Disk errors handling

Author: PMazarovich

logstash_async/database.py

@@ -11,7 +11,6 @@
 from logstash_async.constants import constants
 from logstash_async.utils import ichunked
 
-
 DATABASE_SCHEMA_STATEMENTS = [
     '''
     CREATE TABLE IF NOT EXISTS `event` (
@@ -29,6 +28,10 @@ class DatabaseLockedError(Exception):
     pass
 
 
+class DatabaseDiskIOError(Exception):
+    pass
+
+
 class DatabaseCache(Cache):
     """
         Backend implementation for python-logstash-async. Keeps messages on disk in a SQL-lite DB
@@ -47,8 +50,8 @@ def __init__(self, path, event_ttl=None):
 
     @contextmanager
     def _connect(self):
-        self._open()
         try:
+            self._open()
             with self._connection as connection:
                 yield connection
         except sqlite3.OperationalError:
@@ -96,6 +99,12 @@ def _handle_sqlite_error(self):
         _, exc, _ = sys.exc_info()
         if str(exc) == 'database is locked':
             raise DatabaseLockedError from exc
+        if str(exc) == 'disk I/O error':
+            raise DatabaseDiskIOError from exc
+        if str(exc) == "unable to open database file":
+            raise DatabaseDiskIOError from exc
+        if str(exc) == "attempt to write a readonly database":
+            raise DatabaseDiskIOError from exc
 
     # ----------------------------------------------------------------------
     def get_queued_events(self):

logstash_async/worker.py

@@ -14,7 +14,7 @@
 from limits.strategies import FixedWindowRateLimiter
 
 from logstash_async.constants import constants
-from logstash_async.database import DatabaseCache, DatabaseLockedError
+from logstash_async.database import DatabaseCache, DatabaseLockedError, DatabaseDiskIOError
 from logstash_async.memory_cache import MemoryCache
 from logstash_async.utils import safe_log_via_print
 
@@ -128,7 +128,7 @@ def _fetch_events(self):
                 self._flush_queued_events(force=force_flush)
                 self._delay_processing()
                 self._expire_events()
-            except (DatabaseLockedError, ProcessingError):
+            except (DatabaseLockedError, ProcessingError, DatabaseDiskIOError):
                 if self._shutdown_requested():
                     return
 
@@ -150,6 +150,13 @@ def _process_event(self):
                 self._queue.qsize(),
                 exc=exc)
             raise
+        except DatabaseDiskIOError as exc:
+            self._safe_log(
+                'debug',
+                'Disk I/O error, will try again later (queue length %d)',
+                self._queue.qsize(),
+                exc=exc)
+            raise
         except Exception as exc:
             self._log_processing_error(exc)
             raise ProcessingError from exc
@@ -160,7 +167,7 @@ def _process_event(self):
     def _expire_events(self):
         try:
             self._database.expire_events()
-        except DatabaseLockedError:
+        except (DatabaseLockedError, DatabaseDiskIOError):
             # Nothing to handle, if it fails, we will either successfully publish
             # these messages next time or we will delete them on the next pass.
             pass
@@ -242,6 +249,13 @@ def _fetch_queued_events_for_flush(self):
                 'Database is locked, will try again later (queue length %d)',
                 self._queue.qsize(),
                 exc=exc)
+        except DatabaseDiskIOError as exc:
+            self._safe_log(
+                'debug',
+                'Disk I/O error, will try again later (queue length %d)',
+                self._queue.qsize(),
+                exc=exc)
+            raise
         except Exception as exc:
             # just log the exception and hope we can recover from the error
             self._safe_log('exception', 'Error retrieving queued events: %s', exc, exc=exc)
@@ -252,7 +266,7 @@ def _fetch_queued_events_for_flush(self):
     def _delete_queued_events_from_database(self):
         try:
             self._database.delete_queued_events()
-        except DatabaseLockedError:
+        except (DatabaseLockedError, DatabaseDiskIOError):
             pass  # nothing to handle, if it fails, we delete those events in a later run
 
     # ----------------------------------------------------------------------

tests/database_test.py

@@ -7,16 +7,16 @@
 import sqlite3
 import time
 import unittest
+from stat import S_IREAD, S_IRGRP, S_IROTH, S_IWUSR
 
 from logstash_async.constants import constants
-from logstash_async.database import DATABASE_SCHEMA_STATEMENTS, DatabaseCache
+from logstash_async.database import DATABASE_SCHEMA_STATEMENTS, DatabaseCache, DatabaseDiskIOError
 
 
 # pylint: disable=protected-access
 
 
 class DatabaseCacheTest(unittest.TestCase):
-
     TEST_DB_FILENAME = "test.db"
     _connection = None
 
@@ -63,6 +63,15 @@ def close_connection(cls):
             cls._connection.close()
         cls._connection = None
 
+    # ----------------------------------------------------------------------
+    def testIOException(self):
+        self.cache.add_event("message")
+        with self.assertRaises(DatabaseDiskIOError):
+            # change permissions to produce error
+            os.chmod(os.path.abspath("test.db"), S_IREAD | S_IRGRP | S_IROTH)
+            self.cache.add_event("message")
+        os.chmod(os.path.abspath("test.db"), S_IWUSR | S_IREAD)
+
     # ----------------------------------------------------------------------
     def test_add_event(self):
         self.cache.add_event("message")