diff --git a/pytools/persistent_dict.py b/pytools/persistent_dict.py
index 857299f17798ed51d34f4374ac2950a3ac4721ee..aaca40fabb0f50f7b8ee6bc7ed873b2b977e6d48 100644
--- a/pytools/persistent_dict.py
+++ b/pytools/persistent_dict.py
@@ -29,7 +29,6 @@ OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
"""
-import collections.abc as abc
import errno
import hashlib
import logging
@@ -443,125 +442,6 @@ class KeyBuilder:
# }}}
-# {{{ lru cache
-
-class _LinkedList:
- """The list operates on nodes of the form [value, leftptr, rightpr]. To create a
- node of this form you can use `LinkedList.new_node().`
-
- Supports inserting at the left and deleting from an arbitrary location.
- """
- def __init__(self):
- self.count = 0
- self.head = None
- self.end = None
-
- @staticmethod
- def new_node(element):
- return [element, None, None]
-
- def __len__(self):
- return self.count
-
- def appendleft_node(self, node):
- self.count += 1
-
- if self.head is None:
- self.head = self.end = node
- return
-
- self.head[1] = node
- node[2] = self.head
-
- self.head = node
-
- def pop_node(self):
- end = self.end
- self.remove_node(end)
- return end
-
- def remove_node(self, node):
- self.count -= 1
-
- if self.head is self.end:
- assert node is self.head
- self.head = self.end = None
- return
-
- left = node[1]
- right = node[2]
-
- if left is None:
- self.head = right
- else:
- left[2] = right
-
- if right is None:
- self.end = left
- else:
- right[1] = left
-
- node[1] = node[2] = None
-
-
-class _LRUCache(abc.MutableMapping):
- """A mapping that keeps at most *maxsize* items with an LRU replacement policy.
- """
- def __init__(self, maxsize):
- self.lru_order = _LinkedList()
- self.maxsize = maxsize
- self.cache = {}
-
- def __delitem__(self, item):
- node = self.cache[item]
- self.lru_order.remove_node(node)
- del self.cache[item]
-
- def __getitem__(self, item):
- node = self.cache[item]
- self.lru_order.remove_node(node)
- self.lru_order.appendleft_node(node)
- # A linked list node contains a tuple of the form (item, value).
- return node[0][1]
-
- def __contains__(self, item):
- return item in self.cache
-
- def __iter__(self):
- return iter(self.cache)
-
- def __len__(self) -> int:
- return len(self.cache)
-
- def clear(self):
- self.cache.clear()
- self.lru_order = _LinkedList()
-
- def __setitem__(self, item, value):
- if self.maxsize < 1:
- return
-
- try:
- node = self.cache[item]
- self.lru_order.remove_node(node)
- except KeyError:
- if len(self.lru_order) >= self.maxsize:
- # Make room for new elements.
- end_node = self.lru_order.pop_node()
- del self.cache[end_node[0][0]]
-
- node = self.lru_order.new_node((item, value))
- self.cache[item] = node
-
- self.lru_order.appendleft_node(node)
-
- assert len(self.cache) == len(self.lru_order), \
- (len(self.cache), len(self.lru_order))
- assert len(self.lru_order) <= self.maxsize
-
-# }}}
-
-
# {{{ top-level
class NoSuchEntryError(KeyError):
@@ -720,7 +600,7 @@ class WriteOncePersistentDict(_PersistentDictBase):
"""A concurrent disk-backed dictionary that disallows overwriting/deletion.
Compared with :class:`PersistentDict`, this class has faster
- retrieval times.
+ retrieval times because it uses an LRU cache to cache entries in memory.
