You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
233 lines
8.3 KiB
233 lines
8.3 KiB
5 months ago
|
from __future__ import annotations
|
||
|
|
|
||
|
|
import os
|
||
|
|
import pickle
|
||
|
|
import time
|
||
|
|
from typing import TYPE_CHECKING
|
||
|
|
|
||
|
|
from fsspec.utils import atomic_write
|
||
|
|
|
||
|
|
try:
|
||
|
|
import ujson as json
|
||
|
|
except ImportError:
|
||
|
|
if not TYPE_CHECKING:
|
||
|
|
import json
|
||
|
|
|
||
|
|
if TYPE_CHECKING:
|
||
|
|
from typing import Any, Dict, Iterator, Literal
|
||
|
|
|
||
|
|
from typing_extensions import TypeAlias
|
||
|
|
|
||
|
|
from .cached import CachingFileSystem
|
||
|
|
|
||
|
|
Detail: TypeAlias = Dict[str, Any]
|
||
|
|
|
||
|
|
|
||
|
|
class CacheMetadata:
|
||
|
|
"""Cache metadata.
|
||
|
|
|
||
|
|
All reading and writing of cache metadata is performed by this class,
|
||
|
|
accessing the cached files and blocks is not.
|
||
|
|
|
||
|
|
Metadata is stored in a single file per storage directory in JSON format.
|
||
|
|
For backward compatibility, also reads metadata stored in pickle format
|
||
|
|
which is converted to JSON when next saved.
|
||
|
|
"""
|
||
|
|
|
||
|
|
def __init__(self, storage: list[str]):
|
||
|
|
"""
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
storage: list[str]
|
||
|
|
Directories containing cached files, must be at least one. Metadata
|
||
|
|
is stored in the last of these directories by convention.
|
||
|
|
"""
|
||
|
|
if not storage:
|
||
|
|
raise ValueError("CacheMetadata expects at least one storage location")
|
||
|
|
|
||
|
|
self._storage = storage
|
||
|
|
self.cached_files: list[Detail] = [{}]
|
||
|
|
|
||
|
|
# Private attribute to force saving of metadata in pickle format rather than
|
||
|
|
# JSON for use in tests to confirm can read both pickle and JSON formats.
|
||
|
|
self._force_save_pickle = False
|
||
|
|
|
||
|
|
def _load(self, fn: str) -> Detail:
|
||
|
|
"""Low-level function to load metadata from specific file"""
|
||
|
|
try:
|
||
|
|
with open(fn, "r") as f:
|
||
|
|
loaded = json.load(f)
|
||
|
|
except ValueError:
|
||
|
|
with open(fn, "rb") as f:
|
||
|
|
loaded = pickle.load(f)
|
||
|
|
for c in loaded.values():
|
||
|
|
if isinstance(c.get("blocks"), list):
|
||
|
|
c["blocks"] = set(c["blocks"])
|
||
|
|
return loaded
|
||
|
|
|
||
|
|
def _save(self, metadata_to_save: Detail, fn: str) -> None:
|
||
|
|
"""Low-level function to save metadata to specific file"""
|
||
|
|
if self._force_save_pickle:
|
||
|
|
with atomic_write(fn) as f:
|
||
|
|
pickle.dump(metadata_to_save, f)
|
||
|
|
else:
|
||
|
|
with atomic_write(fn, mode="w") as f:
|
||
|
|
json.dump(metadata_to_save, f)
|
||
|
|
|
||
|
|
def _scan_locations(
|
||
|
|
self, writable_only: bool = False
|
||
|
|
) -> Iterator[tuple[str, str, bool]]:
|
||
|
|
"""Yield locations (filenames) where metadata is stored, and whether
|
||
|
|
writable or not.
|
||
|
|
|
||
|
|
Parameters
|
||
|
|
----------
|
||
|
|
writable: bool
|
||
|
|
Set to True to only yield writable locations.
|
||
|
|
|
||
|
|
Returns
|
||
|
|
-------
|
||
|
|
Yields (str, str, bool)
|
||
|
|
"""
|
||
|
|
n = len(self._storage)
|
||
|
|
for i, storage in enumerate(self._storage):
|
||
|
|
writable = i == n - 1
|
||
|
|
if writable_only and not writable:
|
||
|
|
continue
|
||
|
|
yield os.path.join(storage, "cache"), storage, writable
|
||
|
|
|
||
|
|
def check_file(
|
||
|
|
self, path: str, cfs: CachingFileSystem | None
|
||
|
|
) -> Literal[False] | tuple[Detail, str]:
|
||
|
|
"""If path is in cache return its details, otherwise return ``False``.
|
||
|
|
|
||
|
|
If the optional CachingFileSystem is specified then it is used to
|
||
|
|
perform extra checks to reject possible matches, such as if they are
|
||
|
|
too old.
|
||
|
|
"""
|
||
|
|
for (fn, base, _), cache in zip(self._scan_locations(), self.cached_files):
|
||
|
|
if path not in cache:
|
||
|
|
continue
|
||
|
|
detail = cache[path].copy()
|
||
|
|
|
||
|
|
if cfs is not None:
|
||
|
|
if cfs.check_files and detail["uid"] != cfs.fs.ukey(path):
|
||
|
|
# Wrong file as determined by hash of file properties
|
||
|
|
continue
|
||
|
|
if cfs.expiry and time.time() - detail["time"] > cfs.expiry:
|
||
|
|
# Cached file has expired
|
||
|
|
continue
|
||
|
|
|
||
|
|
fn = os.path.join(base, detail["fn"])
|
||
|
|
if os.path.exists(fn):
|
||
|
|
return detail, fn
|
||
|
|
return False
|
||
|
|
|
||
|
|
def clear_expired(self, expiry_time: int) -> tuple[list[str], bool]:
|
||
|
|
"""Remove expired metadata from the cache.
