110 lines
2.8 KiB
Python
110 lines
2.8 KiB
Python
"""简单的跨进程文件缓存。
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Gunicorn worker 共享缓存文件；任一进程删除或重建缓存后，其他 worker
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会通过文件签名变化立即放弃旧的内存副本。
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"""
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import hashlib
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import os
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import pickle
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import tempfile
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import time
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_cache = {}
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_file_signatures = {}
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CACHE_DIR = os.path.join(
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os.path.dirname(os.path.dirname(os.path.abspath(__file__))),
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'tmp_cache',
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'simple',
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)
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def _path(key):
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os.makedirs(CACHE_DIR, exist_ok=True)
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filename = hashlib.md5(key.encode('utf-8')).hexdigest() + '.cache'
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return os.path.join(CACHE_DIR, filename)
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def _signature(path):
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try:
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stat = os.stat(path)
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return stat.st_ino, stat.st_mtime_ns, stat.st_size
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except OSError:
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return None
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def get(key):
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path = _path(key)
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current_signature = _signature(path)
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entry = _cache.get(key)
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if entry is not None and current_signature == _file_signatures.get(key) and current_signature is not None:
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if entry['expire'] > time.time():
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return entry['data']
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delete(key)
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return None
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# 文件已被其他 worker 删除或替换，不能继续使用本进程的旧副本。
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_cache.pop(key, None)
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_file_signatures.pop(key, None)
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if current_signature is None:
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return None
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try:
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with open(path, 'rb') as f:
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entry = pickle.load(f)
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except (OSError, EOFError, pickle.PickleError, ValueError, TypeError):
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return None
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if not isinstance(entry, dict) or entry.get('expire', 0) <= time.time():
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delete(key)
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return None
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_cache[key] = entry
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_file_signatures[key] = _signature(path)
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return entry['data']
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def set(key, data, ttl=60):
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entry = {'data': data, 'expire': time.time() + ttl}
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path = _path(key)
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fd, temp_path = tempfile.mkstemp(dir=CACHE_DIR, suffix='.tmp')
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try:
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with os.fdopen(fd, 'wb') as f:
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pickle.dump(entry, f, protocol=pickle.HIGHEST_PROTOCOL)
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os.replace(temp_path, path)
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except Exception:
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try:
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os.unlink(temp_path)
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except OSError:
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pass
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raise
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_cache[key] = entry
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_file_signatures[key] = _signature(path)
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def delete(key):
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"""删除指定缓存项；共享文件消失后其他 worker 会立即失效。"""
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_cache.pop(key, None)
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_file_signatures.pop(key, None)
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try:
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os.remove(_path(key))
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except FileNotFoundError:
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pass
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def clear(key=None):
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if key:
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delete(key)
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return
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_cache.clear()
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_file_signatures.clear()
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try:
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for filename in os.listdir(CACHE_DIR):
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if filename.endswith('.cache'):
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try:
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os.remove(os.path.join(CACHE_DIR, filename))
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except FileNotFoundError:
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pass
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except FileNotFoundError:
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pass
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