Manage transport-level write flow control. Blocks send() when transport buffer exceeds high water mark, preventing memory issues with large streaming responses.
| 83 | |
| 84 | |
| 85 | class FlowControl: |
| 86 | """Manage transport-level write flow control. |
| 87 | |
| 88 | Blocks send() when transport buffer exceeds high water mark, |
| 89 | preventing memory issues with large streaming responses. |
| 90 | """ |
| 91 | __slots__ = ('_transport', 'read_paused', 'write_paused', '_is_writable_event') |
| 92 | |
| 93 | def __init__(self, transport): |
| 94 | self._transport = transport |
| 95 | self.read_paused = False |
| 96 | self.write_paused = False |
| 97 | self._is_writable_event = asyncio.Event() |
| 98 | self._is_writable_event.set() |
| 99 | |
| 100 | async def drain(self): |
| 101 | """Wait until transport is writable.""" |
| 102 | await self._is_writable_event.wait() |
| 103 | |
| 104 | def pause_reading(self): |
| 105 | if not self.read_paused: |
| 106 | self.read_paused = True |
| 107 | self._transport.pause_reading() |
| 108 | |
| 109 | def resume_reading(self): |
| 110 | if self.read_paused: |
| 111 | self.read_paused = False |
| 112 | self._transport.resume_reading() |
| 113 | |
| 114 | def pause_writing(self): |
| 115 | if not self.write_paused: |
| 116 | self.write_paused = True |
| 117 | self._is_writable_event.clear() |
| 118 | |
| 119 | def resume_writing(self): |
| 120 | if self.write_paused: |
| 121 | self.write_paused = False |
| 122 | self._is_writable_event.set() |
| 123 | |
| 124 | |
| 125 | def _get_cached_date_header(): |