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243 | class FileSystemLockManager(LockManager):
"""
A lock manager that implements locking using local files.
Attributes:
lock_files_directory: the directory where lock files are stored
"""
def __init__(self, lock_files_directory: Path):
self.lock_files_directory = lock_files_directory.expanduser().resolve()
self._locks: Dict[str, _LockInfo] = {}
def _ensure_lock_files_directory_exists(self):
self.lock_files_directory.mkdir(parents=True, exist_ok=True)
def _lock_path_for_key(self, key: str) -> Path:
if (lock_info := self._locks.get(key)) is not None:
return lock_info["path"]
return self.lock_files_directory.joinpath(key).with_suffix(".lock")
def _get_lock_info(self, key: str, use_cache=True) -> Optional[_LockInfo]:
if use_cache:
if (lock_info := self._locks.get(key)) is not None:
return lock_info
lock_path = self._lock_path_for_key(key)
try:
with open(lock_path, "rb") as lock_file:
lock_info = pydantic_core.from_json(lock_file.read())
lock_info["path"] = lock_path
expiration = lock_info.get("expiration")
lock_info["expiration"] = (
pendulum.parse(expiration) if expiration is not None else None
)
self._locks[key] = lock_info
return lock_info
except FileNotFoundError:
return None
async def _aget_lock_info(
self, key: str, use_cache: bool = True
) -> Optional[_LockInfo]:
if use_cache:
if (lock_info := self._locks.get(key)) is not None:
return lock_info
lock_path = self._lock_path_for_key(key)
try:
lock_info_bytes = await anyio.Path(lock_path).read_bytes()
lock_info = pydantic_core.from_json(lock_info_bytes)
lock_info["path"] = lock_path
expiration = lock_info.get("expiration")
lock_info["expiration"] = (
pendulum.parse(expiration) if expiration is not None else None
)
self._locks[key] = lock_info
return lock_info
except FileNotFoundError:
return None
def acquire_lock(
self,
key: str,
holder: str,
acquire_timeout: Optional[float] = None,
hold_timeout: Optional[float] = None,
) -> bool:
self._ensure_lock_files_directory_exists()
lock_path = self._lock_path_for_key(key)
if self.is_locked(key) and not self.is_lock_holder(key, holder):
lock_free = self.wait_for_lock(key, acquire_timeout)
if not lock_free:
return False
try:
Path(lock_path).touch(exist_ok=False)
except FileExistsError:
if not self.is_lock_holder(key, holder):
logger.debug(
f"Another actor acquired the lock for record with key {key}. Trying again."
)
return self.acquire_lock(key, holder, acquire_timeout, hold_timeout)
expiration = (
pendulum.now("utc") + pendulum.duration(seconds=hold_timeout)
if hold_timeout is not None
else None
)
with open(Path(lock_path), "wb") as lock_file:
lock_file.write(
pydantic_core.to_json(
{
"holder": holder,
"expiration": str(expiration)
if expiration is not None
else None,
},
)
)
self._locks[key] = {
"holder": holder,
"expiration": expiration,
"path": lock_path,
}
return True
async def aacquire_lock(
self,
key: str,
holder: str,
acquire_timeout: Optional[float] = None,
hold_timeout: Optional[float] = None,
) -> bool:
await anyio.Path(self.lock_files_directory).mkdir(parents=True, exist_ok=True)
lock_path = self._lock_path_for_key(key)
if self.is_locked(key) and not self.is_lock_holder(key, holder):
lock_free = await self.await_for_lock(key, acquire_timeout)
if not lock_free:
return False
try:
await anyio.Path(lock_path).touch(exist_ok=False)
except FileExistsError:
if not self.is_lock_holder(key, holder):
logger.debug(
f"Another actor acquired the lock for record with key {key}. Trying again."
)
return self.acquire_lock(key, holder, acquire_timeout, hold_timeout)
expiration = (
pendulum.now("utc") + pendulum.duration(seconds=hold_timeout)
if hold_timeout is not None
else None
)
async with await anyio.Path(lock_path).open("wb") as lock_file:
await lock_file.write(
pydantic_core.to_json(
{
"holder": holder,
"expiration": str(expiration)
if expiration is not None
else None,
},
)
)
self._locks[key] = {
"holder": holder,
"expiration": expiration,
"path": lock_path,
}
return True
def release_lock(self, key: str, holder: str) -> None:
lock_path = self._lock_path_for_key(key)
if not self.is_locked(key):
ValueError(f"No lock for transaction with key {key}")
if self.is_lock_holder(key, holder):
Path(lock_path).unlink(missing_ok=True)
self._locks.pop(key, None)
else:
raise ValueError(f"No lock held by {holder} for transaction with key {key}")
def is_locked(self, key: str, use_cache: bool = False) -> bool:
if (lock_info := self._get_lock_info(key, use_cache=use_cache)) is None:
return False
if (expiration := lock_info.get("expiration")) is None:
return True
expired = expiration < pendulum.now("utc")
if expired:
Path(lock_info["path"]).unlink()
self._locks.pop(key, None)
return False
else:
return True
def is_lock_holder(self, key: str, holder: str) -> bool:
if not self.is_locked(key):
return False
if not self.is_locked(key):
return False
if (lock_info := self._get_lock_info(key)) is None:
return False
return lock_info["holder"] == holder
def wait_for_lock(self, key: str, timeout: Optional[float] = None) -> bool:
seconds_waited = 0
while self.is_locked(key, use_cache=False):
if timeout and seconds_waited >= timeout:
return False
seconds_waited += 0.1
time.sleep(0.1)
return True
async def await_for_lock(self, key: str, timeout: Optional[float] = None) -> bool:
seconds_waited = 0
while self.is_locked(key, use_cache=False):
if timeout and seconds_waited >= timeout:
return False
seconds_waited += 0.1
await anyio.sleep(0.1)
return True
|