better MemCacheUnit implement

qlib/data/cache.py

@@ -13,6 +13,7 @@ import pickle
 import traceback
 import redis_lock
 import contextlib
+import abc
 from pathlib import Path
 import numpy as np
 import pandas as pd
@@ -39,33 +40,127 @@ class QlibCacheException(RuntimeError):
     pass
 
 
-class MemCacheUnit(OrderedDict):
+class MemCacheUnit(abc.ABC):
     """Memory Cache Unit."""
 
-    # TODO: use min_heap to replace ordereddict for better performance
-
     def __init__(self, *args, **kwargs):
-        self.size_limit = kwargs.pop("size_limit", None)
-        # limit_type: check size_limit type, length(call fun: len) or size(call fun: sys.getsizeof)
+        self.size_limit = kwargs.pop("size_limit", 0)
         self.limit_type = kwargs.pop("limit_type", "length")
-        super(MemCacheUnit, self).__init__(*args, **kwargs)
-        self._check_size_limit()
+
+        assert self.limit_type in ["length", "sizeof"], ValueError(
+            "limit_type shoule be one of ['length', 'sizeof']"
+        )
+        assert self.size_limit >= 0, ValueError(
+            "size_limit shoule not be negative.The default 0 means unlimited!"
+        )
+
+        # limit_flag: whether to popitem or not
+        self._limit_flag = 1 if self.size_limit > 0 else 0
+        self._size = 0
+        self.od = OrderedDict()
 
     def __setitem__(self, key, value):
-        super(MemCacheUnit, self).__setitem__(key, value)
-        self._check_size_limit()
+        # TODO: thread safe?__setitem__ failure might cause inconsistent size?
+
+        # precalculate the size after od.__setitem__
+        self._adjust_size(key, value)
+
+        self.od.__setitem__(key, value)
+
+        # move the key to end,make it latest
+        self.od.move_to_end(key)
+
+        # pop the oldest items beyond size limit
+        while self._size * self._limit_flag > self.size_limit:
+            self.popitem(last=False)
 
     def __getitem__(self, key):
-        value = super(MemCacheUnit, self).__getitem__(key)
-        super(MemCacheUnit, self).__delitem__(key)
-        super(MemCacheUnit, self).__setitem__(key, value)
-        return value
+        v = self.od.__getitem__(key)
+        self.od.move_to_end(key)
+        return v
 
-    def _check_size_limit(self):
-        if self.size_limit is not None:
-            get_cur_size = lambda x: len(x) if self.limit_type == "length" else sum(map(sys.getsizeof, x.values()))
-            while get_cur_size(self) > self.size_limit:
-                self.popitem(last=False)
+    def __contains__(self, key):
+        return key in self.od
+
+    def __len__(self):
+        return self.od.__len__()
+
+    def __repr__(self):
+        return f"{self.__class__.__name__}<limit_type:{self.limit_type} size_limit:{self.size_limit if self.is_limited else 'no limit'} total_size:{self._size}>\n{self.od.__repr__()}"
+
+    def set_limit_size(self, limit):
+        self.size_limit = limit
+
+    def set_limit(self, is_limited=True):
+        self._limit_flag = 1 if is_limited else 0
+
+    @property
+    def is_limited(self):
+        return bool(self._limit_flag)
+
+    @property
+    def total_size(self):
+        return self._size
+
+    def clear(self):
+        self._size = 0
+        self.od.clear()
+
+    @abc.abstractmethod
+    def _adjust_size(self, key, value):
+        raise NotImplementedError
+
+    @abc.abstractmethod
+    def popitem(self, last=True):
+        raise NotImplementedError
+
+    @abc.abstractmethod
+    def pop(self, key):
+        raise NotImplementedError
+
+
+class MemCacheLengthUnit(MemCacheUnit):
+    def __init__(self, size_limit=0):
+        super().__init__(size_limit=size_limit, limit_type="length")
+
+    def _adjust_size(self, key, value):
+        if key not in self.od:
+            self._size += 1
+
+    def popitem(self, last=True):
+        k, v = self.od.popitem(last=last)
+        self._size -= 1
+
+        return k, v
+
+    def pop(self, key):
+        v = self.od.pop(key)
+        self._size -= 1
+
+        return v
+
+
+class MemCacheSizeofUnit(MemCacheUnit):
+    def __init__(self, size_limit=0):
+        super().__init__(size_limit=size_limit, limit_type="sizeof")
+
+    def _adjust_size(self, key, value):
+        if key in self.od:
+            self._size = self._size - sys.getsizeof(self.od[key]) + sys.getsizeof(value)
+        else:
+            self._size += sys.getsizeof(value)
+
+    def popitem(self, last=True):
+        k, v = self.od.popitem(last=last)
+        self._size -= sys.getsizeof(v)
+
+        return k, v
+
+    def pop(self, key):
+        v = self.od.pop(key)
+        self._size -= sys.getsizeof(v)
+
+        return v
 
 
 class MemCache:
@@ -79,22 +174,20 @@ class MemCache:
         mem_cache_size_limit: cache max size.
         limit_type: length or sizeof; length(call fun: len), size(call fun: sys.getsizeof).
         """
-        if limit_type not in ["length", "sizeof"]:
+        
+        size_limit = C.mem_cache_size_limit if mem_cache_size_limit is None else mem_cache_size_limit
+        
+        if limit_type == "length":
+            self.__calendar_mem_cache = MemCacheLengthUnit(size_limit)
+            self.__instrument_mem_cache = MemCacheLengthUnit(size_limit)
+            self.__feature_mem_cache = MemCacheLengthUnit(size_limit)
+        elif limit_type == "sizeof":
+            self.__calendar_mem_cache = MemCacheSizeofUnit(size_limit)
+            self.__instrument_mem_cache = MemCacheSizeofUnit(size_limit)
+            self.__feature_mem_cache = MemCacheSizeofUnit(size_limit)
+        else:
             raise ValueError(f"limit_type must be length or sizeof, your limit_type is {limit_type}")
 
-        self.__calendar_mem_cache = MemCacheUnit(
-            size_limit=C.mem_cache_size_limit if mem_cache_size_limit is None else mem_cache_size_limit,
-            limit_type=limit_type,
-        )
-        self.__instrument_mem_cache = MemCacheUnit(
-            size_limit=C.mem_cache_size_limit if mem_cache_size_limit is None else mem_cache_size_limit,
-            limit_type=limit_type,
-        )
-        self.__feature_mem_cache = MemCacheUnit(
-            size_limit=C.mem_cache_size_limit if mem_cache_size_limit is None else mem_cache_size_limit,
-            limit_type=limit_type,
-        )
-
     def __getitem__(self, key):
         if key == "c":
             return self.__calendar_mem_cache