49 lines
1.6 KiB
Python
49 lines
1.6 KiB
Python
"""Tiny JSON store (one file, atomic writes, one process-wide lock)."""
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from __future__ import annotations
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import json
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import os
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import contextlib
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import fcntl
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import threading
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LOCK = threading.RLock()
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class Store:
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def __init__(self, path: str):
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self.path = path
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os.makedirs(os.path.dirname(os.path.abspath(path)), exist_ok=True)
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self.data = {"digests": {}, "submissions": [], "rate": {}, "cursor": 0, "seen_urls": []}
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if os.path.exists(path):
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with open(path, encoding="utf-8") as f:
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self.data.update(json.load(f))
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def save(self) -> None:
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with LOCK:
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tmp = self.path + ".tmp"
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with open(tmp, "w", encoding="utf-8") as f:
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json.dump(self.data, f, ensure_ascii=False, indent=1)
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os.chmod(tmp, 0o600)
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os.replace(tmp, self.path)
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def reload(self) -> None:
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with LOCK:
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if os.path.exists(self.path):
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with open(self.path, encoding="utf-8") as f:
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self.data.update(json.load(f))
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@contextlib.contextmanager
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def tx(self):
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"""Cross-process transaction: lock file, reload from disk, mutate self.data, save.
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The web server, mailbox worker and daily job are separate processes sharing one file."""
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with LOCK:
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with open(self.path + ".lock", "a") as lk:
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fcntl.flock(lk, fcntl.LOCK_EX)
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try:
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self.reload()
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yield self.data
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self.save()
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finally:
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fcntl.flock(lk, fcntl.LOCK_UN)
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