diff options
Diffstat (limited to 'msb-core/openresty-ext/src/assembly/resources/openresty/nginx/luaext/vendor/shcache.lua')
| -rw-r--r-- | msb-core/openresty-ext/src/assembly/resources/openresty/nginx/luaext/vendor/shcache.lua | 440 |
1 files changed, 0 insertions, 440 deletions
diff --git a/msb-core/openresty-ext/src/assembly/resources/openresty/nginx/luaext/vendor/shcache.lua b/msb-core/openresty-ext/src/assembly/resources/openresty/nginx/luaext/vendor/shcache.lua deleted file mode 100644 index 32a9b6c..0000000 --- a/msb-core/openresty-ext/src/assembly/resources/openresty/nginx/luaext/vendor/shcache.lua +++ /dev/null @@ -1,440 +0,0 @@ --- Copyright (C) 2013 Matthieu Tourne --- @author Matthieu Tourne <matthieu@cloudflare.com> - --- small overlay over shdict, smart cache load mechanism - -local M = {} - -local resty_lock = require("resty.lock") - -local DEBUG = false - --- defaults in secs -local DEFAULT_POSITIVE_TTL = 10 -- cache for, successful lookup -local DEFAULT_NEGATIVE_TTL = 2 -- cache for, failed lookup -local DEFAULT_ACTUALIZE_TTL = 2 -- stale data, actualize data for - --- default lock options, in secs -local function _get_default_lock_options() - return { - exptime = 1, -- max wait if failing to call unlock() - timeout = 0.5, -- max waiting time of lock() - max_step = 0.1, -- max sleeping interval - } -end - -local function prequire(m) - local ok, err_or_module = pcall(require, m) - if not ok then - return nil, err_or_module - end - return err_or_module -end - -local conf = prequire("conf") -if conf then - DEFAULT_NEGATIVE_TTL = conf.DEFAULT_NEGATIVE_TTL or DEFAULT_NEGATIVE_TTL - DEFAULT_ACTUALIZE_TTL = conf.DEFAULT_ACTUALIZE_TTL or DEFAULT_ACTUALIZE_TTL -end - -local band = bit.band -local bor = bit.bor -local st_format = string.format - --- there are only really 5 states total - -- is_stale is_neg is_from_cache -local MISS_STATE = 0 -- 0 0 0 -local HIT_POSITIVE_STATE = 1 -- 0 0 1 -local HIT_NEGATIVE_STATE = 3 -- 0 1 1 -local STALE_POSITIVE_STATE = 5 -- 1 0 1 - --- stale negative doesn't really make sense, use HIT_NEGATIVE instead --- local STALE_NEGATIVE_STATE = 7 -- 1 1 1 - --- xor to set -local NEGATIVE_FLAG = 2 -local STALE_FLAG = 4 - -local STATES = { - [MISS_STATE] = 'MISS', - [HIT_POSITIVE_STATE] = 'HIT', - [HIT_NEGATIVE_STATE] = 'HIT_NEGATIVE', - [STALE_POSITIVE_STATE] = 'STALE', - -- [STALE_NEGATIVE_STATE] = 'STALE_NEGATIVE', -} - -local function get_status(flags) - return STATES[flags] or st_format('UNDEF (0x%x)', flags) -end - -local EMPTY_DATA = '_EMPTY_' - --- install debug functions -if DEBUG then - local resty_lock_lock = resty_lock.lock - - resty_lock.lock = function (...) - local _, key = unpack({...}) - print("lock key: ", tostring(key)) - return resty_lock_lock(...) - end - - local resty_lock_unlock = resty_lock.unlock - - resty_lock.unlock = function (...) - print("unlock") - return resty_lock_unlock(...) - end -end - - --- store the object in the context --- useful for debugging and tracking cache status -local function _store_object(self, name) - if DEBUG then - print('storing shcache: ', name, ' into ngx.ctx') - end - - local ngx_ctx = ngx.ctx - - if not ngx_ctx.shcache then - ngx_ctx.shcache = {} - end - ngx_ctx.shcache[name] = self -end - -local obj_mt = { - __index = M, -} - --- default function for callbacks.encode / decode. -local function _identity(data) - return data -end - --- shdict: ngx.shared.DICT, created by the lua_shared_dict directive --- callbacks: see shcache state machine for user defined functions --- * callbacks.external_lookup is required --- * callbacks.encode : optional encoding before saving to shmem --- * callbacks.decode : optional decoding when retreiving from shmem --- opts: --- * opts.positive_ttl : save a valid external loookup for, in seconds --- * opts.positive_ttl : save a invalid loookup for, in seconds --- * opts.actualize_ttl : re-actualize a stale record for, in seconds --- * opts.lock_options : set option to lock see : http://github.com/agentzh/lua-resty-lock --- for more details. --- * opts.locks_shdict : specificy the name of the shdict containing the locks --- (useful if you might have locks key collisions) --- uses "locks" by default. --- * opts.name : if shcache object is named, it will automatically --- register itself in ngx.ctx.shcache (useful for logging). -local function new(self, shdict, callbacks, opts) - if not shdict then - return nil, "shdict does not exist" - end - - -- check that callbacks.external_lookup is set - if not callbacks or not callbacks.external_lookup then - return nil, "no external_lookup function defined" - end - - if not callbacks.encode then - callbacks.encode = _identity - end - - if not callbacks.decode then - callbacks.decode = _identity - end - - local opts = opts or {} - - -- merge default lock options with the ones passed to new() - local lock_options = _get_default_lock_options() - if opts.lock_options then - for k, v in pairs(opts.lock_options) do - lock_options[k] = v - end - end - - local name = opts.name - - local obj = { - shdict = shdict, - callbacks = callbacks, - - positive_ttl = opts.positive_ttl or DEFAULT_POSITIVE_TTL, - negative_ttl = opts.negative_ttl or DEFAULT_NEGATIVE_TTL, - - -- ttl to actualize stale data to - actualize_ttl = opts.actualize_ttl or DEFAULT_ACTUALIZE_TTL, - - lock_options = lock_options, - - locks_shdict = opts.lock_shdict or "locks", - - -- STATUS -- - - from_cache = false, - cache_status = 'UNDEF', - cache_state = MISS_STATE, - lock_status = 'NO_LOCK', - - -- shdict:set() pushed out another value - forcible_set = false, - - -- cache hit on second attempt (post lock) - hit2 = false, - - name = name, - } - - local locks = ngx.shared[obj.locks_shdict] - - -- check for existence, locks is not directly used - if not locks then - ngx.log(ngx.CRIT, 'shared mem locks is missing.\n', - '## add to you lua conf: lua_shared_dict locks 5M; ##') - return nil - end - - local self = setmetatable(obj, obj_mt) - - -- if the shcache object is named - -- keep track of the object in the context - -- (useful for gathering stats at log phase) - if name then - _store_object(self, name) - end - - return self -end -M.new = new - --- acquire a lock -local function _get_lock(self) - local lock = self.lock - if not lock then - lock = resty_lock:new(self.locks_shdict, self.lock_options) - self.lock = lock - end - return lock -end - --- remove the lock if there is any -local function _unlock(self) - local lock = self.lock - if lock then - local ok, err = lock:unlock() - if not ok then - ngx.log(ngx.ERR, "failed to unlock :" , err) - end - self.lock = nil - end -end - -local function _return(self, data, flags) - -- make sure we remove the locks if any before returning data - _unlock(self) - - -- set cache status - local cache_status = get_status(self.cache_state) - - if cache_status == 'MISS' and not data then - cache_status = 'NO_DATA' - end - - self.cache_status = cache_status - - return data, self.from_cache -end - -local function _set(self, ...) - if DEBUG then - local key, data, ttl, flags = unpack({...}) - print("saving key: ", key, ", for: ", ttl) - end - - local ok, err, forcible = self.shdict:set(...) - - self.forcible_set = forcible - - if not ok then - local key, data, ttl, flags = unpack({...