add evict call back func in lrucache

README.markdown

@@ -45,9 +45,14 @@ local _M = {}
 -- alternatively: local lrucache = require "resty.lrucache.pureffi"
 local lrucache = require "resty.lrucache"
 
+local function call_back(key, value)
+    ngx.log(ngx.ERR, "evict:", key, ":", value)
+end
+
 -- we need to initialize the cache on the lua module level so that
 -- it can be shared by all the requests served by each nginx worker process:
-local c, err = lrucache.new(200)  -- allow up to 200 items in the cache
+local c, err = lrucache.new(2, call_back)  -- allow up to 2 items in the cache
+-- local c, err = lrucache.new(2, nil, call_back)  -- for `resty.lrucache.pureffi`
 if not c then
     error("failed to create the cache: " .. (err or "unknown"))
 end
@@ -61,6 +66,12 @@ function _M.go()
     c:set("dog", { age = 10 }, 0.1)  -- expire in 0.1 sec
     c:delete("dog")
 
+    c:set("dog", 32)
+    c:set("parrto", 12) -- in log "evict:cat:56"
+    c:set("cat", 56, 0.1)  -- in log "evict:dog:32"
+    ngx.sleep(1)
+    ngx.say("cat:", c:get("cat")) -- in log "evict:cat:56"
+
     c:flush_all()  -- flush all the cached data
 end
 
@@ -151,7 +162,9 @@ local lrucache = require "resty.lrucache.pureffi"
 
 new
 ---
-`syntax: cache, err = lrucache.new(max_items [, load_factor])`
+`syntax: cache, err = lrucache.new(max_items [, evict_cb])`
+
+`syntax: cache, err = lrucache.new(max_items [, load_factor, evict_cb])`
 
 Creates a new cache instance. Upon failure, returns `nil` and a string
 describing the error.
@@ -167,6 +180,11 @@ saturated to 1; likewise, if load-factor is smaller than `0.1`, it will be
 clamped to `0.1`). This argument is only meaningful for
 `resty.lrucache.pureffi`.
 
+The `evict_cb` argument specifies the item's destory call back. When use `set`
+add new item or `get`(item with ttl), may trigger remove old item, with this
+call back you can do some clean up job. The `evict_cb` will receive two param:
+key and value.
+
 [Back to TOC](#table-of-contents)
 
 set

lib/resty/lrucache.lua

@@ -151,7 +151,7 @@ local function ptr2num(ptr)
 end
 
 
-function _M.new(size)
+function _M.new(size, evict_cb)
     if size < 1 then
         return nil, "size too small"
     end
@@ -164,6 +164,7 @@ function _M.new(size)
         node2key = {},
         num_items = 0,
         max_items = size,
+        evict_cb = evict_cb,
     }
     return setmetatable(self, mt)
 end
@@ -195,6 +196,9 @@ function _M.get(self, key)
 
     if node.expire >= 0 and node.expire < ngx_now() then
         -- print("expired: ", node.expire, " > ", ngx_now())
+        if self.evict_cb then
+            pcall(self.evict_cb, key, val)
+        end
         return nil, val, node.user_flags
     end
 
@@ -241,6 +245,9 @@ function _M.set(self, key, value, ttl, flags)
             -- print(key, ": evicting oldkey: ", oldkey, ", oldnode: ",
             --         tostring(node))
             if oldkey then
+                if self.evict_cb then
+                    pcall(self.evict_cb, oldkey, hasht[oldkey])
+                end
                 hasht[oldkey] = nil
                 key2node[oldkey] = nil
             end

