RAHHH

backend/lib/python3.12/site-packages/twisted/logger/_buffer.py

@@ -0,0 +1,54 @@
+# -*- test-case-name: twisted.logger.test.test_buffer -*-
+# Copyright (c) Twisted Matrix Laboratories.
+# See LICENSE for details.
+
+"""
+Log observer that maintains a buffer.
+"""
+
+from collections import deque
+from typing import Deque, Optional
+
+from zope.interface import implementer
+
+from ._interfaces import ILogObserver, LogEvent
+
+_DEFAULT_BUFFER_MAXIMUM = 64 * 1024
+
+
+@implementer(ILogObserver)
+class LimitedHistoryLogObserver:
+    """
+    L{ILogObserver} that stores events in a buffer of a fixed size::
+
+        >>> from twisted.logger import LimitedHistoryLogObserver
+        >>> history = LimitedHistoryLogObserver(5)
+        >>> for n in range(10): history({'n': n})
+        ...
+        >>> repeats = []
+        >>> history.replayTo(repeats.append)
+        >>> len(repeats)
+        5
+        >>> repeats
+        [{'n': 5}, {'n': 6}, {'n': 7}, {'n': 8}, {'n': 9}]
+        >>>
+    """
+
+    def __init__(self, size: Optional[int] = _DEFAULT_BUFFER_MAXIMUM) -> None:
+        """
+        @param size: The maximum number of events to buffer.  If L{None}, the
+            buffer is unbounded.
+        """
+        self._buffer: Deque[LogEvent] = deque(maxlen=size)
+
+    def __call__(self, event: LogEvent) -> None:
+        self._buffer.append(event)
+
+    def replayTo(self, otherObserver: ILogObserver) -> None:
+        """
+        Re-play the buffered events to another log observer.
+
+        @param otherObserver: An observer to replay events to.
+        """
+        for event in self._buffer:
+            otherObserver(event)