to speed up insertion of a large number of records
+        """Insert a large number of records within a single transaction
 
         Example:
 
@@ -243,13 +249,13 @@ class SQLiteDict(BaseStorage):
             ...         d1[i] = i * 2
 
         """
-        self._can_commit = False
-        try:
-            yield
-            if hasattr(self._local_context, 'con'):
-                self._local_context.con.commit()
-        finally:
-            self._can_commit = True
+        with self._lock:
+            self._can_commit = False
+            try:
+                yield
+                self._connection.commit()
+            finally:
+                self._can_commit = True
 
     def __del__(self):
         self.close()
-- 
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