lib/resty/lrucache/pureffi.lua

@@ -318,7 +318,7 @@ local mt = { __index = _M }
 -- load-factor is specified, it will be clamped to the range of [0.1, 1](i.e.
 -- if load-factor is greater than 1, it will be saturated to 1, likewise,
 -- if load-factor is smaller than 0.1, it will be clamped to 0.1).
-function _M.new(size, load_factor)
+function _M.new(size, load_factor, evict_cb)
     if size < 1 then
         return nil, "size too small"
     end
@@ -350,6 +350,7 @@ function _M.new(size, load_factor)
         val_v = new_tab(size, 0),
         bucket_v = ffi_new(int_array_t, bucket_sz),
         num_items = 0,
+        evict_cb = evict_cb,
     }
     -- "note_v" is an array of all the nodes used in the LRU queue. Exprpession
     -- node_v[i] evaluates to the element of ID "i".
@@ -489,6 +490,9 @@ function _M.get(self, key)
     local expire = node.expire
     if expire >= 0 and expire < ngx_now() then
         -- print("expired: ", node.expire, " > ", ngx_now())
+        if self.evict_cb then
+            pcall(self.evict_cb, key, self.val_v[node_id])
+        end
         return nil, self.val_v[node_id], node.user_flags
     end
 
@@ -526,6 +530,9 @@ function _M.set(self, key, value, ttl, flags)
             -- evict the least recently used key
             -- assert(not queue_is_empty(self.cache_queue))
             node = queue_last(self.cache_queue)
+            if self.evict_cb then
+                pcall(self.evict_cb, self.key_v[node.id], self.val_v[node.id])
+            end
             remove_key(self, self.key_v[node.id])
         else
             -- take a free queue node

t/009-evict-call-back.t

@@ -0,0 +1,53 @@
+# vim:set ft= ts=4 sw=4 et fdm=marker:
+use lib '.';
+use t::TestLRUCache;
+
+repeat_each(2);
+
+plan tests => repeat_each() * (blocks() * 3);
+
+no_long_string();
+run_tests();
+
+__DATA__
+
+=== TEST 1: evict with call back
+--- config
+    location = /t {
+        content_by_lua_block {
+            local function evict_cb(k,v)
+                ngx.say(k, v)
+            end
+            local lrucache = require "resty.lrucache"
+            local c = lrucache.new(1, evict_cb)
+
+            collectgarbage()
+
+            c:set("dog", 12)
+            c:set("cat", 14)
+        }
+    }
+--- response_body
+dog12
+
+
+
+=== TEST 2: evict with call back, ttl
+--- config
+    location = /t {
+        content_by_lua_block {
+            local function evict_cb(k,v)
+                ngx.say(k, v)
+            end
+            local lrucache = require "resty.lrucache"
+            local c = lrucache.new(1, evict_cb)
+
+            collectgarbage()
+
+            c:set("dog", 12, 0.1)
+            ngx.sleep(1)
+            c:get("dog")
+        }
+    }
+--- response_body
+dog12

t/100-pureffi/009-evict-call-back.t

@@ -0,0 +1,53 @@
+# vim:set ft= ts=4 sw=4 et fdm=marker:
+use lib '.';
+use t::TestLRUCache;
+
+repeat_each(2);
+
+plan tests => repeat_each() * (blocks() * 3);
+
+no_long_string();
+run_tests();
+
+__DATA__
+
+=== TEST 1: evict with call back
+--- config
+    location = /t {
+        content_by_lua_block {
+            local function evict_cb(k,v)
+                ngx.say(k, v)
+            end
+            local lrucache = require "resty.lrucache.pureffi"
+            local c = lrucache.new(1, nil, evict_cb)
+
+            collectgarbage()
+
+            c:set("dog", 12)
+            c:set("cat", 14)
+        }
+    }
+--- response_body
+dog12
+
+
+
+=== TEST 2: evict with call back, ttl
+--- config
+    location = /t {
+        content_by_lua_block {
+            local function evict_cb(k,v)
+                ngx.say(k, v)
+            end
+            local lrucache = require "resty.lrucache.pureffi"
+            local c = lrucache.new(1, nil, evict_cb)
+
+            collectgarbage()
+
+            c:set("dog", 12, 1)
+            ngx.sleep(1)
+            c:get("dog")
+        }
+    }
+--- response_body
+dog12