change: make lrucache lock optional

apisix/core/lrucache.lua

@@ -17,6 +17,7 @@
 
 local lru_new = require("resty.lrucache").new
 local resty_lock = require("resty.lock")
+local log = require("apisix.core.log")
 local tostring = tostring
 local ngx = ngx
 local get_phase = ngx.get_phase
@@ -69,10 +70,11 @@ local function new_lru_fun(opts)
     local item_ttl = opts and opts.ttl or GLOBAL_TTL
     local item_release = opts and opts.release
     local invalid_stale = opts and opts.invalid_stale
+    local limit_concurrency = opts and opts.limit_concurrency
     local lru_obj = lru_new(item_count)
 
     return function (key, version, create_obj_fun, ...)
-        if not can_yield_phases[get_phase()] then
+        if not limit_concurrency or not can_yield_phases[get_phase()] then
             local cache_obj = fetch_valid_cache(lru_obj, invalid_stale,
                                 item_ttl, item_release, key, version)
             if cache_obj then
@@ -99,6 +101,8 @@ local function new_lru_fun(opts)
         end
 
         local key_s = tostring(key)
+        log.info("try to lock with key ", key_s)
+
         local elapsed, err = lock:lock(key_s)
         if not elapsed then
             return nil, "failed to acquire the lock: " .. err
@@ -108,6 +112,7 @@ local function new_lru_fun(opts)
                         nil, key, version)
         if cache_obj then
             lock:unlock()
+            log.info("unlock with key ", key_s)
             return cache_obj.val
         end
 
@@ -116,6 +121,7 @@ local function new_lru_fun(opts)
             lru_obj:set(key, {val = obj, ver = version}, item_ttl)
         end
         lock:unlock()
+        log.info("unlock with key ", key_s)
 
         return obj, err
     end