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-rw-r--r--util/cache.lua73
1 files changed, 43 insertions, 30 deletions
diff --git a/util/cache.lua b/util/cache.lua
index 9453697c..72b74351 100644
--- a/util/cache.lua
+++ b/util/cache.lua
@@ -1,11 +1,3 @@
-local cache_methods = {};
-local cache_mt = { __index = cache_methods };
-
-local function new(size)
- assert(size > 0, "cache size must be greater than zero");
- local data = {};
- return setmetatable({ data = data, count = 0, size = size, head = nil, tail = nil }, cache_mt);
-end
local function _remove(list, m)
if m.prev then
@@ -14,29 +6,32 @@ local function _remove(list, m)
if m.next then
m.next.prev = m.prev;
end
- if list.tail == m then
- list.tail = m.prev;
+ if list._tail == m then
+ list._tail = m.prev;
end
- if list.head == m then
- list.head = m.next;
+ if list._head == m then
+ list._head = m.next;
end
- list.count = list.count - 1;
+ list._count = list._count - 1;
end
local function _insert(list, m)
- if list.head then
- list.head.prev = m;
+ if list._head then
+ list._head.prev = m;
end
- m.prev, m.next = nil, list.head;
- list.head = m;
- if not list.tail then
- list.tail = m;
+ m.prev, m.next = nil, list._head;
+ list._head = m;
+ if not list._tail then
+ list._tail = m;
end
- list.count = list.count + 1;
+ list._count = list._count + 1;
end
+local cache_methods = {};
+local cache_mt = { __index = cache_methods };
+
function cache_methods:set(k, v)
- local m = self.data[k];
+ local m = self._data[k];
if m then
-- Key already exists
if v ~= nil then
@@ -47,27 +42,33 @@ function cache_methods:set(k, v)
else
-- Remove from list
_remove(self, m);
- self.data[k] = nil;
+ self._data[k] = nil;
end
- return;
+ return true;
end
-- New key
if v == nil then
- return;
+ return true;
end
-- Check whether we need to remove oldest k/v
- if self.count == self.size then
- self.data[self.tail.key] = nil;
- _remove(self, self.tail);
+ if self._count == self.size then
+ local tail = self._tail;
+ local on_evict = self._on_evict;
+ if on_evict then
+ on_evict(tail.key, tail.value);
+ end
+ _remove(self, tail);
+ self._data[tail.key] = nil;
end
m = { key = k, value = v, prev = nil, next = nil };
- self.data[k] = m;
+ self._data[k] = m;
_insert(self, m);
+ return true;
end
function cache_methods:get(k)
- local m = self.data[k];
+ local m = self._data[k];
if m then
return m.value;
end
@@ -75,7 +76,7 @@ function cache_methods:get(k)
end
function cache_methods:items()
- local m = self.head;
+ local m = self._head;
return function ()
if not m then
return;
@@ -86,6 +87,18 @@ function cache_methods:items()
end
end
+function cache_methods:count()
+ return self._count;
+end
+
+local function new(size, on_evict)
+ size = assert(tonumber(size), "cache size must be a number");
+ size = math.floor(size);
+ assert(size > 0, "cache size must be greater than zero");
+ local data = {};
+ return setmetatable({ _data = data, _count = 0, size = size, _head = nil, _tail = nil, _on_evict = on_evict }, cache_mt);
+end
+
return {
new = new;
}