add SQLite semaphore mockup

archivebox/builtin_plugins/chrome/apps.py

@@ -86,23 +86,23 @@ class ChromeDependencyConfigs(BaseConfigSet):
     CHROME_EXTRA_ARGS: List[str] = []
     CHROME_DEFAULT_ARGS: List[str] = ['--timeout={TIMEOUT-10}']
     
-    def load(self) -> Self:
-        # for each field in the model, load its value
-        # load from each source in order of precedence (lowest to highest):
-        # - schema default
-        # - ArchiveBox.conf INI file
-        # - environment variables
-        # - command-line arguments
+    # def load(self) -> Self:
+    #     # for each field in the model, load its value
+    #     # load from each source in order of precedence (lowest to highest):
+    #     # - schema default
+    #     # - ArchiveBox.conf INI file
+    #     # - environment variables
+    #     # - command-line arguments
         
-        LOADED_VALUES: Dict[str, Any] = {}
-
-        for field_name, field in self.__fields__.items():
-            def_value   = field.default_factory() if field.default_factory else field.default
-            ini_value   = settings.INI_CONFIG.get_value(field_name)
-            env_value   = settings.ENV_CONFIG.get_value(field_name)
-            cli_value   = settings.CLI_CONFIG.get_value(field_name)
-            run_value   = settings.RUN_CONFIG.get_value(field_name)
-            value = run_value or cli_value or env_value or ini_value or def_value
+    #     LOADED_VALUES: Dict[str, Any] = {}
+
+    #     for field_name, field in self.__fields__.items():
+    #         def_value   = field.default_factory() if field.default_factory else field.default
+    #         ini_value   = settings.INI_CONFIG.get_value(field_name)
+    #         env_value   = settings.ENV_CONFIG.get_value(field_name)
+    #         cli_value   = settings.CLI_CONFIG.get_value(field_name)
+    #         run_value   = settings.RUN_CONFIG.get_value(field_name)
+    #         value = run_value or cli_value or env_value or ini_value or def_value
 
 class ChromeConfigs(ChromeDependencyConfigs):
     # section: ConfigSectionName = 'ALL_CONFIGS'

archivebox/plugantic/base_queue.py

@@ -36,6 +36,7 @@ class BaseQueue(BaseHook):
         return AttrDict(all_tasks)
 
     def get_huey_config(self, settings) -> dict:
+        """Get the config dict to insert into django.conf.settings.DJANGO_HUEY['queues']."""
         return {
             "huey_class": "huey.SqliteHuey",
             "filename": settings.QUEUE_DATABASE_NAME,
@@ -58,6 +59,7 @@ class BaseQueue(BaseHook):
         }
         
     def get_supervisor_config(self, settings) -> dict:
+        """Ge the config dict used to tell sueprvisord to start a huey consumer for this queue."""
         return {
             "name": f"worker_{self.name}",
             "command": f"archivebox manage djangohuey --queue {self.name}",

archivebox/plugantic/ini_to_toml.py

@@ -63,7 +63,7 @@ def convert(ini_str: str) -> str:
 
 ### Basic Assertions
 
-test_input = """
+test_input = r"""
 [SERVER_CONFIG]
 IS_TTY=False
 USE_COLOR=False
@@ -225,7 +225,7 @@ NODE_VERSION=v21.7.3
 """
 
 
-expected_output = '''[SERVER_CONFIG]
+expected_output = r'''[SERVER_CONFIG]
 IS_TTY = false
 USE_COLOR = false
 SHOW_PROGRESS = false

archivebox/queues/semaphores.py

@@ -0,0 +1,101 @@
+import time
+import uuid
+from functools import wraps
+from django.db import connection, transaction
+from django.utils import timezone
+from huey.exceptions import TaskLockedException
+
+class SqliteSemaphore:
+    def __init__(self, db_path, table_name, name, value=1, timeout=None):
+        self.db_path = db_path
+        self.table_name = table_name
+        self.name = name
+        self.value = value
+        self.timeout = timeout or 86400  # Set a max age for lock holders
+
+        # Ensure the table exists
+        with connection.cursor() as cursor:
+            cursor.execute(f"""
+                CREATE TABLE IF NOT EXISTS {self.table_name} (
+                    id TEXT PRIMARY KEY,
+                    name TEXT,
+                    timestamp DATETIME
+                )
+            """)
+
+    def acquire(self, name=None):
+        name = name or str(uuid.uuid4())
+        now = timezone.now()
+        expiration = now - timezone.timedelta(seconds=self.timeout)
+
+        with transaction.atomic():
+            # Remove expired locks
+            with connection.cursor() as cursor:
+                cursor.execute(f"""
+                    DELETE FROM {self.table_name}
+                    WHERE name = %s AND timestamp < %s
+                """, [self.name, expiration])
+
+            # Try to acquire the lock
+            with connection.cursor() as cursor:
+                cursor.execute(f"""
+                    INSERT INTO {self.table_name} (id, name, timestamp)
+                    SELECT %s, %s, %s
+                    WHERE (
+                        SELECT COUNT(*) FROM {self.table_name}
+                        WHERE name = %s
+                    ) < %s
+                """, [name, self.name, now, self.name, self.value])
+
+                if cursor.rowcount > 0:
+                    return name
+
+        # If we couldn't acquire the lock, remove our attempted entry
+        with connection.cursor() as cursor:
+            cursor.execute(f"""
+                DELETE FROM {self.table_name}
+                WHERE id = %s AND name = %s
+            """, [name, self.name])
+
+        return None
+
+    def release(self, name):
+        with connection.cursor() as cursor:
+            cursor.execute(f"""
+                DELETE FROM {self.table_name}
+                WHERE id = %s AND name = %s
+            """, [name, self.name])
+        return cursor.rowcount > 0
+
+
+LOCKS_DB_PATH = settings.CONFIG.OUTPUT_DIR / 'locks.sqlite3'
+
+def lock_task_semaphore(db_path, table_name, lock_name, value=1, timeout=None):
+    """
+    Lock which can be acquired multiple times (default = 1).
+
+    NOTE: no provisions are made for blocking, waiting, or notifying. This is
+    just a lock which can be acquired a configurable number of times.
+
+    Example:
+
+    # Allow up to 3 workers to run this task concurrently. If the task is
+    # locked, retry up to 2 times with a delay of 60s.
+    @huey.task(retries=2, retry_delay=60)
+    @lock_task_semaphore('path/to/db.sqlite3', 'semaphore_locks', 'my-lock', 3)
+    def my_task():
+        ...
+    """
+    sem = SqliteSemaphore(db_path, table_name, lock_name, value, timeout)
+    def decorator(fn):
+        @wraps(fn)
+        def inner(*args, **kwargs):
+            tid = sem.acquire()
+            if tid is None:
+                raise TaskLockedException(f'unable to acquire lock {lock_name}')
+            try:
+                return fn(*args, **kwargs)
+            finally:
+                sem.release(tid)
+        return inner
+    return decorator