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-- lock version

local redis = require 'resty.redis'

local resty_lock = require "resty.lock"

local cproxy = require 'init'

local serv_count = #cproxy["redis_server"]

local cache_key = ngx.var.cache_key

-- init redis

local redisInstance = redis:new()

-- 数据存储分布

local hash = ngx.crc32_long(cache_key) % serv_count + 1

local serv_config = cproxy["redis_server"][hash]

local host = serv_config.host

local port = serv_config.port or "6379"

redisInstance:set_timeout(1000)

local ok, err = redisInstance:connect(host, port)

if not ok then

ngx.log(ngx.ERR, "failed to connect:" .. err)

return ngx.exit(ngx.HTTP_SERVICE_UNAVAILABLE)

end

if serv_config.password then

ok, err = redisInstance:auth(serv_config.password)

if err then

ngx.log(ngx.ERR, err)

return ngx.exit(ngx.HTTP_SERVICE_UNAVAILABLE)

end

end

if serv_config.db then

redisInstance:select(serv_config.db)

end

local req_method = ngx.req.get_method()

if req_method == "GET" then

local res, err = redisInstance:get(cache_key)

if res == ngx.null then

-- cache miss

local lock, err = resty_lock:new("my_locks", {timeout = 10})

if not lock then

ngx.log(ngx.ERR, "failed to create lock:"..err)

return ngx.exit(ngx.HTTP_SERVICE_UNAVAILABLE)

end

local elapsed, err = lock:lock(cache_key)

if not elapsed then

ngx.log(ngx.ERR, "failed to acquire the lock:"..err)

return ngx.exit(ngx.HTTP_SERVICE_UNAVAILABLE)

end

-- lock successfully acquired!

-- someone might have already put the value into the cache

-- so we check it again!

res, err = redisInstance:get(cache_key)

if res == ngx.null then

else

local ok, err = lock:unlock()

if not ok then

ngx.log(ngx.ERR, "failed to unlock:"..err)

return ngx.exit(ngx.HTTP_SERVICE_UNAVAILABLE)

end

ngx.say(res)

return

end

-- fetch data into redis

local ret = ngx.location.capture("/subrequest_fastcgi", { method = ngx.HTTP_GET, args = ngx.req.get_uri_args()})

if not ret then

local ok, err = lock:unlock()

if not ok then

ngx.log(ngx.ERR, "failed to unlock:"..err)

return ngx.exit(ngx.HTTP_SERVICE_UNAVAILABLE)

end

return ngx.exit(ngx.HTTP_SERVICE_UNAVAILABLE)

end

-- update cache with the newly fetched value

local ok, err = redisInstance:set(cache_key, ret.body)

if not ok then

local ok, err = lock:unlock()

if not ok then

ngx.log(ngx.ERR, "failed to unlock:"..err)

return ngx.exit(ngx.HTTP_SERVICE_UNAVAILABLE)

end

ngx.log(ngx.ERR, "failed to update cache")

return ngx.exit(ngx.HTTP_SERVICE_UNAVAILABLE)

end

local ok, err = lock:unlock()

if not ok then

ngx.log(ngx.ERR, "failed to unlock:"..err)

return ngx.exit(ngx.HTTP_SERVICE_UNAVAILABLE)

end

ngx.var.fetch_status = "MISS"

ngx.var.store_status = "STORE"

ngx.say(ret.body)

else

--ngx.log(ngx.ERR, "exist.....")

ngx.var.fetch_status = "HIT"

ngx.var.store_status = "BYPASS"

ngx.say(res)

return

end

end