|
| 1 | +import logging |
| 2 | +import sqlite3 |
| 3 | +import threading |
| 4 | +import uuid |
| 5 | +import queue |
| 6 | + |
| 7 | +LOGGER = logging.getLogger("SqliteWorker") |
| 8 | +SILENT_TOKEN_SUFFIX = '-silent' |
| 9 | + |
| 10 | + |
| 11 | +class SqliteWorker: |
| 12 | + """Sqlite thread-safe object.""" |
| 13 | + |
| 14 | + def __init__(self, file_name, max_queue_size=100, execute_init=(), max_count=50): |
| 15 | + self._file_name = file_name |
| 16 | + self._sql_queue = queue.Queue(maxsize=max_queue_size) |
| 17 | + self._results = {} |
| 18 | + self._tokens = set() |
| 19 | + self._select_events = {} |
| 20 | + self._lock = threading.Lock() |
| 21 | + self._close_event = threading.Event() |
| 22 | + self._thread = threading.Thread(target=self._run, daemon=True) |
| 23 | + self._thread.start() |
| 24 | + self.execute_init = execute_init |
| 25 | + self.max_count = max_count |
| 26 | + |
| 27 | + def _run(self): |
| 28 | + try: |
| 29 | + self._process_queries() |
| 30 | + except Exception as err: |
| 31 | + LOGGER.critical( |
| 32 | + "Unhandled exception in query processor: %s", err, exc_info=True) |
| 33 | + raise |
| 34 | + |
| 35 | + def _process_queries(self): |
| 36 | + with sqlite3.connect(self._file_name, check_same_thread=False, detect_types=sqlite3.PARSE_DECLTYPES) as conn: |
| 37 | + cursor = conn.cursor() |
| 38 | + for action in self.execute_init: |
| 39 | + cursor.execute(action) |
| 40 | + conn.commit() |
| 41 | + |
| 42 | + count = 0 |
| 43 | + while not self._close_event.is_set() or not self._sql_queue.empty(): |
| 44 | + try: |
| 45 | + token, query, values = self._sql_queue.get(timeout=1) |
| 46 | + except queue.Empty: |
| 47 | + continue |
| 48 | + if query: |
| 49 | + count += 1 |
| 50 | + self._execute_query(cursor, token, query, values) |
| 51 | + |
| 52 | + if count >= self.max_count or self._sql_queue.empty(): |
| 53 | + count = 0 |
| 54 | + conn.commit() |
| 55 | + |
| 56 | + def _execute_query(self, cursor, token: str, query, values): |
| 57 | + try: |
| 58 | + cursor.execute(query, values) |
| 59 | + if not token.endswith(SILENT_TOKEN_SUFFIX): |
| 60 | + with self._lock: |
| 61 | + self._results[token] = cursor.fetchall() |
| 62 | + except sqlite3.Error as err: |
| 63 | + LOGGER.error("Query error: %s: %s: %s", query, values, err) |
| 64 | + self._handle_query_error(token, err) |
| 65 | + self._notify_query_done(token) |
| 66 | + |
| 67 | + def _is_select_query(self, query): |
| 68 | + return query.lower().lstrip().startswith("select") |
| 69 | + |
| 70 | + def _notify_query_begin(self, token): |
| 71 | + self._select_events.setdefault(token, threading.Event()) |
| 72 | + |
| 73 | + def _notify_query_done(self, token): |
| 74 | + self._select_events[token].set() |
| 75 | + |
| 76 | + def _handle_query_error(self, token, err): |
| 77 | + with self._lock: |
| 78 | + self._results[token] = err |
| 79 | + |
| 80 | + def close(self): |
| 81 | + self._close_event.set() |
| 82 | + self._sql_queue.put((None, None, None), timeout=5) |
| 83 | + self._thread.join() |
| 84 | + |
| 85 | + def execute(self, query, values=None, always_return_token=False): |
| 86 | + if self._close_event.is_set(): |
| 87 | + raise RuntimeError("Worker is closed") |
| 88 | + |
| 89 | + should_return_token = ( |
| 90 | + always_return_token or |
| 91 | + self._is_select_query(query) |
| 92 | + ) |
| 93 | + |
| 94 | + token = uuid.uuid4().hex |
| 95 | + if should_return_token is None: |
| 96 | + token += SILENT_TOKEN_SUFFIX |
| 97 | + |
| 98 | + self._sql_queue.put((token, query, values or []), timeout=5) |
| 99 | + self._notify_query_begin(token) |
| 100 | + |
| 101 | + if should_return_token: |
| 102 | + return token |
| 103 | + return None |
| 104 | + |
| 105 | + def execute_and_fetch(self, query, values=None, always_synchronous=True): |
| 106 | + return self.fetch_results(self.execute(query, values, always_return_token=always_synchronous)) |
| 107 | + |
| 108 | + def fetch_results(self, token): |
| 109 | + if token is None: |
| 110 | + return |
| 111 | + with self._lock: |
| 112 | + event = self._select_events.get(token) |
| 113 | + if event is None: |
| 114 | + return |
| 115 | + event.wait() |
| 116 | + with self._lock: |
| 117 | + return self._results.pop(token, None) |
| 118 | + |
| 119 | + @property |
| 120 | + def queue_size(self): |
| 121 | + return self._sql_queue.qsize() |
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