.. automethod:: __init__
.. automethod:: __getitem__
@@ -742,14 +622,15 @@ class WriteOncePersistentDict(_PersistentDictBase):
"""
_PersistentDictBase.__init__(self, identifier, key_builder, container_dir)
self._in_mem_cache_size = in_mem_cache_size
- self.clear_in_mem_cache()
+ from functools import lru_cache
+ self._fetch = lru_cache(maxsize=in_mem_cache_size)(self._fetch)
def clear_in_mem_cache(self) -> None:
"""
.. versionadded:: 2023.1.1
"""
- self._cache = _LRUCache(self._in_mem_cache_size)
+ self._fetch.cache_clear()
def _spin_until_removed(self, lock_file, stacklevel):
from os.path import exists
@@ -807,19 +688,14 @@ class WriteOncePersistentDict(_PersistentDictBase):
def fetch(self, key, _stacklevel=0):
hexdigest_key = self.key_builder(key)
- # {{{ in memory cache
+ (stored_key, stored_value) = self._fetch(hexdigest_key, 1 + _stacklevel)
- try:
- stored_key, stored_value = self._cache[hexdigest_key]
- except KeyError:
- pass
- else:
- logger.debug("%s: in mem cache hit [key=%s]",
- self.identifier, hexdigest_key)
- self._collision_check(key, stored_key, 1 + _stacklevel)
- return stored_value
+ self._collision_check(key, stored_key, 1 + _stacklevel)
- # }}}
+ return stored_value
+
+ def _fetch(self, hexdigest_key, _stacklevel=0): # pylint:disable=method-hidden
+ # This is separate from fetch() to allow for LRU caching
# {{{ check path exists and is unlocked
@@ -829,7 +705,7 @@ class WriteOncePersistentDict(_PersistentDictBase):
if not isdir(item_dir):
logger.debug("%s: disk cache miss [key=%s]",
self.identifier, hexdigest_key)
- raise NoSuchEntryError(key)
+ raise NoSuchEntryError(hexdigest_key)
lock_file = self._lock_file(hexdigest_key)
self._spin_until_removed(lock_file, 1 + _stacklevel)
@@ -852,9 +728,7 @@ class WriteOncePersistentDict(_PersistentDictBase):
f"Remove the directory '{item_dir}' if necessary. "
f"(caught: {type(e).__name__}: {e})",
stacklevel=1 + _stacklevel)
- raise NoSuchEntryInvalidKeyError(key)
-
- self._collision_check(key, read_key, 1 + _stacklevel)
+ raise NoSuchEntryInvalidKeyError(hexdigest_key)
# }}}
@@ -871,16 +745,15 @@ class WriteOncePersistentDict(_PersistentDictBase):
f"Remove the directory '{item_dir}' if necessary."
f"(caught: {type(e).__name__}: {e})",
stacklevel=1 + _stacklevel)
- raise NoSuchEntryInvalidContentsError(key)
+ raise NoSuchEntryInvalidContentsError(hexdigest_key)
# }}}
- self._cache[hexdigest_key] = (key, read_contents)
- return read_contents
+ return (read_key, read_contents)
def clear(self):
_PersistentDictBase.clear(self)
- self._cache.clear()
+ self._fetch.cache_clear()
class PersistentDict(_PersistentDictBase):
diff --git a/pytools/test/test_persistent_dict.py b/pytools/test/test_persistent_dict.py
index 73d8f6e6c00c23e416431d05cf24e7c56acd8bef..0989bb06b316584fb04088f87ee1e4f6536fe20b 100644
--- a/pytools/test/test_persistent_dict.py
+++ b/pytools/test/test_persistent_dict.py
@@ -309,6 +309,14 @@ def test_write_once_persistent_dict_lru_policy():
pdict.fetch(4)
assert pdict.fetch(1) is not val1
+ # test clear_in_mem_cache
+ val1 = pdict.fetch(1)
+ pdict.clear_in_mem_cache()
+ assert pdict.fetch(1) is not val1
+
+ val1 = pdict.fetch(1)
+ assert pdict.fetch(1) is val1
+
finally:
shutil.rmtree(tmpdir)