|
||
|
|
|
||
|
|
Returns names of files corresponding to expired metadata and a boolean
|
||
|
|
flag indicating whether the writable cache is empty. Caller is
|
||
|
|
responsible for deleting the expired files.
|
||
|
|
"""
|
||
|
|
expired_files = []
|
||
|
|
for path, detail in self.cached_files[-1].copy().items():
|
||
|
|
if time.time() - detail["time"] > expiry_time:
|
||
|
|
fn = detail.get("fn", "")
|
||
|
|
if not fn:
|
||
|
|
raise RuntimeError(
|
||
|
|
f"Cache metadata does not contain 'fn' for {path}"
|
||
|
|
)
|
||
|
|
fn = os.path.join(self._storage[-1], fn)
|
||
|
|
expired_files.append(fn)
|
||
|
|
self.cached_files[-1].pop(path)
|
||
|
|
|
||
|
|
if self.cached_files[-1]:
|
||
|
|
cache_path = os.path.join(self._storage[-1], "cache")
|
||
|
|
self._save(self.cached_files[-1], cache_path)
|
||
|
|
|
||
|
|
writable_cache_empty = not self.cached_files[-1]
|
||
|
|
return expired_files, writable_cache_empty
|
||
|
|
|
||
|
|
def load(self) -> None:
|
||
|
|
"""Load all metadata from disk and store in ``self.cached_files``"""
|
||
|
|
cached_files = []
|
||
|
|
for fn, _, _ in self._scan_locations():
|
||
|
|
if os.path.exists(fn):
|
||
|
|
# TODO: consolidate blocks here
|
||
|
|
cached_files.append(self._load(fn))
|
||
|
|
else:
|
||
|
|
cached_files.append({})
|
||
|
|
self.cached_files = cached_files or [{}]
|
||
|
|
|
||
|
|
def on_close_cached_file(self, f: Any, path: str) -> None:
|
||
|
|
"""Perform side-effect actions on closing a cached file.
|
||
|
|
|
||
|
|
The actual closing of the file is the responsibility of the caller.
|
||
|
|
"""
|
||
|
|
# File must be writeble, so in self.cached_files[-1]
|
||
|
|
c = self.cached_files[-1][path]
|
||
|
|
if c["blocks"] is not True and len(c["blocks"]) * f.blocksize >= f.size:
|
||
|
|
c["blocks"] = True
|
||
|
|
|
||
|
|
def pop_file(self, path: str) -> str | None:
|
||
|
|
"""Remove metadata of cached file.
|
||
|
|
|
||
|
|
If path is in the cache, return the filename of the cached file,
|
||
|
|
otherwise return ``None``. Caller is responsible for deleting the
|
||
|
|
cached file.
|
||
|
|
"""
|
||
|
|
details = self.check_file(path, None)
|
||
|
|
if not details:
|
||
|
|
return None
|
||
|
|
_, fn = details
|
||
|
|
if fn.startswith(self._storage[-1]):
|
||
|
|
self.cached_files[-1].pop(path)
|
||
|
|
self.save()
|
||
|
|
else:
|
||
|
|
raise PermissionError(
|
||
|
|
"Can only delete cached file in last, writable cache location"
|
||
|
|
)
|
||
|
|
return fn
|
||
|
|
|
||
|
|
def save(self) -> None:
|
||
|
|
"""Save metadata to disk"""
|
||
|
|
for (fn, _, writable), cache in zip(self._scan_locations(), self.cached_files):
|
||
|
|
if not writable:
|
||
|
|
continue
|
||
|
|
|
||
|
|
if os.path.exists(fn):
|
||
|
|
cached_files = self._load(fn)
|
||
|
|
for k, c in cached_files.items():
|
||
|
|
if k in cache:
|
||
|
|
if c["blocks"] is True or cache[k]["blocks"] is True:
|
||
|
|
c["blocks"] = True
|
||
|
|
else:
|
||
|
|
# self.cached_files[*][*]["blocks"] must continue to
|
||
|
|
# point to the same set object so that updates
|
||
|
|
# performed by MMapCache are propagated back to
|
||
|
|
# self.cached_files.
|
||
|
|
blocks = cache[k]["blocks"]
|
||
|
|
blocks.update(c["blocks"])
|
||
|
|
c["blocks"] = blocks
|
||
|
|
c["time"] = max(c["time"], cache[k]["time"])
|
||
|
|
c["uid"] = cache[k]["uid"]
|
||
|
|
|
||
|
|
# Files can be added to cache after it was written once
|
||
|
|
for k, c in cache.items():
|
||
|
|
if k not in cached_files:
|
||
|
|
cached_files[k] = c
|
||
|
|
else:
|
||
|
|
cached_files = cache
|
||
|
|
cache = {k: v.copy() for k, v in cached_files.items()}
|
||
|
|
for c in cache.values():
|
||
|
|
if isinstance(c["blocks"], set):
|
||
|
|
c["blocks"] = list(c["blocks"])
|
||
|
|
self._save(cache, fn)
|
||
|
|
self.cached_files[-1] = cached_files
|
||
|
|
|
||
|
|
def update_file(self, path: str, detail: Detail) -> None:
|
||
|
|
"""Update metadata for specific file in memory, do not save"""
|
||
|
|
self.cached_files[-1][path] = detail
|