}) - ngx.log(ngx.ERR, 'failed to set key: ', key, ', err: ', err) - end - - return ok -end - --- check if the data returned by :get() is considered empty -local function _is_empty(data, flags) - return flags and band(flags, NEGATIVE_FLAG) and data == EMPTY_DATA -end - --- save positive, encode the data if needed before :set() -local function _save_positive(self, key, data) - if DEBUG then - print("key: ", key, ". save positive, ttl: ", self.positive_ttl) - end - data = self.callbacks.encode(data) - return _set(self, key, data, self.positive_ttl, HIT_POSITIVE_STATE) -end - --- save negative, no encoding required (no data actually saved) -local function _save_negative(self, key) - if DEBUG then - print("key: ", key, ". save negative, ttl: ", self.negative_ttl) - end - return _set(self, key, EMPTY_DATA, self.negative_ttl, HIT_NEGATIVE_STATE) -end - --- save actualize, will boost a stale record to a live one -local function _save_actualize(self, key, data, flags) - local new_flags = bor(flags, STALE_FLAG) - - if DEBUG then - print("key: ", key, ". save actualize, ttl: ", self.actualize_ttl, - ". new state: ", get_status(new_flags)) - end - - _set(self, key, data, self.actualize_ttl, new_flags) - return new_flags -end - -local function _process_cached_data(self, data, flags) - if DEBUG then - print("data: ", data, st_format(", flags: %x", flags)) - end - - self.cache_state = flags - self.from_cache = true - - if _is_empty(data, flags) then - -- empty cached data - return nil - else - return self.callbacks.decode(data) - end -end - --- wrapper to get data from the shdict -local function _get(self, key) - -- always call get_stale() as it does not free element - -- like get does on each call - local data, flags, stale = self.shdict:get_stale(key) - - if data and stale then - if DEBUG then - print("found stale data for key : ", key) - end - - self.stale_data = { data, flags } - - return nil, nil - end - - return data, flags -end - -local function _get_stale(self) - local stale_data = self.stale_data - if stale_data then - return unpack(stale_data) - end - - return nil, nil -end - -local function load(self, key) - -- start: check for existing cache - local data, flags = _get(self, key) - - -- hit: process_cache_hit - if data then - data = _process_cached_data(self, data, flags) - return _return(self, data) - end - - -- miss: set lock - - -- lock: set a lock before performing external lookup - local lock = _get_lock(self) - local elapsed, err = lock:lock(key) - - if not elapsed then - -- failed to acquire lock, still proceed normally to external_lookup - -- unlock() might fail. - ngx.log(ngx.ERR, "failed to acquire the lock: ", err) - self.lock_status = 'ERROR' - -- _unlock won't try to unlock() without a valid lock - self.lock = nil - else - -- lock acquired successfuly - - if elapsed > 0 then - - -- elapsed > 0 => waited lock (other thread might have :set() the data) - -- (more likely to get a HIT on cache_load 2) - self.lock_status = 'WAITED' - - else - - -- elapsed == 0 => immediate lock - -- it is less likely to get a HIT on cache_load 2 - -- but still perform it (race condition cases) - self.lock_status = 'IMMEDIATE' - end - - -- perform cache_load 2 - data, flags = _get(self, key) - if data then - -- hit2 : process cache hit - - self.hit2 = true - - -- unlock before de-serializing cached data - _unlock(self) - data = _process_cached_data(self, data, flags) - return _return(self, data) - end - - -- continue to external lookup - end - - -- perform external lookup - data, err = self.callbacks.external_lookup() - - if data then - -- succ: save positive and return the data - - _save_positive(self, key, data) - return _return(self, data) - else - ngx.log(ngx.WARN, 'external lookup failed: ', err) - end - - -- external lookup failed - -- attempt to load stale data - data, flags = _get_stale(self) - if data and not _is_empty(data, flags) then - -- hit_stale + valid (positive) data - - flags = _save_actualize(self, key, data, flags) - -- unlock before de-serializing data - _unlock(self) - data = _process_cached_data(self, data, flags) - return _return(self, data) - end - - if DEBUG and data then - -- there is data, but it failed _is_empty() => stale negative data - print('STALE_NEGATIVE data => cache as a new HIT_NEGATIVE') - end - - -- nothing has worked, save negative and return empty - _save_negative(self, key) - return _return(self, nil) -end -M.load = load - -return M
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