| # Copyright 2024 The HuggingFace Inc. team. All rights reserved. | |
| # | |
| # Licensed under the Apache License, Version 2.0 (the "License"); | |
| # you may not use this file except in compliance with the License. | |
| # You may obtain a copy of the License at | |
| # | |
| # http://www.apache.org/licenses/LICENSE-2.0 | |
| # | |
| # Unless required by applicable law or agreed to in writing, software | |
| # distributed under the License is distributed on an "AS IS" BASIS, | |
| # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |
| # See the License for the specific language governing permissions and | |
| # limitations under the License. | |
| import platform | |
| import time | |
| def precise_sleep(seconds: float, spin_threshold: float = 0.010, sleep_margin: float = 0.005): | |
| """ | |
| Wait for `seconds` with better precision than time.sleep alone at the expense of more CPU usage. | |
| Parameters: | |
| - seconds: duration to wait | |
| - spin_threshold: if remaining <= spin_threshold -> spin; otherwise sleep (seconds). Default 10ms | |
| - sleep_margin: when sleeping leave this much time before deadline to avoid oversleep. Default 5ms | |
| Note: | |
| The default parameters are chosen to prioritize timing accuracy over CPU usage for the common 30 FPS use case. | |
| """ | |
| if seconds <= 0: | |
| return | |
| system = platform.system() | |
| # On macOS and Windows the scheduler / sleep granularity can make | |
| # short sleeps inaccurate. Instead of burning CPU for the whole | |
| # duration, sleep for most of the time and spin for the final few | |
| # milliseconds to achieve good accuracy with much lower CPU usage. | |
| if system in ("Darwin", "Windows"): | |
| end_time = time.perf_counter() + seconds | |
| while True: | |
| remaining = end_time - time.perf_counter() | |
| if remaining <= 0: | |
| break | |
| # If there's more than a couple milliseconds left, sleep most | |
| # of the remaining time and leave a small margin for the final spin. | |
| if remaining > spin_threshold: | |
| # Sleep but avoid sleeping past the end by leaving a small margin. | |
| time.sleep(max(remaining - sleep_margin, 0)) | |
| else: | |
| # Final short spin to hit precise timing without long sleeps. | |
| pass | |
| else: | |
| # On Linux time.sleep is accurate enough for most uses | |
| time.sleep(seconds) | |