--- a/src/eric7/EricUtilities/EricCache.py Wed Jul 13 11:16:20 2022 +0200
+++ b/src/eric7/EricUtilities/EricCache.py Wed Jul 13 14:55:47 2022 +0200
@@ -13,73 +13,74 @@
class EricCache:
"""
Class implementing a LRU cache of a specific size.
-
+
If the maximum number of entries is exceeded, the least recently used item
is removed from the cache. A cache hit moves the entry to the front of the
cache.
"""
+
def __init__(self, size=100):
"""
Constructor
-
+
@param size maximum number of entries that may be stored in the cache
@type int
@exception ValueError raised to indicate an illegal 'size' parameter
"""
if size < 0:
raise ValueError("'size' parameter must be positive.")
-
+
self.__size = size
-
+
# internal objects
self.__keyList = []
- self.__store = {} # stores the cache entries
- self.__accesStore = {} # stores the last access date and times
+ self.__store = {} # stores the cache entries
+ self.__accesStore = {} # stores the last access date and times
self.__hits = 0
self.__misses = 0
self.__maxsize = 0
- self.__maxCacheTime = 0 # 0 seconds means aging is disabled
-
+ self.__maxCacheTime = 0 # 0 seconds means aging is disabled
+
self.__cacheTimer = QTimer()
self.__cacheTimer.setSingleShot(True)
self.__cacheTimer.timeout.connect(self.__pruneCache)
-
+
def __moveLast(self, key):
"""
Private method to move a cached item to the MRU position.
-
+
@param key key of the item to be retrieved
@type any hashable type that can be used as a dict key
"""
self.__keyList.remove(key)
self.__keyList.append(key)
-
+
def __adjustToSize(self):
"""
Private method to adjust the cache to its size.
"""
if self.__size:
- removeList = self.__keyList[:-self.__size]
- self.__keyList = self.__keyList[-self.__size:]
+ removeList = self.__keyList[: -self.__size]
+ self.__keyList = self.__keyList[-self.__size :]
for key in removeList:
del self.__store[key]
del self.__accesStore[key]
else:
self.reset()
-
+
def getSize(self):
"""
Public method to get the maximum size of the cache.
-
+
@return maximum number of entries of the cache
@rtype int
"""
return self.__size
-
+
def setSize(self, newSize):
"""
Public method to change the maximum size of the cache.
-
+
@param newSize maximum number of entries that may be stored in the
cache
@type int
@@ -87,20 +88,20 @@
if newSize >= 0:
self.__size = newSize
self.__adjustToSize()
-
+
def getMaximumCacheTime(self):
"""
Public method to get the maximum time entries may exist in the cache.
-
+
@return maximum cache time in seconds
@rtype int
"""
return self.__maxCacheTime
-
+
def setMaximumCacheTime(self, time):
"""
Public method to set the maximum time entries may exist in the cache.
-
+
@param time maximum cache time in seconds
@type int
"""
@@ -111,13 +112,13 @@
if self.__maxCacheTime > 0:
self.__cacheTimer.setInterval(self.__maxCacheTime * 1000)
self.__cacheTimer.start()
-
+
def get(self, key):
"""
Public method to get an entry from the cache given its key.
-
+
If the key is present in the cache, it is moved to the MRU position.
-
+
@param key key of the item to be retrieved
@type any hashable type that can be used as a dict key
@return cached item for the given key or None, if the key is not
@@ -132,14 +133,14 @@
else:
self.__misses += 1
return None
-
+
def add(self, key, item):
"""
Public method to add an item to the cache.
-
+
If the key is already in use, the cached item is replaced by the new
one given and is moved to the MRU position
-
+
@param key key of the item to be retrieved
@type any hashable type that can be used as a dict key
@param item item to be cached under the given key
@@ -151,15 +152,15 @@
self.__keyList.append(key)
self.__store[key] = item
self.__accesStore[key] = QDateTime.currentDateTimeUtc()
-
+
self.__adjustToSize()
-
+
self.__maxsize = max(self.__maxsize, len(self.__keyList))
-
+
def remove(self, key):
"""
Public method to remove an item from the cache.
-
+
@param key key of the item to be retrieved
@type any hashable type that can be used as a dict key
"""
@@ -167,7 +168,7 @@
del self.__store[key]
del self.__accesStore[key]
self.__keyList.remove(key)
-
+
def clear(self):
"""
Public method to clear the cache.
@@ -175,11 +176,11 @@
self.__keyList = []
self.__store = {}
self.__accesStore = {}
-
+
def reset(self):
"""
Public method to reset the cache.
-
+
This is like clear() but sets the various counters to their initial
value as well.
"""
@@ -187,20 +188,20 @@
self.__hits = 0
self.__misses = 0
self.__maxsize = 0
-
+
def length(self):
"""
Public method to get the current length of the cache.
-
+
@return current length of the cache
@rtype int
"""
return len(self.__keyList)
-
+
def info(self):
"""
Public method to get some information about the cache.
-
+
@return dictionary containing the cache info
@rtype dict (with keys "hits", "misses", "maxsize", "currsize")
"""
@@ -210,19 +211,19 @@
"maxsize": self.__maxsize,
"currsize": self.length(),
}
-
+
def __pruneCache(self):
"""
Private slot to prune outdated cache entries and restart the timer.
"""
if self.__maxCacheTime > 0:
current = QDateTime.currentDateTimeUtc()
-
+
keysToBeDeleted = []
for key, lastAccessTime in self.__accesStore.items():
if lastAccessTime.secsTo(current) > self.__maxCacheTime:
keysToBeDeleted.append(key)
for key in keysToBeDeleted:
self.remove(key)
-
+
self.__cacheTimer.start()
